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Item Infrared Study of the Adsorption of Water on to the Surface of Rutile(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (10), 1977) Griffiths, David M; Rochester, Colin H.Infrared spectra of the surface of three samples of rutile which had been (a) calcined in air at 723 K and heated in oxygen at 673 K, (b) calcined in air at 973 K and heated in oxygen at 673 K, and (c) calcined in air at 723 K and heated in hydrogen at 673 K have been recorded as a function of the extent of hydroxylation and hydration of the oxide surface. The adsorption and desorption characteristics of associatively adsorbed and chemisorbed water on rutile have been established in detail and are discussed primarily in terms of adsorptive interactions involving the {110}, {100} and {101} surface planes. Calcination of rutile at high temperature (973 K) enhanced the chemisorption of water on {110} planes at the expense of the associative adsorption of water on Ti4+ ion sites in the {100} and {101} planes. Mild reduction of rutile in hydrogen decreased the ability of the oxide to adsorb water molecularly. The effect of reduction was completely reversed by subsequent heat treatment of the oxide in oxygen.Item Infrared Study of the Adsorption of Acetone on Rutile(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (02), 1978) Griffiths, David M.; Rochester, Colin H.The associative adsorption of acetone onto Lewis acidic Ti4+ ion sites on rutile is followed by the formation of a surface enolate complex which reacts with a further acetone molecule to give mesityl oxide. The enolate is also an intermediate in the exchange of hydrogen atoms between acetone and hydroxyl groups on rutile. The effects of dehydroxylation and dehydration of the rutile surface on the associative adsorption of acetone and on the formation of the enolate complex and mesityl oxide have been studied using infrared spectroscopy. The reversibility of the surface reactions has been established, in part by a study of the adsorption of mesityl oxide, which not only associatively adsorbs onto Ti4+ ion sites but also decomposes to enolate complex and coordinatively liganded acetone molecules. Reduction of rutile in hydrogen decreases the Lewis acidity of the oxide surface but promotes the formation of surface acetate ions by the chemisorption of acetone.Item Infrared study of adsorption on silica from two-component and three-component liquid mixtures(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (09-12), 1978) Buckland, Anthony D.; Rochester, Colin H.; Trebilco, Deborah-Anne; Wigfield, KennethAn infrared cell of novel design is described and has been used for the measurement of spectra of discs of powdered silica immersed in liquid mixtures of 2,2,4-trimethylpentane + cyclohexanone, 1,4-dimethylbenzene + cyclohexanone and 2,2,4-trimethylpentane + 1,4-dimethylbenzene + cyclohexanone. The proportions of surface silanol groups perturbed by interaction with each component of the liquid mixtures were evaluated from absorbance data taken from the spectra. With certain provisos, infrared spectroscopy provides a valuable method for the study of adsorption behaviour at the interface between solids and multi-component liquid mixtures.Item Infrared Study of the Adsorption of Diketones on Silica Immersed in Carbon Tetrachloride(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (08), 1978) Cross, Stephen N. W.; Rochester, Colin H.The adsorption of pentan-3-one and four diketones onto silica immersed in carbon tetrachloride has been studied by infrared spectroscopy. The primary surface–adsorbate interaction for all five ketones involved the formation of hydrogen bonds between surface silanol groups and ketone groups in adsorbate molecules. At low surface coverages of silica by hexan-2,5-dione two isolated silanol groups formed hydrogen bonds to the two ketone groups in each adsorbed hexan-2,5-dione molecule. In contrast, a single silanol group formed a hydrogen bond to one of the two ketone groups in each hexan-2,3-dione molecule adsorbed at the solid/liquid interface. The second ketone group in each molecule was apparently unperturbed by the oxide surface. The mode of adsorption of pentan-2,4-dione on silica was complicated by the stability of the enol form of the diketone. Spectra of pentan-2,4-dione adsorbed from the gas phase and from carbon tetrachloride solution have established that both the keto and enol forms of the diketone existed on silica at the solid/vapour and the solid/liquid interfaces. Corresponding enolization could not occur for 3,3-dichloropentan-2,4-dione which was adsorbed on silica as the diketone. The electronic effect of 3,3-dichloro substitution weakened the surface–adsorbate interaction.Item Infrared study of the adsorption of anisoles on silica immersed in heptane(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (05), 1978) Rochester, Colin H.; Trebilco, Deborah-AnneInfrared spectra have been reported of silica immersed in solutions of anisole, six substituted anisoles (4-nitro, 4-chloro, 4-bromo, 4-methyl, 2-fluoro and 2,6-dimethyl), nitrobenzene and 4-nitrotoluene in heptane. Surface silanol groups were perturbed by hydrogen bonding interactions with either methoxy-groups or the benzene nuclei of adsorbed anisole molecules. Electron with drawing substituents in the anisole ring weakened both types of interaction. The proportion of perturbed silanol groups involved in interactions with benzene nuclei decreased with increasing electron withdrawing power of 4-substituents. Surface silanol groups formed hydrogen bonds with the nitro-groups of adsorbed nitrobenzene and 4-nitrotoluene molecules. An adsorptive interaction involving hydrogen-bond acceptance by nitro-group probably also occurred for 4-nitroanisole.Item Infrared study of the surface of silica immersed in liquid mixtures of hydrocarbons(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (06), 1977) Rochester, Colin H.; Trebilco, Deborah-AnneA simple infrared cell is described which enables studies to be made of the perturbation of surface hydroxyl groups caused by the immersion of powdered oxides in hydrocarbon solvents. Results are presented for silica in n-heptane + benzene and in n-heptane + toluene mixtures over the complete liquid composition ranges. Absorbance values taken from the spectra give the proportion of surface hydroxyl groups which are perturbed by contact with each component of a liquid mixture. Hence spectroscopic isotherms were deduced for the adsorption of each component onto specific (hydroxyl group) sites in the oxide surface.Item Infrared study of effects of sulphur-poisoning on the adsorption of carbon monoxide by nickel(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (04), 1977) Rochester, Colin H.; Terrell, Robert J.The effects of preadsorbed hydrogen sulphide, n-propyl mercaptan, dimethyl sulphide, thiophene and carbonyl sulphide on the adsorption of carbon monoxide by silica supported nickel have been compared by study of the infrared spectra of adsorbed carbonyl species. The formation of bridged or multicentre bonded surface carbonyl species was irreversibly poisoned by all five sulphur compounds. The strength of adsorption of carbon monoxide molecules which were linearly bonded to surface nickel atoms was weakened by sulphiding of the metal. On sulphided nickel the infrared spectra are interpreted in terms of the predominant mode of adsorption involving two and possibly three carbon monoxide molecules linearly bonded to single nickel atoms. The resulting surface species are considered to be intermediates in the formation of nickel tetracarbonyl.Item Infrared study of the adsorption of sulphur compounds on silica and silica-supported nickel(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (04), 1977) Rochester, Colin H.; Terrell, Robert J.Hydrogen bonding interactions between isolated hydroxyl groups on silica and adsorbed hydrogen sulphide, n-propyl mercaptan, dimethyl sulphide and thiophene molecules have been detected by infrared spectroscopy. Chemisorption of n-propyl mercaptan and dimethyl sulphide on silica primarily involved reaction of adsorbate molecules with strained siloxane bridges in the oxide surface. Thiophene was slowly chemisorbed on silica to give surface species, infrared spectra of which showed no evidence for unsaturation. The formation of the species involved slow exchange of hydrogen atoms between thiophene molecules and surface hydroxyl groups. Adsorption of carbonyl sulphide on silica could not be detected by infrared spectroscopy. Infrared spectra of n-propyl mercaptan and thiophene on nickel/silica resembled the corresponding spectra for the adsorbates on silica alone. No infrared bands due to surface species formed from hydrogen sulphide or carbonyl sulphide on nickel were detected. Dimethyl sulphide was predominantly associatively chemisorbed on nickel although some dissociative adsorption to give species containing CH2 groups may also have taken place.Item Enthalpies and entropies of ionization of 2- and 3-substituted phenols in methanol + water mixtures(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (04), 1977) Rochester, Colin H.; Wilson, David N.Enthalpies of solution and enthalpies and entropies of ionization of three (Me, Cl and NO2) 2-substituted phenols, three (Me, Cl, NO2) 3-substituted phenols, and 3,5-dinitrophenol in methanol + water mixtures have been determined for the entire range of solvent composition. Comparison of the medium effects on the thermodynamics of ionization of different phenols is made by analyses of the contributions which arise from the separate effects of solvent on the solvation of neutral phenols and phenoxide anions. The results confirm the inadequacy of theories which predict the relative effects of solvent on the thermodynamics of ionization of neutral acids solely by consideration of solvation effects involving the charged acid anions. Compensation between the influence of solvent on enthalpies and entropies of ionization is characterized.Item Sorption of Water Vapour by some Derivatives of Bovine Serum Albumin(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (1), 1977) Rochester, Colin H.; Westerman, A. ValerieIsotherms for the sorption of water vapour by succinyl, acetyl, amidino, methyl and carbodiimide derivatives of bovine serum albumin at 298 K have been determined gravimetrically. The effects of the specific chemical modifications on the uptake of water by B.S.A. are discussed by consideration of the groups in the protein which are possible sites for water sorption. Adsorption onto both side chain polar or ionic groups and main chain peptide groups occurs. Release of main chain peptide groups from the a-helical conformation enhances their capacity to sorb water.