A comprehensive theoretical study regarding the solvent effect on the Diels-Alder reaction with hetero-dienophiles consist of 2,3-dimethylbutadien and diethylazodicarboxylate was done. Reaction rates in the various solutions were studied by the SCRF–DFT theory, and a good agreement with the experimental results was obtained. According to the natural bond orbital analysis, it was confirmed that the stabilization energy of the C-N bonds contributes to the strong interaction between the solvents and transition state structures (TSs). Topological analyses showed a linear correlation between the interaction energy and the sum of electron density on the bond critical point of C-N at the TSs. Moreover, with the increase in the overall electron density of the C-N bond critical point, its vibrational frequencies were decreased. Finally, some correlations between the quantum reactivity indices and the rate constant in the presence of twenty three solvents were investigated.

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