Browsing by Author "Rochester, Colin H"

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    Infrared Study of the Adsorption of [2H4]Acetic Acid on to Rutile
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (12), 1977) Griffiths, David M; Rochester, Colin H
    Infrared spectroscopic studies are reported of the adsorption of [2H4]acetic acid onto three samples of rutile which differed in their extents either of hydration or of reduction. Acetic acid was associatively adsorbed on Lewis acidic electron acceptor Ti4+ sites in the rutile surface: this mode of adsorption was prevented by the preadsorption of water or by reduction of rutile in hydrogen. Weakly adsorbed acetic acid dimers appeared on the surface of rutile which had been pretreated in oxygen but not on reduced rutile. Chemisorption of acetic acid generated water, surface deuteroxyl groups and [2H3]acetate ions predominantly in a highly symmetrical bidentate chelate configuration. Both the presence of adsorbed water and prereduction of rutile in hydrogen hindered the chemisorption of acetic acid on rutile.
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    Infrared Study of the Adsorption of Hexafluoroacetone on to Rutile
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (12), 1977) Griffiths, David M; Rochester, Colin H
    Infrared spectra have been recorded of hexafluoroacetone adsorbed on four samples of rutile which differed in their extents of dehydration by thermal activation or of reduction in hydrogen. Physically adsorbed hexafluoroacetone molecules interacted as hydrogen bond acceptors with surface hydroxyl groups, as electron donors with Ti4+ ions, and as electron acceptors with Ti3+ ions. Chemisorptive interactions involving surface hydroxyl groups or O2– ions led to the formation of trifluoroacetate ions and precursor species resembling salts of hexafluoropropan-2,2-diol. In general, reduction of rutile in hydrogen weakened adsorptive interactions involving H-bond donation or electron acceptance by the oxide surface. In contrast interactions involving electron donation or nucleophilic attack of hexafluoroacetone by hydroxyl groups or O2– ions were enhanced by reduction of the oxide in hydrogen.
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    Infrared Study of the Adsorption of Aromatic Esters on Silica Immersed in Carbon Tetrachloride
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1981, 77 (05), 1981) Cross, Stephen N. W; Rochester, Colin H
    Infrared spectra are reported of silica preheated at 843–948 K and immersed in solutions of benzyl acetate, ethyl benzoate and benzyl benzoate in carbon tetrachloride. The predominant surface–adsorbate interaction involved the formation of hydrogen bonds between isolated surface silanol groups and the (C[double bond, length as m-dash]O)-groups of adsorbed ester molecules. A small proportion of the adsorbed ester molecules were each linked to the silica surface via two hydrogen bonds, one involving the (C[double bond, length as m-dash]O)-group and the other involving aromatic π-electrons. The results are compared with previous data for the adsorption of ethyl acetate and ethyl cyanoacetate and are discussed in relation to the electronic effects of substituent groups in the ester molecules.
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    Infrared Study of the Adsorption of Ethyl Cyanoacetate on Silica Immersed in Carbon Tetrachloride
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1981, 77 (05), 1981) Cross, Stephen N. W; Rochester, Colin H
    Infrared spectra are reported of silica immersed in solutions of ethyl cyanoacetate in carbon tetrachloride. The surface–adsorbate interaction for silica which had been preheated at 1073 K involved the formation of hydrogen bonds between pairs of isolated surface silanol groups and both the cyano and carbonyl groups in each adsorbed ethyl cyanoacetate molecule. For silica which had been evacuated at 298 K adjacent interacting surface silanol groups also provided sites for the adsorption of ethyl cyanoacetate. The adsorbed molecules were again bonded to the surface via both their cyano and carbonyl groups. Each carbonyl group was involved in a hydrogen bonding interaction with a single surface silanol group. This contrasts with the observation that pairs of adjacent interacting silanol groups each formed two hydrogen bonds with the carbonyl oxygen atom of a single ethyl acetate molecule adsorbed on silica immersed in carbon tetrachloride.