- PROCESS FOR CO-PRODUCING OLEFINS AND DIESTERS OR DIACIDS STARTING FROM UNSATURATED FATS
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In order to produce both an olefinic fraction and a composition of diacids or diesters of fats, a process is carried out which comprises, in succession: a) metathesis of an unsaturated fat with ethylene in the presence of at least one non-aqueous ionic liquid; b) separating and recycling the ionic liquid used in the first step; c) separating, by distillation, the olefinic fraction (fraction A) from the unsaturated fat mono-ester or mono-basic acid fraction (fraction B) formed in step a); d) homometathesis of the mono-unsaturated fat ester or acid cut (fraction B) which allows the co-production of unsaturated fat diesters or diacids (fraction C) and ethylene which is recycled to the first methathesis step of the process; and e) optionally, recycling the ionic liquid containing the catalyst used in step d). Of particular application to an oleic sunflower oil, an oleic rapeseed oil or to a mixture of mono-alcohol esters of said oils, whereupon the process can produce both an olefinic fraction (mainly composed of 1-decene) and a composition of diesters or diacids wherein, in general, over half of the chains is constituted by unsaturated C18 chains (mainly composed of octadecene-9 1,18-diacid or diester) and to recycle the ethylene employed.
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Page/Page column 3-4
(2008/06/13)
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- Regarding the mechanism of olefin metathesis with sol-gel-supported Ru-based complexes bearing a bidentate carbene ligand. Spectroscopic evidence for return of the propagating Ru carbene
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Two isotopically and structurally labeled Ru-based carbenes (2-d 4 and 13) have been prepared and attached to the surface of monolithic sol-gel glass. The resulting glass-supported complexes (18-d n and 19) exhibit significant catalytic activity in promoting olefin metathesis reactions and provide products of high purity. Through analysis of the derivatized glass pellets used in a sequence of catalytic ring-closing metathesis reactions mediated by various supported Ru carbenes, it is demonstrated that free Ru carbene intermediates in solution can be scavenged by support-bound styrene ether ligands prior to the onset of competing transition metal decomposition. The observations detailed herein provide rigorous evidence that the initially proposed release/return mechanism is, at least partially, operative. The present investigations shed light on a critical aspect of the mechanism of an important class of Ru-based metathesis complexes (those bearing a bidentate styrene ether ligand).
- Kingsbury, Jason S.,Hoveyda, Amir H.
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p. 4510 - 4517
(2007/10/03)
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