3,5-二甲基苯酚的合成与应用

Preparation and application of 3,5-dimethyl phenol

以间二甲苯和异丙醇为原料,经过烷基化、氧化、酸解反应合成3,5-二甲基苯酚。对反应产物结构进行了表征,并通过不断优化,确定了反应总收率在50%左右的反应工艺条件。烷基化工艺条件:原料摩尔比n(间二甲苯)∶n(异丙醇)∶n(三氯化铝)=8∶1∶1,反应温度为70℃,反应时间为7 h,在此工艺下产品收率为75%,纯度为90%;氧化工艺条件:5-异丙基间二甲苯30 g,NHPI 3.26 g,AIBN 1.0 g,乙腈200 m L,空气流速为600 m L/min,反应温度50℃,反应时间16 h;酸解工艺条件:氧化反应液20 g,浓硫酸与丙酮混合液50 g(浓硫酸质量分数为5%),反应温度为50℃,反应时间为2 h。最终通过实验得出适合整个反应的最优化工艺条件,完成了3,5-二甲基苯酚的实验室合成,同时为工业化开发3,5-二甲基苯酚新型合成路线提供了依据。

Using m-xylene and isopropyl alcohol as raw materials ,through alkylation ,oxidation,acidolysis reaction to obtain 3,5-dimethyl phenol .The structure of reaction product was characterized ,and through continuous optimization ,determine the reaction process conditions that the total yield of 3 ,5-dimethyl phe-nol can over 50%.The best conditions of preparation of the alkylation reaction were got as follows：the molar ratio of n（m-xylene）∶n（isopropyl alcohol ）∶n（aluminum chloride）=8∶1∶1,the reaction tempera-ture of 70℃,the reaction time of 7 h,in these conditions ,the yield of product is 75%,the purity is 90%;The best conditions of preparation of the oxidation reaction were got as follows：5-isopropyl-m-xylene 30 g,NHPI 3.26 g,AIBN 1.0 g,acetonitrile 200 mL,air velocity is 600 mL/min,the reaction tempera-ture of 50 ℃,the reaction time of 16 h;and the best conditions of preparation of the acidolysis reaction were got as follows：the liquid of oxidation reaction 20 g,the miscible liquids of concentrated sulfuric acid and acetone （ mass fraction of concentrated sulfuric acid is 5%） ,the reaction temperature of 50℃,the re-action time of 2 h.Finally,the optimum process conditions of the reaction was selected through experi-ment,completed the synthesis of 3,5-dimethyl phenol in the laboratory .At the same time,it provide the basis for the new synthetic route of 3 ,5-dimethyl phenol in industry .