Acetylene homologues

The higher acetylenic homologues have been prepared by Burton and Spawn from 1,1,1,2,2-pentachloroperfluoroalkanes and Zn in DMF (equation 94). The pentachloro precursors were obtained from the corresponding commercially available... 

Vogt, "The Chemistry of Acetylene," Rein-hold,NY (1945) 4)P.Piganiol,"Acetylene, Homologues et Derive es, Masson,Paris (1945) 5)R.L.Hasche,ChMetEng 52,No 10, 116-19(1945)(Acetylene industry in wartime Germany) 6a) SP. Reppe, "Advances in Acetylene Chemistry (as developed at the IG Farbenindustrie A-G), PB Rept 1112(CWS IDR No 4149Xabout 1946) 6b)w. Reppe,... 

Vogt, "The Chemistry of Acetylene, Reinhold,NY( 1945) 4)P.Piganiol,"Acetylene, Homologues et De rive es, Masson,Paris (1945) 5)R L Hasche, ChMetEng 52,No 10,... 

P.Piganiol, "Acetylene Homologues, and Derivatives, Mapleton House, Brooklyn... 

P.Piganiol, "Acetylene Homologues, and Derivatives," Mapleton House, Brooklyn (1950X3 ranslated from the French by F.A. Hessel J.B.Rust), 276-9(NumefDUS references are given) 6c M.KouIkes... 

A brown explosive form is produced if excess sodium is used in preparation of thiophene homologues—possibly because of sulfur compounds [1], As normally produced, it is a dry stable solid, but material prepared from acetylene and sodium-oil dispersions ignites in air [2],... 

Solutions ofLiC=CH and NaC-CH in liquid NHj are mostly prepared by the so-called titration method, which involves controlled addition of pieces of metal to boiling ammonia while introducing acetylene. The blue colour of the dissolved metal serves as an indicator. This method is also applicable in the case of homologues, but is less attractive for economical reasons (one third of the acetylene is reduced to ethene). Derivauzation of solutions of HCsCM obtained from MNH2 or M and acetylene, in most cases gives only minor amounts of disubstituied acetylenes RCsCR, so it is inferred that di-metallated acetylene C C occurs at best in only very small concentrations in liquid ammonia. 

Commercially available VP is usually over 99% pure but does contain several methyl-substituted homologues and 2-pyrrolidinone. The vinylation of 2-pyrrolidinonc is carried out under alkaline catalysis analogous to the vinylation of alcohols. 2-Pyrrolidinone is treated with ca 5% potassium hydroxide, then water and some pyrrolidinone are distilled at reduced pressure. A ca 1 1 mixture (by vol) of acetylene and nitrogen is heated at 150- L60°C and ca 2 MPa (22 atm). Fresh 2-pyrrulidiuone and catalyst are added continuously while product is withdrawn. Conversion is limited to ca 60% to avoid excessive formation of hy-products. The AI-vinyl-2-pynolidinone is distilled at 70-85°C at 670 Pa (5 mm Hg) and the yield is 70-80%. 

It was shown that, on aging in air, copper(I) acetylide oxidises to this, which was also prepared independently from butadiyne. It also seems to result from reaction of copper solutions of mixed I and II valencies with acetylene. Further oxidation appears to give higher homologues. The explosive properties remain. Essentially, this is the Cu II mediated oxidative coupling, by which higher acetylenes are normally prepared synthetically, operating spontaneously. 

Synthesis of a 26jt-electron homologue 81 (1992JA9969) (Scheme 37) has been achieved via the reductive dimerization of dialdehyde 84, prepared from iodopyrrole 82 and an acetylene, employing Sonogashira coupling to obtain 83 after deprotection. For p-methyl-substituted derivatives, a refined procedure has been reported by Kim et al. (1999JOC8048). Similarly 85 obtained from intermediate 83 has been converted into 80. 

Higher homologues of acetylene can also be obtained from acetylene itself. Acetylene is converted into acetylide and the acetylide is reacted with alkyl halide to get a higher homologue. 

Symmetrical triply bridged phane hydrocarbons of type 14 were reported by Hubert and Dale in 1965 36 Their synthetic method — cyclizing trimerization of appropriate acetylene precursors — made the members 14a-14g accessible36,31 but failed with the highly strained [2.2.2]phane 2. In its UV-spectrum 14a differs from its higher homologues chiefly by less intensive absorption and by quenched vibrational... 

It is best to speak at this time of hydrocarbons derived from benzene by the substitution in the ring of unsaiurated open chain radicals. Just as the homologues of benzene are prepared by substitution of a saturated paraffin radical, methyl, ethyl, propyl, etc., in the benzene ring, so other series of hydrocarbons have been obtained by substituting radicals of the unsaturated open chain hydrocarbons of the ethylene and acetylene series. These new compounds will be poorer in hydrogen than the benzene series by two and four atoms respectively. 

The CD spectra of polymers of a series of homologue chiral terminal acetylenes shows a marked dependence on the distance of the asymmetric centre from the triple bond. The relation between the two facts is however unclear, even because the UV spectrum results from the superposition of several bands, owing to the extended conjugation. 

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