2,4-二硝基-6-溴苯胺连续重氮化的工艺研究

Continuous process for diazotization of 2,4-dinitro-6-bromoaniline

采用具有脉冲变径结构的微通道反应器,以2,4-二硝基-6-溴苯胺为原料,质量分数40%NOHSO 4为重氮化试剂,连续合成了2,4-二硝基-6-溴苯胺重氮盐。考察了2,4-二硝基-6-溴苯胺摩尔比、反应温度、98%H_(2)SO_(4)用量、停留时间等因素对重氮化反应的影响。通过实验确定较优工艺条件为:2,4-二硝基-6-溴苯胺与40%NOHSO 4摩尔比为1∶1.01,98%H_(2)SO_(4)用量为2,4-二硝基-6-溴苯胺2倍,反应温度为70℃,停留时间为250 s。该条件下,2,4-二硝基-6-溴苯胺转化率达99.4%,重氮盐选择性达96.9%。与已报道的间歇工艺相比,连续流工艺大幅缩短了反应时间,提高了重氮盐的纯度,具有一定的工业化应用前景。

2,4-dinitro-6-bromoaniline diazonium sulfate was continuously synthesized in microchannel reactor with pulse varying diameter structure,and 2,4-dinitro-6-bromoaniline and 40%NOHSO 4 were used as raw material and diazotization reagent separately.The effects of molar ratio of 2,4-dinitro-6-bromoaniline,temperature,98%H_(2)SO_(4) dosage and residence time on diazotization were investigated.The optimum conditions are determined as follows:the molar ratio of 2,4-dinitro-6-bromoaniline diazonium to 40%NOHSO 4 is 1∶1.01,the dosage of 98%H_(2)SO_(4) is 2 times compared with that of raw material,the reaction temperature is 70℃,the residence time is 250 s.Under this condition,the conversion and the selectivity can reach 99.4%and 96.9%,respectively.Compared with reported batch processes,the continuous flow process described greatly shortens reaction time,improves purity of diazonium sulfate,and has a certain industrial application prospect.