羧酸离子液体/氧气催化氧化芳甲醇

Catalytic oxidation of aryl methyl alcohol over carboxylate ionic liquid/O2

摘要:

在组合体系“1-乙基-3-甲基咪唑乙酸盐（[EMIm][OAc]）/O2”作用下，以芳甲醇为原料，经氧化反应，合成了系列芳甲醛（酮）类化合物。通过对条件进行优化，得到适宜反应条件为：芳甲醇与1-乙基-3-甲基咪唑乙酸盐物质量比为1 : 1，氧气压力为0.2 MPa，温度为130 ℃，时间为12 h。在此条件下，实现了苯甲醛克级规模制备，得到20种芳甲醛（酮），产率为65%~96%。根据研究结果与相关文献报道，提出了[EMIm][OAc]通过阴离子作用于苯甲醇，经O2氧化，脱水得到苯甲醛的反应机理。

Abstract:

Series of aromatic formaldehydes (ketones) were synthesized via the oxidation of aryl methyl alcohols in the presence of the combination of 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) and O2. Through screening the reaction conditions, the optimum conditions were obtained as follows: the moles ratio of aryl methyl alcohols and [EMIm][OAc] is 1/1, O2 pressure 0.2 MPa, reaction temperature 130 ℃, and reaction time 12 h. Under the optimal conditions, the gram-scale preparation of benzaldehyde was realized, and 20 aromatic ketones (formaldehydes) products with yields ranging from 65% to 96% were obtained. Moreover, according to related studies and in combination with the results of control experiments, the oxidation reaction mechanism was reasonably proposed: anion [OAc] of [EMIm][OAc] activated benzyl alcohol, O2 oxidation and dehydration to form benzaldehyde.