Catalytic Conversions in Water. Part 21: Mechanistic Investigations on the Palladium-Catalysed Aerobic Oxidation of Alcohols in Water†
摘要:
Water-soluble complexes of palladium(II) with phenanthroline-derivatives are stable, recyclable catalysts for the selective aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic liquid-liquid system. The active catalyst is a dihydroxy-bridged palladium dimer. Kinetics of the reaction, ligand and anion effects are discussed.
Cells of the fungus, Geotrichum candidum, were immobilized on a water-absorbing polymer and used for stereoselective oxidation and reduction in an organic solvent using cyclohexanone, cyclopentanol or alkan-2-ols as additive. Enantiomerically pure (R)-1-arylethanols were obtained by the stereoselective oxidation of racemic 1-arylethanols, whereas enantiomerically pure (S)-1-arylethanols were obtained by the reduction of the corresponding ketones, in contrast to reduction in water by the free cells in which (R)- or (S)-1-arylethanols were produced in low ee.The reaction mechanism was investigated by measuring the partition of the substrates and products between the organic phase and aqueous phase in the polymer around which the cells were immobilized. Deuterated compounds were used to determine the role of the additives.
Enantiomeric Analysis of Homologous Series of Secondary Alcohols by Deuterium NMR Spectroscopy in a Chiral Nematic Liquid Crystal: Influence of Molecular Geometry on Chiral Discrimination
NMR measurements of the differential ordering effect (DOE) are presented for homologous series of 22 chiral secondary aliphatic alcohols dissolved in a poly-(gamma-benzyl-L-glutamate) (PBLG)/dichloromethane liquid-crystalline solvent. The quadrupolar splittings of the solutes, which were deuterated at their chiral centres, were measured as a function of the PBLG concentration and temperature. The proton dipolar splittings of the dichloromethane in each sample were also measured and used as a reference. The results are analysed qualitatively in terms of the structures of the molecules and their asymmetric (or chiral) characteristics. Emphasis is put on comparative analysis of the chiral discrimination in members of each particular homologous series and on evaluating the Limits of the technique for molecules that have two very similar groups attached to their stereogenic centres.
Stereochemistry of the Primary Carbon. I. Optically Active n-Butanol-1-d<sup>1</sup>
作者:Andrew Streitwieser
DOI:10.1021/ja01116a038
日期:1953.10
Catalytic Conversions in Water. Part 21: Mechanistic Investigations on the Palladium-Catalysed Aerobic Oxidation of Alcohols in Water†
Water-soluble complexes of palladium(II) with phenanthroline-derivatives are stable, recyclable catalysts for the selective aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic liquid-liquid system. The active catalyst is a dihydroxy-bridged palladium dimer. Kinetics of the reaction, ligand and anion effects are discussed.
Photochemistry of Racemic and Resolved 2-Iodooctane. Effect of Solvent Polarity and Viscosity on the Chemistry
作者:Fang Gao、David Boyles、Rodney Sullivan、Robert N. Compton、Richard M. Pagni
DOI:10.1021/jo020472r
日期:2002.12.1
resolved 2-iodooctane was examined in cyclopentane, methanol, and 2-methyl-2-propanol, media with differing polarities and viscosities. The photochemistry of racemic 2-iodooctane was also examined in the gas phase. The photochemistry of 2-deuterio- and 1,1,1-trideuterio-2-iodooctane in cyclopentane and methanol was also studied. The photoreactions in cyclopentane, 2-methyl-2-propanol, and the gas phase