document_title: Trolls (film)

question_text: who plays princess poppy in the movie trolls

text: Trolls (film)

text: Plot[edit]

text: The Trolls are small creatures who live in an almost perpetual state of happiness, singing, dancing and hugging all day. However, they are discovered by the Bergens, large miserable creatures, who can feel happy only after eating a Troll. The Bergens imprison the trolls and eat them every year on a special occasion, called Trollstice. The Trolls, led by their king, King Peppy, with his baby daughter, Princess Poppy, escape through underground tunnels on the day of Trollstice, when Prince Gristle Jr. was going to eat his first Troll. Enraged, Gristle Jr.’s father King Gristle Sr. banishes his Chef who was in charge of the Trollstice preparation.

text: 20 years later, (at the age of 20) Poppy throws a big party to celebrate the Trolls' escape, despite the fears and warnings of the gray troll, Branch, that loud parties will attract the Bergens. A Zen troll named Creek arrives and tells Branch to start being happy instead of being grumpy; Branch refuses. At the party, Branch's fears come true, when Chef sees the fireworks and kidnaps Guy Diamond, Biggie with Mr. Dinkles, Fuzzbert, Smidge, Satin with Chenille, D.J. Suki, Cooper, and Creek (which Poppy tried to rescue). Chef, then takes the kidnapped Trolls back to Bergen Town, while secretly plotting to overthrow its monarchy in revenge for her banishment.

text: Alone inside the bunker, Branch looks at a bunch of homemade party invitations, indicating that he appreciates Poppy’s offers of friendship and internally would like to have fun with the rest of the trolls. Meanwhile, Poppy goes on a rescue mission alone, as no other troll is willing to venture to Bergen Town, including Branch. But later on, when Poppy gets into trouble, she is saved by Branch, who thinks she will not make it if she goes alone.

text: Once inside the Bergen king's castle, Poppy and Branch witness Creek apparently get eaten by Gristle Jr. (who is now king), but Poppy remains hopeful that Creek survived. Poppy and Branch find the rest of the captured Trolls being guarded by a scullery maid named Bridget. Poppy discovers that Bridget is secretly in love with King Gristle Jr. and offers to help her get a date with the king while trying to confirm if Creek is alive.

text: While setting Bridget up for the date, Branch refuses to sing and triggers an argument with Poppy, revealing that, as a child, his grandmother was captured and got killed while trying to save him, because his singing compromised his location to Chef. Branch's guilt and shame over his grandmother's death caused his color to turn from blue to gray.

text: After Poppy comforts him with a hug, Branch decides to help Bridget and the trolls, though he still refuses to sing. Bridget, disguised under the name of 'Lady Glitter Sparkles' gets her date with Gristle Jr. at a roller rink and arcade restaurant and Gristle Jr. asks her to be his "plus one" at Trollstice. Poppy notices Creek being held captive inside the jewel adorning the king's mantle.

text: Having helped Bridget, the Trolls attempt to rescue Creek from Gristle's room and steal his jewel but discover that it is empty. The Trolls are then captured by Chef and are shocked to discover that Creek sold them out to the Bergens to spare himself from being eaten. Creek lures out every troll from Troll village and they are captured by Chef and the other Bergen cooks. With all the Trolls captured and soon to be eaten, a heartbroken Poppy becomes sad after she had been betrayed by her friend, loses hope as she and all the other Trolls turn gray.

text: Branch sings “True Colors” for the princess to cheer her up, and also confesses his affection for her. Poppy, after regaining her colors, returns Branch's feelings, and they both end up restoring all the trolls' colors including Branch's. Bridget saves the trolls, willing to sacrifice herself. Poppy wishes to return the favor, and with Branch and her friends, shows the Bergens that Bridget was Lady Glitter Sparkles and that they too, can find happiness within themselves.

text: Chef refuses to accept the peace and tries to kill the Trolls, but is knocked into a serving cart that is sent rolling out of Bergen Town. Chef is set on fire with Creek, who was still in her pouch. Both species celebrate, bringing new life to the town and renewing the life of the troll tree. Poppy is then declared queen of the Trolls, and Poppy and Branch share a hug.

text: In a mid-credits scene, Chef and Creek's cart stops rolling. Chef prepares to eat Creek herself, but they soon find out they are on top of a monster, who opens his mouth and eats them.

text: Cast[edit]

text:
Anna Kendrick as Poppy, the princess and later queen of the Trolls
Iris Dohrn voices a baby Poppy.
Justin Timberlake as Branch, a paranoid, disgruntled Troll survivalist
Liam Henry voices a younger Branch.
Zooey Deschanel as Bridget, a kind-hearted Bergen who works as a scullery maid to Chef and has feelings for Gristle.[11]
Christopher Mintz-Plasse as Prince Gristle, the prince (later king) of the Bergens. He is Bridget's love interest.[11]
Christine Baranski as Chef, a mean-spirited Bergen chef who is in charge of Troll preparation.[11]
Russell Brand as Creek, a Troll with a positive personality and zen-like wisdom later revealed to be a coward and double-crosser willing to sell out all the Trolls just so he won't be eaten.[11][12]
Gwen Stefani as DJ Suki, the Trolls' resident disc jockey.[11][13]
James Corden as Biggie, a chubby, friendly Troll.[11][14]
Jeffrey Tambor as King Peppy, the king of the Trolls and Poppy's father.[11]
Ron Funches as Cooper, a giraffe-like Troll that walks on all fours.[11][15]
Icona Pop as Satin and Chenille, twin trolls who are joined by their hair and love fashion.[11][16]
Kunal Nayyar as Guy Diamond, a glittery silver Troll with a highly Auto-Tuned voice who is always naked.[11][17]
John Cleese as King Gristle Sr., Gristle's father and the ruler of the Bergens at the start of the film.[11]
Walt Dohrn as Mr. Dinkles, Biggie's pet worm.[11]
Dohrn also voices Smidge, Fuzzbert, Cloud Guy, Tunnel Troll and Wedgie Bergen #2.
GloZell as Grandma Rosiepuff, an elderly Troll and Branch's late grandmother who was taken by a Bergen while saving Branch.[18] In the UK version, newsreader Susanna Reid voices the character and in the Australian version, Dami Im voices the character.[19]
Meg DeAngelis as Moxie Dewdrop, a dancing Troll.[18] Noodlerella voices the character in the UK version.
Ricky Dillon as Aspen Heitz, a Troll skitterboarder.[18]
Kandee Johnson as Mandy Sparkledust, a Troll who designs and repairs all the treasures of Troll Town.[18]
Quvenzhané Wallis as Harper, a Troll artist who paints with her hair.[11]
Mike Mitchell as Darius, Vinny the Phone, Captain Starfunkle, Spider, Wedgie Bergen #1, Chad, Card
Grace Helbig as Cookie Sugarloaf, one of the trolls. Carrie Hope Fletcher voices the character in the UK version.[20]
Curtis Stone as Todd, a royal guard that works for the Bergen Royal Family.
Rhys Darby as Bibbly, a Bergen shopkeeper of the Bib Store.

text: Production[edit]

text: DreamWorks announced plans for a film based on the Troll toyline as early as 2010. This version was to be written by Adam Wilson and his wife Melanie.[21] By 2012, Chloë Grace Moretz had already been cast in the female lead role and Jason Schwartzman was reported to have been offered the male lead.[22] In September 2012, 20th Century Fox and DreamWorks Animation announced that the film with the working title Trolls would be released on June 5, 2015, with Anand Tucker set to direct the film, written by Wallace Wolodarsky and Maya Forbes.[1]

text: By April 2013, DreamWorks Animation had acquired the intellectual property for the Trolls franchise from the Dam Family and Dam Things. Having "big plans for the franchise," DreamWorks Animation became the exclusive worldwide licensor of the merchandise rights, except for Scandinavia, where Dam Things remains the licensor.[23] In May 2013, the film was pushed back for a year to November 4, 2016.[24] The same month, DreamWorks Animation announced that Mike Mitchell and Erica Rivinoja has been hired as a director and screenplay writer to "reimagine" the film as a musical comedy, which will present the origin of the Trolls' colorful hair.[25] On June 16, 2014, Anna Kendrick joined the cast to voice Poppy, a princess.[26] On September 15, 2015, Deadline Hollywood reported that Justin Timberlake will voice a character named Branch.[9] Timberlake previously worked with DreamWorks Animation as the voice of Arthur "Artie" Pendragon in Shrek the Third in 2007. The full cast announced their respective roles via announcements on Twitter on January 6, 2016.[27]

text: Music[edit]

text: Justin Timberlake served as an executive producer for the film's music and released the original song "Can't Stop the Feeling!" on May 6, 2016.[28] The song reached No. 1 in the official charts of 17 countries, including the United States and Canada. Timberlake along with the film cast, with guest appearances from Earth, Wind & Fire and Ariana Grande, contributed to the soundtrack.[29] The soundtrack album was certified Platinum by the Recording Industry Association of America[30] and the Australian Recording Industry Association.[31]

text: Release[edit]

text: The film's opening premiere opened at the BFI London Film Festival Event on October 8, 2016 as a special BFI presentation, and was theatrically released on November 4, 2016, in the United States by 20th Century Fox.

text: Home media[edit]

text: Trolls was released on Digital HD on January 24, 2017, and on DVD and Blu-ray on February 7, 2017.[32] The film topped the home video sales chart for two consecutive weeks.[33][34]

text: Reception[edit]

text: Box office[edit]

text: Trolls grossed $153.7 million in the US and Canada and $193.2 million in other countries for a worldwide total of $346.8 million, against a budget of $125 million.[6]

text: In the United States and Canada, Trolls was released alongside the releases of Doctor Strange and Hacksaw Ridge, and was projected to gross $35–40 million from 4,060 theaters in its opening weekend.[35] On its first day, the film grossed $12.3 million (including $900,000 made from Thursday night previews). It went on to open to $46.5 million, finishing second at the box office behind Doctor Strange.[36]

text: Critical response[edit]

text: On review aggregator website Rotten Tomatoes, the film has an approval rating of 74% based on 148 reviews; the average rating is 6.2/10. The site's critical consensus reads, "Trolls brings its instantly recognizable characters to the big screen in a colorful adventure that, while geared toward the younger set, isn't without rewards for parents."[37] On Metacritic, which assigns a normalized rating, the film has a score of 56 out of 100, based on 32 critics, indicating "mixed or average reviews".[38] Audiences polled by CinemaScore gave the film an average grade of "A" on an A+ to F scale,[39] while PostTrak reported filmgoers gave it an 80% overall positive score.[36]

text: Lindsey Bahr of Associated Press gave the film a positive review and said, "Ultimately, the 'get happy' moral of the story, while trite compared to something like Inside Out, is sufficiently sweet enough for its audience. Did you expect more from a piece of candy?"[40] Bill Zwecker of Chicago Sun-Times gave the film three-and-a-half stars out of four and said, "You simply will walk out — or perhaps dance out — of the theater feeling very happy yourself."[41] Andy Webster of The New York Times said, "Exuberant, busy and sometimes funny, DreamWorks Animation's Trolls is determined to amuse."[42]

text: The Hollywood Reporter called the film "an admittedly vibrant-looking but awfully recognizable animated musical comedy concoction."[3] Alonso Duralde of TheWrap said the film "combines the barely-there characterization and irritating cutesiness of The Smurfs with the hideous character design and awful pop covers of Strange Magic."[43] Betsy Bozdech of Common Sense Media gave the movie 4 stars. She said, "Make no mistake: Kids are going to love this movie. Trolls is cute, it's colorful, it has tons of catchy songs, and the messages are positive and easy to understand (happiness is inside everyone, if you know where/how to find it, and you shouldn't have to change who you are to get someone to like you)."[44]

text: Accolades[edit]

text:
List of awards and nominations

Award

Date of ceremony

Category

Recipient(s)

Result

Ref(s)

Academy Awards

February 26, 2017

Best Original Song

"Can't Stop the Feeling!" – Max Martin, Shellback and Justin Timberlake

Nominated

[45][46]

American Music Awards

November 19, 2017

Top Soundtrack

Trolls: Original Motion Picture Soundtrack

Nominated

[47]

Annie Awards

February 4, 2017

Outstanding Achievement, Character Design in an Animated Feature Production

Tim Lamb and Craig Kellman

Nominated

[48]

Outstanding Achievement, Production Design in an Animated Feature Production

Kendal Cronkhite and Tim Lamb

Nominated

Outstanding Achievement, Storyboarding in an Animated Feature Production

Claire Morrissey

Nominated

Outstanding Achievement, Voice Acting in an Animated Feature Production

Zooey Deschanel

Nominated

Billboard Music Awards

May 21, 2017

Top Soundtrack/Cast Album

Trolls: Original Motion Picture Soundtrack

Nominated

[49]

Critics' Choice Awards

December 11, 2016

Best Animated Feature

Trolls

Nominated

[50]

Best Song

"Can't Stop the Feeling!" – Max Martin, Shellback and Justin Timberlake

Nominated

Golden Globe Awards

January 8, 2017

Best Original Song

Nominated

[51]

Grammy Awards

February 12, 2017

Best Song Written for Visual Media

Won

[52]

Guild of Music Supervisors Awards

February 16, 2017

Best Song/Recording Created for a Film

Nominated

[53]

Hollywood Film Awards

November 6, 2016

Hollywood Song Award

"Can't Stop the Feeling!" by Justin Timberlake

Won

[54]

Hollywood Music in Media Awards

November 17, 2016

Best Song Written for an Animated Film

"Can't Stop the Feeling!" – Max Martin, Shellback and Justin Timberlake

Won

[55][56]

Best Soundtrack From a Movie

Trolls: Original Motion Picture Soundtrack

Nominated

Outstanding Music Supervision – Film

Justin Timberlake

Nominated

iHeartRadio Music Awards

March 5, 2017

Best Song from a Movie

"Can't Stop the Feeling!" by Justin Timberlake

Nominated

[57]

Nickelodeon Kids' Choice Awards

March 11, 2017

Favorite Animated Movie

Trolls

Nominated

[58]

Favorite Voice From an Animated Movie

Justin Timberlake and Anna Kendrick

Nominated

Favorite Frenemies

Nominated

Favorite Soundtrack

Trolls: Original Motion Picture Soundtrack

Nominated

Satellite Awards

February 19, 2017

Best Animated or Mixed Media Feature

Trolls

Nominated

[59]

Best Original Song

"Can't Stop the Feeling!" – Max Martin, Shellback and Justin Timberlake

Nominated

Saturn Awards

June 28, 2017

Best Animated Film

Trolls

Nominated

[60]

St. Louis Gateway Film Critics Association

December 18, 2016

Best Soundtrack

Nominated

[61]

Teen Choice Awards

July 31, 2016

Choice AnTEENcipated Movie

Nominated

[62]

Choice Music: Song from a Movie or TV Show

"Can't Stop the Feeling!" by Justin Timberlake

Nominated

World Soundtrack Awards

October 18, 2017

Best Original Song written directly for a Film

"Can't Stop the Feeling!" – Max Martin, Shellback and Justin Timberlake

Nominated

[63]

text: Regarding music award shows, only film-related categories are included on this list.

text: Franchise[edit]

text: Trolls World Tour (2020 sequel)[edit]

text: On February 28, 2017, Universal Pictures, the studio's new distributor and parent company since 2016, and DreamWorks Animation announced that a sequel titled Trolls 2 would be released on April 10, 2020, with Kendrick and Timberlake reprising their roles of Poppy and Branch.[64] On October 4, 2017, the release date for the sequel was moved up to February 14, 2020, as Fast & Furious 9 took its original April 10, 2020 slot. Along with the new release date, it was announced that Dohrn will be returning to direct and Shay will return to produce the sequel. On December 6, 2017, the film was pushed back to an April 17, 2020 release.[65]

text: In May 2018, it was confirmed that Sam Rockwell, Chance the Rapper, Anthony Ramos, Karan Soni, Flula Borg, and Jamie Dornan joined the cast. Corden, Icona Pop, Funches, and Nayyar will also reprise their roles.[66]

text: A new title for the sequel, Trolls World Tour, was announced in June 2018.[67]

text: Television special[edit]

text: Trolls Holiday is a half-hour[68] television special that aired on November 24, 2017 on NBC.[69] Set after the film, Poppy realizes that the Bergens have no holidays to celebrate. She enlists Branch and their friends (the Snack Pack) to show their best friend Bridget and other Bergens the importance of holidays. Most of the original cast (including Kendrick, Timberlake, Deschanel, Mintz-Plasse, Corden, Funches, Nayyar and Dohrn) all reprise their roles from the film. The likely-Christmas Special is also directed by Crawford and written by Josh Bycel & Jonathan Fener with music by Jeff Morrow.[68] Its soundtrack album that features seven songs was released on October 27, 2017.[70] It is now available on Netflix and on DVD by Universal Pictures Home Entertainment. The bonus features of the DVD also include one episode of Spirit Riding Free and two of Home: Adventures with Tip & Oh.

text: Animated series[edit]

text: A 26-episode animated series based on the film, entitled Trolls: The Beat Goes On! that airs on Netflix premiered on January 19, 2018.[71][72] The show stars Amanda Leighton as Poppy, Skylar Astin as Branch, and Funches who is reprising his role as Cooper.[73]

text: Notes[edit]

text: ^  In 2018, the film's distribution rights were transferred to Universal Pictures via its acquisition of DreamWorks Animation.

tag: ol


document_title: Egyptian pyramids

question_text: when was the last pyramid in egypt built

root

text: Egyptian pyramids

text: Historical development

text: By the time of the Early Dynastic Period, those with sufficient means were buried in bench-like structures known as mastabas.[8][9]

tag: p

text: The second historically-documented Egyptian pyramid is attributed to the architect Imhotep, who planned what Egyptologists believe to be a tomb for the pharaoh Djoser. Imhotep is credited with being the first to conceive the notion of stacking mastabas on top of each other, creating an edifice composed of a number of "steps" that decreased in size towards its apex. The result was the Pyramid of Djoser, which was designed to serve as a gigantic stairway by which the soul of the deceased pharaoh could ascend to the heavens. Such was the importance of Imhotep's achievement that he was deified by later Egyptians.[10]

text: The most prolific pyramid-building phase coincided with the greatest degree of absolutist rule. It was during this time that the most famous pyramids, the Giza pyramid complex, were built. Over time, as authority became less centralized, the ability and willingness to harness the resources required for construction on a massive scale decreased, and later pyramids were smaller, less well-built and often hastily constructed.

text: Long after the end of Egypt's own pyramid-building period, a burst of pyramid-building occurred in what is present-day Sudan, after much of Egypt came under the rule of the kings of Napata. While Napatan rule was brief, ending in 661 BC, Egyptian culture made an indelible impression, and during the later Kingdom of Meroë (approximately in the period between 300 BCE – 300 CE), this flowered into a full-blown pyramid-building revival, which saw more than two hundred Egyptian-inspired indigenous royal pyramid-tombs constructed in the vicinity of the kingdom's capital cities.

text: Al-Aziz Uthman (1171–1198) tried to destroy the Giza pyramid complex. He gave up after damaging the Pyramid of Menkaure because the task proved too huge.[11]

text: Pyramid symbolism

text: The shape of Egyptian pyramids is thought to represent the primordial mound from which the Egyptians believed the earth was created. The shape of a pyramid is thought to be representative of the descending rays of the sun, and most pyramids were faced with polished, highly reflective white limestone, in order to give them a brilliant appearance when viewed from a distance. Pyramids were often also named in ways that referred to solar luminescence. For example, the formal name of the Bent Pyramid at Dahshur was The Southern Shining Pyramid, and that of Senwosret at el-Lahun was Senwosret is Shining.

text: While it is generally agreed that pyramids were burial monuments, there is continued disagreement on the particular theological principles that might have given rise to them. One suggestion is that they were designed as a type of "resurrection machine."[12]

text: The Egyptians believed the dark area of the night sky around which the stars appear to revolve was the physical gateway into the heavens. One of the narrow shafts that extend from the main burial chamber through the entire body of the Great Pyramid points directly towards the center of this part of the sky. This suggests the pyramid may have been designed to serve as a means to magically launch the deceased pharaoh's soul directly into the abode of the gods.[12]

text: All Egyptian pyramids were built on the west bank of the Nile, which, as the site of the setting sun, was associated with the realm of the dead in Egyptian mythology.[13]

text: Number and location of pyramids

text: In 1842, Karl Richard Lepsius produced the first modern list of pyramids – see Lepsius list of pyramids – in which he counted 67. A great many more have since been discovered. As of November 2008, 118 Egyptian pyramids have been identified.[3]

text: The location of Pyramid 29, which Lepsius called the "Headless Pyramid", was lost for a second time when the structure was buried by desert sands subsequent to Lepsius' survey. It was found again only during an archaeological dig conducted in 2008.[14]

text: Many pyramids are in a poor state of preservation or buried by desert sands. If visible at all, they may appear as little more than mounds of rubble. As a consequence, archaeologists are continuing to identify and study previously unknown pyramid structures.

text: The most recent pyramid to be discovered was that of Sesheshet at Saqqara, mother of the Sixth Dynasty pharaoh Teti. The discovery was announced by Zahi Hawass, Secretary General of the Egyptian Supreme Council of Antiquities, on 11 November 2008.[4][15]

text: All of Egypt's pyramids, except the small Third Dynasty pyramid of Zawyet el-Amwat (or Zawyet el-Mayitin), are sited on the west bank of the Nile, and most are grouped together in a number of pyramid fields. The most important of these are listed geographically, from north to south, below.

text: Abu Rawash

text: Abu Rawash is the site of Egypt's most northerly pyramid (other than the ruins of Lepsius pyramid number one)[5]— the mostly ruined Pyramid of Djedefre, son and successor of Khufu. Originally it was thought that this pyramid had never been completed, but the current archaeological consensus is that not only was it completed, but that it was originally about the same size as the Pyramid of Menkaure, which would have placed it among the half-dozen or so largest pyramids in Egypt.

text: Its location adjacent to a major crossroads made it an easy source of stone. Quarrying – which began in Roman times – has left little apart from about 15 courses of stone superimposed upon the natural hillock that formed part of the pyramid's core. A small adjacent satellite pyramid is in a better state of preservation.

text: Giza

text: Giza is the location of the Pyramid of Khufu (also known as the "Great Pyramid" and the "Pyramid of Cheops"); the somewhat smaller Pyramid of Khafre (or Kephren); the relatively modest-sized Pyramid of Menkaure (or Mykerinus), along with a number of smaller satellite edifices known as "Queen's pyramids"; and the Great Sphinx of Giza.

text: Of the three, only Khafre's pyramid retains part of its original polished limestone casing, near its apex. This pyramid appears larger than the adjacent Khufu pyramid by virtue of its more elevated location, and the steeper angle of inclination of its construction – it is, in fact, smaller in both height and volume.

text: The Giza pyramid complex has been a popular tourist destination since antiquity, and was popularized in Hellenistic times when the Great Pyramid was listed by Antipater of Sidon as one of the Seven Wonders of the Ancient World. Today it is the only one of those wonders still in existence.

text: Zawyet el-Aryan

text: This site, halfway between Giza and Abu Sir, is the location for two unfinished Old Kingdom pyramids. The northern structure's owner is believed to be pharaoh Nebka, while the southern structure, known as the Layer Pyramid, may be attributable to the Third Dynasty pharaoh Khaba, a close successor of Sekhemkhet. If this attribution is correct, Khaba's short reign could explain the seemingly unfinished state of this step pyramid. Today it stands around 17 m (56 ft) high; had it been completed, it is likely to have exceeded 40 m (130 ft).

text: Abu Sir

text: There are a total of fourteen pyramids at this site, which served as the main royal necropolis during the Fifth Dynasty. The quality of construction of the Abu Sir pyramids is inferior to those of the Fourth Dynasty – perhaps signaling a decrease in royal power or a less vibrant economy. They are smaller than their predecessors, and are built of low-quality local limestone.

text: The three major pyramids are those of Niuserre, which is also the best preserved, Neferirkare Kakai and Sahure. The site is also home to the incomplete Pyramid of Neferefre. Most of the major pyramids at Abu Sir were built similar construction techniques, comprising a rubble core surrounded by steps of mud bricks with a limestone outer casing. The largest of these 5th-Dynasty pyramids, the Pyramid of Neferirkare Kakai, is believed to have been built originally as a step pyramid some 70 m (230 ft) high and then later transformed into a "true" pyramid by having its steps filled in with loose masonry.

text: Saqqara

text: Major pyramids located here include the Pyramid of Djoser – generally identified as the world's oldest substantial monumental structure to be built of dressed stone – the Pyramid of Userkaf, the Pyramid of Teti and the Pyramid of Merikare, dating to the First Intermediate Period of Egypt. Also at Saqqara is the Pyramid of Unas, which retains a pyramid causeway that is one of the best-preserved in Egypt. Together with the pyramid of Userkaf, this pyramid was the subject of one of the earliest known restoration attempts, conducted by Khaemweset, a son of Ramesses II.[16] Saqqara is also the location of the incomplete step pyramid of Djoser's successor Sekhemkhet known as the Buried Pyramid. Archaeologists believe that had this pyramid been completed, it would have been larger than Djoser's.

text: South of the main pyramid field at Saqqara is a second collection of later, smaller pyramids, including those of Pepi I, Isesi, Merenre, Pepi II and Ibi. Most of these are in a poor state of preservation.

text: The Fourth Dynasty pharaoh Shepseskaf either did not share an interest in, or have the capacity to undertake pyramid construction like his predecessors. His tomb, which is also sited at south Saqqara, was instead built as an unusually large mastaba and offering temple complex. It is commonly known as the Mastabat al-Fir’aun.[17]

text: A previously unknown pyramid was discovered at north Saqqara in late 2008. Believed to be the tomb of Teti's mother, it currently stands approximately 5 m (16 ft) high, although the original height was closer to 14 m (46 ft).

text: Dahshur

text: This area is arguably the most important pyramid field in Egypt outside Giza and Saqqara, although until 1996 the site was inaccessible due to its location within a military base, and was relatively unknown outside archaeological circles.

text: The southern Pyramid of Sneferu, commonly known as the Bent Pyramid, is believed to be the first Egyptian pyramid intended by its builders to be a "true" smooth-sided pyramid from the outset; the earlier pyramid at Meidum had smooth sides in its finished state – but it was conceived and built as a step pyramid, before having its steps filled in and concealed beneath a smooth outer casing of dressed stone.

text: As a true smooth-sided structure, the Bent Pyramid was only a partial success – albeit a unique, visually imposing one; it is also the only major Egyptian pyramid to retain a significant proportion of its original smooth outer limestone casing intact. As such it serves as the best contemporary example of how the ancient Egyptians intended their pyramids to look.

text: Several kilometeres to the north of the Bent Pyramid is the last – and most successful – of the three pyramids constructed during the reign of Sneferu; the Red Pyramid is the world's first successfully completed smooth-sided pyramid. The structure is also the third largest pyramid in Egypt – after the pyramids of Khufu and Khafra at Giza.

text: Also at Dahshur is the pyramid known as the Pyramid of Amenemhat III, as well as a number of small, mostly ruined subsidiary pyramids.

text: Mazghuna

text: Located to the south of Dahshur, several mudbrick pyramids were built in this area in the late Middle Kingdom, perhaps for Amenemhat IV and Sobekneferu.

text: Lisht

text: Two major pyramids are known to have been built at Lisht – those of Amenemhat I and his son, Senusret I. The latter is surrounded by the ruins of ten smaller subsidiary pyramids. One of these subsidiary pyramids is known to be that of Amenemhat's cousin, Khaba II.[18] The site which is in the vicinity of the oasis of the Faiyum, midway between Dahshur and Meidum, and about 100 kilometres south of Cairo, is believed to be in the vicinity of the ancient city of Itjtawy (the precise location of which remains unknown), which served as the capital of Egypt during the Twelfth Dynasty.

text: Meidum

text: The pyramid at Meidum is one of three constructed during the reign of Sneferu, and is believed by some to have been started by that pharaoh's father and predecessor, Huni. However, that attribution is uncertain, as no record of Huni's name has been found at the site.

text: It was constructed as a step pyramid, and then later converted into the first "true" smooth-sided pyramid when the steps were filled in, and an outer casing added.

text: The pyramid suffered several catastrophic collapses in ancient and medieval times; medieval Arab writers described it as having seven steps – although today only the three uppermost of these remain, giving the structure its odd, tower-like appearance. The hill on which the pyramid is situated is not a natural landscape feature – it is the small mountain of debris created when the lower courses and outer casing of the pyramid gave way.

text: Hawara

text: Amenemhat III was the last powerful ruler of the Twelfth Dynasty, and the pyramid he built at Hawarra, near the Faiyum, is believed to post-date the so-called "Black Pyramid" built by the same ruler at Dahshur. It is the Hawarra pyramid that is believed to have been Amenemhet's final resting place.

text: el-Lahun

text: The pyramid of Senusret II at el-Lahun is the southernmost royal-tomb pyramid structure in Egypt. Its builders reduced the amount of work necessary to construct it by ingeniously using as its foundation and core a 12-meter-high natural limestone hill.

text: El-Kurru

text: Piye, the first ruler of the Egyptian 25th dynasty, built a pyramid at El-Kurru. He was the first Egyptian pharaoh to be buried in a pyramid in centuries.

text: Nuri

text: Taharqa, a legitimate ruler and Pharaoh of Egypt, built his pyramid at Nuri. It was the largest in the area (North Sudan).

text: Construction dates

text: The following table lays out the chronology of the construction of most of the major pyramids mentioned here. Each pyramid is identified through the pharaoh who ordered it built, his approximate reign, and its location.

text:
Pyramid / Pharaoh
Reign
Field

Djoser
c. 2670 BC
Saqqara

Sneferu
c. 2612–2589 BC
Dashur

Sneferu
c. 2612–2589 BC
Meidum

Khufu
c. 2589–2566 BC
Giza

Djedefre
c. 2566–2558 BC
Abu Rawash

Khafre
c. 2558–2532 BC
Giza

Menkaure
c. 2532–2504 BC
Giza

Userkaf
c. 2494–2487 BC
Saqqara

Sahure
c. 2487–2477 BC
Abu Sir

Neferirkare Kakai
c. 2477–2467 BC
Abu Sir

Nyuserre Ini
c. 2416–2392 BC
Abu Sir

Amenemhat I
c. 1991–1962 BC
Lisht

Senusret I
c. 1971–1926 BC
Lisht

Senusret II
c. 1897–1878 BC
el-Lahun

Amenemhat III
c. 1860–1814 BC
Hawara

Khendjer
c. 1764–1759 BC
Saqqara

Piye
c. 721 BC
El-Kurru

Taharqa
c. 664 BC
Nuri

tag: table

text: Construction techniques

text: Constructing the pyramids involved moving huge quantities of stone. The quarried blocks were likely transported to the construction site by wooden sleds, with sand in front of the sled wetted to reduce friction. Droplets of water created bridges between the grains of sand, helping them stick together.[20]


document_title: State of the Union

question_text: when are state of the union addresses given

text: State of the Union

text: Ceremony[edit]

text: The practice arises from a duty given to the president in the Constitution of the United States:

text: He shall from time to time give to Congress information of the State of the Union and recommend to their Consideration such measures as he shall judge necessary and expedient.

text: Although the language of this State of the Union Clause[5] of the Constitution is not specific, since the 1930s, the President makes this report annually in late January or early February. Between 1934 and 2013 the date has been as early as January 3,[6] and as late as February 12.[7]

text: While not required to deliver a speech, every president since Woodrow Wilson, with the notable exception of Herbert Hoover,[8] has made at least one State of the Union report as a speech delivered before a joint session of Congress. Before that time, most presidents delivered the State of the Union as a written report.[6]

text: Since Franklin Roosevelt, the State of the Union is given typically each January before a joint session of the United States Congress and is held in the House of Representatives chamber of the United States Capitol. Newly inaugurated presidents generally deliver an address to Congress in February of the first year of their term, but this speech is not officially considered to be a "State of the Union".[6]

text: What began as a communication between president and Congress has become a communication between the president and the people of the United States. Since the advent of radio, and then television, the speech has been broadcast live on most networks, preempting scheduled programming. To reach the largest audience, the speech, once given during the day, is now typically given in the evening, after 9pm ET (UTC-5).

text: History[edit]

text: George Washington delivered the first regular annual message before a joint session of Congress on January 8, 1790, in New York City, then the provisional U.S. capital. In 1801, Thomas Jefferson discontinued the practice of delivering the address in person, regarding it as too monarchical (similar to the Speech from the Throne). Instead, the address was written and then sent to Congress to be read by a clerk until 1913 when Woodrow Wilson re-established the practice despite some initial controversy. However, there have been exceptions to this rule. Presidents during the latter half of the 20th century[who?] have sent written State of the Union addresses. The last President to do this was Jimmy Carter in 1981, after his defeat by Ronald Reagan and days before his term ended.[9]

text: For many years, the speech was referred to as "the President's Annual Message to Congress".[10] The actual term "State of the Union" first emerged in 1934 when Franklin D. Roosevelt used the phrase, becoming its generally accepted name since 1947.[10]

text:
Franklin Delano Roosevelt

State of the Union (Four Freedoms) (January 6, 1941)

Franklin Delano Roosevelt's January 6, 1941 State of the Union Address introducing the theme of the Four Freedoms (starting at 32:02)

Problems playing this file? See media help.

text: Prior to 1934, the annual message was delivered at the end of the calendar year, in December. The ratification of the 20th Amendment on January 23, 1933, changed the opening of Congress from early March to early January, affecting the delivery of the annual message. Since 1934, the message or address has been delivered to Congress in January or February.

text: The Twentieth Amendment also established January 20 as the beginning of the presidential term. In years when a new president is inaugurated, the outgoing president may deliver a final State of the Union message, but none has done so since Jimmy Carter sent a written message in 1981. In 1953 and 1961, Congress received both a written State of the Union message from the outgoing president and a separate State of the Union speech by the incoming president. Since 1989, in recognition that the responsibility of reporting the State of the Union formally belongs to the president who held office during the past year, newly inaugurated Presidents have not officially called their first speech before Congress a "State of the Union" message.

text: In 1936, President Roosevelt set a precedent when he delivered the address at night. Only once before—when Woodrow Wilson asked Congress to order the U.S. into World War I—had a sitting president addressed Congress at night.[11]

text: Warren Harding's 1922 speech was the first to be broadcast on radio, albeit to a limited audience,[12] while Calvin Coolidge's 1923 speech was the first to be broadcast across the nation.[2] Harry S. Truman's 1947 address was the first to be broadcast on television. Lyndon B. Johnson's address in 1965 was the first delivered in the evening.[12] Three years later, in 1968, television networks in the United States, for the first time, imposed no time limit for their coverage of a State of the Union address. Delivered by Lyndon B. Johnson, this address was followed by extensive televised commentary by, among others, Daniel Patrick Moynihan and Milton Friedman.[13] Ronald Reagan's 1986 State of the Union Address is the only one to have been postponed. He had planned to deliver it on January 28, 1986 but postponed it for a week after learning of the Space Shuttle Challenger disaster and instead addressed the nation on the day's events.[14][15] Bill Clinton's 1997 address was the first broadcast available live on the World Wide Web.[16]

text: Delivery of the speech[edit]

text: A formal invitation is made by the Speaker of the House to the President several weeks before each State of the Union Address.[17][18]

text: Invitations[edit]

text: Every member of Congress can bring one guest to the State of the Union address. The President may invite up to 24 guests with the First Lady in her box. The Speaker of the House may invite up to 24 guests in the Speaker’s box. Seating for Congress on the main floor is by a first-in, first-served basis with no reservations. The Cabinet, Supreme Court justices, members of the Diplomatic Corps, and Joint Chiefs have reserved seating.

text: Protocol of entry into House chamber[edit]

text: By approximately 8:30 pm on the night of the address, the members of the House have gathered in their seats for the joint session.[19] Then, the Deputy Sergeant at Arms addresses the Speaker and loudly announces the Vice President and members of the Senate, who enter and take the seats assigned for them.[19]

text: The Speaker, and then the Vice President, specify the members of the House and Senate, respectively, who will escort the President into the House chamber.[19] The Deputy Sergeant at Arms addresses the Speaker again and loudly announces, in order, the Dean of the Diplomatic Corps, the Chief Justice of the United States and the Associate Justices, and the Cabinet, each of whom enters and takes their seats when called.[19] The justices take the seats nearest to the Speaker's rostrum and adjacent to the sections reserved for the Cabinet and the members of the Joint Chiefs of Staff.[20]

text: Just after 9 pm, as the President reaches the door to the chamber,[21] the House Sergeant at Arms stands just inside the doors, faces the Speaker, and waits until the President is ready to enter the chamber.[20] When the President is ready, the Sergeant at Arms always announces his entrance, loudly stating the phrase: "Mister Speaker, the President of the United States!"[21]

text: As applause and cheering begins, the President slowly walks toward the Speaker's rostrum, followed by members of his Congressional escort committee.[21] The President's approach is slowed by pausing to shake hands, hug, kiss, and autograph copies of his speech for Members of Congress.[20] After he takes his place at the House Clerk's desk,[21] he hands two manila envelopes, previously placed on the desk and containing copies of the speech, to the Speaker and Vice President.

text: After continuing applause from the attendees has diminished, the Speaker introduces the President to the Representatives and Senators, stating: "Members of Congress, I have the high privilege and distinct honor of presenting to you the President of the United States."[20][21] This leads to a further round of applause and, eventually, the beginning of the address by the President.[21]

text: At close of the ceremony, attendees leave on their own accord. The Sergeants at Arms guides the President out of the Chamber. Some politicians stay to shake hands with and congratulate the President on his way out.

text: Designated survivor and other logistics[edit]

text: Customarily, one cabinet member (the designated survivor) does not attend the speech, in order to provide continuity in the line of succession in the event that a catastrophe disables the President, the Vice President, and other succeeding officers gathered in the House chamber. Additionally, since the September 11 attacks in 2001, a few members of Congress have been asked to relocate to undisclosed locations for the duration of the speech to form a rump Congress in the event of a disaster.[22] Since 2003, each chamber of Congress has formally named a separate designated survivor.[23][24]

text: Both the Speaker and the Vice President sit at the Speaker's desk, behind the President for the duration of the speech. If either is unavailable, the next highest-ranking member of the respective house substitutes. Once the chamber settles down from the President's arrival, the Speaker officially presents the President to the joint session of Congress. The President then delivers the speech from the podium at the front of the House Chamber.

text: In the State of the Union the President traditionally outlines the administration's accomplishments over the previous year, as well as the agenda for the coming year, often in upbeat and optimistic terms.[25] Since the 1982 address, it has also become common for the President to honor special guests sitting in the gallery, such as American citizens or visiting heads of state. During that 1982 address, President Ronald Reagan acknowledged Lenny Skutnik for his act of heroism following the crash of Air Florida Flight 90.[26] Since then, the term "Lenny Skutniks" has been used to refer to individuals invited to sit in the gallery, and then cited by the President, during the State of the Union.[27][28]

text: State of the Union speeches usually last a little over an hour, partly because of the large amounts of applause that occur from the audience throughout. The applause is often political in tone, with many portions of the speech being applauded only by members of the President's own party. As non-political officeholders, members of the Supreme Court or the Joint Chiefs of Staff rarely applaud in order to retain the appearance of political impartiality. In recent years, the presiding officers of the House and the Senate, the Speaker and the Vice President, respectively, have departed from the neutrality expected of presiding officers of deliberative bodies, as they, too, stand and applaud in response to the remarks of the President with which they agree.

text: For the 2011 address, Senator Mark Udall of Colorado proposed a break in tradition wherein all members of Congress sit together regardless of party, as well as the avoiding of standing;[29] this was in response to the 2011 Tucson Shooting in which Representative Gabrielle Giffords was shot and wounded in an assassination attempt. This practice was also repeated during the 2012 address and every address after.[30]

text: Opposition response[edit]

text: Since 1966,[31] the speech has been followed on television by a response or rebuttal by a member of the major political party opposing the President's party. The response is typically broadcast from a studio with no audience. In 1970, the Democratic Party put together a TV program with their speech to reply to President Nixon, as well as a televised response to Nixon's written speech in 1973.[32] The same was done by Democrats for President Reagan's speeches in 1982 and 1985. The response is not always produced in a studio; in 1997, the Republicans for the first time delivered the response in front of high school students.[33] In 2004, the Democratic Party's response was also delivered in Spanish for the first time, by New Mexico Governor Bill Richardson.[34] In 2011, Minnesota Congresswoman Michele Bachmann also gave a televised response for the Tea Party Express, a first for a political movement.[35]

text: Significance[edit]

text: Although much of the pomp and ceremony behind the State of the Union address is governed by tradition rather than law, in modern times, the event is seen as one of the most important in the US political calendar. It is one of the few instances when all three branches of the US government are assembled under one roof: members of both houses of Congress constituting the legislature, the President's Cabinet constituting the executive, and the Chief Justice and Associate Justices of the Supreme Court constituting the judiciary. In addition, the military is represented by the Joint Chiefs of Staff, while foreign governments are represented by the Dean of the Diplomatic Corps. The address has also been used as an opportunity to honor the achievements of some ordinary Americans, who are typically invited by the President to sit with the First Lady.[28]

text: Local versions[edit]

text: Certain states have a similar annual address given by the governor. For most of them, it is called the State of the State address. In Iowa, it is called the Condition of the State Address; in Kentucky, Massachusetts, Pennsylvania, and Virginia, the speech is called the State of the Commonwealth address. The mayor of Washington, D.C. gives a State of the District address. American Samoa has a State of the Territory address given by the governor. Puerto Rico has a State Address given by the governor.

text: Some cities or counties also have an annual State of the City Address given by the mayor, county commissioner or board chair, including Sonoma County, California; Orlando, Florida; Cincinnati, Ohio; New Haven, Connecticut; Parma, Ohio; Detroit, Michigan; Seattle, Washington; Birmingham, Alabama; Boston, Massachusetts; Los Angeles, California; Buffalo, New York; Rochester, New York; San Antonio, Texas; McAllen, Texas; and San Diego, California. The Mayor of the Metropolitan Government of Nashville and Davidson County in Nashville, Tennessee gives a speech similar called the State of Metro Address. Some university presidents give a State of the University address at the beginning of every academic term.[36][37] Private companies usually have a "State of the Corporation" or "State of the Company" address given by the respective CEO.[38]

text: The State of the Union model has also been adopted by the European Union,[39] and in France since the presidency of Emmanuel Macron.

text: Historic speeches[edit]

text: This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (January 2018) (Learn how and when to remove this template message)

text:
President James Monroe first stated the Monroe Doctrine during his seventh annual State of the Union Address to Congress on December 2, 1823. It became a defining moment in the foreign policy of the United States and one of its longest-standing tenets, and would be invoked by many U.S. statesmen and several U.S. presidents, including Theodore Roosevelt, John F. Kennedy, and Ronald Reagan.
The Four Freedoms were goals first articulated by Franklin D. Roosevelt on January 6, 1941. In an address known as the Four Freedoms speech, he proposed four fundamental freedoms that people "everywhere in the world" ought to enjoy: freedom of speech and expression, freedom of worship, freedom from want, and freedom from fear.
During his State of the Union Address on January 11, 1944, FDR proposed the Second Bill of Rights. Roosevelt's argument was that the "political rights" guaranteed by the constitution and the Bill of Rights had "proved inadequate to assure us equality in the pursuit of happiness".
During his State of the Union address on January 8, 1964, Lyndon B. Johnson introduced legislation that would come to be known as the "War on Poverty". This legislation was proposed by Johnson in response to a national poverty rate of around nineteen percent. The speech led the United States Congress to pass the Economic Opportunity Act, which established the Office of Economic Opportunity (OEO) to administer the local application of federal funds targeted against poverty.
During his State of the Union address on January 15, 1975, Gerald R. Ford very bluntly stated that "the state of the Union is not good: Millions of Americans are out of work... We depend on others for essential energy. Some people question their Government's ability to make hard decisions and stick with them; they expect Washington politics as usual." Ford said he didn't "expect much, if any, applause. The American people want action, and it will take both the Congress and the President to give them what they want. Progress and solutions can be achieved, and they will be achieved."

tag: ul

text: In his 2002 State of the Union Address, President George W. Bush identified North Korea, Iran, and Iraq as representing significant threats to the United States. He said, "States like these and their terrorist allies constitute an axis of evil, arming to threaten the peace of the world". In this speech, he would outline the objectives for the War on Terror.

text: TV ratings[edit]

text: Television ratings for recent State of the Union Addresses were:[40][41][42]

text:
Date
President
Viewers,
millions

Households,
millions

Rating
Networks

1/30/2018
Donald Trump
45.551
32.168
26.9
ABC, CBS, FOX, NBC, ESTRELLA, TELEMUNDO, UNIVISION, CNN, FOX BUSINESS, FOXNC, MSNBC, PBS

2/28/2017
Donald Trump
47.741
33.857
28.7
ABC, CBS, FOX, NBC, UNIVISION, PBS, CNN, FOX BUSINESS, FOXNC, MSNBC, NBC UNIVERSO

1/12/2016
Barack Obama
31.334
23.040
19.6
ABC, AL JAZEERA AMERICA, AZTECA, CBS, CNN, FOX, FOX BUSINESS, FOXNC, GALAVISION, MSNBC, NBC, NBC UNIVERSO, UNIVISION**

1/20/2015
Barack Obama
31.710
23.137
19.9
ABC, AL JAZEERA AMERICA, AZTECA, CBS, CNN, FOX, FOX BUSINESS, FOXNC, GALAVISION, MSNBC, MUNDOFOX, NBC, UNIVISION**

1/28/2014
Barack Obama
33.299
23.949
20.7
CBS, ABC, NBC, FOX, AZTECA, FOX BUSINESS, FOXNC, CNN, MSNBC, CNBC, AL JAZEERA AMERICA, GALAVISION, MUN2, UNIVISION**

2/12/2013
Barack Obama
33.497
24.767
21.8
FOX, ABC, CBS, NBC, PBS, AZTECA, UNIVISION, MFX, CNBC, CNN, FOX BUSINESS, FOXNC, MSNBC, CURRENT, CENTRIC, GALAVISION

1/24/2012
Barack Obama
37.752
27.569
24.0
ABC, CBS, FOX, NBC, TELEMUNDO, TF, UNIVISION, CNBC, CNN, FOX BUSINESS, FOXNC, GALAVISION, MSNBC, MUN2

1/25/2011
Barack Obama
42.789
30.871
26.6
ABC, CBS, FOX, NBC, TELEMUNDO, UNIVISION, CNN, CENTRIC, CNBC, FOXNC, MSNBC

1/27/2010
Barack Obama
48.009
34.182
29.8
ABC, CBS, FOX, NBC, TELEMUNDO, UNIVISION, CNN, BET, CNBC, FOXNC, MSNBC

2/24/2009
Barack Obama
52.373
37.185
32.5
ABC, CBS, FOX, NBC, CNBC, CNN, FOXNC, MSNBC, TELEMUNDO, UNIVISION

1/28/2008
George W. Bush
37.515
27.702
24.7
ABC, CBS, FOX, NBC, CNN, FOXNC, MSNBC, TELEMUNDO**, UNIVISION

1/24/2007
George W. Bush
45.486
32.968
29.6
ABC, CBS, FOX, NBC, CNN, FOXNC, MSNBC, TELEMUNDO, UNIVISION

2/01/2006
George W. Bush
43.179
30.528
31.2
ABC, CBS, FOX, NBC, CNN, FOXNC, MSNBC, TELEMUNDO, AZTECA AMERICA, TELFUTURA

2/02/2005
George W. Bush
39.432
28.359
35.3
ABC, CBS, FOX, NBC, CNN, FOXNC, MSNBC, TELEMUNDO, TELEFUTURA

1/20/2004
George W. Bush
43.411
30.286
28.0
ABC, CBS, FOX, NBC, CNN, CNBC, FOXNC, MSNBC

1/28/2003
George W. Bush
62.061
41.447
38.8
ABC, CBS, FOX, NBC, CNN, CNBC, FOXNC, MSNBC

1/29/2002
George W. Bush
51.773
35.547
33.6
ABC, CBS, FOX, NBC, CNN, CNBC, FOXNC, MSNBC

2/27/2001
George W. Bush
39.793
28.201
27.6
ABC, CBS, FOX, NBC, CNN, FOXNC, MSNBC

1/27/2000
Bill Clinton
31.478
22.536
22.4
ABC, CBS, FOX, NBC, CNN, FOXNC, MSNBC

1/19/1999
Bill Clinton
43.500
30.700
31.0
ABC, CBS, FOX, NBC, CNN, FOXNC, MSNBC

1/27/1998
Bill Clinton
53.077
36.513
37.2
ABC, CBS, FOX, NBC, CNN, FOXNC, MSNBC, CNBC

2/04/1997
Bill Clinton
41.100
27.600
28.4
ABC, CBS, FOX, NBC, CNN

1/23/1996
Bill Clinton
40.900
28.400
29.6
ABC, CBS, FOX, NBC, CNN

1/24/1995
Bill Clinton
42.200
28.100
29.5
ABC, CBS, NBC, CNN

1/25/1994
Bill Clinton
45.800
31.000
32.9
ABC, CBS, NBC, CNN

2/17/1993
Bill Clinton
66.900
41.200
44.3
ABC, CBS, NBC, CNN


document_title: Compulsory education

question_text: when did it become illegal to not go to school

text: Compulsory education

text: History of compulsory education[edit]

text: Antiquity[edit]

text: Compulsory education was not unheard of in ancient times. However instances are generally tied to royal, religious or military organization—substantially different from modern notions of compulsory education.

text: Hellenic[edit]

text: Plato's The Republic (c. 424–c. 348 BCE) is credited with having popularized the concept of compulsory education in Western intellectual thought. Plato's rationale was straightforward. The ideal city would require ideal individuals, and ideal individuals would require an ideal education. Popularization of Plato's ideas began with the wider Renaissance and the translation of Plato's works by Marsilio Ficino (1433–1499), culminating in the Enlightenment. The Enlightenment philosopher Jean-Jacques Rousseau, known for his own work on education, Emile, or On Education had said To get a good idea of public education, read Plato’s Republic. It is not a political treatise, as those who merely judge books by their title think, but it is the finest, most beautiful work on education ever written.

text: In Sparta boys between the age 6 and 7 left their homes and were sent to military school. School courses were harsh and have been described as a "brutal training period". Between the age of 18 and 20, Spartan males had to pass a test that consisted of fitness, military ability, and leadership skills. A student's failure meant a forfeiture of citizenship (perioidos) and political rights. Passing was a rite of passage to manhood and citizenry, in which he would continue to serve in the military and train as a soldier until the age of 60, when the soldier could retire to live with his family.[2]

text: Judea[edit]

text: Every parent in Judea since ancient times was required to teach their children at least informally. Over the centuries, as cities, towns and villages developed, a class of teachers called Rabbis evolved. According to the Talmud (tractate Bava Bathra 21a), which praises the sage Joshua ben Gamla with the institution of formal Jewish education in the 1st century AD, Ben Gamla instituted schools in every town and made formal education compulsory from age 6-8.[3]

text: Medieval Era[edit]

text: The Aztec Triple Alliance, which ruled from 1428 to 1521 in what is now central Mexico, is considered to be the first state to implement a system of universal compulsory education.[4][5]

text: Early Modern Era[edit]

text: The Protestant Reformation prompted the establishment of compulsory education for boys and girls, first in regions that are now part of Germany, and later in Europe and in the United States.

text: Martin Luther's seminal text An die Ratsherren aller Städte deutschen Landes (To the Councillors of all Towns in German Countries,1524) called for establishing compulsory schooling so that all parishioners would be able to read the Bible by themselves.[6] The Protestant South-West of the Holy Roman Empire soon followed suit. In 1559, the German Duchy Württemberg established a compulsory education system for boys.[7] In 1592, the German Duchy Palatinate-Zweibrücken became the first territory in the world with compulsory education for girls and boys,[8] followed in 1598 by Strasbourg, then a free city of the Holy Roman Empire and now part of France.

text: In Scotland, the School Establishment Act of 1616 commanded every parish to establish a school for everyone paid for by parishioners. The Parliament of Scotland confirmed this with the Education Act of 1633 and created a local land-based tax to provide the required funding. The required majority support of parishioners, however, provided a tax evasion loophole which heralded the Education Act of 1646. The turmoil of the age meant that in 1661 there was a temporary reversion to the less compulsory 1633 position. However, in 1696 a new Act re-established the compulsory provision of a school in every parish with a system of fines, sequestration, and direct government implementation as a means of enforcement where required.

text: In the United States, following Luther and other Reformers, the Separatist Congregationalists who founded Plymouth Colony in 1620, obliged parents to teach their children how to read and write.[9] The Massachusetts School Laws, three legislative acts enacted in the Massachusetts Bay Colony in 1642, 1647, and 1648, are commonly regarded as the first steps toward compulsory education in the United States. The 1647 law, in particular, required every town having more than 50 families to hire a teacher, and every town of more than 100 families to establish a school.[10] The Puritan zeal for learning was reflected in the early and rapid rise of educational institutions; e.g., Harvard College was founded as early as 1636.[11]

text: Prussia implemented a modern compulsory education system in 1763. It was introduced by the Generallandschulreglement (General School Regulation), a decree of Frederick the Great in 1763-5.[12] The Generallandschulreglement, authored by Johann Julius Hecker, asked for all young citizens, girls and boys, to be educated from age 5 to age 13-14 and to be provided with a basic outlook on (Christian) religion, singing, reading and writing based on a regulated, state-provided curriculum of text books. The teachers, often former soldiers, were asked to cultivate silk worms to make a living besides contributions from the local citizens and municipalities.[13][14]

text: In Austria, Hungary and the Lands of the Bohemian Crown (Czech lands), mandatory primary education was introduced by Empress Maria Theresa in 1774.[12]

text: Late Modern Era[edit]

text: Europe[edit]

text: Compulsory school attendance based on the Prussian model gradually spread to other countries. It was quickly adopted by the governments in Denmark-Norway and Sweden, and also in Finland, Estonia and Latvia within the Russian Empire, but it was rejected in Russia itself.[15][16]

text: The United Kingdom was slow to introduce compulsory education due to the upper class defending its educational privileges.[16] In England and Wales, the Elementary Education Act 1870 paved the way for compulsory education by establishing school boards to set up schools in any places that did not have adequate provision. Attendance was made compulsory until age 10 in 1880. The Education Act of 1996 made it an obligation on parents to require children to have a full-time education from age 5 to 16. However, attendance at school itself is not compulsory: Section 7 of the Act allows for home education.

text: France was equally slow to introduce compulsory education, this time due to conflicts between the secular state and the Catholic Church,[16] and as a result between anti-clerical and Catholic political parties. The first set of Jules Ferry Laws, passed in 1881, made primary education free for girls and boys; communes and departments had the shared responsibility to fund it. In 1882, the second set of Jules Ferry Laws made education compulsory for girls and boys until the age of 13. In 1936, the upper age limit was raised to 14.[17] In 1959, it was further extended to 16.[18]

text: United States[edit]

text: In 1852, Massachusetts was the first U.S. state to pass a contemporary universal public education law. In particular, the Massachusetts General Court required every town to create and operate a grammar school. Fines were imposed on parents who did not send their children to school, and the government took the power to take children away from their parents and apprentice them to others if government officials decided that the parents were "unfit to have the children educated properly".[19]

text: The spread of compulsory attendance in the Massachusetts tradition throughout the U.S., especially for Native Americans, has been credited to General Richard Henry Pratt.[20] Pratt used techniques developed on Native Americans in a prisoner of war camp in Fort Marion, Augustine, Florida, to force demographic minorities across America into government schools.[20] His prototype was the Carlisle Indian Industrial School in Pennsylvania.

text: In 1918, Mississippi was the last state to enact a compulsory attendance law.[21]

text: In 1922 an attempt was made by the voters of Oregon to enact the Oregon Compulsory Education Act, which would require all children between the ages of 8 and 16 to attend State School. Only leaving exceptions for mentally or physically unfit children, exceeding a certain living distance from a state school, or having written consent from a county superintendent to receive private instruction.[22] The law was passed by popular vote but was later ruled unconstitutional by the United States Supreme Court in Pierce v. Society of Sisters, determining that "a child is not a mere creature of the state". This case settled the dispute about whether or not private schools had the right to do business and educate within the United States.

text: Asia[edit]

text: In Japan, compulsory education was established shortly after the Meiji Restoration in 1868. Initially, it was strongly influenced by the Prussian education system. After World War II, it was rebuilt to a large extent, and the new education model is largely influenced by the American model.[23] In the Indian kingdom of Travancore, Queen Gowri Parvati Bayi issued a royal rescript declaring universal education and formally recognized the role of State ensure the right of education from public revenue in 1817.

text: Per-country variations in the age range of compulsory education[edit]

text: The following table indicates at what ages compulsory education starts and ends, country by country. The most common age for starting compulsory education is 6, although this varies between 3 and 8.[24][25]

text:
Country
Lower
age range
Upper
age range
Notes

Argentina
6
18

Australia
5
15/17
Upper age limit varies among states. Waived if pursuing full-time employment or full-time education.

Austria
6
15
Compulsory education only requires nine years spent in school.

Belgium
6
18
In Belgium, only compulsory education applies. School is not compulsory.

Bulgaria
5
16
Since 2012, compulsory education includes two years of preschool education before children start primary school.[26][27]

Brazil
4
17
Last changed in 2009.[28]

Canada
6
16
Except Ontario and New Brunswick: 6-18. Some provinces have exemptions at 14.

China
6
15

Croatia
6
15

Cyprus
5
15
Compulsory education starts with one mandatory year of pre-primary (preschool) education.[29]

Egypt
6
14

Estonia
6/7
15/16
6 year olds can enter if they turn 7 by 1st of October in the same year.[30]

Finland
7
15
Beginning age is negotiable ± 1 year. Ends after graduation from comprehensive school, or at least 9 years.

France
6
16
Compulsory education only

Germany
6
16
Varies slightly between states.[31][32]

Haiti
6
11
The Haitian Constitution mandates that education be free of charge. However, even public schools charge substantial fees. 80% of children go to private schools.

Hong Kong
6
17
Hong Kong laws state that education is free for 12 years except for private schools or subsidized schools.

Hungary
3
16
Since 2015, kindergarten is compulsory from age 3, although exceptions are made for developmental reasons.[33][34]

India
6
14
The Right of Children to Free and Compulsory Education Act in August 2009 made education free and compulsory for children aged between 6 and 14.

Indonesia
6
15

Israel
3
18
Compulsory education takes place from kindergarten through to 12th grade.

Iran
6
12[35]

Italy
6
16

Jamaica
5
16
Parents could face charges of Child Neglect if they prevent their children from going to school without valid reasons. Not enforced.

Japan
6
15

Latvia
5
16[24][36]

Luxembourg
4
16 [24]

Malaysia
6
12[37]

Maldives
6
15

Mexico
6
18
Schooling is required through upper secondary school (Preparatoria).[38]

Morocco
6
15

Netherlands
5
18
Students are allowed to leave early after obtaining their 'start qualification' (MBO level 2, HAVO or VWO degree).

Norway
6
15
A total of ten years (of study, and not schooling, as suggested here), where Primary school is year 1-7 (without grades), and Lower Secondary school (with grades) is year 8-10.[39]

Poland
7
18
Polish law distinguishes between compulsory school (obowiązek szkolny) and compulsory education (obowiązek nauki).

Portugal
6
18
It is the law that children living in Portugal (if there for 4 months or more) must go to school. Home schooling is available with registration at a school and quarterly examinations in the Portuguese curriculum only.

Russia
6
17
Student may leave after age 15 with the approval of parents and the local authority.[40]

Slovenia
6
15

Singapore
7
15[41]
Compulsory Education Act 2000. Children with special needs or those with permission to be homeschooled are exempted from the act but in November 2016 the government announced that the Act will extend to children with moderate and severe special needs beginning in 2019.[42][43]

Spain
6
16

Syria
6
15
Typical ages for 9 years of compulsory education from grade 1 to grade 9.

Sweden
7
16[44]

Switzerland
4-6
15
Varies by canton.[24]

Taiwan
7
18
Typical ages for 12 years of compulsory education (starting from 2014).

Turkey
6
18
From the 1st to the 12th grade, education is compulsory. Starting in the educational year of 2012-2013, an education reform took effect to bring the compulsory education up to the end of high school. The system is commonly referred to as 4+4+4.

United Kingdom
5[45]
18[46]
Requirement is for a full-time education, but attendance at a school is not compulsory (section 7 of The Education Act 1996).

United States
5-8
15-18
Ages vary between states. Beginning age varies 5-8, ending age varies 15-18.[47] In case Wisconsin v. Yoder, the Supreme Court determined in 1972 that Amish children could not be placed under compulsory education laws past the 8th grade.

Uruguay
6
14

Zimbabwe
6
16
Typical ages for 11 years of compulsory education.

text: Number of pupils and students enrolled in compulsory education[edit]

text: Due to population growth and the proliferation of compulsory education, UNESCO calculated in 2006 that over the subsequent 30 years, more people would receive formal education than in all prior human history.[48]

text: Criticism[edit]

text: Critics of compulsory education argue that education violates the freedom of children, is a method of political control, is ineffective at teaching kids how to deal with the real world and has extremely negative effects on children leading to higher rates of apathy, bullying, stress and depression.


document_title: Alkene

question_text: what type of polymer is made by bonding an alkene to one or more alkanes or alkenes

text: Alkene

text: Structure[edit]

text: Bonding[edit]

text: Like a single covalent bond, double bonds can be described in terms of overlapping atomic orbitals, except that, unlike a single bond (which consists of a single sigma bond), a carbon–carbon double bond consists of one sigma bond and one pi bond. This double bond is stronger than a single covalent bond (611 kJ/mol for C=C vs. 347 kJ/mol for C–C)[1] and also shorter, with an average bond length of 1.33 ångströms (133 pm).

text: Each carbon of the double bond uses its three sp2 hybrid orbitals to form sigma bonds to three atoms (the other carbon and two hydrogen atoms). The unhybridized 2p atomic orbitals, which lie perpendicular to the plane created by the axes of the three sp² hybrid orbitals, combine to form the pi bond. This bond lies outside the main C–C axis, with half of the bond on one side of the molecule and half on the other.

text: Rotation about the carbon–carbon double bond is restricted because it incurs an energetic cost to break the alignment of the p orbitals on the two carbon atoms. As a consequence, substituted alkenes may exist as one of two isomers, called cis or trans isomers. More complex alkenes may be named with the E–Z notation for molecules with three or four different substituents (side groups). For example, of the isomers of butene, the two methyl groups of (Z)-but-2-ene (a.k.a. cis-2-butene) appear on the same side of the double bond, and in (E)-but-2-ene (a.k.a. trans-2-butene) the methyl groups appear on opposite sides. These two isomers of butene are slightly different in their chemical and physical properties.

text: A 90° twist of the C=C bond (which may be determined by the positions of the groups attached to the carbons) requires less energy than the strength of a pi bond, and the bond still holds. This contradicts a common textbook assertion that the p orbitals would be unable sustain such a bond. In truth, the misalignment of the p orbitals is less than expected because pyramidalization takes place (See: pyramidal alkene). trans-Cyclooctene is a stable strained alkene and the orbital misalignment is only 19° with a dihedral angle of 137° (normal 120°) and a degree of pyramidalization of 18°.[4] The trans isomer of cycloheptene is stable only at low temperatures.

text: Shape[edit]

text: As predicted by the VSEPR model of electron pair repulsion, the molecular geometry of alkenes includes bond angles about each carbon in a double bond of about 120°. The angle may vary because of steric strain introduced by nonbonded interactions between functional groups attached to the carbons of the double bond. For example, the C–C–C bond angle in propylene is 123.9°.

text: For bridged alkenes, Bredt's rule states that a double bond cannot occur at the bridgehead of a bridged ring system unless the rings are large enough.[5] Following Fawcett and defining S as the total number of non-bridgehead atoms in the rings,[6] bicyclic systems require S ≥ 7 for stability[5] and tricyclic systems require S ≥ 11.[7]

text: Physical properties[edit]

text: The physical properties of alkenes and alkanes are similar. They are colourless, nonpolar, combustable, and almost odorless. The physical state depends on molecular mass: like the corresponding saturated hydrocarbons, the simplest alkenes, ethene, propene, and butene are gases at room temperature. Linear alkenes of approximately five to sixteen carbons are liquids, and higher alkenes are waxy solids.

text: Reactions[edit]

text: Alkenes are relatively stable compounds, but are more reactive than alkanes, either because of the reactivity of the carbon–carbon pi-bond or the presence of allylic CH centers. Most reactions of alkenes involve additions to this pi bond, forming new single bonds. Alkenes serve as a feedstock for the petrochemical industry because they can participate in a wide variety of reactions, prominently polymerization and alkylation.

text: Addition reactions[edit]

text: Alkenes react in many addition reactions, which occur by opening up the double-bond. Most of these addition reactions follow the mechanism of electrophilic addition. Examples are hydrohalogenation, halogenation, halohydrin formation, oxymercuration, hydroboration, dichlorocarbene addition, Simmons–Smith reaction, catalytic hydrogenation, epoxidation, radical polymerization and hydroxylation.

text: Hydrogenation[edit]

text: Hydrogenation of alkenes produces the corresponding alkanes. The reaction is carried out under pressure at a temperature of 200 °C in the presence of a metallic catalyst. Common industrial catalysts are based on platinum, nickel or palladium. For laboratory syntheses, Raney nickel (an alloy of nickel and aluminium) is often employed. The simplest example of this reaction is the catalytic hydrogenation of ethylene to yield ethane:

text: Hydration[edit]

text: Hydration, the addition of water across the double bond of alkenes, yields alcohols. The reaction is catalyzed by strong acids such as sulfuric acid. This reaction is carried out on an industrial scale to produce ethanol.

text: Alkenes can also be converted into alcohols via the oxymercuration–demercuration reaction , the hydroboration–oxidation reaction or by Mukaiyama hydration.

text: Halogenation[edit]

text: In electrophilic halogenation the addition of elemental bromine or chlorine to alkenes yields vicinal dibromo- and dichloroalkanes (1,2-dihalides or ethylene dihalides), respectively. The decoloration of a solution of bromine in water is an analytical test for the presence of alkenes:

text: Related reactions are also used as quantitative measures of unsaturation, expressed as the bromine number and iodine number of a compound or mixture.

text: Hydrohalogenation[edit]

text: Hydrohalogenation is the addition of hydrogen halides such as HCl or HI to alkenes to yield the corresponding haloalkanes:

text: If the two carbon atoms at the double bond are linked to a different number of hydrogen atoms, the halogen is found preferentially at the carbon with fewer hydrogen substituents. This patterns is known as Markovnikov's rule. The use of radical initiators or other compounds can lead to the opposite product result. Hydrobromic acid in particular is prone to forming radicals in the presence of various impurities or even atmospheric oxygen, leading to the reversal of the Markovnikov result:[8]

text: Halohydrin formation[edit]

text: Alkenes react with water and halogens to form halohydrins by an addition reaction. Markovnikov regiochemistry and anti stereochemistry occur.

text: Oxidation[edit]

text: Alkenes are oxidized with a large number of oxidizing agents. In the presence of oxygen, alkenes burn with a bright flame to produce carbon dioxide and water. Catalytic oxidation with oxygen or the reaction with percarboxylic acids yields epoxides. Reaction with ozone in ozonolysis leads to the breaking of the double bond, yielding two aldehydes or ketones. Reaction with concentrated, hot KMnO4 (or other oxidizing salts) in an acidic solution will yield ketones or carboxylic acids.

text: This reaction can be used to determine the position of a double bond in an unknown alkene.

text: The oxidation can be stopped at the vicinal diol rather than full cleavage of the alkene by using milder (dilute,lower temperature) KMnO4 or with osmium tetroxide or other oxidants.

text: Photooxygenation[edit]

text: In the presence of an appropriate photosensitiser, such as methylene blue and light, alkenes can undergo reactions with reactive oxygen species generated by the photosensitiser, such as hydroxyl radicals, singlet oxygen or superoxide ion. These reactive photochemical intermediates are generated in what are known as Type I, Type II, and Type III processes, respectively.[citation needed] These various alternative processes and reactions can be controlled by choice of specific reaction conditions, leading to a wide range of different products. A common example is the [4+2]-cycloaddition of singlet oxygen with a diene such as cyclopentadiene to yield an endoperoxide:

text: Another example is the Schenck ene reaction, in which singlet oxygen reacts with an allylic structure to give a transposed allyl peroxide:

text: Polymerization[edit]

text: Polymerization of alkenes is a reaction that yields polymers of high industrial value at great economy, such as the plastics polyethylene and polypropylene. Polymers from alkene monomers are referred to in a general way as polyolefins or in rare instances as polyalkenes. A polymer from alpha-olefins is called a polyalphaolefin (PAO). Polymerization can proceed via either a free-radical or an ionic mechanism, converting the double to a single bond and forming single bonds to join the other monomers. Polymerization of conjugated dienes such as buta-1,3-diene or isoprene (2-methylbuta-1,3-diene) results in largely 1,4-addition with possibly some 1,2-addition of the diene monomer to a growing polymer chain.

text: Metal complexation[edit]

text: Alkenes are ligands in transition metal alkene complexes. The two carbon centres bond to the metal using the C–C pi- and pi*-orbitals. Mono- and diolefins are often used as ligands in stable complexes. Cyclooctadiene and norbornadiene are popular chelating agents, and even ethylene itself is sometimes used as a ligand, for example, in Zeise's salt. In addition, metal–alkene complexes are intermediates in many metal-catalyzed reactions including hydrogenation, hydroformylation, and polymerization.

text: Reaction overview[edit]

text:
Reaction name
Product
Comment

Hydrogenation
alkanes
addition of hydrogen

Hydroalkenylation
alkenes
hydrometalation / insertion / beta-elimination by metal catalyst

Halogen addition reaction
1,2-dihalide
electrophilic addition of halogens

Hydrohalogenation (Markovnikov)
haloalkanes
addition of hydrohalic acids

Anti-Markovnikov hydrohalogenation
haloalkanes
free radicals mediated addition of hydrohalic acids

Hydroamination
amines
addition of N–H bond across C–C double bond

Hydroformylation
aldehydes
industrial process, addition of CO and H2

Sharpless bishydroxylation
diols
oxidation, reagent: osmium tetroxide, chiral ligand

Woodward cis-hydroxylation
diols
oxidation, reagents: iodine, silver acetate

Ozonolysis
aldehydes or ketones
reagent: ozone

Olefin metathesis
alkenes
two alkenes rearrange to form two new alkenes

Diels–Alder reaction
cyclohexenes
cycloaddition with a diene

Pauson–Khand reaction
cyclopentenones
cycloaddition with an alkyne and CO

Hydroboration–oxidation
alcohols
reagents: borane, then a peroxide

Oxymercuration-reduction
alcohols
electrophilic addition of mercuric acetate, then reduction

Prins reaction
1,3-diols
electrophilic addition with aldehyde or ketone

Paterno–Büchi reaction
oxetanes
photochemical reaction with aldehyde or ketone

Epoxidation
epoxide
electrophilic addition of a peroxide

Cyclopropanation
cyclopropanes
addition of carbenes or carbenoids

Hydroacylation
ketones
oxidative addition / reductive elimination by metal catalyst

Hydrophosphination
phosphines

text: Synthesis[edit]

text: Industrial methods[edit]

text: Alkenes are produced by hydrocarbon cracking. Raw materials are mostly natural gas condensate components (principally ethane and propane) in the US and Mideast and naphtha in Europe and Asia. Alkanes are broken apart at high temperatures, often in the presence of a zeolite catalyst, to produce a mixture of primarily aliphatic alkenes and lower molecular weight alkanes. The mixture is feedstock and temperature dependent, and separated by fractional distillation. This is mainly used for the manufacture of small alkenes (up to six carbons).[9]

text: Related to this is catalytic dehydrogenation, where an alkane loses hydrogen at high temperatures to produce a corresponding alkene.[1] This is the reverse of the catalytic hydrogenation of alkenes.

text: This process is also known as reforming. Both processes are endothermic and are driven towards the alkene at high temperatures by entropy.

text: Catalytic synthesis of higher α-alkenes (of the type RCH=CH2) can also be achieved by a reaction of ethylene with the organometallic compound triethylaluminium in the presence of nickel, cobalt, or platinum.

text: Elimination reactions[edit]

text: One of the principal methods for alkene synthesis in the laboratory is the room elimination of alkyl halides, alcohols, and similar compounds. Most common is the β-elimination via the E2 or E1 mechanism,[10] but α-eliminations are also known.

text: The E2 mechanism provides a more reliable β-elimination method than E1 for most alkene syntheses. Most E2 eliminations start with an alkyl halide or alkyl sulfonate ester (such as a tosylate or triflate). When an alkyl halide is used, the reaction is called a dehydrohalogenation. For unsymmetrical products, the more substituted alkenes (those with fewer hydrogens attached to the C=C) tend to predominate (see Zaitsev's rule). Two common methods of elimination reactions are dehydrohalogenation of alkyl halides and dehydration of alcohols. A typical example is shown below; note that if possible, the H is anti to the leaving group, even though this leads to the less stable Z-isomer.[11]

text: Alkenes can be synthesized from alcohols via dehydration, in which case water is lost via the E1 mechanism. For example, the dehydration of ethanol produces ethene:

text: An alcohol may also be converted to a better leaving group (e.g., xanthate), so as to allow a milder syn-elimination such as the Chugaev elimination and the Grieco elimination. Related reactions include eliminations by β-haloethers (the Boord olefin synthesis) and esters (ester pyrolysis).

text: Alkenes can be prepared indirectly from alkyl amines. The amine or ammonia is not a suitable leaving group, so the amine is first either alkylated (as in the Hofmann elimination) or oxidized to an amine oxide (the Cope reaction) to render a smooth elimination possible. The Cope reaction is a syn-elimination that occurs at or below 150 °C, for example:[12]

text: The Hofmann elimination is unusual in that the less substituted (non-Saytseff) alkene is usually the major product.

text: Alkenes are generated from α-halosulfones in the Ramberg–Bäcklund reaction, via a three-membered ring sulfone intermediate.

text: Synthesis from carbonyl compounds[edit]

text: Another important method for alkene synthesis involves construction of a new carbon–carbon double bond by coupling of a carbonyl compound (such as an aldehyde or ketone) to a carbanion equivalent. Such reactions are sometimes called olefinations. The most well-known of these methods is the Wittig reaction, but other related methods are known.

text: The Wittig reaction involves reaction of an aldehyde or ketone with a Wittig reagent (or phosphorane) of the type Ph3P=CHR to produce an alkene and Ph3P=O. The Wittig reagent is itself prepared easily from triphenylphosphine and an alkyl halide. The reaction is quite general and many functional groups are tolerated, even esters, as in this example:[13]

text: Related to the Wittig reaction is the Peterson olefination. This uses a less accessible silicon-based reagent in place of the phosphorane, but it allows for the selection of E- or Z-products. If an E-product is desired, another alternative is the Julia olefination, which uses the carbanion generated from a phenyl sulfone. The Takai olefination based on an organochromium intermediate also delivers E-products. A titanium compound, Tebbe's reagent, is useful for the synthesis of methylene compounds; in this case, even esters and amides react.

text: A pair of carbonyl compounds can also be reductively coupled together (with reduction) to generate an alkene. Symmetrical alkenes can be prepared from a single aldehyde or ketone coupling with itself, using titanium metal reduction (the McMurry reaction). If two different ketones are to be coupled, a more complex, indirect method such as the Barton–Kellogg reaction may be used.

text: A single ketone can also be converted to the corresponding alkene via its tosylhydrazone, using sodium methoxide (the Bamford–Stevens reaction) or an alkyllithium (the Shapiro reaction).

text: Synthesis from alkenes: olefin metathesis and hydrovinylation[edit]

text: Alkenes can be prepared by exchange with other alkenes, in a reaction known as olefin metathesis. Frequently, loss of ethene gas is used to drive the reaction towards a desired product. In many cases, a mixture of geometric isomers is obtained, but the reaction tolerates many functional groups. The method is particularly effective for the preparation of cyclic alkenes, as in this synthesis of muscone:

text: Transition metal catalyzed hydrovinylation is another important alkene synthesis process starting from alkene itself.[14] In general, it involves the addition of a hydrogen and a vinyl group (or an alkenyl group) across a double bond. The hydrovinylation reaction was first reported by Alderson, Jenner, and Lindsey by using rhodium and ruthenium salts, other metal catalysts commonly employed nowadays included iron, cobalt, nickel, and palladium. The addition can be done highly regio- and stereoselectively, the choices of metal centers, ligands, substrates and counterions often play very important role.[15][16][17] Recent studies showed that the use of N-heterocyclic carbene with Ni can be useful for the selective preparations of functionalized geminal olefins or 1,1-disubstituted alkenes.[18][19]

text: From alkynes[edit]

text: Reduction of alkynes is a useful method for the stereoselective synthesis of disubstituted alkenes. If the cis-alkene is desired, hydrogenation in the presence of Lindlar's catalyst (a heterogeneous catalyst that consists of palladium deposited on calcium carbonate and treated with various forms of lead) is commonly used, though hydroboration followed by hydrolysis provides an alternative approach. Reduction of the alkyne by sodium metal in liquid ammonia gives the trans-alkene.[20]

text: For the preparation multisubstituted alkenes, carbometalation of alkynes can give rise to a large variety of alkene derivatives.

text: Rearrangements and related reactions[edit]

text: Alkenes can be synthesized from other alkenes via rearrangement reactions. Besides olefin metathesis (described above), a large number of pericyclic reactions can be used such as the ene reaction and the Cope rearrangement.

text: In the Diels–Alder reaction, a cyclohexene derivative is prepared from a diene and a reactive or electron-deficient alkene.

text: Nomenclature[edit]

text: Although the nomenclature is not followed widely, according to IUPAC, alkenes are acyclic hydrocarbons with one double bond between carbon centers. Olefins comprise a larger collection of cyclic and acyclic alkenes as well as dienes and polyenes.[21]

text: IUPAC names[edit]

text: To form the root of the IUPAC names for alkenes, simply change the -an- infix of the parent to -en-. For example, CH3-CH3 is the alkane ethANe. The name of CH2=CH2 is therefore ethENe.

text: In higher alkenes, where isomers exist that differ in location of the double bond, the following numbering system is used:

text:
Number the longest carbon chain that contains the double bond in the direction that gives the carbon atoms of the double bond the lowest possible numbers.
Indicate the location of the double bond by the location of its first carbon.
Name branched or substituted alkenes in a manner similar to alkanes.
Number the carbon atoms, locate and name substituent groups, locate the double bond, and name the main chain.

text: Cis–trans notation[edit]

text: In the specific case of disubstituted alkenes where the two carbons have one substituent each, cis–trans notation may be used. If both substituents are on the same side of the bond, it is defined as cis-. If the substituents are on either side of the bond, it is defined as trans-.

text: E–Z notation[edit]

text: When an alkene has more than one substituent (especially necessary with 3 or 4 substituents), the double bond geometry is described using the labels E and Z. These labels come from the German words entgegen, meaning "opposite", and zusammen, meaning "together". Alkenes with the higher priority groups (as determined by CIP rules) on the same side of the double bond have these groups together and are designated Z. Alkenes with the higher priority groups on opposite sides are designated E. A mnemonic to remember this: Z notation has the higher priority groups on "ze zame zide."

text: Groups containing C=C double bonds[edit]

text: IUPAC recognizes two names for hydrocarbon groups containing carbon–carbon double bonds, the vinyl group and the allyl group.[2]


document_title: Main-group element

question_text: what category of elements is the most common in the periodic table

text: Main-group element

text: In chemistry and atomic physics, the main group is the group of elements whose lightest members are represented by helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine as arranged in the periodic table of the elements. The main group includes the elements (except hydrogen, which is sometimes not included) in groups 1 and 2 (s-block), and groups 13 to 18 (p-block). The s-block elements are primarily characterised by one main oxidation state, and the p-block elements, when they have multiple oxidation states, often have common oxidation states separated by two units.

text: Group 12 elements are often considered to be transition metals; however, zinc (Zn), cadmium (Cd), and mercury (Hg) share some properties of both groups, and many scientists believe they should be included in the main group.[1][2] Occasionally, even the group 3 elements as well as the lanthanides and actinides have been included, because especially the group 3 elements and lanthanides are electropositive elements with only one main oxidation state like the group 1 and 2 elements. The position of the actinides is more questionable, but the most common and stable of them, thorium (Th) and uranium (U), are similar to main-group elements as thorium is an electropositive element with only one main oxidation state (+4), and uranium has two main ones separated by two oxidation units (+4 and +6).[3]

text: In older nomenclature the main-group elements are groups IA and IIA, and groups IIIB to 0 (CAS groups IIIA to VIIIA). Group 12 is labelled as group IIB in both systems. Group 3 is labelled as group IIIA in the older nomenclature (CAS group IIIB).

text: Main-group elements (with some of the lighter transition metals) are the most abundant elements on Earth, in the Solar System, and in the Universe. They are sometimes also called the representative elements.