Kinetics and Mechanism of the Anilinolysis of p-p-Diclyclohexyl Phosphinic Chloride in Acetonitrile

초록

The reactions of p-p-dicyclohexyl phosphinic chloride (1) with X-anilines in acetonitrile at 60.0 °C are studied kinetically. The Hammet ρX (ρnuc = &#8722;1.95) and Br&ouml;nsted βX (βnuc = 0.71) values, and the secondary inverse kinetic isotope effects (kH/kD = 0.843 < 1) involving deuterated aniline (XC6H4ND2) nucleophiles are obtained. The small magnitudes of ρX and βX values, and secondary inverse DKIEs suggest a concerted SN2 mechanism with early transition state (TS) involving predominantly backside nucleophilic attack. Relatively much smaller rates of 1, compared to other chlorophosphinates is rationalized by the steric effects of the cyclohexyl ligands.