Kazuo Taya

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.

Visible light cleavage of water by CdS photoanode coated with polymer-pendant Ru(bpy)2+3 film containing RuO2 dispersions

Abstract Simultaneous formation of H 2 and O 2 by visible light cleavage of water was achieved using n -CdS photoanode coated with polymer-pendant Ru(bpy) 2+ 3 film containing RuO 2 dispersions. The Ru complex worked as a relay to transport the holes formed on the CdS surface to the RuO 2 catalyst where water oxidation takes place.

Different behavior between Pt and Pd catalysts in the hydrogenolysis of cyclohexanediones and hydroxycyclohexanones

Abstract Hydrogenolysis reactions of cyclohexanediones, hydroxycyclohexanones, and some related alicyclic ketones were studied over Pt, Pd, Ir, and Rh catalysts at atmospheric hydrogen pressure in t -butyl alcohol as a solvent. Pt and Pd had high catalytic activities for the hydrogenolysis of carbon-oxygen bonds. However, Ir and Rh scarcely had any activity unless 1,3-cyclohexanedione and 3-hydroxycyclohexanone were involved. The mechanisms of the hydrogenolysis differed with Pt and Pd. In the hydrogenation of 4-methoxycyclohexanone, Pt afforded cyclohexyl methyl ether as the hydrogenolysis product; while Pd afforded cyclohexanone, which was then hydrogenated to cyclohexanol. Thus Pt cleaved the carbon-oxygen double bond, and Pd cleaved the carbon-oxygen single bond. Deuterolysis of cyclohexanone and 4-methoxycyclohexanone on Pt gave mainly d 2 species of cyclohexane and cyclohexyl methyl ether as the hydrogenolysis products. This indicated that the carbon-oxygen double bonds were directly cleaved to yield methylene groups on Pt. Almost of all 3-hydroxycyclohexanone was hydrogenolyzed to cyclohexanone on Pd; whereas cyclohexanone as well as cyclohexanol was not hydrogenolyzed at all. In the case of Pd, the carbon-oxygen single bond was cleaved when it was activated by formation of π-oxoallyl adsorbed species on the catalyst at the carbon-oxygen double bond.

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.

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.

Hydrolysis of water-insoluble esters by octadecyl immobilized H-ZSM-5 catalyst in a water–toluene system

In the hydrolysis of water–insoluble esters in a water-toluene system octadecyltrichlorosilane-treated ZSM-5, which floated at the interface of the two liquids, was observed to be a solid interface catalyst.

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.

Hydrogenation and hydrogenolysis of methylcyclohexane-1,4-dione on Pt and Pd catalysts

Relative hydrogenation reactivity of the two carbonyl groups of methylcyclohexane-1,4-dione can be estimated beside that of two related compounds, 2- and 3-methyl-cyclohexanones. The reaction is accompanied with hydrogenolysis on Pt and Pd. The less hindered 4-carbonyl group is selectively hydrogenolyzed.AbstractОтносительную реактивность к гидрированию двух карбонильных групп метилциклогексан-1,4-диона определяли наряду с реактивностями двух родственных соединений, а именно 2- и 3-метилциклогексанонов. Реакция сопровождается гидрогенолизом на Pt и Pd. Менее экранированная 4-карбонильная группа подвергается селективному гидрогенолизу.

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.