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硫酸烷基酯(二甲酯、二乙酯)是十分活泼的烷基化试剂,常用于酚、胺和羧酸等的烷基化.在只有一个烷基参与反应的条件下,反应时间长(六小时左右),产率不高,一般为60—70％.在碱性介质中酚易氧化,反应液色泽深,而且常加入连二亚硫酸钠或氯化亚锡;残留的酚较多,后处理麻烦且多耗试剂.我们对用硫酸二甲酯或二乙酯使酚醚化的传统方法作了改进.在消耗试剂不多的情况下,产率提高10—30％,反应时间减少到1—2小时,勿需加入还原剂,反应液色泽浅;操作简便,产品质量稳定。本方法可用于实验室制备.特别值得指出的是:硫酸二乙酯两个乙基都可参与反应,且对苯二酚二乙醚的产率高达85％以上.这在高感光性重氮盐的工业生产中颇为有用.本方法不适于制备对苯二酚的单甲醚.实验结果见下表.
Alkyl sulfates (dimethyl esters, diethyl esters) are very reactive alkylating agents commonly used in the alkylation of phenols, amines and carboxylic acids, etc. With only one alkyl group involved in the reaction, the long reaction time (About six hours), the yield is not high, usually 60-70% .In alkaline medium phenol easy oxidation, the reaction liquid deep color, and often join sodium dithionite or stannous chloride; residual phenol more, Post-processing is troublesome and consumes more reagents.We improved the traditional method of phenol etherification with dimethyl sulfate or diethyl ester.Under the condition of low consumption of reagents, the yield increased by 10-30% and the reaction time decreased To 1-2 hours, do not need to join the reducing agent, the reaction liquid light color; easy to operate, product quality and stability. This method can be used in laboratory preparation.It is worth noting that diethyl sulfate can participate in both reactions and the yield of hydroquinone diethyl ether is more than 85% Of industrial production is quite useful.This method is not suitable for the preparation of hydroquinone monomethyl ether.Experimental results in the table below.