相转移催化下蒎烯的环氧化反应

Phase-transfer catalytic epoxidation of α-pinene and β-pinene

采用季铵盐A 1作相转移催化剂 ,质量分数为 5 0 %的H2 O2 作氧化剂 ,三氯甲烷作溶剂 ,在加入少量钨酸钠的条件下 ,实现了α 蒎烯和 β 蒎烯的环氧化反应 .考察了季铵盐 (A 1)的浓度、钨酸钠浓度、H2 O2 与蒎烯的量比、反应温度对环氧化反应的影响 .结果表明 ,季铵盐和钨酸钠的浓度分别为 0 .0 6 ,0 .0 3mol/L时的催化效果最佳 ;α 和 β 蒎烯的转化率随着H2 O2 与蒎烯的量比增大而增大 ,当H2 O2 与α 蒎烯和 β 蒎烯的量比分别为 2 .0和 1.8时 ,其转化率均可达到 10 0 % ;较高的温度不利于环氧化反应的进行 ,因此 ,环氧化反应温度需控制在 2 0℃以下 .

The epoxidation of α-pinene and β-pinene by 50% (mass fraction) hydrogen peroxide and a small amount of sodium tungstate, in the presence of quaternary ammonium salt A-1 as a phase transfer catalyst, is carried out. The effects of the A-1 concentration, the sodium tungstate concentration, the molar ratio of H_2O_2 to pinene, and the reaction temperature are investigated. The epoxidation can be performed well when the concentration of quaternary ammonium salt and sodium tungstate is 0.06 mol/L and 0.03 mol/L, respectively. The conversions of pinene increase with the increase of the molar ratio of hydrogen peroxide to pinene, and when the molar ratios of H_2O_2 to α-pinene and β-pinene are raised to 2.0 and 1.8 respectively, the conversion rate of α-pinenes or β- pinenes can both reach 100%. In addition, low reaction temperature is beneficinl to the epoxidation, and thus the epoxidation should be conducted below 20 ℃.