Research in organic chemistry education has revealed that students often rely on rote memorization when learning mechanisms. Not much is known about student productive resources for causal reasoning. To investigate incipient stages of student causal reasoning about single mechanistic steps of organic reactions, we developed a theoretical framework for this type of mechanistic reasoning. Inspired by mechanistic approaches from philosophy of science, primarily philosophy of organic chemistry, the framework divides reasoning about mechanisms into structural and energetic accounts as well as static and dynamic approaches to change. In qualitative interviews, undergraduate organic chemistry students were asked to think aloud about the relative activation energies of contrasting cases, i.e. two different reactants undergoing a leaving group departure step. The analysis of students’ reasoning demonstrated the applicability of the framework and expanded the framework by different levels of complexity of relations that students constructed between differences of the molecules and changes that occur in a leaving group departure. We further analyzed how students’ certainty about the relevance of their reasoning for a claim about activation energy corresponded to their static and dynamic approaches to change and how students’ success corresponded to the complexity of relations that they constructed. Our findings support the necessity for clear communication of and stronger emphasis on the fundamental basis of elementary steps in organic chemistry. Implications for teaching the structure of mechanistic reasoning in organic chemistry and for the design of mechanism tasks are discussed.

中文翻译：

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通过机械框架的角度解决有机化学学生推理的复杂性

有机化学教育的研究表明，学生在学习机制时经常依赖死记硬背。关于因果推理的学生生产资源知之甚少。为了调查关于有机反应的单个机械步骤的学生因果推理的初始阶段，我们为这种类型的机械推理建立了理论框架。受到科学哲学（主要是有机化学哲学）的机械方法的启发，该框架将有关机制的推理分为结构和能量方面以及静态和动态的变化方法。在定性访谈中，要求有机化学本科生大声思考对比案例的相对激活能，即两种不同的反应物正在进行离去基团离去步骤。对学生推理的分析证明了该框架的适用性，并通过在分子差异与离开组离开中发生的变化之间构造的不同复杂程度的关系来扩展了该框架。我们进一步分析了学生对激活能量主张的推理的相关性的确定性如何与其静态和动态的改变方法相对应，以及学生的成功如何与他们所建立的关系的复杂性相对应。我们的发现支持有机化学基本步骤的基本基础上明确沟通和加强强调的必要性。