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Analysis of the effect of substitution on the intramolecular hydrogen bond of malonaldehyde by ab initio calculations at the 3–21G level

1991; Elsevier BV; Volume: 228; Linguagem: Inglês

10.1016/0166-1280(91)90052-l

1872-7999

Miguel A. Rı́os, Jesús Rodríguez‐Otero,

Free Radicals and Antioxidants

We carried out an ab initio study of various derivatives of malonaldehyde by using the 3–21G basis and full optimization in order to analyse the influence of substituents on the features of the intramolecular hydrogen bond. The results show the hydrogen bond to be strengthened by electron-releasing and weakened by electron-withdrawing substituents. The estimated hydrogen-bond energies of all the compounds studied are closely related to the corresponding O…O bond distances. We also studied the intramolecular proton transfer by tunnelling and found its rate to be lower than that in the parent compound (malonaldehyde ). This lowering is attributed to the fact that the substituents raise the energy barrier.