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    Dehydrogenation and isomerization of n-butenes on mixed tin + antimony oxide catalysts
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (06), 1978) Irvine, Elizabeth A.; Taylor, Duncan
    The dehydrogenation and concurrent isomerization of the three n-butenes have been investigated at 474 K on a range of mixed tin + antimony oxide catalysts outgassed at 698 K. The initial approximately zero order reaction rates were used as a measure of catalytic activity to construct patterns of activity as a function of catalyst composition. Comparison of the patterns with those for the isomerization of 3,3-dimethylbut-1-ene and for the selective oxidation of propene on the same catalysts indicate that dehydrogenation of but-1-ene involves a π-allyl intermediate, while isomerization occurs through carbonium ion formation. For the cis- and trans-isomers, it is suggested that both reactions occur via a common allyl (but not π-allyl) type of intermediate.
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    Isomerization of n-butenes on A-type zeolites studied by infrared spectroscopy. Part 1.—n-butene adsorption on zeolites containing alkali and alkaline earth cations
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (06), 1978) Förster, Horst; Seelemann, Rudolf
    Adsorption of n-butenes on highly activated type A-zeolites containing alkali and alkaline earth cations is studied by infrared spectroscopy. The rate of adsorption is determined by the butene–zeolite interaction, depending on the dipole moment and the steric requirements of the butene molecules, and the occupancy of the cation sites. The n-butenes are strongly physisorbed without fragmentation with preservation of the C[double bond, length as m-dash]C bond. The adsorption is accompanied by the appearance of forbidden i.r. fundamentals, small frequency shifts, a change in band intensities and a decrease in band widths. Narrow bands point to a largely restricted rotational freedom. The frequency shift of the C[double bond, length as m-dash]C band is cation sensitive and shows a direct polarizing power dependence. Under formation of a π-complex the butenes are attached to the cations in a “side on” mode. In the case of the alkali and alkaline earth forms isomerization is not affected. In the far infrared region phonon induced absorptions are observable.