Benchmark quantum chemical computations on acid-catalyzed Diels-Alder reactions

CHED 353

Ryan A. Newton, newton325@duq.edu1, Joshua A Plumley, plumleyj@duq.edu2, and Jeffrey D. Evanseck, evanseck@duq.edu1. (1) Department of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, (2) Center for Computational Sciences, Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh, PA 15282
Experimental activation energies, enthalpies and entropies are well known for the AlCl3 catalyzed and uncatalyzed Diels-Alder reaction between butadiene and methyl acrylate in benzene. Experimental geometries for butadiene and methyl acrylate are also known in the gas phase. Activation barriers and geometries have been computed for the AlCl3 catalyzed and uncatalyzed Diels-Alder reaction between butadiene and methyl acrylate in the gas phase and in solvent at different levels of theory. The HF, MP2, and B3LYP quantum chemical methods have been employed with a variety of basis sets ranging from small inflexible basis sets to large basis sets with additional polarization and diffuseness. Computed and experimental results have been compared to determine the best level of theory to describe accurately the AlCl3 catalyzed Diels-Alder reaction between butadiene and methyl acrylate as well as the uncatalyzed parent system. The focus of this work is to identify appropriate levels of theory in describing acid catalyzed Lewis acid Diels-Alder reactions. The different levels of theory and their performance will be discussed.