Effects of electron acceptors and radical scavengers on nonchain radical nucleophilic substitution reactions

The yields of reaction products from thermal nucleophilic substitution reactions in dimethyl sulfoxide (DMSO) of six o- and p-nitrohalobenzenes (1) with the sodium salt of ethyl alpha-cyanoacetate carbanion [Na+-CH(CN)CO2Et) (2) were found to be markedly diminished by addition of small amounts of strong electron acceptors (p-dinitrobenzene, m-dinitrobenzene, and o-dinitrobenzene) (Table II), but little or no diminished effects on the yields of reaction products were observed by addition of radical scavengers (such as galvinoxyl, nitroxyl, etc.) (Table III). The results are consistent with the conclusion that these reactions proceed via a nonchain radical nucleophilic substitution mechanism.