4621-04-9Relevant articles and documents
Ru/hydroxyapatite as a dual-functional catalyst for efficient transfer hydrogenolytic cleavage of aromatic ether bonds without additional bases
Hua, Manli,Song, Jinliang,Xie, Chao,Wu, Haoran,Hu, Yue,Huang, Xin,Han, Buxing
, p. 5073 - 5079 (2019/09/30)
Cleavage of aromatic ether bonds is a key step for lignin valorization, and the development of novel heterogeneous catalysts with high activity is crucial. Herein, bifunctional Ru/hydroxyapatite has been prepared via ion exchange and subsequent reduction. The obtained Ru/hydroxyapatite could efficiently catalyze the cleavage of various compounds containing aromatic ether bonds via transfer hydrogenolysis without additional bases. Systematic studies indicated that the basic nature of hydroxyapatite and electron-enriched Ru sites resulted in the high activity of the catalyst. A mechanism study revealed that the direct cleavage of aromatic ether bonds was the main reaction pathway.
Ductile Pd-Catalysed Hydrodearomatization of Phenol-Containing Bio-Oils Into Either Ketones or Alcohols using PMHS and H2O as Hydrogen Source
Di Francesco, Davide,Subbotina, Elena,Rautiainen, Sari,Samec, Joseph S. M.
supporting information, p. 3924 - 3929 (2018/09/14)
A series of phenolic bio-oil components were selectively hydrodearomatized by palladium on carbon into the corresponding ketones or alcohols in excellent yields using polymethylhydrosiloxane and water as reducing agent. The selectivity of the reaction was governed by the water concentration where selectivity to alcohol was favoured at higher water concentrations. As phenolic bio-oil examples cardanol and beech wood tar creosote were studied as substrate to the developed reaction conditions. Cardanol was hydrodearomatized into 3-pentadecylcyclohexanone in excellent yield. From beech wood tar creosote, a mixture of cyclohexanols was produced. No hydrodeoxygenation occurred, suggesting the applicability of the reported method for the production of ketone-alcohol oil from biomass. (Figure presented.).
Hydrogenolysis of lignin model compounds into aromatics with bimetallic Ru-Ni supported onto nitrogen-doped activated carbon catalyst
Hu, Yinghui,Jiang, Guangce,Xu, Guoqiang,Mu, Xindong
, p. 316 - 326 (2018/01/05)
Lignin is the most abundant and renewable resources for production of natural aromatics. In this paper, new bimetallic catalytic system of Ru and Ni supported onto nitrogen-doped activated carbon (Ru-Ni-AC/N) was developed and its performances on hydrogenolysis of lignin model compounds under mild reaction conditions (1.0 MPa, 230 °C, in aqueous) were investigated. The results indicate that Ru-Ni-AC/N was a highly active, selective and stable catalyst for the conversion of lignin model compounds into aromatics, e.g. phenol, benzene and their derivatives. As verified by BET, XRD, HRTEM, XPS, H2-TPR and ICP-MS, the strong synergistic effects between i) Ru and Ni and ii) metals and N-groups were contributed to its excellent aromatics selectivity. What's more, the introduction of electron rich N atoms on AC was beneficial to the stabilization of metal particles, which greatly enhanced the durability of the catalyst.
Cytochrome P450 catalyzed oxidative hydroxylation of achiral organic compounds with simultaneous creation of two chirality centers in a single C-H activation step
Roiban, Gheorghe-Doru,Agudo, Ruben,Reetz, Manfred T.
supporting information, p. 8659 - 8663 (2014/08/18)
Regio- and stereoselective oxidative hydroxylation of achiral or chiral organic compounds mediated by synthetic reagents, catalysts, or enzymes generally leads to the formation of one new chiral center that appears in the respective enantiomeric or diastereomeric alcohols. By contrast, when subjecting appropriate achiral compounds to this type of C-H activation, the simultaneous creation of two chiral centers with a defined relative and absolute configuration may result, provided that control of the regio-, diastereo-, and enantioselectivity is ensured. The present study demonstrates that such control is possible by using wild type or mutant forms of the monooxygenase cytochrome P450 BM3 as catalysts in the oxidative hydroxylation of methylcyclohexane and seven other monosubstituted cyclohexane derivatives.
Experimental determination of the conformational free energies (A values) of fluorinated substituents in cyclohexane by dynamic 19F NMR spectroscopy. Part 2. Extension to fluoromethyl, difluoromethyl, pentafluoroethyl, trifluoromethylthio and trifluoromethoxy groups
Carcenac, Yvan,Tordeux, Marc,Wakselman, Claude,Diter, Patrick
, p. 447 - 457 (2007/10/03)
The synthesis of monosubstituted and 1,4-substituted cyclohexanes bearing one of the title groups is described. The conformational analysis of these compounds was studied by 19F NMR spectroscopy at various temperatures. Chemical shifts for each conformer above the coalescence temperature were obtained by binomial regression from low temperature values, allowing the high precision determination of the equilibrium constants, and the corresponding thermodynamic parameters (ΔG°, ΔH°, ΔS°) of the fluorinated substituents. For A values (-ΔG°298K), the following averaged data were obtained: 1.59 (CFH2), 1.85 (CF2H), 2.67 (C2F5), 0.79 (OCF3) and 1.18 (SCF3) [in kcal mol-1]. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
Synthesis of (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol, the aggregation pheromone of the ambrosia beetle Platypus quercivorus, its racemate, (1R,4R)- and (1S,4S)-isomers
Mori, Kenji
, p. 2133 - 2142 (2007/10/03)
(S)-Perillyl alcohol was converted to (R)-cryptone (91.5-93% ee) in six steps, which was then treated with methyllithium to give (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol, the aggregation pheromone of the ambrosia beetle Platypus quercivorus. The racemic pheromone was also prepared by methylation of (±)-cryptone. Both (1R,4R)- and (1S,4S)-isomers (98% ee) of the pheromone were synthesized from the enantiomers of dihydrolimonene oxide.
Compounds having protected hydroxy groups
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, (2008/06/13)
The present invention relates to compounds with protected hydroxy groups of formula (I) These compounds are precursors for organoleptic agents, such as fragrances, and masking agents and for antimicrobial agents. When activated, the compounds of formula (I) are cleaved and form one or more organoleptic and/or antimicrobial compounds.
PERFUME COMPOSITION
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, (2008/06/13)
A perfume composition contains specified ketones, salicylates and alcohols/acetates/propionates. Use of such a perfume composition inhibits development of human body malodour. The combination of specified materials makes it possible to avoid inclusion of individual components with powerful, unacceptable odours. The perfume composition may be used in various products notably in a fabric conditioning product used during the rinsing or tumble drying of fabrics after washing to soften the fabrics.
'Designer yeast': A new reagent for enantioselective Baeyer-Villiger oxidations
Stewart, Jon D.,Reed, Kieth W.,Kayser, Margaret M.
, p. 755 - 757 (2007/10/03)
The catalytic repertoire of baker's yeast has been expanded to include enantioselective Baeyer-Villiger oxidations. To create this catalyst, the Acinetobacter sp. cyclohexanone monooxygenase gene was inserted into a yeast expression vector and this was used to create a 'designer yeast' that performed oxidation reactions. Whole cell-mediated Baeyer-Villiger reactions were carried out on a 1.0 mmol scale and several cyclic ketones were converted in 20-30 h into the corresponding lactones in isolated yields of 60-83%. Under the reaction conditions, ketone reduction constituted only a minor side-reaction. Oxidation of prochiral 4-substituted cyclohexanones produced lactones with very high enantioselectivities.
The Interaction of π orbitals with a carbocation over three σ bonds
Lambert, Joseph B.,Ciro, Sol M.
, p. 1940 - 1945 (2007/10/03)
The semi-π analogue of double hyperconjugation ("hyperconjugation/conjugation") has been examined in 4-isopropylidenecyclohexyl mesylate (4-OMs) by comparison with the saturated analogue, trans-4-isopropylcyclohexyl mesylate (5-OMs). The unsaturated substrate reacts in 97% trifluoroethanol only four times faster than the saturated substrate. Raber-Harris plots indicate that both substrates react by ks mechanisms; i.e., solvolysis occurs with solvent assistance rather than carbocation formation. These results are consistent with the absence of a direct, through-bond interaction of the double bond with the reactive center. The absence is caused at least in part by less than ideal overlap of the γ,δ π orbitals with the α,β σ orbitals. In contrast, an electron-rich tin atom attached to the 4-position provides a large rate enhancement and changes the mechanism to carbocation formation through double hyperconjugation.
