In the example below, the oxygen of the hydroxide ion donates an electron pair to bond with the carbon at the end of the bromopropane molecule. The bond between the carbon and the bromine then undergoes heterolytic fission, with the bromine atom taking the donated electron and becoming the bromide ion (Br). This is a S2 reaction occurs by backside attack. This means that the hydroxide ion attacks the carbon atom from the other side, exactly opposite the bromine ion. Because of this backside attack, S2 reactions result in a reversal of the configuration of the electrophile. If the electrophile is chiral, it typically keeps its chirality, though the S2 product's configuration is flipped as compared to that of the original electrophile (Walden inversion).
An ambident nucleophile is one that can attack from two or more places, resulting in two or more products. For example, the thiocyanate ion (SCN) may attack from either the S or the N. For this reason, the S2 reaction of an alkyl halide with SCN often leads to a mixture of RSCN (an alkyl thiocyanate) and RNCS (an alkyl isothiocyanate). Similar mixtures will happen in the Kolbe nitrile synthesis.
Alkyl metal halides are carbon nucleophiles found in the Grignard reaction, Blaise reaction, Reformatsky reaction, and Barbier reaction, organolithium reagents, and anions of a terminal alkyne.
Enols are also carbon nucleophiles. The formation of an enol is catalyzed by acid or base. Enols are ambident nucleophiles, but, in general, nucleophilic at the carbon atom next to the carbons with double bond (alpha carbon atom).
Enols are commonly used in condensation reactions, including the Claisen condensation and the aldol condensation reactions.
Examples of oxygen nucleophiles are water (HO), hydroxide anion, alcohols, alkoxide anions, hydrogen peroxide, and carboxylate anions.
Of sulfur nucleophiles, hydrogen sulfide and its salts, thiols (RSH), thiolate anions (RS), anions of thiolcarboxylic acids (RC(O)-S), and anions of dithiocarbonates (RO-C(S)-S) and dithiocarbamates (RN-C(S)-S) are used most often.
In general, sulfur is very nucleophilic because of its large size, which makes it readily polarizable, and its lone pairs of electrons are readily accessible.
Nitrogen nucleophiles include ammonia, azide, amines, and nitrites.
Taishō period
The , also known as the Taishō era, was a after "Meiji" and before "Shōwa." This period started on July 30, 1912 and ended on December 25, 1926. During this time, the emperor was .
The "nengō" "Taishō" means "Great Justice" or "Great Righteousness".
The years in which Taishō was the Japanese monarch comprise this period or era.
Lanarkshire derby
The Lanarkshire Derby is a football rivalry in Lanarkshire, Scotland, and matches are played between two of Motherwell, Hamilton Academical, Airdrie United and Albion Rovers.
This game is the biggest Lanarkshire derby, and big crowds usually come to watch this match, at either Fir Park or Excelsior Stadium. For a very long time, Motherwell and Airdrieonians were the two biggest teams in Lanarkshire, up until Airdrie went out of business in 2002. There has only been one game between these two teams since Airdrie re-formed as Airdrie United, in the 2007 Scottish Cup. A Richie Foran goal won it for Motherwell that day, in front of a crowd of 5,924, the highest ever for an Airdrie United match. Also, this match had often been the final of the Lanarkshire Cup, a competition where teams from all-over Lanarkshire played in. This competition stopped in 1996.
This game is the second-biggest Lanarkshire derby, and the most Southern of all the derbies. Up until 2008, both teams were mostly in different divisions. Then Hamilton got promoted to the SPL and both teams were to play each other a lot. This ended when Hamilton got relegated in 2011, meaning that Motherwell are now the only SPL team in Lanarkshire.
This game is between the two middle-rated teams in Lanarkshire, and is not as big as when one of the teams play Motherwell. Both teams have usually been in a league lower than the SPL, so this is not thought to be a big derby.
This game is big for both teams, as they were both in the Monklands area, until Airdrie moved to a new stadium in the Petersburn area in 1998. The first match between Albion and Airdrie (as United), was in 2010, when Airdrie beat Albion Rovers 1-0 at Cliftonhill. Since that game, both teams are in the same division in the 2011-12 season.
This is not a big derby match, as both teams have been in different divisions for most of their existence. They were in the same league in 2001, but have not met each other since, making this derby the smallest. Coatbridge and Hamilton are 6 miles apart.
This is the least remembered of the derbies, as Albion have been in the lower divisions for most of their existence, whilst Motherwell have been in the top division. There is also no bad feeling between the two, as a few young Motherwell players have gone out on loan to Albion Rovers over the years.
Camposaurus
Camposaurus is a dinosaur from the Late Triassic of North America. It is a relative of "Coelophysis". This relationship was upheld by a recent phylogenetic anlysis.
With fossils dating back to 205–210 million years ago (mya), it is the oldest known neotheropod. It is known from partial lower leg bones and other fragmentary material.
A study of "Camposaurus arizoniensis" by Ezcurra and Brusatte discovered two unique features. This meant the specimen was a valid genus and species. "Camposaurus" is definitely a neotheropod. Based on phylogenetic analysis, its closest known relative is "Megapnosaurus rhodensis", because they share similarities in the tibia, and ankle. Spielman et al. (2007) put "Camposaurus" in the family Coelophysidae.
Staurikosaurus
Staurikosaurus is a genus of Upper Triassic theropod dinosaurs found in Brazil. It was a small, lightly built carnivore.
The rarity of "Staurikosaurus" remains may be a result of it being uncommon while alive, or because it lived in an environment such as a forest, where fossils rarely form.
At just , 80 centimetres tall (31 in), and weighing just 30 kilograms (66 lb), "Staurikosaurus" was tiny in comparison to later theropods like "Megalosaurus". "Staurikosaurus" and the related "Herrerasaurus" are definitely theropods and evolved after the sauropod line had split from the theropods.
The fossil record of "Staurikosaurus" is poor, but the skeletal structure of the legs is known. "Staurikosaurus" was a quick runner for its size. It also had just two vertebrae joining the pelvis to the spine, a distinctly primitive arrangement.
The available teeth for Staurikosaurus strongly suggest a carnivorous diet.
The tail of "Staurikosaurus" was relatively long (with more than 40 vertebrae) compared to the rest of its body and was held straight and off the ground as it ran. The rear part of "Staurikosauruss tail is stiffened by features of the tail vertebrae. Ostrom thought this was a dynamic stabilizer to help balance while leaping and running.
Ostend manifesto
The Ostend Manifesto was an 1854 document describing the reasons for the United States to buy Cuba. Cuba was to be added as a slave state of the United States.
Electronic Delay Storage Automatic Calculator
Electronic Delay Storage Automatic Calculator (EDSAC) was an early British computer. It was made by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England. EDSAC was the first stored-program electronic computer. It was also the first to run a computer game.
Later the project was supported by J. Lyons & Co. Ltd., a British company. They were rewarded with the first commercial computer, LEO I. LEO I was based on the EDSAC design. EDSAC ran its first programs on 6 May 1949, when it calculated a table of square numbers and a list of prime numbers.
Voting age