浓硫酸催化制备4，6-二氨基间苯二酚盐酸盐

Synthesis of 4,6-diaminobenzene-1,3-diol dihydrochloride catalyzed by concentrated sulfuric acid

4,6-二氨基间苯二酚(DAR)盐酸盐单体的制备是合成高性能纤维聚对苯撑苯并双口恶唑(PBO)的关键,而间苯二酚乙酰化、肟化法是高效制备该单体的重要方法。新方法采用浓硫酸作为催化剂改进二肟中间体Beckmann重排、水解制备DAR的过程,成功制备得高纯度的DAR单体。并通过对温度、浓硫酸使用量等影响反应的主要因素进行比较研究,总结出浓硫酸催化制备DAR的合适条件。该方法不仅有效解决了使用多聚磷酸制备DAR时操作复杂等问题,而且节约了成本,缩短了反应时间。

Concentrated sulfuric acid was used to prepare the 4,6-diaminobenzene-1,3-diol dihydrochloride（DAR）by beckmann rearrangement of dioxime in high yields and high regioselectivity. Conditions for beckmann rearrangement were well studied,especially for effect of the temperature and ratio of concentrated sulfuric acid to dioxime. The results showed that the temperature control was critical in the synthesis of DAR, and the beckmann rearrangement was optimised to be car- ried out at 95（C with the molar ratio of concentrated sulfuric acid to dioxime 8 ~ 1. By using this method,the experiments were carried out with easier operation, shorter time and reduced cost.