An Improved Mechanistic Interpretation of the Acid-Catalyzed Dehydration of Methylcyclohexanols

The acid-catalyzed dehydration of regioisomeric methylcyclohexanols is a classic organic chemistry experiment featured in a variety of laboratory textbooks and literature. The mechanistic details of this reaction have received an inconsistent and occasionally inaccurate treatment, wherein the reaction has been described as a mix of E1, E2-like, acid-catalyzed E2, and base-catalyzed E2 processes. We provide an overview of how this reaction has been represented in the chemistry education literature and describe a model for its mechanistic interpretation as an El reaction that is typically analyzed before thermodynamic equilibrium is established. This model is supported by new experimental data and computational explorations of the reactive intermediates and cycloalkene products. We provide clear recommendations for how this reaction should be presented to students.