Abstract: The mechanism of benzyl alcohol oxidation to benzaldehyde catalyzed by Ti/SiO₂ in different solvents was studied by the density function theory B3LYP method. Total six possible reaction pathways and the corresponding optimal structures of reactants, transition states, intermediates, and products were located at the B3LYP/6-31G* level of theory. The reaction barriers were then calculated at the B3LYP/6–311++G(d,p) level of theory both in gas phase and in solvents. The calculation results show that a very high reaction barrier exists for the pathways where no catalyst is involved, suggesting that the oxidation cannot occur, while when Ti/SiO₂ is involved, a reaction barrier about 123.8 kJ/mol is found for that in the acetonitrile solvent, indicating that the oxidation of benzyl alcohol by H₂O₂ to benzyl aldehyde can happen at about 353 K in the acetonitrile solvent. It is also found that the title reaction has a relative lower barrier in non-polar or low-polar solvent but relative higher barrier in a high-polar solvent.

Key words: density function theory, benzyl alcohol, oxidation, reaction mechanism, benzaldehyde, titanium, silica, supported catlayst