1.3- Butadiyne, from oxidative coupling

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. 

Functionahzed polymers can be prepared from m-substituted phenols the HRP-catalyzed oxidative polymerization of m-ethynylphenol (76) using hydrogen peroxide in a solution of methanol/phosphate buffer (pH 7, 50 50 vol %) under air resulted in a phenol polymer having the ethynyl groups unaffected in the side chain [132]. hi contrast, a reaction with a conventional oxidation catalyst (Cu(I)Cl/TEED) led to coupling of the acetylene moiety to produce bis(3-hydroxyphenyl)butadiyne (78, Scheme 17) [132]. 

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