The Deoxygenation of α-Phenyl-N-alkylnitrones by Trialkyl Phosphites

Abstract

The rates of deoxygenation by trialkyl phosphites were measured for ev-phenyl-N-aikylnitrones.The reaction rates are of first order with both trialkyl phosphites and nitrones respectively.The Arrhenius plot of rate constants vs.temperature gives a straight line. The activation energy (dE), activation entropy (dS) afford 20.0 kca!/mol and -28.2 e.u. (at 1200C) respectively.The relative rates of n itrones with TEP t the Taft equation, 1o9(k/ko)= 2.47 *+1 53 E, and those of phosphites with N-ethylnitrone fit the Taft equation, log(k/kg)=-1.23 g*+2.86 E, .These facts seem to suggest that the deoxygenation reaction proceeds through nuleophilic attack of the phosphorus ato of phosphite on the nitrogen atomofnitrone.