Elucidation of Structural Isomers from the Homogeneous Rhodium-Catalyzed Isomerization of Vegetable Oils

Andjelkovic, Dejan D.; Min, Byungrok; Ahn, Dong U.; Larock, Richard C.

doi:10.1021/jf0612124

Cited by 44 publications

(53 citation statements)

References 45 publications

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“…Over the years, due to an increasing demand for bio-based monomers and drying oils, a number of processes for the conjugation of carbon-carbon double bonds in regular vegetable oils have been developed with the goal of enhancing their reactivity towards polymerization and auto-oxidation [6][7][8][9][10]. With a high percentage of fatty acids (~84%) [11] bearing a natural system of triply conjugated carbon-carbon double bonds (Figure 1), tung oil constitutes an ideal candidate for the preparation of bio-based materials.…”

Section: Introductionmentioning

confidence: 99%

Effect of Microwave Cure on the Thermo-Mechanical Properties of Tung Oil-Based/Carbon Nanotube Composites

et al. 2015

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Tung oil is uniquely reactive among plant-based natural oils due to the series of conjugated carbon-carbon double bonds in its fatty acid chains. These conjugated carbon-carbon double bonds impart a high reactivity towards cationic polymerization in the presence of other reactive co-monomers, such as divinylbenzene and styrene. An impressive decrease in the cure time of tung oil-based thermosets has been achieved when the resins investigated were microwaved in the presence of carbon nanotubes (CNTs). However, the fast cure compromised the overall thermo-mechanical properties of the materials investigated. Microwave power, exposure time, and CNT loading effects have been assessed by means of dielectric analysis (DEA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and proton nuclear magnetic resonance ( 1 H NMR) spectroscopy of extracts obtained by Soxhlet extraction. Possible reasons were proposed to explain the overall inferior properties observed whenever faster cure rates were achieved.

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Section: Introductionmentioning

confidence: 99%

Effect of Microwave Cure on the Thermo-Mechanical Properties of Tung Oil-Based/Carbon Nanotube Composites

et al. 2015

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“…Apart from the biochemical processes, homogeneous and heterogeneous catalysed isomerizations are also possible. [RhCl(C 8 H 14 ) 2 ] 2 can be used as homogeneous catalyst for the isomerization of vegetable oils [26]. Heterogeneous catalysts contain common hydrogenation metals, e.g., ruthenium [27], nickel [28], rhodium [29], and iridium [30], although the low CLA yield still prevents their industrial application.…”

Section: Introductionmentioning

confidence: 99%

Direct Isomerization of Linoleic Acid to Conjugated Linoleic Acids (CLA) using Gold Catalysts

Bauer¹,

Horlacher²,

Claus³

2009

Chem Eng & Technol

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, activated carbon, titanium silicalite TS-1, were prepared and used for the isomerization of linoleic acid (cis-9,cis-12-octadecadienoic acid) to conjugated linoleic acids (CLA) in the presence of hydrogen at 165°C in a batch reactor. The best results were obtained using a catalyst with 2 wt % Au on TS-1, which exhibits a high selectivity (78 %) towards CLA. The two biologically active target CLA isomers, i.e., cis-9,trans-11-CLA and trans-10,cis-12-CLA, were the main products. During the isomerization of linoleic acid to CLA, consecutive reactions also took place. These were the hydrogenation of linoleic acid and CLA to monounsaturated octadecenoic acids and the further hydrogenation of monounsaturated acids to stearic acid. Thus, gold catalysts are capable of isomerizing linoleic acid to CLA and hydrogenating their double bonds to an extent that depends on the Au catalyst used.

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“…[78] Similar to the isomerization process in strong alkali, it is generally observed that the higher the temperature, the higher the portion of the thermodynamically more stable trans,transisomers. [75] Despite the advantages, homogeneous metal complexes are often of little commercial value due to the prohibitive catalyst (preparation) costs.…”

Section: Homogeneous Metal Complexesmentioning

confidence: 99%

“…Next, additional Lewis acid promoters such as SnCl 2 .2H 2 O are often required to achieve appropriate activities, as in the case of most Pt and Rh complexes. [75,[78][79] And finally, hydride donors such as alcohols and formic acid are frequently applied to accelerate the conjugation process, [5d, 73-74, 75-76, 80] but their presence often lowers the CLA selectivity owing to hydrogenation side-reactions. [76,80] The use of formic acid presents an additional hazard, while removal of the residual formic acid is difficult and expensive.…”

Section: Homogeneous Metal Complexesmentioning

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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Elucidation of Structural Isomers from the Homogeneous Rhodium-Catalyzed Isomerization of Vegetable Oils

Cited by 44 publications

References 45 publications

Effect of Microwave Cure on the Thermo-Mechanical Properties of Tung Oil-Based/Carbon Nanotube Composites

Effect of Microwave Cure on the Thermo-Mechanical Properties of Tung Oil-Based/Carbon Nanotube Composites

Direct Isomerization of Linoleic Acid to Conjugated Linoleic Acids (CLA) using Gold Catalysts

Catalytic Production of Conjugated Fatty Acids and Oils

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