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从植物中提取有机物是化学实验的重要内容和方法,也是学生比较感兴趣的内容之一。其提取机理、操作设计、生物检验等,既能培养学生的实验操作技能,又能培养学生理论联系实际、分析解决问题的能力,还能使学生对医药等行业有所认识。因此,一些可行的提取实验是开展探究性实验教学的好素材。“从茶叶中提取咖啡因”就是一例。我在分析“从茶叶中提取咖啡因”的传统做法存在的不足的基础上,对该实验进行了改进,并做了分析,希望对广大师生课外开展探究性实验有所帮助。一、传统做法1.“从茶叶中提取咖啡因”的两种传统做法(1)采用普通仪器进行提取。称取茶叶,用纱布包好;再放入已加有适量水和碳酸钙粉末的烧杯中;煮沸30 min;取出茶叶压干,趁热抽滤;将滤液冷却后用氯仿萃取两次,萃取液作为提取液备用。
The extraction of organic compounds from plants is an important part of chemical experiments and methods, but also one of the more interested students. The extraction mechanism, operation design, biological testing, can not only cultivate students’ experimental skills, but also cultivate the students theory with practice, analyze the ability to solve problems, but also enable students to understand the pharmaceutical and other industries. Therefore, some feasible extraction experiments are good materials for exploratory experimental teaching. “Extracting caffeine from tea” is one example. Based on the analysis of the shortcomings of the traditional method of extracting caffeine from tea, I made some improvements to the experiment and made some analysis. I hope it will be helpful for the majority of teachers and students to conduct exploratory experiments outside of home. First, the traditional approach 1. “Extraction of caffeine from tea,” the two traditional practices (1) using ordinary equipment for extraction. Weigh the tea, wrapped with gauze; then add the amount of water and calcium carbonate powder has been added to the beaker; boil 30 min; remove the tea pressed dry hot filtration; the filtrate was cooled and extracted twice with chloroform, extraction Liquid as an extract spare.