Kinetics and Mechanism of the Aminolysis of Cycloalkylmethyl Arenesulfonates

Nucleophilic substitution reactions of cycloalkylmethyl arenesulfonates (CmH2n−1CH2OSO2C6H4Z) with anilines (XC6H4NH2) in methanol at 65.0 °C were studied. The reactivity order (n=4>6>7>5) reflects largely the order of steric effect of the ring size (SEs term) except for n=5, which exhibits the least reactivity. This reversal of the order for n=5 is considered to result from large rate retardation due to polar effect of the ρ*σ* term. Application of the Taft equation to the rate data for n=5 and 6 gives ρ*=17·4 and S=2·3 with correlation coefficient of 0·90. The σ* values for n=4 and 7 are estimated to be −0·23 and −0·11, respectively. The positive ρXZ values of ca 0·3 are consistent with previous results for the reactions at primary reaction centers.