This study demonstrated the kinetics of nucleophilic substitution reactions of butyl methyl chlorophosphate (2) with X-anilines (XC6H4NH2) and deuterated X-anilines (XC6H4ND2) in MeCN at 55.0 +/- 0.1 degrees C together with the general optimized method for the synthesis of 2 under mild conditions. Different spectroscopic characterizations revealed the formation of 2 with high purity. The free energy relationship with the substituents X in the anilines exhibited biphasic concavity upwards with a break point at X = H, which induced large negative rho X and small positive beta X values. The deuterium kinetic isotope effects (DKIEs) were secondary inverse (k(H)/k(D) < 1: 0.702-0.918) and the magnitudes were increased with the change of nucleophiles from weakly basic to strongly basic anilines. A concerted mechanism with a rate-limiting leaving group departing from the intermediate is proposed based on the selectivity parameters and the variation of DKIEs with X.