Revisiting the reactions of t-BuX (X = Br, I) with monoalcohols: a mechanistic analysis through numerical integration and nonlinear regression methods

The reactions of two tertiary butyl halides, i.e., t-BuBr and t-BuI, with monoalcohols (methanol, i-propanol, and t-butanol) have been studied at several temperatures during extended periods of time to acquire kinetic data for both the solvolytic step and the subsequent reactions. Reaction progress was followed by conductimetry, and calibration curves were obtained for all systems under study to derive concentration versus time curves for the significant intermediate species, the formed acid, HX. The GMS comprehensive mechanism, previously proposed by Goncalves, Martins, and Simoes for these reactions, was successfully tested using numerical integration associated with nonlinear regression, confirming the predicted distinct behaviors for methanol (and for that matter also for primary alcohols), secondary, and tertiary alcohols. Results show that accurate rate constants could be obtained in all cases and that the step that follows solvolysis can affect significantly the solvolytic rate constant and therefore any consequent reliable mechanistic analysis.