KINETIC STUDIES ON THE AMINOLYSIS OF 1-(TRIMETHYLSILYL)ETHYL ARENESULPHONATES IN ACETONITRILE AND METHANOL

Article abstract of DOI:10.1002/poc.610070705

Nucleophilic substitution reactions of 1-(trimethylsilyl)ethyl arenesulphonates with anilines and benzylamines in acetonitrile and methanol at 65.0 deg C were studied.The cross-interaction constants, ρ_XZ, between substituents in the nucleophile (X) and leaving group (Z) are relatively small (0.10 for XC6H4NH2 in MeCN) but similar to those for other S_N2 processes at a secondary carbon atom.This provides further evidence for an approximately constant, loose S_N2 transition state at a secondary carbon regardless of the size of the C_α substituent.The transition-state variations with substituents X and Z are in accord with that expected from the positive ρ_XZ value observed: a stronger nucleophile and/or nucleofuge leads to an earlier transition state, i. e. a lower degree of bond making and breaking.