THEORETICAL KINETICS STUDY OF TAUTOMERISM OF THYMINE IN GAS PHASE

The current work is a theoretical study of the tautomerism of thymine in the gas phase. 18 structures were found in the isomerization reaction of thymine, which some of which are reported for the first time. Thirty hydrogen transfer reactions were carried out. In 24 of the reactions, the hydrogen abstractions N―H→O, N―H→C, and C―H→O were considered. The potential energy surface for all trajectories was determined for 18 tautomers and 40 transition states. The RRKM-TST model was used to calculate the rate constants of the reactions to examine their kinetics. At temperatures of 250.15 to 425.15 K, nonlinear least-squares fitting were used to calculate the rate constants expressions.