- Carbenium ions generated upon adsorption of 4-methoxystyrenes onto acid zeolites. A kinetic study
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Adsorption of vinylanisole and trans-(4-methoxyphenyl)-1-propene into HY, Hβ and HZSM-5 allows us to detect the corresponding substituted 1,3- bis(4-methoxyphenyl)-1-propylium (2), 1-(4-methoxyphenyl)-6-methoxy-1- indanylium (5) and 1,3-bis(4-methoxyphenyl)-2-propen-1-ylium (8) cations as reactive intermediates. The kinetics can be followed by conventional spectrophotometers. Cation 2 appears as the shorter lived species, decaying in hours for the HY sample and within days when embedded in HZSM-5 zeolite. Cyclic indanyl cation 5 shows a-lifetime much longer than 2. A growth of 8 concomitantly with the decay of 2 has been also observed. This has been taken as a proof of a hydride transfer from neutral 1,3-bis(4-methoxyphenyl)-1- propenes (the corresponding acyclic dimers observed as products) as donors to cations 2 as acceptors leading to 8.
- Fornes, Vicente,Garcia, Hermenegildo,Marti, Vicente,Fernandez, Lorenzo
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- Anomalous behaviour of Pd(II) on phenylpropanoids
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Exposure of phenylpropanoids like methyleugenol, eugenol and methylchavicol to Pd(II) chloride in acetic acid results in α,β linked unsymmetrical dimers. Dimeric coupling is characteristic of phenylpropanoids whereas cyclisation to indanes require the pre
- Thappa,Agarwal,Dhar
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p. 731 - 733
(2007/10/03)
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