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Start date: 1980Subject: search.filters.subject.Infrared spectroscopy

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    Adsorption of Butenes on NaY and Dehydroxylated Y Zeolites Studies by Infrared Spectroscopy
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1981, 77 (06), 1981) Datka, Jerzy
    Butene molecules adsorbed on NaY and dehydroxylated Y zeolites are bonded to electrophilic acid sites (Na+ ions or Lewis-acid sites) by their π electrons. The interaction of butene molecules with Lewis-acid sites results in an increase in the extinction coefficient of the band for the antisymmetric stretching vibration of the CH3 group thus indicating an increased polarization of the C—H bond. The rates of desorption of the butenes from NaY or dehydroxylated zeolites increase in the sequence but-1-ene < cis-but-2-ene < trans-but-2-ene. These differences are explained by considering the steric factor. At low pressures the maximum butene content in Y zeolites is 3 molecules per supercage.
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    Infrared Study of Carbon Monoxide Adsorption on Calcium and Strontium Oxides
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1981, 77 (05), 1981) Coluccia, Salvatore; Garrone, Edoardo; Guglielminotti, Eugenio
    CO adsorption on CaO and SrO takes place, as on MgO, via a disproportionation reaction leading to both surface carbonates and unusual surface species with a complex vibrational spectrum in the low-frequency range. These are thought to be negatively charged CO polymers, the simplest ones being (CO)2–2. A strong electrostatic interaction between negative species and surface cations accounts for the marked dependence of the infrared signal on the lattice parameter of the solids. The increasing basicity along the series MgO, CaO, SrO causes: (i) a marked increase in the total adsorptive capacity; (ii) an increase in the relative population of polymers with respect to dimers; (iii) an increase in the importance of a Boudouart-like reaction upon desorption.
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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.