1002-79-5Relevant articles and documents
Elucidation of structural isomers from the homogeneous rhodium-catalyzed isomerization of vegetable oils
Andjelkovic, Dejan D.,Min, Byungrok,Ahn, Dong,Larock, Richard C.
, p. 9535 - 9543 (2006)
The structural isomers formed by the homogeneous rhodium-catalyzed isomerization of several vegetable oils have been elucidated. A detailed study of the isomerization of the model compound methyl linoleate has been performed to correlate the distribution of conjugated isomers, the reaction kinetics, and the mechanism of the reaction. It has been shown that [RhCl(C8H 8)2]2 is a highly efficient and selective isomerization catalyst for the production of highly conjugated vegetable oils with a high conjugated linoleic acid (CLA) content, which is highly desirable in the food industry. The combined fraction of the two major CLA isomers [(9Z,11E)-CLA and (10E,12Z)-CLA] in the overall CLA mixture is in the range from 76.2% to 93.4%. The high efficiency and selectivity of this isomerization method along with the straightforward purification process render this approach highly promising for the preparation of conjugated oils and CLA. Proposed improvements in catalyst recovery and reusability will only make this method more appealing to the food, paint, coating, and polymer industries in the future.
Transformation of Methyl Linoleate to its Conjugated Derivatives with Simple Pd(OAc)2/Lewis Acid Catalyst
Senan, Ahmed M.,Zhang, Sicheng,Qin, Shuhao,Chen, Zhuqi,Yin, Guochuan
, p. 1481 - 1489 (2017)
With the rapid depletion of fossil resources, the exploitation of biomass to partly replace fossil resources as the source of carbon in the chemical industry constitutes a promising alternative for the near future. This work introduces catalytic transformation of vegetable oil, i.e., methyl linoleate, to its conjugated esters by a simple Pd(OAc)2/Sc(OTf)3 catalyst, which has extensive applications in industry. It was found that adding non-redox metal ions like Sc(III) to a simple Pd(OAc)2 catalyst can effectively improve its isomerization activity in toluene/t-BuOH solvent, whereas Pd(OAc)2 alone is inactive. Preliminary mechanistic investigations together with previous studies suggested that the in situ-generated heterobimetallic Pd(II)/Sc(III) dimer serves as the key species for methyl linoleate isomerization, and the reaction proceeds by [1,3]-hydrogen shift mechanism involving a formal Pd(II)/Pd(IV) cycle.
Design of ru-zeolites for hydrogen-free production of conjugated linoleic acids
Philippaerts, An,Goossens, Steven,Vermandel, Walter,Tromp, Moniek,Turner, Stuart,Geboers, Jan,Van Tendeloo, Gustaaf,Jacobs, Pierre A.,Sels, Bert F.
, p. 757 - 767 (2011)
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 RuO2 species in Ru/Cs-USY(40). Copyright
Absorption Kinetics of the Main Conjugated Linoleic Acid Isomers in Commercial-Rich Oil after Oral Administration in Rats
Rodríguez-Alcalá, Luís M.,Ares, Irma,Fontecha, Javier,Martínez-Larra?aga, María-Rosa,Anadón, Arturo,Martínez, María-Aránzazu
, p. 7680 - 7686 (2017)
This study aimed to assess the oral absorption and plasma kinetics of two main isomers contained in commercial conjugated linoleic acid (CLA)-rich oil (Tonalin TG-80), rumenic acid (RA), and C18:2 trans-10, cis-12. The isomer plasma disposition after the single oral dose of 3000 mg of Tonalin TG-80/kg, containing 1200 mg/kg of each isomer, was studied in rats. The isomer plasma concentrations were determined by gas chromatography with flame ionization detection. The plasma kinetics showed rapid oral absorption of RA and C18:2 trans-10, cis-12 (t1/2a 0.34 ± 0.09 and 0.53 ± 0.01 h) and slow elimination (t1/2β 25.68 ± 3.29 and 18.12 ± 1.71 h); the maximal isomer plasma concentrations (Cmax) of 8.48 ± 0.98 and 7.67 ± 0.80 μg mL-1, respectively, were estimated at 2.08 ± 0.14 and 2.26 ± 0.11 h. Our results from a preclinical kinetic study in rats help to design future studies in humans for evaluating the CLA isomer dose-response.
Dissociation of proton-bound complexes reveals geometry and arrangement of double bonds in unsaturated lipids
Pham, Huong T.,Prendergast, Matthew B.,Dunstan, Christopher W.,Trevitt, Adam J.,Mitchell, Todd W.,Julian, Ryan R.,Blanksby, Stephen J.
, p. 170 - 177 (2015)
Double bond position and stereochemistry in unsaturated lipids can have profound impact on biological properties and activities but the assignment of these features by mass spectrometry is frequently challenging. Conventional techniques for lipid identification rely on collision-induced dissociation (CID) and are most often unable to differentiate between lipid isomers, particularly those involving double bond position and geometry (i.e., cis and trans). In this study, CID performed on proton-bound complexes of fatty acid methyl esters and iodoaniline (and related reagents) reveals unusual fragmentation patterns. CID products are shown to result from proton transfer and are associated with specific structures of the unsaturated lipids. Notably, CID of these complexes can not only distinguish cis- and trans-fatty acid methyl esters, but also differentiate conjugated double bond arrangements from non-conjugated analogs. Herein, the mechanisms underpinning this unique CID behavior are investigated by stable isotope labeling and are proposed to involve both carbene and free radical intermediates.
Superior anticarcinogenic activity of trans, trans-conjugated linoleic acid in N-methyl-N-nitrosourea-induced rat mammary tumorigenesis
Islam, Mohammad A.,Kim, Young S.,Oh, Tae W.,Kim, Gon S.,Won, Chung K.,Kim, Hoon G.,Choi, Myung S.,Kim, Jeong O.,Ha, Yeong L.
, p. 5670 - 5678 (2010)
The anticarcinogenic activity of a mixture of trans,trans-conjugated linoleic acid (trans,trans-CLA) was investigated in rat mammary tumorigenesis induced by N-methyl-N-nitrosourea (MNU), with references to cis-9,trans-11-CLA and trans-10,cis-12-CLA isomers. Female, 7-week-old Sprague-Dawley rats were intraperitoneally injected with MNU (50 mg/kg of body weight) and then subjected to one of five diets (control, 1% trans,trans-CLA, 1% cis-9,trans-11-CLA, 1% trans-10,cis-12-CLA, and 1% linoleic acid; 8 rats/group) for 16 weeks. Food and water were made available ad libitum. trans,trans-CLA significantly (p 0.05) reduced tumor incidence, number, multiplicity, and size and significantly (p 0.05) increased apoptosis, relative to cis-9,trans-11-CLA and trans-10,cis-12-CLA. The molecular mechanism of trans,trans-CLA was elucidated by measuring apoptosis-related gene products and fatty acid composition in tumors. trans,trans-CLA led to increases in the p53 protein and Bax protein levels but suppressed the expression of Bcl-2 protein. The activation of caspase-3 led to the cleavage of poly(ADP-ribose) polymerase, which resulted in the execution of apoptosis. In addition, trans,trans-CLA reduced cytosolic phospholipase A2, cyclooxygenease-2, and peroxisome proliferator-activated receptor γ protein levels. These results suggest that the trans,trans-CLA inhibits MNU-induced rat mammary tumorigenesis through the induction of apoptosis in conjunction with the reduction of arachidonic acid metabolites and that the efficacy of trans,trans-CLA is superior to cis-9,trans-11-CLA and trans-10,cis-12-CLA.
Sustainable and efficient methodology for CLA synthesis and identification
Moreno, Maria,Gomez, M. Victoria,Cebrian, Cristina,Prieto, Pilar,De La Hoz, Antonio,Moreno, Andres
, p. 2584 - 2594 (2013/02/23)
Microwave-assisted organic synthesis and continuous-flow techniques have been successfully employed for the preparation of conjugated linoleic acids (CLA), compounds with high health beneficial effects. A good production rate of CLA was obtained. A sustainable methodology for the differentiation of both positional and geometrical CLA isomers (diene), based on the analysis by NMR spectroscopy of the resulting Diels-Alder cycloadducts with an appropriate dienophile, was developed.
Proazaphosphatrane P(RNCH2CH2)3N (R = Me, i-Pr)-catalyzed isomerization of allylaromatics, allyl phenyl sulfide, allyl phenyl sulfone, and bis-allymethylene double bond-containing compounds
Yu, Zhengkun,Yan, Shenggang,Zhang, Guangtao,He, Wei,Wang, Liandi,Li, Yu,Zeng, Fanlong
, p. 111 - 117 (2007/10/03)
Using a proazaphosphatrane catalyst, P(RNCH2CH2) 3N (R = Me, i-Pr), allylaromatics and allyl phenyl sulfide were selectively isomerized to the corresponding vinyl isomers in yields up to > 99% in CH3CN at 40°C. Efficient transformation of allyl phenyl sulfone at ambient temperature afforded an isomerization/dimerization product in >95% yield. Conjugation of bis-allylmethylene double bond-containing compounds gave the corresponding conjugated isomers for cis,cis-9,12- octadecadienol and its methyl ether in yields up to 97%, and desilylation/conjugation products were obtained from the catalytic reaction of the trimethylsilyl ether of cis,cis-9,12-octadecadienol. The reaction mechanism is discussed based upon the 1H and 31P NMR-monitored reactions in CD3CN or CH3CN under the reaction conditions.
Simple method of preparation of methyl trans-10,cis-12- and cis-9,trans-11-octadecadienoates from methyl linoleate
Berdeaux,Voinot,Angioni,Juaneda,Sebedio
, p. 1749 - 1755 (2007/10/03)
Pure conjugated isomers of linoleic acid were prepared on a large scale by alkali-isomerization of purified methyl linoleate. The methyl esters of alkali-isomerized linoleic acid contained mainly the methyl cis-9,trans-11- and trans-10,cis-12-octadecadienoates (44 and 47%, respectively). These two isomers were then separated and purified by a series of low-temperature crystallizations from acetone. The isomeric purity obtained for the cis-9,trans-11-octadecadienoate isomer was >90% and that of the trans-10,cis-12-octadecadienoate isomer was 89 to 97%. The isolated yield of the two isomers corresponded to 18 and 25.7%, respectively, of the starting material. The structure of the two isomers was confirmed using partial hydrazine reduction, silver nitrate-thin-layer chromatography of the resulting monoenes and gas chromatography coupled with mass spectrometry of the 4,4-dimethyloxazoline derivatives. Fourier transform infrared spectroscopy of the monoenes gave the confirmation of the geometry of each double bond.
