Telomerization and dimerization of isoprene by in situ generated palladium-carbene catalysts |
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Authors: | Ralf Jackstell Dirk Michalik Matthias Beller |
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Affiliation: | a Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Strasse 29 A, 18059 Rostock, Germany b Université Cadi Ayyad, Faculté des Sciences Semlalia, Département de Chimie Bd. Prince My Abdellah, B.P. 2390, 40001 Marrakech, Morocco |
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Abstract: | The palladium-catalyzed telomerization of isoprene with methanol and dimerization of isoprene have been studied in presence of in situ generated palladium-carbene catalysts. Unprecedented catalyst productivity has been observed for these two reactions. A selectivity switch from the telomer to the dimer product occurred by using different substituted carbene ligands. Among the imidazolium salts tested 1,3-dimesitylimidazolium mesylate (1), 1,3-dimesityl-4,5-dihydroimidazolium chloride (3) gave the best yields for telomerization reaction whereas 1,3-bis-(2,6-diisopropylphenyl)-4,5-dihydroimidazolium tetrafluoroborate (5) and 1,3-bis-(2,6-diisopropylphenyl)-4,5-dimethyl-4,5-dihydroimidazolium chloride (9) form dimers in high yield and good selectivity. |
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Keywords: | Carbenes Dimerization Homogeneous catalysis Isoprene Palladium Telomerization |
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