Hydrogenation Of Cyclohexanone Research Articles

Nickel Boride Catalysts in Organic Synthesis (IV). The Effect of Water Washing on P‐2 Nickel Boride Catalyst

AbstractWater washing of P‐2 nickel boride brings about a new catalyst designated as P‐2W nickel boride. This P‐2W catalyst is more reactive than P‐1 or P‐2 in the hydrogenation of cyclohexanone and nitrobenzene. The P‐2W, however, is less selective than P‐2 in the hydrogenation of cyclic olefins.

Attractive interactions of alkyl substituents with palladium catalyst in the hydrogenation of cyclohexanones

Cyclohexanone and its 4-alkyl-substituted derivatives were hydrogenated over Pd catalyst in cyclohexane solvent both individually and competitively in pairs (cyclohexanone and one of the derivatives). Most of the derivatives were less reactive than cyclohexanone individually, but more reactive competitively. These findings were explained in terms of attractive interactions between Pd and the alkyl substituents. Similar results were obtained on 2- and 3-alkyl-substituted cyclohexanones. The rate of cyclohexanone hydrogenation was different in five different hexane isomers used individually as solvents. This solvent effect was also explicably based on the concept of Pd-alkyl interactions.

Solvent‐Reactant‐Support interactions in liquid phase hydrogenation

AbstractThe effect of mixed solvents and catalyst support on the rate and selectivity of Ru‐catalyzed liquid phase hydrogenations has been studied. Experiments in 1‐propanol/water mixtures with Ru/C showed the adsorption of reactants on the catalyst and the reaction rate to vary with the composition of the solvent system. The influence of the support, in combination with the solvent surrounding the catalytic metal, on the selectivity in the competitive hydrogenation of cyclohexanone and cyclohexene has been studied using hydrophilic and hydrophobic supports in water/hydrocarbon mixtures. The results demonstrate the importance of both solvent‐support interactions and partition of the reactant between bulk solvent and adsorbed solvent.

Substituent Effects in Heterogeneous Catalysis. VII. Temperature Independence of the Relative Rates in Metal-catalyzed Hydrogenation of Cyclohexanone and Its 2-Alkyl Derivatives

Abstract The rates of hydrogenation of cyclohexanone and its 2-alkyl derivatives have been measured using decalin as the solvent in a temperature range of −5 to 68 °C over Ru/Al2O3, Rh/Al2O3, and Pt/Al2O3 catalysts. As predicted previously, 2-methyl-, 2-ethyl-, and 2-propylcyclohexanone have exhibited nearly identical temperature dependencies in adsorption and hydrogenation, while cyclohexanone and 2-isopropylcyclohexanone had quite different dependencies.

Substituent Effects in Heterogeneous Catalysis. VI. Competitive Hydrogenation of Methylenecyclohexane and 2-Methyl-methylenecyclohexane over Platinum Group Metals

Abstract Methylenecyclohexane and its 2-methyl derivative were hydrogenated competitively in cyclohexane at 30 °C over platinum group metals. The methyl derivative was less reactive than the unsubstituted olefin on all the metal catalysts used. The reactivity of the methyl derivative relative to the unsubstituted olefin was not much different in going from one catalyst to another. However, Pd was unique in its very high activity for double bond migration. MINDO/2 calculations have revealed that the olefinic double bonds of the substituted and unsubstituted olefins are essentially identical in bond order but somewhat different in charge density. The observed methyl substituent effect is compared with that observed previously in hydrogenation of cyclohexanone and its 2-methyl derivative.

ChemInform Abstract: SUBSTITUENT EFFECTS IN HETEROGENEOUS CATALYSIS. III. COMPETITIVE HYDROGENATION OF CYCLOHEXANONE AND 2‐ALKYLCYCLOHEXANONES OVER PLATINUM GROUP METALS

Chemischer InformationsdienstVolume 10, Issue 18 Preparative Organic Chemistry ChemInform Abstract: SUBSTITUENT EFFECTS IN HETEROGENEOUS CATALYSIS. III. COMPETITIVE HYDROGENATION OF CYCLOHEXANONE AND 2-ALKYLCYCLOHEXANONES OVER PLATINUM GROUP METALS T. CHIHARA, T. CHIHARASearch for more papers by this authorK. TANAKA, K. TANAKASearch for more papers by this author T. CHIHARA, T. CHIHARASearch for more papers by this authorK. TANAKA, K. TANAKASearch for more papers by this author First published: May 1, 1979 https://doi.org/10.1002/chin.197918170AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue18May 1, 1979 RelatedInformation

ChemInform Abstract: SUBSTITUENT EFFECTS IN HETEROGENEOUS CATALYSIS. IV. ADSORPTION ESTIMATIONS DURING COMPETITIVE HYDROGENATION OF CYCLOHEXANONE AND ITS 2‐ALKYL DERIVATIVES

Chemischer InformationsdienstVolume 10, Issue 18 Preparative Organic Chemistry ChemInform Abstract: SUBSTITUENT EFFECTS IN HETEROGENEOUS CATALYSIS. IV. ADSORPTION ESTIMATIONS DURING COMPETITIVE HYDROGENATION OF CYCLOHEXANONE AND ITS 2-ALKYL DERIVATIVES T. CHIHARA, T. CHIHARASearch for more papers by this authorK. TANAKA, K. TANAKASearch for more papers by this author T. CHIHARA, T. CHIHARASearch for more papers by this authorK. TANAKA, K. TANAKASearch for more papers by this author First published: May 1, 1979 https://doi.org/10.1002/chin.197918171AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume10, Issue18May 1, 1979 RelatedInformation

Substituent Effects in Heterogeneous Catalysis. V. Steric Hindrance of Bulky AlkyI Substituents in Cyclohexanone Hydrogenation

Abstract The reactivities of 2-isopropyl- and 2-t-butylcyclohexanone were measured relative to cyclohexanone in both individual and competitive hydrogenation over Ru/Al2O3, Rh/Al2O3, and Pt/Al2O3. The results obtained suggest that alkyl substitution sterically hinders much more significantly the ketone adsorption than the following surface reaction. A molecular model is presented for adsorption of each ketone.

Substituent Effects in Heterogeneous Catalysis. III. Competitive Hydrogenation of Cyclohexanone and 2-Alkylcyclo-hexanones over Platinum Group Metals

Abstract Cyclohexanone (1) and one of its 2-alkyl (methyl, ethyl, or propyl) derivatives (2) were hydrogenated competitively at 30 °C in cyclohexane over platinum group metals. The alkyl derivatives 2 were all less reactive than 1 on all the catalysts used. The relative reactivity R2⁄R1 was given by log10(R2⁄R1)=σ**+k, with σ** depending only upon the substituent and k upon the catalyst. The greater the substituent size, the more negative was the substituent constant σ**. The catalyst-dependent constant K was in general more negative for a catalyst metal having a smaller atomic radius. The above empirical rate expression has been interpreted based on the absolute reaction rate theory. The σ** values calculated on this theoretical ground were in excellent agreement with the observed values.

Substituent Effects in Heterogeneous Catalysis. IV. Adsorption Estimations during Competitive Hydrogenation of Cyclohexanone and Its 2-Alkyl Derivatives

Abstract Cyclohexanone (1) and its 2-alkyl derivatives (2-methyl-, 2-ethyl-, and 2-propylcyclohexanone (2m, 2e, and 2p)) were hydrogenated both individually and competitively in pairs (1+2) in cyclohexane using Ru/Al2O3, Rh/Al2O3, and Pt/Al2O3 as catalysts. For all the catalysts, the reaction rates in competitive reaction decreased in the sequence, l>>2m>2e>2p, while those in individual reaction were in the relation, 1>2m≈2e≈2p. By the analysis of these kinetic data, the relative values of adsorption equilibrium constants have been estimated for 2m, 2e, and 2p. These experimental values are in good agreement with the theoretical ones which have been derived on the basis of statistical mechanics using an adsorption model characterized by immobile adsorption of the substrate ketones.

Cluster ruthenium hydrogenation catalysts

Tetraruthenium dodecacarbonyl tetrahydride and some of its phosphine-substituted derivatives have been tested as homogeneous hydrogenation catalysts. The hydrogenation of cyclohexanone in the presence of H 4Ru 4(CO) 12 is first order with respect to the catalyst concentration, the substrate concentration and the partial pressure of hydrogen. The ruthenium cluster is recovered unchanged at the end of the reaction.

ATTRACTIVE STERIC EFFECTS OF ALKYL SUBSTITUENTS IN CYCLOHEXANONE HYDROGENATION CATALYZED BY PALLADIUM

Abstract In the Pd-catalyzed competitive hydrogenation of cyclohexanone (A) and its 4-alkyl derivatives (B), most of the bulkier B’s have unexpectedly reacted faster, and this unusual result is indicative of an “Attractive steric effect”, i.e., attractive interaction of the alkyl substituents with the Pd metal surface.

Substituent effects in heterogeneous catalysis I. Competitive hydrogenation of cyclohexanone and methylcyclohexanones over group VIII metals

Abstract Cyclohexanone and one of its methyl-substituted derivatives (2-, 3-, or 4-methylcyclohexanone) were hydrogenated competitively in pairs in cyclohexane solvent at 30 °C over group VIII metal catalysts. All of the methyl-substituted ketones were less reactive than cyclohexanone. The reactivity of a methylcyclohexanone relative to cyclohexanone was dependent upon the reaction mechanism and the atomic radius of the catalyst. INDO calculations, on the other hand, revealed that the carbonyl groups of the substituted and unsubstituted ketones are nearly identical in charge distribution and bond order, thus suggesting that the methyl substituent effect upon the hydrogenation rate is due primarily to steric hindrance to adsorption.

Catalytic deuteration of cyclohexanone and allied reactions over platinum metals

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.

Hydrogenation of Organic Compounds with Urushibara Nickel Catalysts. III. Hydrogenation of Cyclohexanone.

漆原ニッケルによる常温, 常圧におけるシクロヘキサノンのエタノール中におけるシクロヘキサノールへの還元を, (1) 濃度と還元速度, (2) 温度と還元速度, (3) アルカリの還元速度に対する影響, の三つの関係につき定量的に研究し, (1) はLangmuir型の等温吸着式によく一致し, 書 (2) の関係よりこの還元の見掛けの活性化エネルギー一は5.3ca1/mo1であり, (3) においては, 溶媒のエタノールがフェノールフタレインに淡く桃色に呈色する程度のアルカリを加えた場合に還元速度が最大になるという結果を得た。