4,4'-二硝基二苯乙烯-2,2'-二磺酸合成过程中碱的回收利用

对碱性水介质中空气氧化对硝基甲苯邻磺酸(NTS)合成4,4’-二硝基二苯乙烯-2,2’-二磺酸(DNS)的工艺进行了改进．改进的工艺包括:NTS氧化反应液不进行中和而直接冷却结晶获得DNS产品,而过滤得到的碱性母液部分循环回用于DNS合成．采用高效液相色谱对NTS氧化过程和反应液降温冷却过程进行了跟踪．实验结果表明,冷却过程中DNS损失小于0．5％;碱性母液部分多次循环回用后,DNS产品收率稳定在87％以上,产品晶体纯度下降小于0．7％．从经济性和环境效益考虑,该工艺适于工业生产．

Recycling of Alkaline in Synthesis of 4,4' Dinitrostilbene-2,2'-Disulfonic Acid

An improved process of oxidation of 4-nitrotoluene-2-sulfonic acid ( NTS) to 4, 4'-dinitrostilbene-2, 2'-disulfonic acid(DNS) in aqueous alkali medium was studied. The process included separating DNS crystal directly from the reaction-finished reactants by cooling instead of neutralizing, and then recycling the alkaline mother liquid to the next oxidation process. High efficiency liquid chromatography ( HPLC) was employed to detect the content of NTS and DNS during cooling and oxidation courses. The experimental results show that the loss of DNS is less than 0. 5% during the reactants cooling step, and the DNS yield is steady at 87% and the product purity decrease by less than 0. 7% after the alkaline mother liquid having been recycled for many times. The improved process is appropriate to industrial production for its economic effectiveness and environmental benefit.