用H2O2氧化苯乙烯合成苯甲酸

摘要：以30％H2O2做为氧化剂，钨酸钠与含O双齿有机配体(草酸)形成的络合物为催化剂，在无有机溶剂、无相转移剂的条件下，研究了苯乙烯氧化制苯甲酸的反应。研究结果表明，最佳反应条件为：苯乙烯100．0mmol，n(钨酸钠)：n(草酸)：n(苯乙烯)：n(30％H2O2)=2．0：3．2：100．0：440．0，于92℃反应24h，苯甲酸收率98．6％。用GC—MS跟踪了氧化过程中4种主要物质苯乙烯、1-苯基邻二醇、羟基苯乙酮及苯甲酸含量随反应时间的变化关系，提出了其主要氧化机理为苯乙烯经过环氧化反应、水解生成生成1-苯基邻二醇，1-苯基邻二醇再氧化为羟基苯乙酮、最后氧化为苯甲酸。

Highly Selective Oxidation of Styrene to Benzoic Acid with H2 O2 as an Oxidant

The oxidation of styrene to benzoic acid was described. 30% aqueous hydrogen peroxide(H2O2) was used as an oxidant and the reaction was catalyzed by coordination compound system which including the peroxotungstate formed in situ from sodium tungstate dihydrate and oxalic acid without halides and organic solvent. The influences of the reaction conditions including temperature, time, amounts of catalyst and ligand were studied. The results showed that when styrene was 100.0 mmol, the optimum molar ratio of sodium tungstate dihydrate, oxalic acid, styrene and 30% H2O2 was 2.0 ∶ 3.2 ∶ 100.0 ∶ 440.0. The reaction mixture was stirred at 92 ℃ for 24 h, giving benzoic acid in yield of 98.6%. At the same time the products of the oxidation of styrene were characterized by GC-MS(EI, CI source) and GC-IR.According to the analysis of the products, benzoic acid may form via phenol-1,2-ethanediol and α-hydroxyacetophenone intermediate.