ABSTRACT

A less hazardous and energy efficient reaction performed using freshly squeezed citrus juice as solvent has been designed and implemented within a sophomore level organic chemistry laboratory. The primary learning objectives are to enable students to (i) identify and reflect upon various green chemistry principles such as waste prevention, atom economy, less hazardous synthesis, use of safer chemicals, catalysis, design for energy efficiency, and inherently safer chemistry for accident prevention; (ii) use proton NMR spectroscopic data to characterize a synthesized Schiff base (imine); and (iii) describe the reaction mechanism for imine formation, including the reasoning for why citrus juice is an excellent reaction medium. Specifically, 4-nitrobenzaldehyde is combined with 4-methoxyaniline at room temperature in the presence of four different fruit juices as reaction media to successfully synthesize an imine that is expensive to procure commercially. This is followed by students undertaking reduction of the imine to form a secondary amine which has a dramatically distinct color due to the disruption in conjugation. In performing this overall reductive amination, students expand their knowledge on acid-catalyzed imine synthesis and its mechanism, strengthen their practical skills in the laboratory, and reflect on green chemistry principles within the context of fundamental organic reactivity.

摘要

使用鲜榨柑橘汁作为溶剂进行的危害较小且节能的反应已在二年级有机化学实验室中设计和实施。主要学习目标是使学生能够 (i) 识别和反思各种绿色化学原则，例如废物预防、原子经济、危险性较低的合成、使用更安全的化学品、催化、能效设计以及本质上更安全的事故化学预防; (ii) 使用质子 NMR 光谱数据来表征合成的席夫碱（亚胺）；(iii) 描述亚胺形成的反应机制，包括为什么柑橘汁是极好的反应介质的原因。具体来说，在四种不同果汁作为反应介质的情况下，4-硝基苯甲醛在室温下与 4-甲氧基苯胺结合，成功合成了一种商业采购昂贵的亚胺。随后学生将亚胺还原形成仲胺，由于共轭中断，仲胺具有明显不同的颜色。在进行这种整体还原胺化时，学生扩展了他们对酸催化亚胺合成及其机理的知识，加强了他们在实验室的实践技能，并在基本有机反应的背景下反思绿色化学原理。随后学生将亚胺还原形成仲胺，由于共轭中断，仲胺具有明显不同的颜色。在进行这种整体还原胺化时，学生扩展了他们对酸催化亚胺合成及其机理的知识，加强了他们在实验室的实践技能，并在基本有机反应的背景下反思绿色化学原理。随后学生将亚胺还原形成仲胺，由于共轭中断，仲胺具有明显不同的颜色。在进行这种整体还原胺化时，学生扩展了他们对酸催化亚胺合成及其机理的知识，加强了他们在实验室的实践技能，并在基本有机反应的背景下反思绿色化学原理。