2,4-二氯-5-氟嘧啶的合成及废液回收处理利用

Synthesis of 2,4-dichloro-5-fluoropyrimidine and recovery of DMA from waste water

使用5-氟尿嘧啶(5-FU)和三氯氧磷(POCl3)作为原料、N,N-二甲基苯胺(DMA)作为缚酸剂合成2,4-二氯-5-氟嘧啶,系统研究了5-FU与POCl3的摩尔比、5-FU与DMA的摩尔比、反应温度和反应时间对反应收率的影响,简要阐述该反应机理。反应结束后,向废液中加入Na OH固体对废液进行处理,探讨DMA的回收率和副产物磷酸氢二钠的收率与p H的关系。结果表明,在工艺参数为5-FU与POCl3的摩尔比为1:10、5-FU与DMA的摩尔比为1:1.5、回流温度114℃、回流时间2 h时,2,4-二氯-5-氟嘧啶的收率为92.2%;通过加入Na OH固体将废液p H调至7,DMA的回收率和副产物磷酸氢二钠的收率都为最大值。

2,4-Dichloro-5-fluoropyrimidine was prepared by reaction of 5-fluorouracil （5-FU） and phosphorus oxychloride in the presence ofN,N-dimethylaniline （DMA） as acid acceptor. The effect of molar ratio of 5-FU to phosphorus oxychloride, molar ratio of 5-FU toN,N-dimethylaniline, reaction temperature and reaction time was investigated. Furthermore, reaction mechanism was discussed. 5-FU and POCl3 ratio 1：10, 5-FU and DMA ratio 1：1.5, reaction temperature 114℃, reaction time 2 h were the optimum process parameters of synthesizing 2,4-dichloro-5-fluoropyrimidine. Under this process condition, maximum yield of 92.2% of 2,4-dichloro-5- fluoropyrimidine could be obtained. The pH of waste water was then adjusted by adding sodium hydroxide, and the effect of pH on recovery of DMA and yield of by-product disodium hydrogen phosphate was studied. When pH was adjusted to 7, maximum recovery of DMA and maximum yield of by-product disodium hydrogen phosphate could be obtained.