对伞花烃催化选择氧化制备对异丙基苯甲酸

Synthesis of p-isopropyl Benzoic Acid Via Catalytic Oxidation of p-cymene

研究了在以冰醋酸为溶剂，以醋酸钴为催化剂条件下，原料配比、温度、压力等工艺条件对对异丙基甲苯氧化性能的影响．实验表明，当反应温度363～368K，压力1．8～2．6MPa，原料与溶剂质量比1：4～1：3时，可得到85％以上的对异丙基甲苯转化率和67．6％对异丙基苯甲酸收率；研究助剂Mn^2＋、Br^-等对该反应氧化性能的影响，发现Co／Mn／Br^-三元催化剂明显提高反应的选择性和产率．

p-isopropyl benzoic acid, which is used as manufacturing intermediate for an anti-diabetes drug, Nateglinide, has been synthesized by selective oxidation of p-cymene. The direct oxidation of p-cymene in acetic acid by oxygen was catalyzed by cobalt catalyst system. The kinetic evaluations of catalytic reaction show that the oxygen pressure, reaction temperature, concentration of p-eymene and catalyst have remarkable influence on both conversion and selectivity of oxidation. 67.6 % yield of p-isopropyl benzoic acid is obtained after 2.5 h reaction at 365 K of p-eymene （25. %（mass） in acetic acid） under 2.6 MPa oxygen. Mn^2＋ ,Br^- were introduced into the Co catalyst system as promoters. Although no improving effect is observed when these promoters were added separately,the Co/Mn/Br system,which contains both promoters,presents a significant stimulative catalytic performance for p-cymene oxidation. When the optimized catalyst composition of Co（OAe）2 ,Mn（OAc）2 and NaBr （1 ： 2 ： 1 molar ratio） is involved,the selectivity of p-isopropyl benzoic acid comes up to 83.2% at p-cymene conversion 88.5% ,and an yield of 73.6% is obtained.