Ketonization of Carboxylic Acids by Decarboxylation: Mechanism and Scope

Renz, Michael

doi:10.1002/ejoc.200400546

Cited by 281 publications

(260 citation statements)

References 33 publications

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“…A similar problem of the cross-selectivity exists in the industrial synthesis of unsymmetrical ketones, usually methyl ketones, such as methyl cyclopropyl ketone [5], methyl nonyl ketone [6], methyl isopropyl ketone, i etc., from a mixture of two carboxylic acids by their cross-ketonization reaction (Scheme 1). The ketonic decarboxylation, also known as the decarboxylative ketonization of carboxylic acids has a long history [8][9][10][11] and several versions, such as a non-catalytic pyrolysis reaction [12], or an industrial scale vapor phase catalytic process [11,13]. It has been rediscovered several times [8].…”

Section: Introductionmentioning

confidence: 99%

Cross-selectivity in the catalytic ketonization of carboxylic acids

Ignatchenko

DeRaddo

Marino

et al. 2015

Applied Catalysis A: General

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a b s t r a c tA mixture of acetic and 2-methylpropanoic (isobutyric) acids representing non-branched and branched acids, respectively, was catalytically converted to a mixture of ketones in a set of statistically designed experiments (DOE). The selectivity toward the cross-ketonization product was analyzed depending on (a) temperature within 300-450 • C range, (b) molar fraction of each acid in the mixture, from 10% to 90%, and (c) liquid hourly space velocity (LHSV) within 2-12 h −1 , and compared against the selectivity toward two symmetrical ketones. Six metal oxide catalysts were tested and ranked on their ability to yield the cross-product as opposed to the self-condensation product. The catalysts were based on either the anatase form of titania or monoclinic form of zirconia and treated with either KOH or K 2 HPO 4 . The titania catalyst treated by KOH outperformed all other catalysts by providing the cross-selectivity above the statistically expected binomial distribution. The criterion for having a high cross-selectivity in the decarboxylative ketonization is formulated mathematically as the separation of roles of two acids, one being a more active enolic component, and the other being the preferred carbonyl component. According to the suggested criterion, the less branched acetic acid reacts as both the preferred carbonyl and enolic component with untreated catalysts. Therefore, untreated catalysts promote selective formation of the symmetrical ketone, acetone, thereby decreasing the selectivity to the cross-ketone. After alkaline treatment, both the anatase form of titania and monoclinic form of zirconia increase the isobutyric acid participation as the carbonyl component. Acetic acid remains as the preferred enolic component with all treated catalysts, thus increasing the selectivity toward the cross-product in the ketonization of a mixture of carboxylic acids. The condition for achieving a high cross-selectivity by polarizing roles of the two reactants can be extended to other types of cross-condensations.

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Section: Introductionmentioning

confidence: 99%

Cross-selectivity in the catalytic ketonization of carboxylic acids

Ignatchenko

DeRaddo

Marino

et al. 2015

Applied Catalysis A: General

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“…127,128 Subsequently, the formed carboxylic acids can also condensate into ketones with liberation of CO 2 (Scheme 5, reaction 7). 106,107,129,130 As…”

Section: Catalysis Science and Technology Minireviewmentioning

confidence: 99%

Review of catalytic systems and thermodynamics for the Guerbet condensation reaction and challenges for biomass valorization

Gabriëls

Hernández

Sels

et al. 2015

Catal. Sci. Technol.

240

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The Guerbet condensation reaction is an alcohol coupling reaction that has been known for more than a century. Because of the increasing availability of bio-based alcohol feedstock, this reaction is of growing importance and interest in terms of value chains of renewable chemical and biofuel production. Due to the specific branching pattern of the alcohol products, the Guerbet reaction has many interesting applications. In comparison to their linear isomers, branched-chain Guerbet alcohols have extremely low melting points and excellent fluidity. This review provides thermodynamic insights and unravels the various mechanistic steps involved. A comprehensive overview of the homogeneous, heterogeneous and combined homogeneous and heterogeneous catalytic systems described in published reports and patents is also given. Technological considerations, challenges and perspectives for the Guerbet chemistry are discussed.

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“…[3] An interesting reaction to transform carboxylic acids into symmetrical ketones is their coupling or the ketonic decarboxylation. [4] In this reaction, two carboxylic acids are condensed, and a symmetrical ketone is formed with 2nÀ1 carbon atoms, together with one molecule of water and one molecule of CO 2 (Scheme 1). When the reaction is carried out with stearic acid (C 18 ) to obtain stearone, the atom economy, that is, how much mass of the reactants ends up in the product, [5] is as high as 89 %.…”

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confidence: 99%