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系统地研究了AB型新单体:4-(5-氨基-6-羟基-2-苯并噁唑基)苯甲酸(ABA)的合成方法以及产品析出时pH值条件对其分子形态及红外吸收的影响。以4-(5-氨基-6-羟基-2-苯并噁唑基)苯甲酸甲酯(MAB)为原料,60～100℃于碳酸钾水溶液中水解反应至溶液澄清,用还原性弱酸性盐的水液在pH值6.0析出结晶、制得纯度99.5%以上高质量的新单体、经FT-IR归属剖析确认为游离的酸式单体ABA,收率达85%;具有过程工艺简便,单体稳定性优异、且无残留DMF阻聚杂质以及聚合操作安全等特点,在制备聚合级AB型PBO单体中取得新进展。
The synthesis method of 4- (5-amino-6-hydroxy-2-benzoxazolyl) benzoic acid (ABA) and the effect of pH value on the molecular structure and infrared Absorption effects. Starting from 4- (5-amino-6-hydroxy-2-benzoxazolyl) benzoic acid methyl ester (MAB), the product was hydrolyzed in aqueous potassium carbonate solution until the solution was clear at 60-100 ° C. Salt aqueous solution was precipitated and crystallized at a pH value of 6.0 to obtain a new monomer with a purity of over 99.5% and was confirmed by free-living acid monomer ABA by FT-IR analysis. The yield was 85% , Monomer stability is excellent, and there is no residue of residual DMF impurity polymerization and the safe operation of the polymerization, etc., in the preparation of polymerization grade AB PBO monomer made new progress.