Oxidation of secondary alcohols to ketones

Abstract: Inorganic−organic hybrid mesoporous materials were prepared by cocrystallization of a “sandwich” type polyoxometalate, [ZnWZn2(H2O)2(ZnW9O34)2]12-, and branched tripodal organic polyammonium salts, tris[2-(trimethylammonium)ethyl]-1,3,5-benzenetricarboxylate or 1,3,5-tris[4-(N,N,N-trimethylammoniumethylcarboxyl)phenyl]benzene trications. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed formation of three-dimensional perforated coral-shaped amorphous materials with the organic cations surrounding polyoxometalate anions. N2 sorption analysis showed that the hybrid materials have a BET surface area of ∼30−50 m2 g-1 and an average pore diameter of 36 A leading to the classification of these materials as mesoporous materials with moderate surface areas. These hybrid materials behaved as very effective and selective heterogeneous catalysts for the epoxidation of allylic alcohols and oxidation of secondary alcohols to ketones with hydrogen peroxide as oxidant. The activity and...

Abstract: Recent, environmentally-driven trends in the manufacture of fine chemicals are reviewed. Comparison of alternative processes on the basis of their atom utilization and E factor (kg byproducts/kg product) i s discussed. The use of chromium-substituted molecular sieves (CrAPO-5 and 11 and Cr silicalite) as recyclable solid catalysts for benzylic and allylic oxidations, the oxidation of secondary alcohols to ketones and the selective decomposition of alkyl hydroperoxides, is described. New developments in the use of zeolite-encapsulated metal complexes as solid catalysts for oxidations and reductions are reviewed. The use of palladium(0) trisulfonated triphenylphosphine complex as a catalyst for carbonylation in water is reported. Finally, the use of supported aqueous phase catalysts in various processes, including enantioselective hydrogenation, is briefly reviewed.

Abstract: ether became symnietrical in the presence of 5 equiv of 18-crown-6. Comparison of the chemical shift data for the anions of 1 and 2 in the absence and presence of 5 equiv of 18crown-6 reveals a change of 257 Hz for 1 and 144 Hz for 2. The smaller chemical shift change observed for 2 is again consistent with a lesser degree of ion pairing when the counterion is hexafluorophosphate. Central to this argument is the formulation of the crown ether-diazonium salt complex 5 as resulting from insertion of the neck of the arenediazonium cation into a crown ether ~ o l l a r . ~ J ~ J ~ PrevioiJs evidence for this arrangement includes steric effects of substituents in sol~bilization~~'~ and titration cal~rimetric '~ studies and 'H NMR spectral changes of certain macrocyclic polyethers in the presence of arenediazonium salt^.^,'^ Because of insufficient solubility of uncomplexed 2 it was not possible to probe for changes in the 'H NMR spectra of 1 and 2 in 172-dichloroethane upon addition of 18-crown-6. However, such measurements could be made in dimethyl sulfoxide and are summarized in Table V. Although the chemical shifts of the tert-butyl group hydrogens and the 3,5 aromatic ring hydrogens of 1 and 2 are unaffected by the presence of 18-crown-6, the 2,6 aromatic ring hydrogens are shifted upfield by 7-8 Hz in the presence of 18-crown-6. This chemical shift change for only the ortho hydrogens provides further evidence for the proposed diazonium ion-crown ether complex 5.

Abstract: PdCl2–NaOAc catalyses the homogeneous oxidation of secondary alcohols to ketones by O2 at room temperature.

Abstract: Ruthenium trichloride catalyses the homogeneous oxidation of secondary alcohols to ketones, primary amines to nitriles, and 2-aminoalkanes to imines by O2; this is the first example of a homogeneous catalytic oxidation of an amino-group.