Pentadiynes

Heating for longer periods gave more 1,3-pentadiyne. 

Pentadiyn-l -ylcopper Dimethyl-1 -propynylthallium Triethynylaluminium Triethynylantimony Bis(Dimethylthallium) acetylide Tetraethynylgermanium Tetraethynyltin... 

The first such compound to be prepared was the deep-yellow unstable compound 9-arsa-anthracene but the thermally stable colourless arsabenzene (arsenin) can now conveniently be made by a general route from l,4-pentadiyne ... 

The first approach to lithium boratabenzenes (Scheme 3) was an elegant adaption of a more general synthetic strategy (81). Hydrostanna-tion of 1,4-pentadiyne (82) with Bu2SnH2 gives the stanna-2,5-cyclohexadiene 24 (83,84), which on treatment with PhBBr2 produces... 

A derivative of the oxo form of a 3-hydroxyselenophene has been obtained by a quite different route.123 1,5-Diphenyl-1,4-pentadiyn-3-one (94) adds hydrogen selenide and gives a mixture of 2,6-diphenyl-1-seleno-y-pyrone (95) and 2-benzylidene-3-oxo-5-phenyl-2,3-dihydroselenophene (96). 

Figure 5.5 Alkanes, alkenes, aromatics and cyanopolyynes 1, methane 2, ethene 3, propene 4, benzene 5, acetylene 6, propyne 7, butadiyne 8, pentadiyne 9, hexatriyne 10-14, cyanopolyynes (the largest family with the longest molecule to date, 14). (Reproduced from Guillemin et at. 2004 by permission of Elsevier)...

Phenylmercuric acetate, with methallyl alcohol to yield 2-methyl-3-phenylpropion-aldehyde, 51, 17 1-PHENYL-1,3-PENTADIYNE, 50,... 

Ethynylallenes [35], the didehydro analogs of vinylallenes, have also been known for some time, the parent system 7 having been obtained in 1960 by reduction of 3-chloro-l,4-pentadiyne (101) with zinc-copper couple in butanol [36] and the 5-methyl derivative 103 by base-catalyzed isomerization of 1,4-hexadiyne (102) with sodium ethoxide in ethanol (Scheme 5.13) [9]. 

When the diyne is already conjugated as in 1,3-pentadiene 52, with 4 equivalents of nBuLi-TMEDA, an isomerization can also be achieved [91] (Scheme 1.22). The selectivity of this process is low starting material and 1,4-pentadiyne are also found. 

Nitrophenylpropiolic acid, 3113 2-Nonen-4,6,8-triyn-l-al, 3112 Octacarbondioxide pentamer, 3904 Octacarbondioxide tetramer, 3884 Octatetrayne-l,8-dicarboxylic acid, 3235 Oligo(octacarbondioxide), 3108 1,3-Pentadiyne, 1825 2-Penten-4-yn-3-ol, 1879 Phenoxyacetylene, 2920... 

Pentadiyn-l-ylsilver, 1815 Potassium acetylide, 0987 l-Propynylcopper(I), 1098 Rubidium acetylide, 1025 Silver acetylide, 0568... 

Heptasilver nitrate octaoxide, 0047 Nitrogen triiodide-silver amide, 4634 1,3-Pentadiyn-l-ylsilver, 1815 Pentasilver diamidophosphate, 0046 Pentasilver orthodiamidophosphate, 0044 Phenylsilver, 2217... 

Phenyl isocyanate, with ethyl hydrazine-carboxylate to give 4-phenyl-l-car-bethoxysemicarbazide,51,122 Phenylmercuric acetate, with methallyl alcohol to yield 2-methyl-3-phenyl-propionaldehyde, 51, 17 1-PHENYL-1,3-PENTADIYNE, 50, 97 1-PHENYL-1,4-PENTADIYNE. 50, 97 a-Phenylpentanal, from 2-benzyl-4,4,6-trimethyl-5,6-dihydro-l,3(4H)-... 

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