Reactions of Carboxylic Acids on Oxides: 2. Bimolecular Reaction of Aliphatic Acids to Ketones
TL;DR: In this article, the reaction of aliphatic carboxylic acids over oxidic catalysts has been studied, and no agreement in the literature concerning the mechanism of this ketonization reaction has been established.
About: This article is published in Journal of Catalysis.The article was published on 1997-06-01. It has received 167 citations till now. The article focuses on the topics: Ketonic decarboxylation & Ketone.
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TL;DR: This critical review examines transition metal-catalyzed decarboxylative couplings that have emerged within recent years as a powerful strategy to form carbon-carbon or carbon-heteroatom bonds starting from carboxylic acids.
Abstract: This critical review examines transition metal-catalyzed decarboxylative couplings that have emerged within recent years as a powerful strategy to form carbon–carbon or carbon–heteroatom bonds starting from carboxylic acids. In these reactions, C–C bonds to carboxylate groups are cleaved, and in their place, new carbon–carbon bonds are formed. Decarboxylative cross-couplings constitute advantageous alternatives to traditional cross-coupling or addition reactions involving preformed organometallic reagents. Decarboxylative reaction variants are also known for Heck reactions, direct arylation processes, and carbon–heteroatom bond forming reactions.
1,104 citations
TL;DR: In this article, the authors defined the position of this mechanism among other ways of catalytic activation, and the experimental evidence for this mechanism was presented in more detail, among them the deoxygenation of nitrocompounds and carboxylic acids.
Abstract: This review deals with the mechanism that is arbitrarily called below the Mars and Van Krevelen (MvK) mechanism. The characteristic feature of this mechanism is that some products of the reaction leave the solid catalysts’ surface with one or more constituents of the catalysts’ lattice. First in this review, the position of this mechanism amongst other ways of catalytic activation will be defined. Then, the experimental evidence for this mechanism will be presented. Some less common reactions running with this mechanism will be discussed in more detail, among them the deoxygenation of nitrocompounds and carboxylic acids. The participation of the lattice components (O, S, Cl, H) in the formation of products leads to a relation of the catalytic activity with the thermodynamic parameters characterizing the catalysts lattice. A proper use of such quantified relation will be also discussed.
468 citations
TL;DR: A new route to convert crude microalgae oils using ZrO(2)-promoted Ni catalysts into diesel-range alkanes in a cascade reaction is presented.
Abstract: A new route to convert crude microalgae oils using ZrO(2)-promoted Ni catalysts into diesel-range alkanes in a cascade reaction is presented. Ni nanoparticles catalyze the selective cleavage of the C-O of fatty acid esters, leading to the hydrogenolysis of triglycerides. Hydrogenation of the resulting fatty acids to aldehydes (rate-determining step) is uniquely catalyzed via two parallel pathways, one via aldehyde formation on metallic Ni and the second via a synergistic action by Ni and ZrO(2) through adsorbing the carboxylic groups at the oxygen vacancies of ZrO(2) to form carboxylates and subsequently abstracting the α-hydrogen atom to produce ketene, which is in turn hydrogenated to aldehydes and decarbonylated on Ni nanoparticles.
298 citations
TL;DR: The role of α-hydrogen has been proven as a critical requirement for ketonization over catalysts that are active for surface Ketonization and serves as the initial basis for the discussion as mentioned in this paper.
Abstract: Ketonization is a reaction in which two carboxylic acids convert into a ketone, carbon dioxide, and water. While this reaction once found its industrial application for acetone production, it is regaining interest for its value in the upgrading of biomass-derived oxygenates, for example, bio-oils obtained from the fast pyrolysis of biomass. Namely, ketonization is crucial to reduce the detrimental effects of carboxylic acids in bio-oil. This review addresses reaction mechanisms, families of materials that catalyze the reaction (metal oxides and zeolites), and current applications of ketonization in the upgrading of biomass-derived oxygenates. A variety of mechanisms have been proposed to explain the ketonization reaction, and these proposals are critically discussed. The role of the α-hydrogen has been proven as a critical requirement for ketonization over catalysts that are active for surface ketonization and serves as the initial basis for the discussion. The role of crucial reaction intermediates such ...
287 citations
TL;DR: In this article, the authors show that weak bases may play the role of promoters in the decarboxylation of symmetric and unsymmetric ketones. But they do not discuss the effect of weak bases.
282 citations