磺化碱熔法制备2,5-二甲基苯酚

Preparation of 2,5-xylenol by sulfonation and alkali fusion

通过对二甲苯磺化、碱熔法合成2,5-二甲基苯酚,研究了影响磺化、碱熔产物收率和纯度的因素。磺化时酸性滤液回收套用,可减少三废,降低生产成本。最佳磺化条件:缓慢把硫酸往对二甲苯中滴加,硫酸与对二甲苯摩尔比为1.6∶1,反应温度125℃,反应时间2.0 h,2,5-二甲基苯磺酸钠收率为96.87%,纯度为99.30%。碱熔时,通入水蒸气、添加抗氧剂和硬脂酸钠,增加了物料的流动性,提高了收率和纯度。最佳碱熔条件:将KOH、NaOH、潮品钠盐、抗氧剂1035(2,2'-硫代双[3-(3,5-二叔丁基-4-羟基苯基)丙酸酯])和硬脂酸钠混合后投入反应釜,NaOH和KOH质量比3∶2,抗氧剂1035为4 g,硬脂酸钠为9 g,330—340℃保温2.0 h,2,5-二甲基苯酚收率为92.70%,纯度为99.45%。

2,5-Xylenol was synthesized by sulfonation and alkali fusion using p-xylene as the starting material. Some factors influencing the yield and purity of the product in the sulfonation and alkali fusion were studied. By recycling and reusing the acidic filtrate in sulfonation the acid wastewater and the cost were reduced. The optimal sulfonation conditions ： sulfuric acid was added to p-xylene slowly, the molar ratio of sulfuric acid and p-xylene 1.6 ： 1, reaction temperature 125 ℃ , reaction time 2.0 h. The molar yield of sodium 2,5-xylenesulfonate is 96.87%, and the purity is 99.30%. In the alkali fusion, water vapor, sodium stearate and antioxidant were added in order to avoid overoxidation and increase the flow of materials, and improve the yield and purity. The optimal alkali fusion conditions： KOH, NaOH, wet sodium salt, antioxidant 1035 and sodium stearate are mixed into a reaction vessel, the mass ratio of NaOH and KOH 3 ： 2, antioxidant 1035 4 g, sodium stearate 9 g, reaction temperature 330-340 ℃, reaction time 2.0 h. The molar yield of 2,5-xylenol in the alkali fusion is 92.70%, and the purity is 99.45%.