Computational chemistry of the enantioselective hydrogenation of ethyl pyruvate using a cinchonidine-modified platinum catalyst

The enantioselective hydrogenation of α-ketoesters to α-hydroxyesters over a platinum catalyst modified by cinchona alkaloids is a model reaction investigated for its capabilities of producing optically active products using semi-empirical calculation methods. The modification of a heterogeneous catalyzed reaction enhances the selectivity of the catalyst toward one of the enantiomers. Experimentally, others have shown that this modified reaction yields high enantiomeric excess towards the R enantiomer. The yield of one specific enantiomer over another in a reaction can enable industry to reduce cost and pollution by enhancing production of one enantiomer over the other. These enantioselective catalyst modifier can also help increase the activity of the catalyst.; Molecular modeling and computational chemistry techniques, using Gaussian 98, are applied to simulate the hydrogenation of ethyl pyruvate, EP, over a platinum catalyst modified by cinchonidine, CD, in open conformation. The reaction energy values are deterministic of the reaction rates and the qualitative theoretical results are comparable to experimental ones.; The results show that, for the model system, the energy barrier existing between the reactants and R-ethyl lactate is 0.2373 Hartrees, while the energy barrier existing between the reactants and S-ethyl lactate is 0.9589 Hartrees. Where 1 Hartree is equivalent to 627.51 Kcal/mol. The smaller energy barrier for the R enantiomer is implicative of a more favorable yield of the R-ethyl lactate product. This result qualitatively agrees with the results found in experimental literature [2].