关键词: 分子模拟, 氧化, 醛, 羧酸

Abstract: Density functional theory (DFT) simulation method was applied to study the oxidization process of acetaldehyde to acetic acid. Simulation results suggest that, chain initiation step should be the most difficult step under anaerobic condition with a reaction energy barrier 380.78 kJ/mol. However, with the presence of oxygen, the reaction energy barrier could be decreased to116.26 kJ/mol. It has been found that reaction energy barriers in each step of acetyl free radicals reacting to peracetic acid are quite low, and also in chain termination step. It is also noticed that the reaction of peracetic acid to acetic acid is difficult to take place, and it should be the rate control step in the overall reaction process. There are two possible reaction paths in the process. The reaction rate control steps could be homolytic cleavage of peracetic acid to generate acetic acid free radical and hydroxyl free radical, or the reaction of acetaldehyde with peracetic acid to produce acetaldehyde monooxyacetate. The reaction energy barriers of the above two reactions are 147.18 kJ/mol and 137.21 kJ/mol, respectively.

Key words: molecular simulation, oxidation, aldehyde, carboxylic acid