2,6-二甲基苯酚的合成研究

Study on the Preparation of 2,6-Dimethylphenol

2,6-二甲基苯酚是重要的化工原料和精细化工中间体,可以用作合成工程塑料聚苯醚和改性聚苯醚的单体,也可用于高温环氧树脂、农药的生产,还可作照相用药剂,同时还是一些药物的原料和中间体,如抗心律失常药慢心律及维生素E等。2,6-二甲基苯酚的合成国内外已有报道,主要有苯酚的氨甲基化法、卤代苯酚的取代、二甲苯的氧化,但条件都比较苛刻。现在多采用苯酚和邻甲酚与甲醇在催化剂存在下于气相状态下进行反应,催化剂多用氧化镁等金属氧化物,需在高温下反应,且选择性不高,会产生很大比例的对位产物,使质量受到影响。有文献报道用2,6-二甲基苯胺为原料,经重氮化、水解而得产物,水解都是在浓酸(80%的浓度)和高温(160℃)下反应,焦油多、副产物多,本文对此法进行了研究改进,在催化剂硫酸铜的存在下,使水解条件变得温和,水解液可以重复使用,降低了成本,提高了收率,具有重要的应用价值。

2,6-Dimethylphenol was prepared by the diazotization reaction of 2,6-dimethylphenylamine with sodium nitrite in dilute solution of sulfuric acid to form diazonium salt,then the salt was hydrolyzed in the solution of sulfuric acid with copper sulfate.The optimum process conditions were determined:n (2,6-dimethyphenylamine):n(sulfuric acid):n(sodium nitrite) =1.0:3.0:1.05,the concentration of sulfuric acid for hydrolysis initially was 40%,reaction temperature was 120℃.The yield of final product was 87.5%.The target product was confirmed by elemental analysis.IR and ~1HNMR.