对硝基甲苯邻磺酸氧化缩合反应工艺研究

Study on the process conditions of the 4-nitrotoluene-2-sulfonic acid oxidative condensation reaction

本文对三组工艺条件下对硝基甲苯邻磺酸(NTS)的氧化缩合反应进行研究.实验发现,NTS氧化缩合反应分两阶段进行,在生成中间产物4,4′-二硝基二苯乙烷-2,2′-二磺酸(DND)的阶段,NTS浓度和碱浓度对反应的影响较为显著,在中间产物DND生成4,4′-二硝基二苯乙烯-2,2′-二磺酸(DNS)的阶段,温度对反应的影响较为显著;主要副产物4-硝基苯甲醛-2磺酸(NBS)和4-硝基苯甲酸-2磺酸(NSB)可由NTS直接氧化生成,又可由DNS深度氧化发生断键生成;红料现象是在高物料浓度和较高温条件下,大量NTS、DND的快速积聚,物料粘稠度的迅速增大,使体系空气分散不均、局部供氧量不足,造成NTS因局部缺氧而引发聚合反应,导致红料现象发生的主要原因.红料现象发生后,物料粘度进一步增大,使空气分散更加不均匀,导致红料现象加剧和副产物NSB急剧增加.

The study on oxidative condensation of 4-nitrotoluene-2-sulfonic acid（NTS）was carried out with three kinds of process conditions.It was found that the reaction included two steps,the influence of the NTS concentration and the alkali concentration to reaction was more notable when NTS oxidized to form 4,4′-dinitrobibenzyl-2,2′-disulfonic acid（DND）.However,the influence of temperature to reaction was more notable when DND oxidized to form 4,4′-dinitrostilbene-2,2′-disulfonic acid（DNS）.The main by-product 4-nitrobenzaldehyde-2-sulfonic acid（NBS）and 4-nitro-2-sulfobenzoic acid（NSB）could not only be generated by the deep oxidation of the DNS′s bond-breaking as well as direct oxidation of NTS.At the condition of higher temperature and higher NTS concentration,DND and NTS quickly aggregated,which increased the viscosity of the material.So the air was uneven in the system and the oxidation was inadequate in the local area,which easily induced the phenomenon of red material.At the same time,The reaction system after red material became more viscous and aggravated the phenomenon of red material and accelerates over-oxidation of the DNS′s the bond-breaking more seriously and increases more NSB.