The invention provides an improved process for preparing Ethacrynic acid of formula I, including the steps of: (a) reacting 4-butyryl-2,3-dichloro-phenoxy acetic acid of formula II with dimethylamine or its salt to obtain [2,3-dichloro-4-(2-dimethylaminomethylbutyryl)phenoxy] acetic acid of formula III or its salt; (b) hydrolyzing [2,3-dichloro-4-(2-dimethylaminomethylbutyryl)phenoxy] acetic acid hydrochloride of formula III obtained in step a) with t-butyl amine to obtain t-butyl amine salt of Ethacrynic acid; (c) acidifying the t-butyl amine salt of Ethacrynic acid formed in step b) to obtain Ethacrynic acid of formula I; and (d) optionally purifying the obtained Ethacrynic acid with a solvent mixture of alkyl acetate and hydrocarbon solvent. The invention also provides crystalline t-butylamine salt of Ethacrynic acid and process thereof. Also provide compound Ethacrynic acid having a purity of greater than or equal to 99% and a composition including the compound.
本发明提供了一种制备式 I 乙基
丙烯酸的改进工艺,包括以下步骤(a) 将式 II 的 4-丁酰基-
2,3-二氯苯氧基乙酸与
二甲胺或其盐反应,得到式 III 的[2,3-二
氯-4-(2-
二甲氨基甲基丁酰基)苯氧基]
乙酸或其盐;(b) 用
叔丁胺水解步骤 a)中得到的式 III 的[2,3-二
氯-4-(2-
二甲氨基甲基丁酰基)苯氧基]
乙酸盐酸盐,得到
乙草胺的
叔丁胺盐;(c) 将步骤 b) 中形成的
乙酸叔丁基胺盐酸化,得到式 I 的
乙酸;以及 (d) 可选择用
乙酸烷基酯和烃溶剂的混合溶剂纯化得到的
乙酸。本发明还提供了乙基
丙烯酸的结晶
叔丁胺盐及其工艺。还提供纯度大于或等于 99% 的化合物乙基
丙烯酸和包括该化合物的组合物。