Supported Ruthenium Hydroxide Catalyst Research Articles

Aerobic Oxidative Cleavage of Vicinal Diol Fatty Esters by a Supported Ruthenium Hydroxide Catalyst

Oxidative cleavage of fatty acids and fatty acid derivatives can be used to obtained mono- and dicarboxylic acids, which are valuable building blocks in different industries. Although ozonolysis ha...

Selective formation of formic acid from biomass-derived glycolaldehyde with supported ruthenium hydroxide catalysts

Ceria-supported ruthenium hydroxide catalysts, Ru(OH)x/CeO2, with micro- and nanoparticle supports were applied for selective aerobic oxidation of glycolaldehyde (GAD) to formic acid (FA) in water under mild and base-free conditions.

ChemInform Abstract: Development of Highly Active Heterogeneous Oxidation Catalysts Based on the Properties of Metal Hydroxides

AbstractReview: 62 refs.

Catalytic transfer hydrogenation of levulinate esters to γ-valerolactone over supported ruthenium hydroxide catalysts

Production of γ-valerolactone (GVL) from levulinate esters and several alcohols as hydrogen donors via a catalytic transfer hydrogenation (CTH) process was performed over supported ruthenium hydroxide catalysts. Among the catalysts examined, Ru(OH)x supported on high-surface-area, anatase TiO2 containing highly-dispersed ultrasmall Ru(OH)x nano-clusters was found to be the most active catalyst, which converted levulinate esters to GVL in an almost quantitative yield under mild reaction conditions with low catalyst loading. Addition of heterogeneous bases could afford a faster reaction rate in GVL production by accelerating the following intramolecular dealcoholation step. The catalyst was reusable over repeated catalytic cycles without loss of catalytic performance, making this material a potential candidate for efficient GVL production under ambient reaction conditions.

Development of Highly Active Heterogeneous Oxidation Catalysts Based on the Properties of Metal Hydroxides

This manuscript summarizes our recent research results on heterogeneously catalyzed aerobic oxidation reactions using supported metal hydroxide catalysts. Metal hydroxide species possess both Lewis acid and Bronsted base sites on the same metal sites, and various kinds of substrates including alcohols, primary amines, nitriles, and terminal alkynes can be activated by the concerted action of the Lewis acid and Bronsted base pair sites. In the presence of a supported ruthenium hydroxide catalyst (Ru(OH) x /Al2O3), oxidative dehydrogenation of alcohols and primary amines efficiently proceeds to afford the corresponding carbonyl compounds (aldehydes and ketones) and nitriles, respectively. In the presence of ammonia (THF solution), Ru(OH) x /Al2O3 can catalyze ammoxidation of primary alcohols to the corresponding nitriles. This ammoxidation proceeds through the sequential reactions of oxidative dehydrogenation of primary alcohols to aldehydes, dehydrative condensation of the aldehydes with ammonia to aldimines, and oxidative dehydrogenation of the aldimines. In addition, formal α-oxygenation of primary amines to the corresponding primary amides can be realized through the Ru(OH) x /Al2O3-catalyzed oxidative dehydrogenation and nitrile hydration. Moreover, a supported copper hydroxide species on a manganese oxide-based octahedral molecular sieve (Cu(OH) x /OMS-2) can act as an efficient and highly durable heterogeneous catalyst for oxidative homocoupling of terminal alkynes to the corresponding diynes. The catalyses for the above-mentioned oxidation reactions are truly heterogeneous, and the catalysts can be reused several times with keeping their high catalytic performance.

Aerobic Oxidative Transformation of Primary Azides to Nitriles by Ruthenium Hydroxide Catalyst

In the presence of an easily prepared supported ruthenium hydroxide catalyst, Ru(OH)(x)/Al(2)O(3), various kinds of structurally diverse primary azides including benzylic, allylic, and aliphatic ones could be converted into the corresponding nitriles in moderate to high yields (13 examples, 65-94% yields). The gram-scale (1 g) transformation of benzyl azide efficiently proceeded to give benzonitrile (0.7 g, 90% yield) without any decrease in the performance in comparison with the small-scale (0.5 mmol) transformation. The catalysis was truly heterogeneous, and the retrieved catalyst could be reused for the transformation of benzyl azide without an appreciable loss of its high performance. The present transformation of primary azides to nitriles likely proceeds via sequential reactions of imide formation, followed by dehydrogenation (β-elimination) to produce the corresponding nitriles. The Ru(OH)(x)/Al(2)O(3) catalyst could be further employed for synthesis of amides in water through the transformation of primary azides (benzylic and aliphatic ones) to nitriles, followed by sequent hydration of the nitriles formed. Additionally, direct one-pot synthesis from alkyl halides and TBAN(3) (TBA = tetra-n-butylammonium) could be realized with Ru(OH)(x)/Al(2)O(3), giving the corresponding nitriles in moderate to high yields (10 examples, 64-84% yields).

ChemInform Abstract: Green Functional Group Transformations by Supported Ruthenium Hydroxide Catalysts

AbstractReview: ca. 100 refs

Green Functional Group Transformations by Supported Ruthenium Hydroxide Catalysts

This account summarizes our recent research on green functionalgroup transformations using easily prepared supported rutheniumhydroxide catalysts [Ru(OH) x /support,support = Al 2 O 3 , TiO 2 ,or Fe 3 O 4 ]. Various kinds of functionalgroup transformations, e.g. the oxidation (oxidative dehydrogenation)of alcohols and amines, hydrogen-transfer reactions, such as racemizationand reduction, and the hydration of nitriles, can be promoted bythe concerted activation of the substrates (including alcohols,amines, and nitriles) by the Lewis acid and Bronsted basesites on the Ru(OH) x /support catalyst. In addition,we have successfully developed three novel catalytic transformationswith the Ru(OH) x /support catalysts: (1) theoxygenation of primary amines to give amides, (2) the direct oxidativesynthesis of nitriles from primary alcohols and ammonia, and (3)the N-alkylation of ammonia (or its surrogates) with alcohols toproduce symmetrically substituted tertiary or secondary amines.The catalyses for these transformations are truly heterogeneous,and the catalysts retrieved after the transformations can be reusedwith retention of their high catalytic performance. 1 Introduction 2 Preparation and Characterization of Supported Ruthenium HydroxideCatalysts 3 Oxidation of Alcohols and Amines 4 Hydration of Nitriles 5 Oxygenation of Primary Amines To Give Amides 6 Direct Oxidative Synthesis of Nitriles from Primary Alcoholsand Ammonia 7 N-Alkylation of Ammonia with Alcohols To Give Tertiary orSecondary Amines 8 Conclusion

The “Borrowing Hydrogen Strategy” by Supported Ruthenium Hydroxide Catalysts: Synthetic Scope of Symmetrically and Unsymmetrically Substituted Amines

The N-alkylation of ammonia (or its surrogates, such as urea, NH(4)HCO(3), and (NH(4))(2)CO(3)) and amines with alcohols, including primary and secondary alcohols, was efficiently promoted under anaerobic conditions by the easily prepared and inexpensive supported ruthenium hydroxide catalyst Ru(OH)(x)/TiO(2). Various types of symmetrically and unsymmetrically substituted "tertiary" amines could be synthesized by the N-alkylation of ammonia (or its surrogates) and amines with "primary" alcohols. On the other hand, the N-alkylation of ammonia surrogates (i.e., urea and NH(4)HCO(3)) with "secondary" alcohols selectively produced the corresponding symmetrically substituted "secondary" amines, even in the presence of excess amounts of alcohols, which is likely due to the steric hindrance of the secondary alcohols and/or secondary amines produced. Under aerobic conditions, nitriles could be synthesized directly from alcohols and ammonia surrogates. The observed catalysis for the present N-alkylation reactions was intrinsically heterogeneous, and the retrieved catalyst could be reused without any significant loss of catalytic performance. The present catalytic transformation would proceed through consecutive N-alkylation reactions, in which alcohols act as alkylating reagents. On the basis of deuterium-labeling experiments, the formation of the ruthenium dihydride species is suggested during the N-alkylation reactions.

Theoretical and Experimental Studies on Reaction Mechanism for Aerobic Alcohol Oxidation by Supported Ruthenium Hydroxide Catalysts

The experimentally proposed reaction mechanism for the aerobic alcohol oxidation by supported ruthenium hydroxide catalysts (Ru(OH)x/support, support = TiO2 or Al2O3) is theoretically investigated by means of ab initio quantum chemistry calculations with model catalysts “Ru(OH)3(OH2)3” and “RuCl3(OH2)3” for Ru(OH)x/support and RuClx/support, respectively. The experimentally proposed alcoholate formation and β-hydride elimination steps can be verified. In the case of 2-butanol (as a model substrate), the calculated activation energy for the alcoholate formation step with Ru(OH)3(OH2)3 (27.7 kJ mol−1) is much smaller than that with RuCl3(OH2)3 (123.2 kJ mol−1), showing that the alcoholate formation with Ru(OH)x/support much more easily proceeds than that with RuClx/support. The Ru(OH)x/support catalysts possess both Lewis acid (Ru center) and Bronsted base (OH− species) sites on the same metal site. Therefore, the alcoholate formation step can be promoted by the “concerted activation” of an alcohol by the L...

Heterogeneously Catalyzed One-pot Synthesis of Aldimines from Primary Alcohols and Amines by Supported Ruthenium Hydroxides

Abstract The one-pot synthesis of aldimines from primary alcohols and amines via sequential reactions of alcohol oxidation and dehydrative condensation could efficiently be promoted by supported ruthenium hydroxide catalysts, in particular Ru(OH)x/TiO2. The observed catalysis was truly heterogeneous and the retrieved catalyst could be reused without an appreciable loss of high catalytic performance.

ChemInform Abstract: Heterogeneously Catalyzed Efficient Oxygenation of Primary Amines to Amides by a Supported Ruthenium Hydroxide Catalyst.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Heterogeneously catalyzed selective N-alkylation of aromatic and heteroaromatic amines with alcohols by a supported ruthenium hydroxide

The N-alkylation of aromatic and heteroaromatic amines with alcohols could efficiently be promoted by an easily prepared supported ruthenium hydroxide catalyst Ru(OH) x /Al 2O 3. A variety of aromatic and heteroaromatic amines were selectively converted into the corresponding secondary amines in moderate to excellent yields without any co-catalysts such as bases and stabilizing ligands. The observed catalysis was intrinsically heterogeneous and the Ru(OH) x /Al 2O 3 catalyst recovered after the reaction could be reused without an appreciable loss of its high catalytic performance for the N-alkylation.

Highly Dispersed Ruthenium Hydroxide Supported on Titanium Oxide Effective for Liquid‐Phase Hydrogen‐Transfer Reactions

Supported ruthenium hydroxide catalysts (Ru(OH)(x)/support) were prepared with three different TiO(2) supports (anatase TiO(2) (TiO(2)(A), BET surface area: 316 m(2) g(-1)), anatase TiO(2) (TiO(2)(B), 73 m(2) g(-1)), and rutile TiO(2) (TiO(2)(C), 3.2 m(2) g(-1))), as well as an Al(2)O(3) support (160 m(2) g(-1)). Characterizations with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and X-ray absorption fine structure (XAFS) showed the presence of monomeric ruthenium(III) hydroxide and polymeric ruthenium(III) hydroxide species. Judging from the coordination numbers of the nearest-neighbor Ru atoms and the intensities of the ESR signals, the amount of monomeric hydroxide species increased in the order of Ru(OH)(x)<Ru(OH)(x)/TiO(2)(C)<Ru(OH)(x)/Al(2)O(3)<Ru(OH)(x)/TiO(2)(B)<Ru(OH)(x)/TiO(2)(A). These supported ruthenium hydroxide catalysts, especially Ru(OH)(x)/TiO(2)(A), showed high catalytic activities and selectivities for liquid-phase hydrogen-transfer reactions, such as racemization of chiral secondary alcohols and the reduction of carbonyl compounds and allylic alcohols. The catalytic activities of Ru(OH)(x)/TiO(2)(A) for these hydrogen-transfer reactions were at least one order of magnitude higher than those of previously reported heterogeneous catalysts, such as Ru(OH)(x)/Al(2)O(3). These catalyses were truly heterogeneous, and the catalysts recovered after the reactions could be reused several times without loss of catalytic performance. The reaction rates monotonically increased with an increase in the amount of monomeric ruthenium hydroxide species, which suggests that the monomeric species are effective for these hydrogen-transfer reactions.

Heterogeneously Catalyzed Efficient Oxygenation of Primary Amines to Amides by a Supported Ruthenium Hydroxide Catalyst

Heterogeneously Catalyzed Efficient Oxygenation of Primary Amines to Amides by a Supported Ruthenium Hydroxide Catalyst

Heterogeneously Catalyzed Efficient Oxygenation of Primary Amines to Amides by a Supported Ruthenium Hydroxide Catalyst

Heterogeneously Catalyzed Efficient Oxygenation of Primary Amines to Amides by a Supported Ruthenium Hydroxide Catalyst

Selective aerobic oxidations by supported ruthenium hydroxide catalysts

Aerobic oxidations of various alcohols, diols, and amines are efficiently promoted by the easily prepared inexpensive supported ruthenium hydroxide catalysts. A wide variety of substrates including aromatic, aliphatic, and heterocyclic ones can be converted into the desired products in moderate to excellent yields without the need for additives such as bases and electron/hydrogen transfer reagents. The catalysis for these reactions was intrinsically heterogeneous, and supported ruthenium hydroxide catalysts recovered after these reactions could be reused without appreciable loss of the catalytic performances. A reaction mechanism involving ruthenium alkoxide (amide) formation/β-elimination has been proposed for the present catalytic oxidations.