Assessing Basic Separatory Technique Skills in an Organic Experiment Based on an Incomplete Haloform Reaction,Journal of Chemical Education

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Assessing Basic Separatory Technique Skills in an Organic Experiment Based on an Incomplete Haloform Reaction
Journal of Chemical Education ( IF 2.5 ) Pub Date : 2020-03-26 , DOI: 10.1021/acs.jchemed.9b01015
Iveta Kmentová ₁ , Ambroz Almássy ₁ , Lucia Feriancová ₁ , Martin Putala ₁

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We present an experiment which was designed to assess the separation technique skills of the gifted high school students who attended the 50th International Chemistry Olympiad 2018. The procedure consists of two synthetic tasks and is also applicable for teaching undergraduates. The haloform reaction of 2-acetonaphthone with sodium hypochlorite in commercial bleach gave the corresponding carboxylate salt and some unreacted 2-acetonaphthone. This unreacted material is separated and then treated with in situ prepared Brady’s reagent to give a near-quantitative yield of the hydrazone, while acidification of the carboxylate salt affords the corresponding carboxylic acid. The procedure includes several separation techniques: acid–base extraction, TLC analysis, and suction filtration. The grading of the student’s work based on the combined yield of both products avoids having to account for the effects of temperature, reaction time, and reagent quality on the efficiency of the haloform reaction. The duration of the experiment is 3–4 h of working time, depending on the student’s time management skills.

中文翻译：

基于不完全卤仿反应的有机实验中的基本分离技术技能评估

我们提供了一个旨在评估参加了第50届国际化学奥林匹克2018的有才华的高中学生的分离技术技能的实验。该程序包括两个合成任务，也适用于教学本科生。在商业漂白剂中2-乙酰基萘酮与次氯酸钠的卤仿反应得到相应的羧酸盐和一些未反应的2-乙酰基萘酮。分离该未反应的材料，然后原位处理制备布雷迪试剂，得到to的接近定量的产率，而羧酸盐的酸化得到相应的羧酸。该程序包括多种分离技术：酸碱萃取，TLC分析和抽滤。基于两种产品的总收率对学生的作业进行评分，避免了必须考虑温度，反应时间和试剂质量对卤仿反应效率的影响。实验的持续时间为3-4小时的工作时间，具体取决于学生的时间管理技能。

更新日期：2020-04-24

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