间羟基苯甲酸合成工艺研究

Study on the Synthesis of m Hydroxybenzoic Acid

以苯甲酸为原料经磺化及碱熔两步反应合成间羟基苯甲酸，研究了反应的主要影响因素。磺化反应在１８０℃、苯甲酸与发烟硫酸的摩尔比为１∶３条件下反应３ｈ，碱熔反应在间羧基苯磺酸与氢氧化钠和氢氧化钾混合碱的摩尔比为１∶３．６时反应２ｈ，获得了最佳的反应结果，产品总收率８２％，纯度９９％。

The synthesis of m hydroxybenzoic acid was made from benzoic acid by sulfonation followed by reaction with alkali metal hydroxide.A study of the effects on the synthesis was done,which gave the optimum conditions that sulfonation was run at 180℃ for 3 hrs with 1∶3 mole ratio of benzoic acid to oleum followed by reaction with alkali metal hydroxide at 1∶3.6 mole ratio of m sulfobenzoic acid to sodium and potassium hydroxide for 2 hrs.The total yield is 82% with the product purity of 99%.