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In chemistry, a polyyne is any organic compound with alternating single and triple bonds; that is, a series of consecutive alkynes, with ''n'' greater than 1. The simplest example is diacetylene or buta-1,3-diyne, H−C≡C−C≡C−H. These compounds have also been called oligoynes,〔 〕 or carbinoids after "carbyne" , the hypothetical allotrope of carbon that would be the ultimate member of the series.〔 〕〔 In ''Avancés récentes en chimie des acétylènes – Recent advances in acetylene chemistry'' 〕 The synthesis of this substance has been claimed several times since the 1960s, but those reports have been disputed.〔 Indeed, the substances identified as short chains of "carbyne" in many early organic synthesis attempts would be called polyynes today. Polyynes are distinct from polyacetylenes, polymers formally obtained by polymerization of acetylenes. The backbones of polyacetylenes have alternating single and double bonds . In biochemistry and plant biology, "polyacetylene" is routinely used to describe naturally occurring polyynes and related species.〔 Along with cumulenes, polyynes are distinguished from other organic chains by their rigidity, which makes them promising for molecular nanotechnology. Polyynes have been detected in interstellar molecular clouds where hydrogen is scarce. == Synthesis == The first reported synthesis of polyynes was performed in 1869 by Carl Glaser, who observed that copper phenylacetylide (CuC2C6H5) undergoes oxidative dimerization in the presence of air to produce diphenylbutadiyne (C6H5C4C6H5).〔 Using various techniques, polyynes with ''n'' up to 4 or 5 were synthesized during the 1950s.〔 Around 1971, T. R. Johnson and D. R. M. Walton developed the use of end-caps of the form −, where R was usually an ethyl group, to protect the polyyne chain during the chain-doubling reaction using Hay's catalyst (a copper(I)-TMEDA complex).〔 〕〔 〕 With that technique they were able to obtain polyynes like with ''m'' up to 8 in pure state, and with ''m'' up to 16 in solution. Alkynes with the formula and ''n'' from 2 to 6 can be detected in the decomposition products of partially oxidized copper(I) acetylide ( (an acetylene derivative known since 1856 or earlier) by hydrochloric acid. A "carbonaceous" residue left by the decomposition also has the spectral signature of chains.〔 〕 Organometallic polyynes capped with metal complexes are well characterized. To date, the most intense research has concerned rhenium (ReCnRe, ''n''=6-20), ruthenium (RuRuCnRuRu, ''n''=8-20), iron (FeC12CFe), platinum (PtCnPt, ''n''=16-28), palladium (ArCnPd, ''n''=6-10), and cobalt (Co3CnCo3, ''n''=14-26) complexes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「polyyne」の詳細全文を読む スポンサード リンク
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