Synthesis, kinetic study, and reaction mechanism: nucleophilic substitution reactions of butyl methyl chlorophosphate with substituted anilines and deuterated substituted anilines in acetonitrile

Abstract

This study demonstrated the kinetics of nucleophilic substitution reactions of butyl methyl chlorophosphate(2) with X-anilines (XC6 H4 NH2) and deuterated X-anilines (XC6 H4 ND2) in MeCN at 55.0 ± 0.1 °C together with thegeneral optimized method for the synthesis of 2 under mild conditions. Different spectroscopic characterizations revealedthe formation of 2 with high purity. The free energy relationship with the substituents X in the anilines exhibited biphasicconcavity upwards with a break point at X = H, which induced large negative ρX and small positive βX values. Thedeuterium kinetic isotope effects (DKIEs) were secondary inverse (kH /kD < 1: 0.702–0.918) and the magnitudes wereincreased with the change of nucleophiles from weakly basic to strongly basic anilines. A concerted mechanism witha rate-limiting leaving group departing from the intermediate is proposed based on the selectivity parameters and thevariation of DKIEs with X.