Nucleophilic reactions in ethylenic derivatives. Part XIII. Base-catalysed elimination from cis-halogenostyrenes in t-butyl alcohol

Abstract

cis-β-Halogenostyrenes react with t-butoxide in t-butyl alcohol to give phenylacetylenes following an E2-mechanism as shown by several tests. The variations caused by the solvent–base systems on the structure of the transition state have been investigated by means of isotope effects. All evidence points to a shift toward a more ‘reactant like’ transition state on passing from MeO^––MeOH to Bu^tO^–Bu^tOH.