The Baeyer–Villiger reaction: solvent effects on reaction mechanisms

Abstract

This study focuses on the Baeyer-Villiger reaction of propanone and performic acid, with formic acid as catalyst. Continuum solvation methods (EIF-PCM and CPCM) and two density functionals (B3LYP and MPWB1K) are used to study solvent effects on two types of reaction mechanisms: concerted non-ionic and stepwise ionic. The ionic mechanism is the one found in most organic chemistry textbooks; it begins with the protonation of the ketone by the acid catalyst, even though this reaction normally takes place in non-polar solvents such as dichloromethane. Our calculations show that the concerted non-ionic pathway, which is the least energetic in non-polar solvents such as dichloromethane, becomes more energetic the more polar the solvent. After investigating a variety of non-ionic and ionic pathways in water, it is found that the addition step seems to be ionic but the migration step, which is rate-determining, is uncatalyzed, non-ionic and fully concerted. These results confirm the experimental findings in solvents of low to medium polarity that the rate constant of the reaction decreases as the solvent polarity increases. Moreover, we find that contrary to what is commonly accepted, in the addition and migration ionic steps the deprotonation of the ionic species occurs in a concerted manner with the other chemical events taking place.

A quantum chemical study on the free radical scavenging activity of tyrosol and hydroxytyrosol

“…These corrections are in good agreement with those independently obtained by Ardura et al [88] and have been successfully used by other authors [89][90][91].…”

Nano silica boron sulfuric acid as a dual Brønsted/Lewis acid and a heterogeneous catalyst in Baeyer–Villiger oxidation of ketones with hydrogen peroxide

“…Therefore, among a variety of examined solvents, based on the results of Table 2, chloroform was selected as the ideal solvent in these series because the B-V oxidation of ketones proceeded more smoothly. Consequently, these findings are in good agreement with the well-known B-V oxidation mechanism, which involves two steps; the addition step seems to be ionic and the migration step, which is rate-determining, uncatalyzed, non-ionic and fully concerted [27]. It should be also mentioned that, stirring and heating the reaction mixture for 9 h at 80°C under solvent free conditions, was not complete at all (Entry 10).…”

Theoretical Studies on the Asymmetric Baeyer–Villiger Oxidation Reaction of 4‐Phenylcyclohexanone with m‐Chloroperoxobenzoic Acid Catalyzed by Chiral Scandium(III)–N,N′‐Dioxide Complexes

“…Recently, both theoretical and experimental investigations proved that BV oxidation reactions could be accelerated in the presence of acids. The acid molecule was assumed to act as both proton donor and acceptor, decreasing the activation barrier of the addition step 13a,e,f,i,j. Meanwhile, our experiments also indicated that the BV oxidation reaction between 1 a and m ‐CPBA could occur even without the Sc III – N , N ′‐dioxide complex, affording racemic products in a yield of 19 % 19.…”