Theoretical study on the alcoholization mechanism of benzothiadiazole

The alcoholization reaction mechanism and kinetics of benzothiadiazole were studied by HF and B3LYP method sat the level of 6-31G~.The geometric structures of reactants,products,intermediates,and transition states in the reactions were optimized,and vibrational analysis and IRC calculation were preformed to confirm intermediates and transition states.Besides,the rate constants of the reaction were calculated by the classic transition state theory.The results showed that the alcoholization reaction of benzothiadiazole has several pathways and many steps.The activation energies of controlling steps in two paths were 162.5kJ/mol and 140.1kJ/mol,respectively.So the pathway:R+CH_3OH→TS1'→P1+P2 had the smallest activation energy and was the main reaction pathway.