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Formation and catalytic properties of some ruthenium (II) olefin complexes in solution.

University of British Columbia

A kinetic study of the complex formation between chlororuthenate (II) species and the olefinic substrates, 1,1 difluoroethylene, fluoroethylene and acrylamide in aqueous hydrochloric acid solution has been carried out. The kinetics were studied either by measurement of gas uptake or by following spectrophotometrically at 680 mμ the disappearance of the blue Ru (II) species at experimental conditions in which ruthenium, olefin and chloride concentrations were varied. A two step process involving an initial dissociation of a chloride ligand seems likely for these systems, but a detailed discussion is limit ed by lack of information on the equilibria between chlororuthenate (II) species in solution. No evidence was obtained for hydrogenation by molecular hydrogen of the 1,1 difluoroethylene or fluoroethylene through a π-complex formed with the chlororuthenate (II) species. Catalytic hydration of these olefins to acetic acid and acetaldehyde respectively was however observed, and a mechanism is proposed to account for this; this appears to be the first, report of a transition metal catalysed hydration of olefins. Acrylamide was not hydrated but could be catalytically hydrogenated to propionamide; the kinetic data fit a well established mechanism. Similarities between the hydrogenation and hydration processes are pointed out.

Text

2011-06-27

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http://hdl.handle.net/2429/35765

Chemistry

University of British Columbia

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