Mass Spectrometry in Organic Synthesis: Claisen-Schmidt Base-Catalyzed Condensation and Hammett Correlation of Substituent Effects
Mass Spectrometry in Organic Synthesis: Claisen-Schmidt Base-Catalyzed Condensation and Hammett Correlation of Substituent Effects
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DOI：
10.1021/ed500288m
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发表时间：
2014-11-01
影响因子：
3
通讯作者：
Cooks, R. Graham
中科院分区：
文献类型：
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作者：
Bain, Ryan M.;Pulliam, Christopher J.;Cooks, R. Graham
本科生实验室通常使用批量或半微型实验来教授对化学反应性的理解，并进行产品分离和随后的化学和光谱分析。在这项研究中，学生们接触到质谱作为化学合成和分析的一种手段。所使用的电离方法，纸喷雾，是快速的，并且可以与在线分析（通过质谱法）或离线分析（例如，薄层色谱法）。纸喷雾电离过程中的化学合成利用了与pH值和试剂浓度变化相关的加速反应速率。这种变化是由带电微滴的溶剂蒸发引起的。在这些实验中，学生们将纸张喷雾技术与传统的Claisen-Schmidt碱催化缩合的批量合成方法进行了对比。从实验室获得的质谱数据，学生能够模拟取代基对反应速率的电子效应。提供了适合本科有机教学实验室的实验程序。
Undergraduate laboratories generally teach an understanding of chemical reactivity using bulk or semimicroscale experiments with product isolation and subsequent chemical and spectroscopic analysis. In this study students were exposed to mass spectrometry as a means of chemical synthesis as well as analysis. The ionization method used, paper spray, is rapid and can be coupled with online analysis (by mass spectrometry) or off-line analysis (e.g., thin layer chromatography). Chemical synthesis in the course of paper spray ionization takes advantage of the accelerated reaction rates associated with changes in pH and reagent concentrations. Such changes arise from solvent evaporation from charged microdroplets. In these experiments students contrasted paper spray techniques with traditional bulk synthetic methods for the Claisen-Schmidt base-catalyzed condensation. From mass spectral data obtained during the laboratory session, students were able to model electronic effects of substituents on reaction rates. Experimental procedures tailored to the undergraduate organic teaching laboratory are provided.