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Dimerisation of cyclooctene using Grubbs’ catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
41198 45880 2011 9 PDF Available
Title
Dimerisation of cyclooctene using Grubbs’ catalysts
Abstract

The dimerisation of cyclooctene (COE) to 1,9-cyclohexadecadiene, a molecule of interest to the fragrance industry, has been achieved using ruthenium catalysts in organic solvents with significantly better selectivities (47–74%) and yields (39–60%) than previously reported (34% and 30%, respectively). Grubbs’ first and second generation catalysts, the Hoveyda–Grubbs’ catalyst and a phosphonium alkylidene catalyst were tested in a range of organic solvents and ionic liquids (ILs), including 1:1 IL/dichloromethane mixtures and biphasic IL + pentane systems. The best results (74% selectivity, 60% yield) were obtained using Grubbs’ first generation catalyst in 1,2-dichloroethane. The formation of trimer, tetramer and other higher molecular mass products were found to be favoured at low catalyst loadings (<8.5 mol%) and high concentration of cyclooctene (>0.77 mM). Studies of metathesis reactions using 1,9-cyclohexadecadiene as substrate indicated that the monomer–dimer and monomer–trimer reactions are faster than the dimer–dimer reaction. The use of IL media allowed for the recyclability of the catalyst, although a drop in the yield of dimer generally occurred after the first run. Heterogeneized catalysts, where the IL-catalyst system was immobilised onto silica, resulted in fast reactions leading to poor yields of dimer.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (13 K)Download as PowerPoint slideHighlights► High selectivity (74%) and yield (60%) are obtained in the dimerisation of cyclooctene. ► Grubbs’ (1st and 2nd generation), Hoveyda–Grubbs’ and phosphonium catalysts are tested. ► Effect of varying solvent, catalyst loading and substrate concentration are analysed. ► Formation of trimer and tetramer compared to dimer studied, using dimer as substrate. ► Recyclability and immobilisation of catalysts are possible using ionic liquids.

Keywords
Metathesis; Cyclooctene; Grubbs’ catalysts; Ionic liquids; Dimerisation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 408, Issues 1–2, 28 November 2011, Pages 54–62
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us