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Theoretical study of the ketonization reaction mechanism of acetic acid over SiO2
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1  Latvian Institute of Organic Synthesis, 21 Aizkraukles Street, Riga LV1006, Latvia

Abstract: The mechanism of ketonization of acetic acid over SiO2 was investigated by semiempirical quantum chemical AM1 method using the cluster approach. It has been found that the adjacent acid-base pair of the catalytic sites provokes dissociative adsorption of the acetic acid molecules resulting in the formation of surface carboxylate species. The adsorption process proceeds spontaneously. After blocking the acid-base pairs of catalyst, the new portions of acetic acid molecules interact with active species in the gas phase, converting into acyl cations. The adsorbed carboxylate species is attacked from the methyl group side by the acyl cation resulting in the formation of an acetone molecule and CO2 by bimolecular electrophilic substitution reaction.
Keywords: Ketonization; Acetic acid; SiO2; AM1