3-氨基呋咱-4-羧酸的合成

The improved synthesis of 3-aminofurazan-4-carboxylic acid

摘要:

改进了原有3-氨基呋咱-4-羧酸合成方法，以氰基乙酸甲酯为原料，经过取代、环化成盐、水解制备3-氨基呋咱-4-羧酸。利用红外光谱、核磁共振元素分析及质谱确证了产物结构，并考察了物料比、反应温度、反应时间和溶剂用量对环化成盐反应的影响及反应溶剂、pH、温度对酸化反应的影响[考察得到的结果是什么？请在摘要中简要说明。 回复：在摘要中增加了考察结果的简要说明。]，发现增加氢氧化钾用量、提高反应温度、降低体系pH值有利于目标物收率提高。结果表明：确定的最佳环化成盐反应条件为：盐酸羟按：氢氧化钾：2-氰基-2-肟基乙酸甲酯摩尔比为1:4:1，缩合温度25℃，缩合时间2h，环化温度80℃，环化时间2h，溶剂水50mL；最佳酸化反应条件为：溶剂水30mL，pH <1，反应温度5℃，环化成盐反应和酸化反应的总收率为79.7%，高于文献报道的64%。

Abstract:

The synthesis of 3-aminofurazan-4-carboxylic acid was improved, and it was synthesized via substitution, annulation-salt forming reaction and hydrolysis, using cyanoacetate as raw materials. The structure of the product is charactered by IR, NMR and MS. The effects of substrates ratio, reaction temperature, reaction time and solvent on the annulation-salt forming reaction was investigated. And the reaction time and solvent and pH on the hydrolysis was also investigated. It is suggested that the increase of KOH, the increase of reaction temperature can improve the yield of the product. The best annulation-salt forming reaction condition is the mole ratio of hydroxylamine hydrochloride : KOH : methyl-2-cyano-2-(hydroxyimino)acetate =1:4:1, the condensation temperature is 25℃, the reaction time is 2h, the cyclization temperature is 80℃, the reaction time is 2h, the solvent water is 50mL. The best acidification reaction condition is the reaction temperature is 5℃, the solvent water is 30mL, pH＜1. The total yield of annulation-salt forming reaction and hydrolysis was 79.7%, which is higher than the yield of 64% in the reported article.