Resumen de How Much? How Fast? A Study of Kinetics and Thermodynamics through the Lens of Reaction Coordinate Diagrams in Organic Chemistry
Jason G. Liang Lin, Thomas R. Locascio, Alexis Witherspoon, Sean Gao, Joseph Laster, Maggie Tripp, Justin M. Shorb, Charles T. Cox Jr.
Correctly predicting the products and having a qualitative understanding of their ratios is a fundamental skill fostered in organic chemistry. This skill can involve the electron-pushing formalism (EPF) and reaction coordinate diagrams (RCDs). These representations can be important for evaluating whether product formation is driven by a kinetic or thermodynamically favored rationale. For this research, students in organic chemistry were given a two-stage investigation. First, they were given an online multiple-choice assessment surrounding three distinct types of reactions for elucidating understanding of product formation: the Markovnikov addition of HBr to an alkene, an E2 elimination favoring the Zaitsev product, and an E2 elimination favoring the Hofmann product. This task was followed up with a semistructured interview involving these same three reaction contexts to identify what resources were activated in their rationale for determining major and minor products and how these resources were applied to create RCDs. Our findings indicate that these students focus predominately on resources associated with intermediate stability for the stepwise Markovnikov addition, with limited activation of resources regarding product stability. Conversely, resources focusing on product stability were activated more often with concerted eliminations. When provided with possible RCDs, activation of additional resources was observed. These data highlight the need for the integrated use of RCDs and create the impetus for future studies on scaffolding these resources to encourage their activation during analyses of novel reactions.
