4,6-二氯嘧啶清洁合成工艺

Study on clean synthesis process of 4,6-dichloropyrimidine

摘要:

本文报道了一种清洁合成4,6-二氯嘧啶（DCP）工艺。首先，由甲酰胺（HCONH2）、丙二酸二甲酯[CH2(COOCH3)2]和甲醇钠（CH3ONa）制备4,6-二羟基嘧啶（DHP）。当原料配比n[CH2(COOCH3)2]:n(HCONH2):n(CH3ONa) = 1:4:4，反应温度为60 ℃，反应时间2 h，DHP的收率可达到90.4％。然后，DHP与三氯氧化磷（POCl3）在60 ℃下反应2 h可获得DCP。在此反应过程中，5-乙基-2-甲基吡啶为缚酸剂，1,2-二氯乙烷作溶剂，反应的最佳摩尔比为n(DHP):n(POCl3):n(5-乙基-2-甲基吡啶) = 1:2.2:1.8，DCP的收率高达94.5％。通过对反应废水处理工艺的研究，实现DHP废水循环利用。最后，确定以氢氧化钙[Ca(OH)2]处理氯化废水的工艺，缚酸剂的回收率高达94%以上，并且实现磷酸钙[Ca3(PO4)2]与氯化钙（CaCl2）的有效分离，成功解决DCP生产过程中的三废问题，实现DCP清洁生产的目标。

Abstract:

In this paper, a clean process for the synthesis of 4,6-dichloropyrimidine (DCP) was reported. Firstly, 4,6-dihydroxypyrimidine (DHP) was prepared from formamide (HCONH2), dimethyl malonate [CH2(COOCH3)2] and sodium methoxide (CH3ONa) as the catalyst. When the ratio was n[CH2(COOCH3)2]:n(HCONH2):n(CH3ONa) = 1:4:4, and the reaction temperature and time were 60 ℃ and 2 h, respectively, the yield of DHP could reach 90.4%. Then, DHP was reacted with phosphorus oxychloride (POCl3) at 60 ℃ for 2 h to obtain DCP, during this reaction process, 5-ethyl-2-methylpyridine was used as the acid binder, and 1,2-dichloroethane as the solvent. The optimal molar ratio of materials was n(DHP):n(POCl3):n(5-ethyl-2-methylpyridine) = 1:2.2:1.8, the yield of DCP was up to 94.5%. Finally, the chlorinated wastewater was treated with calcium hydroxide[Ca(OH)2] and the recovery rate of the acid binder is larger than 94%. The calcium phosphate[Ca3(PO4)2] can be effectively separated from the calcium chloride (CaCl2) solution, and the recycling of waste water in the DCP production process is realized. Therefore, the wastewater could be avoided successfully and the goal of clean production of DCP was achieved.