“讲一练二考三”理念在有机化学实验教学中的运用——以苯甲酸的制备为例

采用微波辐射及相转移催化剂改进了高锰酸钾氧化制备苯甲酸实验,系统研究了微波功率、反应温度、反应时间、反应物物质的量比、催化剂用量等因素对产率的影响,并同电热套加热方式进行了比较.结果表明,该反应的最佳条件为:微波辐射时间40 min,微波功率80 W,反应温度80℃,相转移催化剂氯化苄基三乙铵用量为甲苯的0.2当量,高锰酸钾与甲苯的物质的量比为4.5:1.与电热套加热方式相比,微波辐射法缩短了反应时间,并显著提高了反应效率.以苯甲酸制备实验为例介绍了“讲一练二考三”教学新理念及其在有机化学实验教学实践中的运用.

Application of "Teaching One,Practicing Two,and Testing Three" in Organic Chemistry Laboratory Course: Taking Preparation of Benzoic Acid as an Example

The preparation of benzoic acid through the oxidation of toluene by KMnO₄ was improved upon microwave irradiation in the presence of benzyl triethylammonium chloride.The reaction conditions such as microwave power, reaction temperature, reaction time, the molar ratio of reactants, and the dosage of catalyst were investigated.The results showed that the optimal reaction conditions were as follows:irradiation time 40 min, microwave power 80 W, reaction temperature 80℃, 0.2 equivalent of catalyst for toluene, and the molar ratio of KMnO₄ to toluene to be 4.5:1.Compared with the traditional heating method, the microwave radiation shortened reaction time, and improved reaction efficiency up to 72.5% yield.Additionally, the preparation of benzoic acid was taken as an example to illustrate the application of the new method, namely, "teaching one, practicing two, and testing three" in organic chemistry laboratory course.