Base-catalysed hydrogen-exchange in some substituted [1-3H]acetylenes

Abstract

The rates of detritiation of X·CC·³H compounds (X ClCH₂, lCH₂, BrCH₂, Alkyl, PhCH₂, Ph, and Me₃Si) by buffered water–methanol (4 : 1 v/v)(pH ca. 8·05) have been measured at 25°. For the compounds with X HalCH₂ or Alkyl, the effects of substituents correlate reasonably well with their Taft σ*-constants. The compounds PhCC³H, and particularly, Me₃SiCC³H are more reactive than would be expected from operation of inductive effects alone, and it is suggested that in these cases there is some conjugative withdrawal of electrons from the alkynyl group.