- The Mechanisms of Cyclisation and 1,2-Bond-shift Rearrangements of 2,2,4,4-Tetramethylpentane on Transition Metal Films
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The cyclisation/rearrangement products of 2,2,4,4-tetramethylpentane in deuterium on sintered films of Ir, Rh, Pd, and Pt, analysed by combined gas-liquid chromatography/mass spectrometry, show that chemisorbed carbene and carbyne species are not responsi
- Clarke, John K. A.,Finlayson, Odilla E.,Rooney, John J.
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- Alkene oligomerization process
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A process for oligomerising alkenes having from 3 to 6 carbon atoms which comprises contacting a feedstock comprising a) one or several alkenes having x carbon atoms, and, b) optionally, one or several alkenes having y carbon atoms, x and y being different, with a catalyst containing a zeolite of the MFS structure type, under conditions to obtain selectively oligomeric product containing predominant amounts of certain oligomers. The process is carried out at a temperature comprised between 125 and 175° C. when the feedstock contains only alkenes with 3 carbon atoms and between 140 and 240° C., preferably between 140 and 200° C. when the feedstock contains comprises at least one alkene with 4 or more carbon atoms.
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- Mechanisms of 1,5-Dehydrocyclisation and Isomerisation of Alkanes on Iridium, Rhodium, Palladium and Platinum Films
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Deuterium tracer studies with a combined gas-liquid chromatography and mass spectrometry analysis of products and using 2,2,4,4-tetramethylpentane (TMP) as a model reactant establish clearly that the selective cyclisation (SCM) of five-carbon chain alkanes on Ir, Rh, Pd and Pt is by the heterogeneous counterpart of reductive elimination of alkyls in organometallic chemistry.A comparison of cyclisation of TMP, 3,3-dimethylpentane and n-pentane on films of the same series of metals and an extended study of cyclisation of 3,3-dimethylpentane and of n-pentane on a series of Pt-Cu alloy films with variation of hydrogen partial pressure show that more than one mechanism of non-selective cyclisation (NSCM) takes place.The isotopic studies show clearly that a monoadsorbed intermediate is sufficient for bond-shift rearrangement of TMP to 2,2,5-trimethylhexane on Ir, Rh, Pd or Pt.An important major conclusion to be derived from the present work is that one surface metal atom comprises the active centre of the catalytic site for a variety of reactions in addition to simple hydrogenation-dehydrogenation.
- Finlayson, Odilla E.,Clarke, John K. A.,Rooney, John J.
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p. 191 - 210
(2007/10/02)
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