- Highly regioselective hydroformylation of 1,5-hexadiene to linear dialdehyde catalyzed by rhodium complexes with tetraphosphorus ligands
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Rhodium-catalyzed hydroformylation of 1,5-hexadiene to corresponding dialdehydes was investigated using tetraphosphorus ligands. These ligands showed a high regioselectivity for linear aldehydes (linear to branch ratio up to 98%) in very good yield (up to 87%). It was found that the introduction of the substituents at the ortho position of the biphenyl moiety has little effect on the regioselectivity and the electron-donating substituents retard the reaction somewhat.
- Yu, Shichao,Chie, Yu-ming,Zhang, Xiaowei,Dai, Liyan,Zhang, Xumu
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experimental part
p. 5575 - 5577
(2011/02/22)
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- Hydroformylation of 1,5-hexadiene catalyzed by rhodium complexes in supercritical carbon dioxide and in toluene: Effects of fluorinated phosphane ligands and reaction conditions
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Rhodium-catalyzed hydroformylation of 1,5-hexadiene to dialdehydes was investigated in compressed CO2 and in toluene using different fluorinated phosphane compounds as ligands at a temperature of 60 °C. Product yields depend greatly on the ligand used and, of the ligands examined, tris[3,5-bis(trifluoromethyl)phenyl]phosphane is the most effective for the production of dialdehydes both in supercritical CO2 (scCO 2) and in toluene. The total yield of the dialdehydes passes through a minimum at about 9 MPa as the CO2 pressure is increased and increases appreciably as the H2 pressure in scCO2 increases. The effect of the syngas (H2/ CO) and H2 pressures on the reaction in scCO2 is different from that in toluene. It has been suggested that scCO2 promotes the hydroformylation reaction. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Fujita, Shin-Ichiro,Fujisawa, Shinya,Bhanage, Bhalchandra M.,Ikushima, Yutaka,Arai, Masahiko
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p. 2881 - 2887
(2007/10/03)
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- Generation of Acyl Radicals from 2-Naphthyl Thioesters
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A series of S-2-naphthyl thioesters were synthesized from the corresponding carboxylic acids or acid chlorides.Irradiation of these thioesters in the presence of a hydrogen source (i.e., 1,4-cyclohexadiene) generated the corresponding aldehydes.In this fashion, primary, secondary, tertiary, and aryl carboxylic acids were converted to the aldehydes in high yields.Intramolecular radical cyclization reactions support the hypothesis that the reaction proceeds via the formation of acyl radicals.The formation of aldehydes was not perturbed by possible Norrish Type II reactions.
- Penn, John H.,Liu, Fang
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p. 2608 - 2612
(2007/10/02)
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- 1,5-Hexadiene selective hydroformylation reaction catalyzed with Rh(acac)2/P(OPh)3 and Rh(acac)(CO)(PPh3)/PPh3 complexes
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Hydroformylation of 1,5-hexadiene, catalyzed by the system Rh(acac)2/P(OPh)3 (I), leads to the formation of mono- and dialdehydes, 4-heptenal, 2-Me-3-hexenal and octane-1,8-dial, 2,5-Me2-hexanedial respectively.The yield of dialdehydes increases with temperature and pressure and reaches 100percent at 80 deg C and 10 atm of CO/H2 = 1.The reaction catalyzed by Rh(acac)(CO)(PPh3)/PPh3 (II) system produces, besides dialdehydes, monoaldehydes with a terminal double bond, namely 6-heptenal and 2-Me-5-hexenal.The migration of the double bonds in monoaldehydes dependsmainly on the donor properties of modifying ligands.Phosphine when used as a modifying ligand (II), because of its strong donor properties, restricts isomerization (double bond migration) and diminishes yield of 4-heptenal.In contrast, when less strongly donating ligands such as phosphite are used as modifying ligands (I), independently of its steric properties, 4-heptenal is the main reaction product.Key words: Hydroformylation; Rhodium; Hexadiene; Catalysis
- Trzeciak, A.M.,Ziolkowski, J.J.
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p. 107 - 112
(2007/10/02)
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- INTRAMOLEKULARE CYCLOADDITIONEN MIT ISOBENZOFURANEN - III. EIN HYDRIERTES NAPHTHOTHIOPHEN AUS EINEM 1-ALKENYLTHIENOFURAN
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The synthesis of tetrahydronaphthothiophene 6 utilizing an intramolecular Diels-Alder reaction with an 1-alkenylthienofuran 4 is described.
- Schoening, A.,Friedrichsen, W.
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p. 1137 - 1138
(2007/10/02)
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