Microkinetic models comprise quantitative, parameterized sets of differential equations that describe each elementary, or pseudo-elementary, step of a reaction mechanism. Parameterization of the rate constants at the level of activation enthalpies and entropies enables all reaction attributes–rates, selectivities, and transient concentrations of all intermediates–to be modeled over a wide range of temperatures and reactant concentrations. The most common approach to microkinetic modeling quantifies the reaction rate constants and activation parameters with the results of ab initio potential energy surface modeling. An alternative approach relies on information-rich kinetic methods to parameterize the kinetic model. Detailed kinetic studies of enantioselective hydroformylation of styrene as catalyzed by rhodium complexes ligated by bis(diazaphospholanes) using operando NMR have been performed. Examination of both catalytic and non-catalytic transformations according to a divide-and-conquer strategy yields a robust microkinetic model of hydroformylation. This model, and sensitivity analyses of factors influencing catalytic rates and selectivity, provide quantitative insights into the origins of the very complicated influence of gas pressures on regioselectivity, enantioselectivity, and catalytic rates.

Empirical microkinetic modeling of enantioselective hydroformylation

2019 Spring National Meeting

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