The present invention provides for an improved practical process for producing DDTr-free p,p′-dicofol and its formulations substantially free of the practically inactive o-p′-dicofol comprising either directly recrystallizing technical dicofol from a suitable solvent such as acetic acid or alkanes, or alternatively preparing the p,p′-dicofol by the steps of (a) dehydrohalogenating technical DDT to give DDE; (b) chlorinating DDE to give Cl-DDT; and (c) hydrolyzing Cl-DDT to dicofol, wherein the technical DDT is initially recrystallized from a suitable solvent such as lower alkyl alcohols and then recrystallizing the resulting p,p′-dicofol from a suitable solvent such as acetic acid or alkanes.
本发明提供了一种生产不含 DDTr 的 p,p′-
三氯杀螨醇及其制剂的改进实用工艺,该工艺基本上不含无实际活性的邻-p′-
三氯杀螨醇,该工艺包括直接从
醋酸或
烷烃等适当溶剂中重结晶工业
三氯杀螨醇,或者通过以下步骤制备 p,p′-
三氯杀螨醇 (a) 脱氢卤化工业 DDT,得到 DDE; (b)
氯化 DDE,得到 Cl-DDT; (c) 将 Cl-DDT
水解为
三氯杀螨醇;(b) 将 DDE
氯化得到 Cl-DDT;以及 (c) 将 Cl-DDT
水解为
三氯杀螨醇,其中工业级 DDT 首先从低级烷基醇等合适的溶剂中重结晶,然后从
醋酸或
烷烃等合适的溶剂中重结晶得到 p,p′-
三氯杀螨醇。