中间体3,5-二氯-2-戊酮的绿色合成工艺开发

Synthesis of 3,5-Dichloro-2-pentanone

α-乙酰基-γ-丁内酯与氯气在无溶剂条件下发生氯化反应,得到α-氯-α-乙酰基-γ-丁内酯和副产氯化氢,α-氯-α-乙酰基-γ-丁内酯在少量水和氯化氢的存在下进行开环、氯代和脱羧反应得到3,5-二氯-2-戊酮。对氯气投料比、反应温度、氯化氢用量等因素进行优化。优化工艺条件为,第一步反应:氯化温度为0~5℃、n(氯气)∶n(α-乙酰基-γ-丁内酯)=1.07∶1.00;第二步反应:水解、脱羧及氯化温度为90℃、n(氯化氢)∶n(α-氯-α-乙酰基-γ-丁内酯)=0.7∶1.0,n(水)∶n(α-氯-α-乙酰基-γ-丁内酯)=0.8∶1.0,通入氯化氢4 h,此条件下,收率达95.2%。

The reaction betweenα-acetyl-γ-butyrolactone and chlorine gas under solvent-free conditions givesα-chloro-α-acetyl-γ-butyrolactone and the by-product hydrogen chloride.Then,α-chloro-α-acetyl-γ-butyrolactone undergoes ring opening reaction and decarboxylation reactions in the presence of a small amount of water and hydrogen chloride to obtain 3,5-dichloro-2-pentanone.The reaction conditions including chlorine feed ratio,reaction temperature,hydrogen chloride dosage and other factors were optimized.The optimized process conditions were as followings:the chlorination temperature was in a range from 0℃to 5℃;the amount of chlorine gas was 1.07 times ofα-chloro-α-acetyl-γ-butyrolactone in molar mass;the temperature of hydrolysis,decarboxylation and chlorination was of 90℃;the amount of hydrogen chloride was 0.7 times ofα-chloro-α-acetyl-γ-butyrolactone in molar mass;the amount of water was 0.8 times ofα-chloro-α-acetyl-γ-butyrolactone in molar mass;and the yield was 95.2%.