Primary and secondary ${alpha}$-deuterium kinetic isotope effects are determined with deuterated aniline nucleophiles in the nucleophilic substitution reactions of benzyl benzenesulfonates and 1-phenylethyl benzenesulfonates in acetonitrile at 30.0^{circ}C. The $k_H/k_D$ values support our previous conclusions regarding the transition state structures proposed for the two reactions based on the cross-interaction constants ${ ho}_{ij}$; the former is a typical $S_N2$ reaction whereas in the latter the four-center transition state may be involved.