Kinetics and mechanism of the anilinolysis of dimethyl and diethyl chloro(thiono)phosphates

The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC6H4ND2) are reported for the reactions of dimethyl chlorophosphate (1), dimethyl chlorothionophosphate (2), diethyl chlorophosphate (3) and diethyl chlorothionophosphate (4) in acetonitrile at 55.0 °C. The obtained kH/kD values are 0.798–0.979, 0.945–1.06, 0.714–0.919 and 1.01–1.10 for 1, 2, 3 and 4, respectively. A concerted mechanism with dominant backside nucleophilic attack is proposed for the reactions of 1 and 3. A concerted mechanism involving partial frontside attack through a hydrogen‐bonded four‐centre‐type transition state (TS) is proposed for the reactions of 2 and 4. Copyright © 2008 John Wiley & Sons, Ltd. Kinetic results yield secondary inverse and primary kinetic isotope effects with deuterated aniline nucleophiles. A concerted mechanism with dominant backside nucleophilic attack is proposed for the reactions of dimethyl and diethyl chloro phosphates, and also a concerted mechanism involving partial frontside nucleophilic attack through a hydrogen‐bonded four‐center‐type TS is proposed for the reactions of dimethyl and diethyl chlorothionophosphate.