Abstract:

Density Functional Theory(DFT) of quantum chemistry method was used to investigate the proton transfer reactions of 6-methyl-4-hydroxy pyrimidine monomer and dimer. By studying the potential energy surface of the isomerization,it was found that there were 9 monomer isomers and 9 transition states in possible reaction pathways. The most stable structure of monomers was analyzed. The lowest and largest reaction activation energy were 22.06 and 356.55 kJ/mol,respectively. The most possible reaction pathways could proceed at room temperature. Two dimers and their transition states were also investigated and it was found that all dimer were more stable than the corresponding monomers. The reaction activation energy of the dimer tautomerization was less than that of the corresponding monomer. Hydrogen bond played an sticking role in those changes and the energies of hydrogen bond were calculated from the total energies of monomers and dimers.

Key words: 6-Methyl-4-hydroxy pyrimidine; Density functional theory; Tautomerization; Transition states; Hydrogen bond