In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula CnH2n−2. Alkynes are traditionally known as acetylenes, although the name acetylene refers to C2H2, known formally as ethyne using IUPAC nomenclature. Like other hydrocarbons, alkynes are hydrophobic but tend to be more reactive. Alkynes are characteristically more unsaturated than alkenes, thus they add two equivalents of bromine whereas an alkene adds only one equivalent in a reaction with hydrobromic acid. Other reactions are listed below. In some reactions, alkynes are less reactive than alkenes. For example, in a molecule with an -ene and an -yne group, addition occurs preferentially at the -ene. Possible explanations involve the two π-bonds in the alkyne delocalising, which would reduce the energy of the π-system or the stability of the intermediates during the reaction.
They show greater tendency to oligomerize than alkenes do. The resulting polymers, called polyacetylenes are conjugated and can exhibit semiconducting properties. In acetylene, the H–C≡C bond angles are 180°. By virtue of this bond angle, alkynes are rod-like. Correspondingly, cyclic alkynes are rare. Benzyne is unstable; the C≡C bond distance of 121 picometers is much shorter than the C=C distance in alkenes or the C–C bond in alkanes. The triple bond is strong with a bond strength of 839 kJ/mol; the sigma bond contributes 369 kJ/mol, the first pi bond contributes 268 kJ/mol and the second pi-bond of 202 kJ/mol bond strength. Bonding discussed in the context of molecular orbital theory, which recognizes the triple bond as arising from overlap of s and p orbitals. In the language of valence bond theory, the carbon atoms in an alkyne bond are sp hybridized: they each have two unhybridized p orbitals and two sp hybrid orbitals. Overlap of an sp orbital from each atom forms one sp–sp sigma bond; each p orbital on one atom overlaps one on the other atom, forming two pi bonds, giving a total of three bonds.
The remaining sp orbital on each atom can form a sigma bond to another atom, for example to hydrogen atoms in the parent acetylene. The two sp orbitals project on opposite sides of the carbon atom. Internal alkynes feature carbon substituents on each acetylenic carbon. Symmetrical examples include 3-hexyne. Terminal alkynes have the formula RC2H. An example is methylacetylene. Terminal alkynes, like acetylene itself, are mildly acidic, with pKa values of around 25, they are far more acidic than alkenes and alkanes, which have pKa values of around 40 and 50, respectively. The acidic hydrogen on terminal alkynes can be replaced by a variety of groups resulting in halo-, silyl-, alkoxoalkynes; the carbanions generated by deprotonation of terminal alkynes are called acetylides. In systematic chemical nomenclature, alkynes are named with the Greek prefix system without any additional letters. Examples include octyne. In parent chains with four or more carbons, it is necessary to say. For octyne, one can either write oct-3-yne when the bond starts at the third carbon.
The lowest number possible is given to the triple bond. When no superior functional groups are present, the parent chain must include the triple bond if it is not the longest possible carbon chain in the molecule. Ethyne is called by its trivial name acetylene. In chemistry, the suffix -yne is used to denote the presence of a triple bond. In organic chemistry, the suffix follows IUPAC nomenclature. However, inorganic compounds featuring unsaturation in the form of triple bonds may be denoted by substitutive nomenclature with the same methods used with alkynes. "-diyne" is used when there are two triple bonds, so on. The position of unsaturation is indicated by a numerical locant preceding the "-yne" suffix, or'locants' in the case of multiple triple bonds. Locants are chosen. "-yne" is used as an infix to name substituent groups that are triply bound to the parent compound. Sometimes a number between hyphens is inserted before it to state which atoms the triple bond is between; this suffix arose as a collapsed form of the end of the word "acetylene".
The final" - e" disappears. Commercially, the dominant alkyne is acetylene itself, used as a fuel and a precursor to other compounds, e.g. acrylates. Hundreds of millions of kilograms are produced annually by partial oxidation of natural gas: 2 CH4 + 3/2 O2 → HC≡CH + 3 H2OPropyne industrially useful, is prepared by thermal cracking of hydrocarbons. Specialty alkynes are prepared by double dehydrohalogenation; the reaction provides a means to generate alkynes from alkenes, which are first halogenated and dehydrohalogenates. For example, phenylacetylene can be generated from styrene by bromination followed by treatment of the resulting of styrene dibromide with sodium amide in ammonia: Via the Fritsch–Buttenberg–Wiechell rearrangement, alkynes are prepared from vinyl bromides. Alkynes can be prepared from aldehydes using the Corey–Fuchs reaction and from aldehydes or ketones by the Seyferth–Gilbert homologation. Featuring a reactive functional group, alkynes participate in many organic reactions.
Such use was pioneered by Ralph Raphael, who in 1955 wrote the first book describing their versatility as intermediates in synthesis. Alkynes characteristically under
The American Basketball Association was a professional basketball league that operated from the 1967–68 season until it ceased to exist with the ABA–NBA merger in 1976. The ABA presented a variety of annual honors to recognize its players and executives. There were six awards presented by the ABA. Three Most Valuable Player awards were presented annually in the All-Star Game, the regular season, the playoffs. In sports, the player judged to be the most important to the team is the Most Valuable Player. Other annual awards include the Executive of the Year, the Coach of the Year, the Rookie of the Year. Honors were presented to players who excelled in the respective categories of: best players, best defensive players, best rookies; the Executive of the Year Award and the All-Defensive Team started in the 1972–73 season, while the rest started in the first season. Julius Erving has won the most ABA awards with five MVP awards—three in the regular season and two in the playoffs. Artis Gilmore has won the most ABA honors with nine.
A total of 80 ABA players and executives have received honor. The American Basketball Association Finals were the championship series of the ABA, a professional basketball league, in which two teams played each other for the title; the ABA was formed in the fall of 1967, the first ABA Finals were played at the end of the league's first season in the spring of 1968. The league ceased operations in 1976 with the ABA–NBA merger and four teams from the ABA continued play in the National Basketball Association. All ABA Finals were in best-of-seven format and were contested between the winners of the Eastern Division and the Western Division finals; the only teams to win the championship more than once were the New York Nets. The Indiana Pacers played in the ABA Finals in 1969, which they lost to the Oakland Oaks, but they won the championship the next year against the Los Angeles Stars, they won in the ABA Finals again in 1972, their first after moving to the Western Division, against the New York Nets and won their final ABA championship against the Kentucky Colonels in 1973.
The New York Nets won their first championship in 1974 against the Utah Stars, their second against the Denver Nuggets in 1976. The last ABA Finals were in 1976; the Most Valuable Player was an annual award first awarded in the 1967–68 season. Every player who has won the award has played for a team with at least 45 regular-season wins; the inaugural award winner was Hall of Famer Connie Hawkins. Hall of Famer Julius Erving won the award all with the New York Nets. Mel Daniels won it twice with the Indiana Pacers. Erving and George McGinnis were joint winners in the 1974–75 season. Seven of the award winners were capable of playing forward, while six were capable of playing center. Two rookies have won the award: Spencer Haywood in the 1969–70 season and Artis Gilmore in the 1971–72 season. With the announcement of McGinnis as a member of the Naismith Memorial Basketball Hall of Fame class of 2017, every ABA MVP has been inducted into the Hall of Fame; the Rookie of the Year Award was an annual award first awarded in the 1967–68 season, to the top rookie of the regular season.
The inaugural award winner was Mel Daniels, who won two MVP awards during his ABA career. Two of the Rookie of the Year winners have won the MVP award in the same season: Spencer Haywood in the 1969–70 season and Artis Gilmore in the 1971–72 season. Two Rookie of the Year winners have been elected to the Naismith Memorial Basketball Hall of Fame: 1970–71 Rookie of the Year Dan Issel and 1975–76 Rookie of the Year David Thompson. Issel and Charlie Scott were joint winners in the 1970–71 season; the Coach of the Year was an annual award first awarded in the 1967–68 season, to the best head coach of the regular season. The inaugural award winner was Vince Cazzetta, who coached the Pittsburgh Pipers to an ABA championship. Oakland Oaks coach Alex Hannum won the award the season after, coached his team to an ABA championship. Larry Brown won the award three times, is the only coach to have won the award multiple times. Two seasons had joint winners—Joe Belmont and Bill Sharman in the 1969–70 season as well as Joe Mullaney and Babe McCarthy in the 1973–74 season.
Hannum and Brown are the only recipients to have been inducted to the Naismith Memorial Basketball Hall of Fame. Every head coach won the award without a losing record; the Playoffs Most Valuable Player Award was an annual award given in the ABA Playoffs. The award was first awarded in the 1968 ABA Playoffs, was retired as part of the ABA–NBA merger; the inaugural award winner was Pittsburgh Pipers' player Connie Hawkins. On all occasions, the player who wins the Playoffs MVP award was from the team that won the ABA championship. Julius Erving, who led the New York Nets to two ABA championships in 1974 and 1976, is the only player to win the award twice; the All-Star Game Most Valuable Player was an annual award given to the best player of the annual All-Star Game. The award was established in the 1968 All-Star Game, was retired as part of the ABA—NBA merger; the first recipient of the award was Larry Brown. Brown and 1971 winner Mel Daniels are the only players to win the award while being on the losing team in the All-Star Game.
Three rookies have won the award: Brown, Spencer Haywood in the 1970 All-Star Game and David Thompson in the 1976 All-Star Game. From 1968 to 1975, the game has matched the best players in the Eastern Division with the best players in the Western Division; the West has won five All-Star Game MVP award
Jeffrey Roger Goodwin is a professor of sociology at New York University. He holds a MA and PhD from Harvard University, his research interests include social movements, political violence, terrorism. He is a past chair of the Comparative and Historical Sociology Section and the Collective Behavior and Social Movements Section of the American Sociological Association; the underlying argument of his best known book, No Other Way Out: States and Revolutionary Movements, 1945-1991, is that revolutionary movements are not only a response to economic inequality or exploitation, but are a response to political repression and violence. Goodwin has written and edited a number of works with his friend and former NYU colleague James M. Jasper, they wrote a famous critique of the political-opportunity theory developed by Charles Tilly and Doug McAdam, republished in Rethinking Social Movements, which Goodwin and Jasper edited. They edited The Contexts Reader, Social Movements, The Social Movements Reader, Passionate Politics, a leading work in the sociology of emotions.
In October 2011, Goodwin was one of 132 New York University faculty and staff members who signed a statement calling for disinvestment in several American companies that do business in Israel. In response to sharp criticism from Congressman Gary Ackerman, Goodwin accused Ackerman of moral blindness and stated that "Ackerman's apparent denial that Israel is occupying Palestinian territories and systematically violating basic Palestinian rights is shocking." No Other Way Out: States and Revolutionary Movements, 1945-1991. Cambridge: Cambridge University Press, 2001 ISBN 978-0-521-62069-7 Passionate Politics: Emotions and Social Movements. Co-edited with James M. Jasper and Francesca Polletta. Chicago: University of Chicago Press, 2001 ISBN 978-0-226-30399-4 Rethinking Social Movements: Structure and Emotion. Co-edited with James M. Jasper. Lanham, MD: Rowman & Littlefield, 2004. ISBN 978-0-7425-2596-2 The Social Movements Reader: Cases and Concepts. Co-edited with James M. Jasper. New York: Blackwell, 2003.
ISBN 978-0-631-22196-8 "'The Struggle Made Me a Non-Racialist': Why There Was So Little Terrorism in the Antiapartheid Struggle," Jeff Goodwin, Vol. 12, No. 2, pp. 193–203. "How Not to Explain Terrorism," Jeff Goodwin, European Journal of Sociology, Vol. 47, No. 3, pp. 477–82. "A Theory of Categorical Terrorism," Jeff Goodwin, Social Forces, Vol. 84, No. 4, pp. 2027–46. "What Do We Really Know About Terrorism?," Jeff Goodwin, Sociological Forum, Vol. 21, No. 2, pp. 315–30. "What Must We Explain to Explain Terrorism," Jeff Goodwin, (a review essay on Jessica Stern, Terror in the Name of God: Why Religious Militants Kill, Social Movement Studies, Vol. 3, No. 2, pp. 259–65. Personal homepage Homepage at NYU