Theoretical Studies on Front-side Nucleophilic Substitution Reactions between Pyridines and Isothiocyano Benzene Sulphonates

초록

The reaction mechanism on the pyridinolysis (X-C5H4N) of isothiocyano benzene sulphonates [(YC6H4O) S(=O)2(NCS)] in acetonitrile is investigated computationally using the CPCM approach at the B3LYP/6-311+G(d,p) level of theory. In the front-side attack, the nucleophile pyridine approaches the substrate from the side syn to leaving group (?NCS). Experimentally, nucleophilic substitution to the sulfur center could proceed through two different mechanisms - concerted or stepwise. The concerted mechanism may involve front- or back-side approach of the nucleophile. In the stepwise mechanism, the mechanism can be either associative or dissociative depending on the rate-determining step.