Shousuke Teratani

Liquid phase oxidation of cyclo-olefins by a PdSO4–heteropolyacid catalyst system

By a PdSO4–heteropolyacid(H3PMo6W6O40)catalyst system in the liquide phase cyclo-olefins, particularly cyclopentene and cyclohexene, are oxidized to the corresponding ketones.

Catalytic deuteration of cyclohexanone and allied reactions over platinum metals

Abstract In order to gain some insight into the mechanism of ketone hydrogenation to alcohol, cyclohexanone was deuterated over platinum metal catalysts under elevated pressure at 80 °C. The straightforward addition of two deuterium atoms to the carbonyl linkage was predominant over the heavy triad (Os, Ir, Pt). In contrast, the deuteration over the light triad (Ru, Rh, Pd) was accompanied by considerable isotopic exchange at the C-2 or C-6 position, leading to substantial proportions of the polydeuterated alcohols. A mechanism for cyclohexanone hydrogenation is presented which consists of three interlinked hydrogenation paths each having a different half-hydrogenated intermediate. The deuterium incorporation into the C-2 or C-6 position is attributable to alternation between the 1-monoadsorbed and 1,2-di-adsorbed intermediates.

Substituent effects in heterogeneous catalysis: VIII. Reactions of 2-methyl- and 2-ethylcyclohexanone with deuterium catalyzed by platinum metals

Abstract 2-Methyl and 2-ethyl derivatives of cyclohexanone were allowed to react with deuterium in tBuOD using platinum group metals as catalysts. The product alcohols and the remaining ketone were examined by mass spectrometry. Over Ru, Os, and Ir, the simple addition of two deuterium atoms to the carbonyl linkage was predominant, accompanied by little isotopic exchange. Over Pt, however, isotopic exchange was significant and over Rh and Pd quite extensive. The samples obtained over Rh and Pd were further analyzed by NMR spectroscopy to determine the loci of the incorporated deuterium atoms. Deuterium exchange over Pd was almost entirely confined to the C(2) and C(6) positions, while that over Rh was smeared beyond these positions. These results can be accounted for by assuming the intermediacy of π-absorbed π-oxaallylic species on Pd and of αβ-diadsorbed species on Rh.

On the hyperfine deuterium distribution of the catalytic reaction of propene with deuterium on copper powders

Abstract The hydrogenation mechanism of propene on a copper catalyst was investigated at room temperature, using deuterium as the reactant instead of protium. Thereby, not only distributions of the produced deuteropropenes and deuteropropanes were determined by mass spectrometry, but also distributions of the deuterated positions in both monodeuteropropenes and monodeuteropropanes were determined, respectively, by microwave spectrometry and NMR spectrometry. From these two distributions, an extended associative mechanism could be confirmed by assuming half-hydrogenated intermediates of the types CH 3 -CH 2 - C ∗ H 2 and CH 3 - C ∗ H-CH 3 , even though the deuterium-exchange reaction occurs much more frequently via the former species. Double-bond migration was confirmed during the reaction, as has already been proposed on nickel catalyst. Some caution is pointed out on the use of the random-distribution law in discussing the reaction mechanism on the basis of deuterium distribution.

Reduction of C-C multiple bonds using an illuminated semiconductor catalyst

Reduction of C–C multiple bonds using Pt/TiO2 powders in alcohols when irradiated gives hydrogenated products in good yields; concurrently alcohol solvents are oxidised to the corresponding carbonyl compounds.

Substituent effects in heterogeneous catalysis: II. Deuteration of 2-methylcyclohexanone over the platinum group metals

Abstract The catalytic reactions between 2-methylcyclohexanone and deuterium on platinum group metals were studied by means of mass and NMR spectrometry. Over Ru, Os, and Ir, only reduction to the corresponding alcohols occurred, brought about by simple addition of two deuterium atoms to the carbonyl bond. In contrast, over Rh and Pd, significant isotopic exchange at the C 2 and C 6 positions also occurred. The results over Pt were intermediate between these two groups. The axial and equatorial deuterium contents at each carbon position were also estimated for Rh and Pd. One characteristic feature was that, over Rh, the axial D content at C 6 is greater than that at C 2 and the reverse is true over Pd. A reaction mechanism for reduction and exchange is presented and discussed.

Comparative studies of homogeneous and heterogeneous catalyses. I. Geraniol hydrogenation catalyzed by Ru, Rh, Ru(PPh3)3Cl2, and Rh(PPh3)3Cl

Abstract Four catalysts (Ru, Rh, Ru(PPh3)3Cl2, and Rh(PPh3)3Cl) were compared using geraniol (A) as a substrate in hydrogenation at high pressures. With all the catalysts, A was first hydrogenated mainly to citronellol (B) and then further to 3,7-dimethyloctanol (C), accompanied by the formation of a few side products. Analysis of the kinetic data suggests that this seemingly consecutive reaction sequence A → B → C is mechanistically regarded as a simultaneous process B → A → C on heterogeneous catalysts although for homogeneous catalysts it is indeed consecutive. No hydrogenolysis accompanied the hydrogenation in homogeneous catalysis, whereas in heterogeneous catalysis, hydrogenolysis to 2,6-dimethyloctane was not negligible. The Rh complex was unique in its significant activity for hydrogen transfer to produce aldehydes, namely, citronellal and 3,7-dimethyloctanal. A mechanism is presented for each of the homogeneous and heterogeneous catalyses.

Application of microwave spectroscopy to the isotopic analysis of the reaction products of methylacetylene with deuterium on nickel catalysts

Abstract The reaction of methylacetylene with deuterium was investigated in a static system over nickel powders at 25 °C, and the products were analyzed by the mass spectroscopic and microwave spectroscopic methods. The propylene yield in the products was ca. 0.8, similar to the result presented in the literature. In sharp contrast with the reaction of propylene with deuterium, the methyl positions of propylene could not be deuterated, suggesting that the double-bond migration does not occur during the reaction. Of all the propylene- d 2 , cis -dideuteropropylene consisted of more than half the product at the 70% conversion. Protium concentration on the surface was estimated to be very low during the reaction. This is in contrast to the situation in the reaction of olefins with deuterium.

CO2-laser-induced surface reaction of CDF3 on SiO2

Abstract The CO 2 -laser-induced surface reaction between CDF 3 adsorbates and the SiO 2 surface proceeds via vibrational excitation of physisorbed CDF 3 to υ = 1, followed by an intermolecular energy transfer, to form surface OD and CF. The excitation of the lattice vibrational mode, on the other hand, results in the dehydration of surface OH.

Selective monoesterification of the longer carbon chain in a mixture of dicarboxylic acids by adsorbing and aligning the acids on alumina

Selective monoesterification of the longer carbon chain in a mixture of dicarboxylic acids, [dodecanedioic acid (C12) plus glutaric acid (C5), adipic acid (C6), pimelic acid (C7), suberic acid (C8), or sebacic acid (C10)] was achieved by adsorbing and aligning the acids on alumina.