A mechanistic study of 1,3,5-trisubstituted-1,2,3-triazoles by Ab initio method

The mechanism of synthesis of 1,3,5-trisubstituted-1,2,4-triazoles from 3-thiopheneacetic acetic acid, 4-pyridine formamidine, and tri-fluoro ethyl hydrazine has been first investigated with B3LYP/6-311++G** method in this article. According to the potential energy profile, it can be predicted that the course of the reaction consists of six elementary reactions. The 3-thiopheneacetic acetic acid and 4-pyridine formamidine form first an intermediate product through a dehydration reaction; the intermediate product further combines with hydrogen ion to form a positive ions; the positive ion reacts with three fluorine ethyl hydrazines by a dehydration reaction to form another positive ions; then, it followed by two isomerization reactions, the final reaction with the acetate ion (Ac−) produces the final product. The research results reveal the laws of synthesis reaction of 1,3,5-trisubstituted-1,2,4-triazoles by the carboxylic acids, amidines, hydrazines, and their derivatives on theoretical level. These studies provide the systematic theoretical basis to design and synthesize new 1,3,5-trisubstituted-1,2,4-triazoles.