2-羟基对苯二甲酸放大工艺

Scale-Up Process of 2-Hydroxyterephthalic Acid

目前2-羟基对苯二甲酸(2-HTA)的生产主要以间羟基苯甲酸、甲酸钾、二氧化碳为原料实验室制备,未见放大生产的报导。为满足市场需求,以间羟基苯甲酸、碳酸氢钾、碳酸钾和氢氧化钾为原料,加入一定量高沸点溶剂,用改进的Koble-Schmi t t法放大生产制备2-羟基对苯二甲酸。考察原料配比、反应温度、反应压力和反应时间对产物收率的影响,用高效液相色谱法(HPLC)分析产物纯度,用DSC测定产物的熔点,用FTIR和1H NMR对产物的结构进行表征。在间羟基苯甲酸与碳酸氢钾、碳酸钾和氢氧化钾物质的量比为2.67∶3.77∶1.3∶1,反应温度180℃,反应压力2.0 MPa,反应时间8 h时,粗产品经混合溶剂一次精制,2-羟基对苯二甲酸的收率达74.87%,纯度99.7%,钾金属离子含量19 mg/kg。结果表明改进的Koble-Schmi t t法放大工艺,成本低、步骤少、环境污染小,适合放大生产。

At present,the 2-hydroxyterephthalic acid(2-HTA) is mainly prepared in the laboratory with m-hydroxybenzoic acid,potassium formate and carbon dioxide as raw materials,and there are no reports of large-scale production.In order to meet the market demand,the m-hydroxyben-zoic acid,potassium bicarbonate,potassium carbonate,and potassium hydroxide are used as raw materials and with a certain amount of solvent with high boiling point to scale up the production of 2-hydroxyterephthalic acid by the modified Koble-Schmitt method.The effects of raw material ratio,reaction temperature,reaction pressure and reaction time on the product yield are investigated.The purity of product is analyzed by the high-perfor-mance liquid chromatography(HPLC),the melting point of product is determined by DSC,and the structure of product is characterized with the FTIR and1H NMR.When the molar ratio of m-hydroxybenzoic acid to potassium bicarbonate to potassium carbonate to potassium hydroxide is 2.67:3.77:1.3:1,the reaction temperature,pressure and time is 180 ℃,2.0 MPa and 8 h respectively,after refining the crude product for one time with a mixed solvent,the yield of 2-hydroxyterephthalic acid achieves 74.87%,the purity is 99.7% and the potassium metal ion content is 19 mg/kg.The results indicate that the modified Koble Schmitt scale-up process has the advantages of low cost,fewer steps,less environment pollutions,and it is suitable for the scale-up production.