17675-24-0Relevant articles and documents
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 (2017/11/03)
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.
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 (2015/10/20)
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.
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.
experimental part, p. 757 - 767 (2012/05/19)
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
