A Cross-Sectional Analysis of Mechanistic Reasoning Strategies for Elimination Reactions in the Organic Chemistry Sequence

This study explores the mechanistic reasoning strategies of students in Organic Chemistry I and II for elimination reactions. Interviews were conducted with 8 participants in Organic Chemistry I and 10 participants in Organic Chemistry II. The Organic Chemistry I participants were given an E1 and E2 elimination reaction and prompted to identify the specific type of reaction and its outcome. In Organic Chemistry II, participants were given the same E1 and E2 reactions as well as an E1cB reaction. The Organic Chemistry I participants analyzed the reaction, focusing on its structural features, before identifying the reaction type. In comparison, the Organic Chemistry II participants largely identified the reaction type first and explained their reasoning only after being prompted. Base strength was a key resource in contrasting the two reactions, and students’ correct reaction identification was linked to their analysis of base strength. Participants in Organic Chemistry II also focused more on kinetic and thermodynamic principles. When given the E1cB mechanism, Organic Chemistry II participants drew heavily on comparisons with other elimination reactions. These findings, along with others in science education research, demonstrate the utility of scaffolding─that is, providing simpler, structured tasks that build on a more-complicated problem. Guided questioning that helps students understand the energetic, structural, and reaction conditions of a reaction can help them produce the correct reaction mechanism.