Evidence for a free radical mechanism in the decomposition of bis(but-2-enyl)tellurium

Article abstract of DOI:10.1016/0022-328X(93)80117-T

Reactions of basic aqueous solution of Na2Te with MeCH=CHCH2Br or CH2=CHCHMeCl give ZZ-, ZE- and EE(MeCH=CHCH2)2.This is interpreted in terms of a mechanism involving attack of Na2Te on the 2-butenyl cation formed from the allyl halide under the basic reaction conditions.The rate of reaction to give the E-configuration is ca. 3 times that to form the Z.Decomposition of (MeCH=CHCH2)2Te in the liquid or gas phases gives all possible products arising from dimerization of the allyl group.This is interpreted in terms of homolytic fission of the Te-C bond followed by coupling of the allyl radicals formed, particularly as no compounds containing CH2-CHCHMeTe are recovered after partial pyrolysis.The products can be fitted to a purely statistical model in which the reactivity ratio of the primary to secondary allyl is ca. 0.63:0.37.The statistical fit is taken to indicate that mechanism other than that involving homolytic fission and free radical coupling play a negligible part.