Rethinking the Mechanistic Approach to Teaching Organic Chemistry

The mechanistic approach to teaching introductory-level organic chemistry─Organic One and Two (Organic I and II) in the United States─continues to predominate since its introduction through Morrison and Boyd’s legendary textbook. In this approach, reactions are taught alongside their electron-pushing mechanisms (EPMs), thereby providing students with a logical method to learn the transformations. Rather than use EPMs as a tool to learn the corresponding reactions, most of the chemical education research (CER) over the past two decades indicates that students need the reactions to infer their EPMs. From a constructivist perspective, the students’ consistent use of structural representations of reactant(s), intermediate(s), and product(s) to propose EPMs illustrates their sense-making processes. As such, instruction on reactions should precede instruction on EPMs, indicating that the standard mechanistic approach may not be cognitively feasible for most students. This Perspective contains four main sections. First, the CER on how students solve electron-pushing tasks is presented to substantiate the claim about students’ use of structural representations to infer EPMs. Second, these research data are interpreted using a constructivist framework. Third, another body of CER is presented to support the assertion of cognitive disconnect. Fourth, the work of three groups who are developing significant improvements to delivering and assessing the mechanistic approach is briefly presented, followed by a few considerations for research and teaching moving forward.