Grignard reaction with acetylene in THF

Kinetics of the reaction between acetylene and phenylmagnesium bromide were investigated in THF and also in the presence of triethylamine. The reactio n proceeds through the formation of bromomagnesiumacetylene (1 1); its furt her reaction with PhMgBr providing bis(bromomagnesium)acetylene (1 2). The disproportionation equilibrium of 1 1, leading to 1 2 and acetylene, which is significant in Et2O solutions, fails in THF. A moderate rate enhancing e ffect of triethylamine in THF solution was found.