Effect of protonation on the atomic and bond properties of the carbonyl group in aldehydes and ketones Original Research Article

Protonation in a series of aldehydes and ketones of formula R1–CO–R2 (with R1, R2=H, Me, Et, Pr and Bu) was studied by using the theory of atoms in molecules to examine the atomic and bond properties of the carbonyl group and its relationship to the energy involved in the protonation process. Based on the results, aldehydes, methyl ketones and the remainder dialkylketones studied exhibit three different behaviours. Protonation results in small differences in the properties of the CO bond. While the atomic charge of the carbonyl group hardly changes, the proton bonded to the oxygen exhibits high positive charge after protonation. Atomic contributions to the total energy depend on molecular size.