Lattice oxygen insertion mechanism in CeO-catalyzed reactions in water: nitrile hydration reaction.

Cerium oxide (CeO) exhibits prominent catalytic activity in various organic reactions owing to its unique acid-base and redox properties. One of the most interesting applications of pure CeO-catalyzed organic reactions is the hydration of nitriles in water. The experimental results showed that the hydration of 2-cyanopyridine to picolinamide in water using CeO catalysts proceeds readily at low temperatures (30-100 °C) in high yields and that this reaction occurs exclusively on CeO among various metal-oxide catalysts.

Utilisation of formed cyano-bridged coordination polymers as precursors of supported Ir-Ni alloy nanoparticles with precisely controlled compositions and sizes.

Ir-Ni alloys supported on SiO have been reported to show high catalytic activity for styrene hydrogenation; however, precise control of compositions and sizes of the Ir-Ni alloys is difficult when conventional metal salts are used as precursors. Furthermore, the concomitant formation of unalloyed Ni nanoparticles disturbs quantitative discussion about Ir-Ni alloy compositions. We report herein a preparation method of Ir-Ni alloys with precisely controlled compositions on SiO using Ni(NO) and an Ir complex possessing CN ligands, [Ir(CN)] or [Ir(ppy)(CN)] (ppy = 2-phenylpyridine), as precursors.

Hydrogenation of -octanoic acid over the MoPt alloy of Mo-Pt/SiO catalyst under solvent-free conditions.

SiO-Supported bimetallic Mo and Pt worked as an effective heterogeneous catalyst for hydrogenation of -octanoic acid at a low temperature of 373 K in the absence of solvent, providing 78% yield of hydrogenated products (62% yield of 1-octanol and 32% yield of octyl octanoate). Based on the catalyst characterization, MoPt alloy (Mo/Pt = 1) was formed by high-temperature reduction and was proposed to be the active site for the reaction.

Porous nanographene formation on γ-alumina nanoparticles transition-metal-free methane activation.

γ-AlO nanoparticles promote pyrolytic carbon deposition of CH at temperatures higher than 800 °C to give single-walled nanoporous graphene (NPG) materials without the need for transition metals as reaction centers. To accelerate the development of efficient reactions for NPG synthesis, we have investigated early-stage CH activation for NPG formation on γ-AlO nanoparticles reaction kinetics and surface analysis. The formation of NPG was promoted at oxygen vacancies on (100) surfaces of γ-AlO nanoparticles following surface activation by CH.

Deoxydehydration of Biomass-Derived Polyols Over Silver-Modified Ceria-Supported Rhenium Catalyst with Molecular Hydrogen.

Olefin production from polyols via deoxydehydration (DODH) was carried out over Ag-modified CeO -supported heterogeneous Re catalysts with H as a reducing agent. Both high DODH activity and low hydrogenation ability for C=C bonds were observed in the reaction of erythritol, giving a 1,3-butadiene yield of up to 90 % under "solvent-free" conditions. This catalyst is applicable to other substrates such as methyl glycosides (methyl α-fucopyranoside: 91 % yield of DODH product; methyl β-ribofuranoside: 88 % yield), which were difficult to be converted to the DODH products over the DODH catalysts reported previously.

CeO-Catalyzed Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate.

CeO acted as an effective and reusable heterogeneous catalyst for the direct synthesis of 2-imidazolidinone from ethylenediamine carbamate (EDA-CA) without further addition of CO in the reaction system. 2-Propanol was the best solvent among the solvents tested from the viewpoint of selectivity to 2-imidazolidinone, and the use of an adequate amount of 2-propanol provided high conversion and selectivity for the reaction. This positive effect of 2-propanol on the catalytic reaction can be explained by the solubility of EDA-CA in 2-propanol under the reaction conditions and no formation of solvent-derived byproducts.

Adsorption of Keggin-Type Polyoxometalates on Rh Metal Particles under Reductive Conditions.

The adsorption of POMs on Rh/SiO in water solvent under strongly reductive conditions was investigated. Aqueous solutions of α-Keggin type silicotungstate and silicovanadotungstates were mixed with Rh/SiO at 393-473 K under 1 MPa of H. Monovanadium-substituted silicotungstate, α-SiVWO (SiVW), was more readily adsorbed than nonsubstituted silicotungstate, α-SiWO (SiW).

Selective Hydrogenolysis of Erythritol over Ir-ReO /Rutile-TiO Catalyst.

Partial hydrogenolysis of erythritol, which can be produced at large scale by fermentation, to 1,4-butanediol (1,4-BuD) is investigated with Ir-ReO /SiO and Ir-ReO /rutile-TiO catalysts. In addition to the higher conversion rate over Ir-ReO /TiO than over Ir-ReO /SiO , which has been also reported for glycerol hydrogenolysis, Ir-ReO /TiO showed higher selectivity to 1,4-BuD than Ir-ReO /SiO , especially at low conversion levels, leading to high 1,4-BuD productivity of 20 mmol  g  h at 373 K (36 % conversion, 33 % selectivity). The productivity based on the noble metal amount is higher than those reported previously, although the maximum yield of 1,4-BuD (23 %) is not higher than the highest reported values.

Biobased Cycloolefin Polymers: Carvone-Derived Cyclic Conjugated Diene with Reactive -Methylene Group for Regioselective and Stereospecific Living Cationic Polymerization.

Carvone, a naturally abundant chiral cyclic α,β-unsaturated carbonyl compound, was chemically transformed into cyclic -methylene conjugated dienes. The -methylene group had high reactivity in cationic polymerization and was efficiently polymerized in a controlled manner via regioselective 1,4-conjugated additions using initiating systems effective for living cationic polymerization of vinyl ethers. The obtained polymers with 1,3-cyclohexenyl units and tetra-substituted olefins in the main chain showed high glass transition temperatures over 110 °C.

One-pot imine synthesis from methylarenes and anilines under air over heterogeneous Cu oxide-modified CeO catalyst.

Cu oxide-modified CeO (CuO-CeO) with 2 wt% Cu loading amount was the most effective and reusable heterogeneous catalyst for selective one-pot imine synthesis from methylarenes and anilines via direct oxidation of the sp C-H bond in the methylarenes with atmospheric air (0.1 MPa) as an oxidant.

Erythritol: Another C4 Platform Chemical in Biomass Refinery.

The potential of erythritol as a platform chemical in biomass refinery is discussed in terms of erythritol production and utilization. Regarding erythritol production, fermentation of sugar or starch has been already commercialized. The shift of the carbon source from glucose to inexpensive inedible waste glycerol is being investigated, which will decrease the price of erythritol.

A nickel-iridium alloy as an efficient heterogeneous catalyst for hydrogenation of olefins.

Nickel and iridium supported on SiO2 (Ni-Ir/SiO2) acted as an effective and reusable heterogeneous catalyst for hydrogenation of olefins, and it showed higher activity and selectivity than the monometallic counterparts. The Ni-Ir/SiO2 catalyst has small Ni-Ir alloy and monometallic Ni particles, and the high catalytic performance can be attributed to the isolated Ni atom in the Ni-Ir alloys.

Preparation of Highly Active Monometallic Rhenium Catalysts for Selective Synthesis of 1,4-Butanediol from 1,4-Anhydroerythritol.

1,4-Butanediol can be produced from 1,4-anhydroerythritol through the co-catalysis of monometallic mixed catalysts (ReO /CeO +ReO /C) in the one-pot reduction with H . The highest yield of 1,4-butanediol was over 80 %, which is similar to the value obtained over ReO -Au/CeO +ReO /C catalysts. Mixed catalysts of CeO +ReO /C showed almost the same performance, giving 89 % yield of 1,4-butanediol.

Ring-opening polymerization of trimethylene carbonate to poly(trimethylene carbonate) diol over a heterogeneous high-temperature calcined CeO catalyst.

CeO2 calcined at 1273 K showed higher activity per surface area than other metal oxides in the ring-opening polymerization of trimethylene carbonate under neat conditions without any additives, providing metal-free and additive-free poly(trimethylene carbonate) diols with no ether bonds with high selectivity. It was demonstrated that CeO2 was a robust and reusable heterogeneous catalyst.

CO Conversion with Alcohols and Amines into Carbonates, Ureas, and Carbamates over CeO Catalyst in the Presence and Absence of 2-Cyanopyridine.

Recent progress on the CeO catalyzed synthesis of organic carbonates, ureas, and carbamates from CO +alcohols, CO +amines, and CO +alcohols+amines, respectively, is reviewed. The reactions of CO with alcohols and amines are reversible ones and the degree of the equilibrium limitation of the synthesis reactions is strongly dependent on the properties of alcohols and amines as the substrates. When the equilibrium limitation of the reaction is serious, the equilibrium conversion of the substrate and the yield of the target product is very low, therefore, the shift of the equilibrium reaction to the product side by the removal of H O is essential in order to get the target product in high yield.

Selective hydrogenation of amides to alcohols in water solvent over a heterogeneous CeO-supported Ru catalyst.

CeO2-supported Ru (Ru/CeO2) worked as an effective and reusable heterogeneous catalyst for the selective dissociation of the C-N bond in amides, particularly primary amides, with H2 in water solvent at low reaction temperature of 333 K, and high yields of the corresponding alcohols were obtained from primary amides.

Transformation of Sugars into Chiral Polyols over a Heterogeneous Catalyst.

Transformation of sugars, while maintaining the intrinsic stereochemical structure, is desirable. However, such a transformation requires multistep synthesis with protection and deprotection of the OH groups. Herein, a new method for selective transformation of sugar derivatives into chiral building blocks and a diol synthon, with retention of the intrinsic configuration (stereo- and regioselectively), is demonstrated.

Formation of a New, Strongly Basic Nitrogen Anion by Metal Oxide Modification.

Development of new hybrid materials having unique and unprecedented catalytic properties is a challenge for chemists, and heterogeneous-homogeneous hybrid catalysts have attracted much attention because of the preferable and exceptional properties that are highly expected to result from combination of the components. Base catalysts are widely used in organic synthesis as key materials, and a new class of base catalysts has made a large impact from academic and industrial viewpoints. Here, a principle for creating a new strong base by hybridization of homogeneous and heterogeneous components is presented.

Selective hydrogenation of nitroarenes to aminoarenes using a MoO-modified Ru/SiO catalyst under mild conditions.

Modification of Ru/SiO with metal oxides (MoO, WO, and ReO) improved the activity and selectivity in the hydrogenation of 3-nitrostyrene to 3-aminostyrene under mild conditions such as 0.3 MPa H, 303 K, and no solvent. Ru-MoO/SiO(Mo/Ru = 1/2) catalyst was applicable to various substituted nitroarenes, providing the corresponding substituted aminoarenes in high yields (85-99%).

Regioselectivity and Reaction Mechanism of Ru-Catalyzed Hydrogenolysis of Squalane and Model Alkanes.

The dependence of the C-C hydrogenolysis activity on reaction parameters and the structure of the substrate alkanes was investigated for Ru/CeO catalyst with very small (dispersion: H/Ru=0.89) Ru particles. The substrate concentration and reaction temperature did not have a significant effect on the selectivity pattern, except that methane production was promoted at high temperatures.

Synthesis of 2-Butanol by Selective Hydrogenolysis of 1,4-Anhydroerythritol over Molybdenum Oxide-Modified Rhodium-Supported Silica.

Rh-MoOx /SiO2 (Mo/Rh=0.13) is an effective catalyst for the hydrogenolysis of 1,4-anhydroerythritol (1,4-AHERY) and provides 2-BuOH in high yield of 51 %. This is the first report of the production of 2-BuOH from 1,4-AHERY by hydrogenolysis.

Direct Copolymerization of CO2 and Diols.

Direct polymerization of CO2 and diols is promising as a simple and environmental-benign method in place of conventional processes using high-cost and/or hazardous reagents such as phosgene, carbon monoxide and epoxides, however, there are no reports on the direct method due to the inertness of CO2 and severe equilibrium limitation of the reaction. Herein, we firstly substantiate the direct copolymerization of CO2 and diols using CeO2 catalyst and 2-cyanopyridine promotor, providing the alternating cooligomers in high diol-based yield (up to 99%) and selectivity (up to >99%). This catalyst system is applicable to various diols including linear C4-C10 α,ω-diols to provide high yields of the corresponding cooligomers, which cannot be obtained by well-known methods such as copolymerization of CO2 and cyclic ethers and ring-opening polymerization of cyclic carbonates.

Self-assembled hybrid metal oxide base catalysts prepared by simply mixing with organic modifiers.

Multidentate materials formed by simply mixing heterogeneous and homogeneous components are promising for construction of versatile active sites on the surface of heterogeneous compounds, however, to the best of our knowledge, there are no reports on such materials. Self-assembly of hetero-hybrid catalytic materials occurs when heterogeneous catalysts having adjacent Lewis acid-Lewis base sites are mixed with an organic modifier that contains at least two Lewis base functional groups. Here we demonstrate the strategy by combining cerium oxide and 2-cyanopyridine that self-assembles to form a charge-transfer complex in methanol that exhibits a 2,000-fold increase in reaction rate for hydromethoxylation of acrylonitrile with high selectivity compared with cerium oxide or 2-cyanopyridine alone.

Catalytic production of branched small alkanes from biohydrocarbons.

Squalane, C30 algae-derived branched hydrocarbon, was successfully converted to smaller hydrocarbons without skeletal isomerization and aromatization over ruthenium on ceria (Ru/CeO2 ). The internal CH2 CH2 bonds located between branches are preferably dissociated to give branched alkanes with very simple distribution as compared with conventional methods using metal-acid bifunctional catalysts.