DNS产品中杂质的生成机理及DNS精制工艺

Mechanism for Impurities Forming During the Synthesis of DNS and Optimization of DNS Preparation

跟踪了对硝基甲苯邻磺酸（NTS）制备4,4′-二硝基二苯乙烯-2,2′-二磺酸（DNS）的过程,推测了4-硝基苯甲醛2-磺酸钠（NBS）与4-硝基苯甲酸2-磺酸钠（NSB）杂质的生成机理。考察了重结晶温度、pH值、结晶次数及光照等因素对DNS产品的纯度及收率的影响,确定了DNS重结晶的优化操作条件。研究结果表明,适宜的重结晶温度约为85℃,优化pH值为9~10,以重结晶后所得精制DNS为原料可制备高品质4,4′-二氨基二苯乙烯-2,2′-二磺酸（DSD酸）。

The oxidation of p-nitrotoluene-2-sulfonic acid to prepare 4,4＇-dlnitrostilbene-2,2＇-disulfonic acid （DNS） was monitored, and the mechanism for the formation of by-products 4-nitrobenzaldehyde-2-sulfonic acid （NBS） and 4-nitro-2-sulfobenzonic acid （NSB） was suggested. By investigating the influences of temperature, pH value, recrystallization times and solar light on the purity and recovery of DNS, optimized conditions for the recrystallization of DNS were obtained： about 85 ℃ and pH = 9--10. Finally, 4,4＇-diaminostilbene-2,2＇- disulfonic acid （DSD） with high quality was synthesized from DNS after purification.