Base-Catalyzed Reactions of Hydrocarbons

Pines, Herman; Schaap, Luke

doi:10.1016/s0360-0564(08)60601-x

Cited by 39 publications

(22 citation statements)

References 39 publications

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“…[23] In basic conditions a large amount of cis,cis product indicates a high degree of stereospecificity, in line with the nature of the proposed intermediate carbanion. Alternatively, carbenium ions can be formed with the assistance of Brønsted acid sites, [24] requiring initial cis/trans product ratios of around one.…”

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confidence: 62%

Design of Ru–Zeolites for Hydrogen‐Free Production of Conjugated Linoleic Acids

et al. 2011

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While conjugated vegetable oils are currently used as additives in the drying agents of oils and paints, they are also attractive molecules for making bio-plastics. Moreover, conjugated oils will soon be accepted as nutritional additives for "functional food" products. While current manufacture of conjugated vegetable oils or conjugated linoleic acids (CLAs) uses a homogeneous base as isomerisation catalyst, a heterogeneous alternative is not available today. This contribution presents the direct production of CLAs over Ru supported on different zeolites, varying in topology (ZSM-5, BETA, Y), Si/Al ratio and countercation (H(+), Na(+), Cs(+)). Ru/Cs-USY, with a Si/Al ratio of 40, was identified as the most active and selective catalyst for isomerisation of methyl linoleate (cis-9,cis-12 (C18:2)) to CLA at 165 °C. Interestingly, no hydrogen pre-treatment of the catalyst or addition of hydrogen donors is required to achieve industrially relevant isomerisation productivities, namely, 0.7 g of CLA per litre of solvent per minute. Moreover, the biologically most active CLA isomers, namely, cis-9,trans-11, trans-10,cis-12 and trans-9,trans-11, were the main products, especially at low catalyst concentrations. Ex situ physicochemical characterisation with CO chemisorption, extended X-ray absorption fine structure measurements, transmission electron microscopy analysis, and temperature-programmed oxidation reveals the presence of highly dispersed RuO(2) species in Ru/Cs-USY(40).

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confidence: 62%

Design of Ru–Zeolites for Hydrogen‐Free Production of Conjugated Linoleic Acids

et al. 2011

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“…The application of the recent developments of homogeneous catalysts for the selective dimerization of alpha olefins to branched alpha olefins is limited and processes to produce 4-methyl-1-pentene are still based on propylene dimerization promoted by heterogeneous catalysts generated by dispersion of alkali metals (sodium or potassium) on potassium carbonate or other appropriate supports [32]. However it is difficult to maintain activity and selectivity at high levels for a very long period of time and some improvements of these type of heterogeneous catalyst have been disclosed [33].…”

Section: -Methyl-1-pentenementioning

confidence: 99%

Oligomerization of Monoolefins by Homogeneous Catalysts

Forestière¹,

Olivier‐Bourbigou²,

Saussine³

2009

Oil & Gas Science and Technology - Rev. IFP

207

199

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Résumé -Oligomérisation des mono-oléfines par des catalyseurs homogènes -Cet article résume les différents schémas réactionnels pour l'oligomérisation des mono-oléfines par catalyse homogène, en particulier pour l'oligomérisation de l'éthylène et des alpha-oléfines. Les principaux sujets abordés sont la production régiosélective ou non de dimères, la production d'alpha-oléfines linéaires par oligomérisation de l'éthylène ainsi que la dimérisation sélective de l'éthylène et sa trimérisation sélective. Plusieurs procédés industriels développés par l'IFP sont présentés pour illustrer ce sujet. Abstract -Oligomerization of Monoolefins by Homogeneous Catalysts

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“…[85] On basic supports, carbanions can be formed, yielding CLA isomers by an allylic mechanism. [86] In this case a high amount of cis,cis isomers are expected to be formed. www.chemsuschem.org…”

Section: Mechanistic Considerationmentioning

confidence: 99%

Catalytic Production of Conjugated Fatty Acids and Oils

et al. 2011

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The reactive double bonds in conjugated vegetable oils are of high interest in industry. Traditionally, conjugated vegetable oils are added to paints, varnishes, and inks to improve their drying properties, while recently there is an increased interest in their use in the production of bioplastics. Besides the industrial applications, also food manufactures are interested in conjugated vegetable oils due to their various positive health effects. While the isomer type is less important for their industrial purposes, the beneficial health effects are mainly associated with the c9,t11, t10,c12 and t9,t11 CLA isomers. The production of CLA-enriched oils as additives in functional foods thus requires a high CLA isomer selectivity. Currently, CLAs are produced by conjugation of oils high in linoleic acid, for example soybean and safflower oil, using homogeneous bases. Although high CLA productivities and very high isomer selectivities are obtained, this process faces many ecological drawbacks. Moreover, CLA-enriched oils can not be produced directly with the homogeneous bases. Literature reports describe many catalytic processes to conjugate linoleic acid, linoleic acid methyl ester, and vegetable oils rich in linoleic acid: biocatalysts, for example enzymes and cells; metal catalysts, for example homogeneous metal complexes and heterogeneous catalysts; and photocatalysts. This Review discusses state-of-the-art catalytic processes in comparison with some new catalytic production routes. For each category of catalytic process, the CLA productivities and the CLA isomer selectivity are compared. Heterogeneous catalysis seems the most attractive approach for CLA production due to its easy recovery process, provided that the competing hydrogenation reaction is limited and the CLA production rate competes with the current homogeneous base catalysis. The most important criteria to obtain high CLA productivity and isomer selectivity are (1) absence of a hydrogen donor, (2) absence of catalyst acidity, (3) high metal dispersion, and (4) highly accessible pore architecture.

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Base-Catalyzed Reactions of Hydrocarbons

Cited by 39 publications

References 39 publications

Design of Ru–Zeolites for Hydrogen‐Free Production of Conjugated Linoleic Acids

Design of Ru–Zeolites for Hydrogen‐Free Production of Conjugated Linoleic Acids

Oligomerization of Monoolefins by Homogeneous Catalysts

Catalytic Production of Conjugated Fatty Acids and Oils

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