“It’s Only the Major Product That We Care About in Organic Chemistry”: An Analysis of Students’ Annotations of Reaction Coordinate Diagrams

Abstract

The purpose of this study was to analyze organic chemistry students' annotations of reaction coordinate diagrams to better understand how they sought connections between reactions and reaction coordinate diagrams. Thirty-six students enrolled in Organic Chemistry II participated in semistructured, think-aloud interviews that asked students to choose a reaction coordinate diagram from a set of three possible diagrams to match a substitution reaction mechanism and then to match an elimination reaction mechanism. Students' annotations of the reaction coordinate diagrams provided in the interviews, and in some cases additional reaction coordinate diagrams generated by the students themselves, were examined. Qualitative analyses indicated that half of the participants considered only the "major" species (reactant, intermediate, and product) to be encoded in reaction coordinate diagrams, whereas the rest of the reaction species (leaving groups, nucleophiles/bases, and solvent molecules) were omitted from their drawings. These findings suggest that because organic chemists frequently write equations that are balanced neither in mass nor in charge, and because these equations tend to focus upon the formation of the major product, students can develop the idea that only the "major" chemical species are important to focus upon when interpreting the symbolic representations of reactions and reaction coordinate diagrams. The implications of these findings for classroom teaching are discussed.

Considering alternative reaction mechanisms: students’ use of multiple representations to reason about mechanisms for a writing-to-learn assignment

“…Studies in the literature also examine students' understandings of RCDs with investigations into how students interpret the meaning of RCD surface features (Lamichhane et al, 2018;Popova and Bretz, 2018a, 2018b, 2018cAtkinson et al, 2020. The studies by Popova and Bretz (2018a, 2018b, 2018c specifically report several findings about how organic chemistry students understand RCDs.…”

“…Studies in the literature also examine students' understandings of RCDs with investigations into how students interpret the meaning of RCD surface features (Lamichhane et al, 2018;Popova and Bretz, 2018a, 2018b, 2018cAtkinson et al, 2020. The studies by Popova and Bretz (2018a, 2018b, 2018c specifically report several findings about how organic chemistry students understand RCDs. For example, Popova and Bretz (2018a) identified that students in their study often viewed RCDs as encoding information that reflects only the major reacting species rather than all components of a reaction, often not considering the submicroscopic level.…”

“…The studies by Popova and Bretz (2018a, 2018b, 2018c specifically report several findings about how organic chemistry students understand RCDs. For example, Popova and Bretz (2018a) identified that students in their study often viewed RCDs as encoding information that reflects only the major reacting species rather than all components of a reaction, often not considering the submicroscopic level. In another article, Popova and Bretz (2018b) identified that students demonstrated challenges when translating between mechanisms and RCDs for substitution and elimination reactions due to incomplete understandings of the information communicated by RCD surface features.…”

Learning to Think in Mechanistic Alternatives: S<SUB>N</SUB>1 vs. E1 and the Gibbs-Helmholtz Equation

“…Furthermore, students tend to focus only on the major product when proposing mechanisms. [4] In this example, more than in any other, it is possible to reflect with learners why E1 elimination reactions can occur at all, even though they have a positive reaction enthalpy (∆H>0). A logical answer to this is that entropy is a thermodynamic quantity that can be introduced as a measure of the striving for energetic equal distribution in chemical reaction systems.…”

FUNdamental Developments in the Undergraduate Organic Chemistry Laboratory

“…Consequently, from the very start of the term, there is a mismatch in laboratory course expectations. Studies have also shown that many students only care about their final products, and it is difficult for them to not focus solely on their results (Popova & Bretz, 2018). Further, the students have described the chemistry lab experience to be an "(The lab is an) isolating and ineffective use of learning time and (we) fail to see how the experiment is relevant (to the course)" Reid & Shah, 2007, p.2 This statement also depicts that there is a lack of perceived relevance from the student perspectives, which in turn affects their overall motivation for the overall lab.…”