α,N-ジフェニルニトロン類の亜リン酸トリエチルによる脱酸素反応

The rates of deoxygenation by triethyl phosphite have been measured for α, N-diphenylnitrone and its mono-substituted derivatives. The kinetic expression of the reaction is of first order with both triethyl phosphite and nitrones respectively. The rate was enhanced by electronwithdrawing substituents, and retarded by electron-donating substituents on either phenyl group of the nitrones. A good Hammett correlation with σp substituent constants was obtained.(ρx= +1.18, r = 0.996; ρy= +1.47, r = 0.987)Introduction of methyl group at ortho-position of N-phenyl group on the nitrone slowed down the reaction rate because of the steric hindrance effect. All these data seem to suggest that the deoxygenation reaction proceeds through nucleophilic attack by triethyl phosphite on the nitrogen atom of nitrone.