醚的制备改进实验——二苯甲基乙基醚

Improvement of Ether Preparation:Benzhydryl Ethyl Ether

醚的制备是有机化学实验的一个重要内容,教材中对应的实验内容是甲基叔丁基醚和正丁醚的制备。通过该部分学习对于深刻理解醇的化学性质和亲核取代反应的SN1、SN2两种机制具有重要的作用。然而,教材中基于SN1机理的甲基叔丁基醚制备实验仍存在需化学计量硫酸催化剂、反应进程不易跟踪、产物难以纯化且产率低等问题。本实验以无水三氯化铁作为催化剂,使用二苯甲醇与乙醇反应,反应混合物经洗涤除杂操作后,可以以88%–90%收率,95%–97%纯度得到二苯甲基乙基醚产物。本实验与现有教材中甲基叔丁基醚制备的反应机理和教学要点一致,但催化剂用量显著降低、产物分离纯化步骤显著减少,产物收率明显提高。本实验有助于学生深入理解碳正离子中间体的性质、有机化学中的路易斯酸碱理论及其催化反应和SN1机理等基本理论,有助于培养学生绿色化学理念。

The ether preparation experiment is important in organic chemistry experiments.“The preparation of methyl tert-butyl ether”and“The preparation of n-butyl ether”are the corresponding experiments in the textbook.Studying these ether preparation experiments is important for a comprehensive understanding of the chemical properties of alcohols and the SN1 and SN2 mechanisms of nucleophilic substitution reactions.However,there are still many issues in“The preparation of methyl tert-butyl ether”based on the SN1 mechanism in the textbook,such as the requirement of a stoichiometric amount of the sulfuric acid catalyst,difficult reaction monitoring,challenging purification of the product,and low yields.Herein,a non-flammable solid,diphenylmethanol,and ethanol were used as starting materials,and anhydrous ferric chloride was used as the catalyst to prepare the desired benzhydryl ethyl ether.After simple washing extractions,the desired benzhydryl ethyl ether product could be purified and obtained in 88%-90%yields and 95%-97%purities.Notably,the reaction mechanism of this experiment is the same as that of methyl tert-butyl ether preparation;however,the catalyst amount is significantly reduced,product separation and purification steps are greatly simplified,and product yield is significantly improved.This experiment is helpful for students to comprehensively understand basic theories,including the properties of carbocation intermediates,organic Lewis acid-base theories and their applications,and the SN1 mechanism.Further,it can cultivate students’appreciation of green chemistry principles.