- Rhodium/Phosphine catalysed selective hydroformylation of biorenewable olefins
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This work reports rhodium catalyzed selective hydroformylation of natural olefins like eugenol, estragole, anethole, prenol and isoprenol using biphenyl based Buchwald phosphine ligands (S-Phos (L1), t-Bu XPhos (L2), Ru-Phos (L3), Johnphos (L4) and DavePhos (L5). Ru-Phos (L3) ligand exhibited high impact on the hydroformylation of eugenol providing high selectivity (90%) of linear aldehyde as major product. In addition, internal natural olefins like anethole and prenol provided moderate to high selectivity (65% and 85% respectively) of branched aldehydes as a major products. The various reaction parameters such as influence of ligands, P/Rh ratio, syngas pressure, temperature, time and solvents have been studied. A high activity and selectivity gained on the way to the linear aldehydes it may be due to the bulky, steric cyclohexyl and isopropoxy groups present in L3 phosphine ligand. Moreover, this catalytic system was smoothly converting natural olefins into corresponding linear and branched aldehydes with higher selectivity under the mild reaction conditions.
- Jagtap, Samadhan A.,Bhanage, Bhalchandra M.
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- A synthetic route to 4-alkyl-α-methylhydrocinnamylaldehydes
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The 4-Alkyl-α-methylhydrocinnamylaldehydes (alkyl-isopropyl, isobutyl, methyl) are frequently used fragrances with desired floral (lilac, cyclamen, lily-of-the-valley) scent. These substances are valued for their good stability in basic solution and, therefore, are frequently used in soaps, detergents, or shampoos. These substances are synthesized by a two-step synthesis involving base catalyzed aldol condensation of 4-alkylbenzaldehyde with propanal followed by selective hydrogenation of the C=C bond. In aldol condensation, selectivity is decreased by formation of undesired products of propanal autocondensation 2-methylpent-2-enal. In this work the reaction conditions for homogenous catalyzed aldol condensation of 4-isobutylbenzadehyde with propanal were tested (catalyst type and amount, molar ratio of reactants, solvent type). Reaction conditions giving the best results (92% conversion, 79% selectivity) were adapted to other 4-alkyl-α-methylcinnamylaldehydes preparation with similar results. In the second step—hydrogenation of aldol product different types of catalyst (nickel, cobalt, palladium or Adkins catalyst), and also different solvents, were tested. Hydrogenation conditions leading to the highest yield (72% selectivity at 95% conversion) were adapted to other 4-alkylhydrocinnamyladehydes with similar results.
- Vrbková, Eva,Vysko?ilová, Eli?ka,Rott, Martin,Zapletal, Martin,?erveny, Libor
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p. 2603 - 2613
(2017/03/22)
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- An efficient TiCl4-catalysed method for the synthesis of para-substituted aromatic aldehydes
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An efficient and highly selective synthesis of para-substituted aromatic aldehydes has been achieved by TiCl4-catalysed Friedel-Crafts alkylation of monosubstituted benzenes with methacrolein diacetyl acetal.
- Zhou, Chenfeng,Su, Weike
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p. 555 - 557
(2015/11/27)
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- Arylation of allylic alcohols in ionic liquids catalysed by a Pd-benzothiazole carbene complex
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The reaction of aryl bromides with allylic alcohols catalysed by a Pd-benzothiazole carbene complex, in tetrabutylammonium bromide as solvent, leads principally to β-arylated carbonyl compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Calo, Vincenzo,Nacci, Angelo,Monopoli, Antonio,Spinelli, Michele
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p. 1382 - 1385
(2007/10/03)
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- Palladium-catalyzed arylation of allylic alcohols with aryl iodides in water
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Palladium-catalyzed arylation of allylic alcohols with aryl iodides are shown to occur in the presence of sodium bicarbonate and tetra-n-butylammonium chloride in pure water using palladium acetate as catalyst. β-aromatic carbonyl compounds are obtained in good yields.
- Zhao,Cai,Hu,Song
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p. 3665 - 3669
(2007/10/03)
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