- High-Density and Thermally Stable Palladium Single-Atom Catalysts for Chemoselective Hydrogenations
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Single-atom catalysts (SACs) have shown superior activity and/or selectivity for many energy- and environment-related reactions, but their stability at high site density and under reducing atmosphere remains unresolved. Herein, we elucidate the intrinsic driving force of a Pd single atom with high site density (up to 5 wt %) under reducing atmosphere, and its unique catalytic performance for hydrogenation reactions. In situ experiments and calculations reveal that Pd atoms tend to migrate into the surface vacancy-enriched MoC surface during the carburization process by transferring oxide crystals to carbide crystals, leading to the surface enrichment of atomic Pd instead of formation of particles. The Pd1/α-MoC catalyst exhibits high activity and excellent selectivity for liquid-phase hydrogenation of substituted nitroaromatics (>99 %) and gas-phase hydrogenation of CO2 to CO (>98 %). The Pd1/α-MoC catalyst could endure up to 400 °C without any observable aggregation of single atoms.
- Baaziz, Walid,Chu, Wei,Ersen, Ovidiu,Greiner, Mark,Liu, Wei,Liu, Yuefeng,Ma, Ying,Pham-Huu, Cuong,Ren, Yujing,Wang, Aiqin,Zhang, Tao,Zhou, Yanan
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supporting information
p. 21613 - 21619
(2020/09/21)
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- Facile reduction of nitroarenes into anilines and nitroalkanes into hydroxylamines via the rapid activation of ammonia· borane complex by supported gold nanoparticles
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Gold nanoparticles supported on titania catalyse, even at a ppm loading level, the quantitative reduction of nitroarenes into anilines and nitroalkanes into alkylhydroxylamines by the ammonia× borane complex. No dehalohalogenation was seen in the case of chloro- or bromonitroarenes, while ester, cyano, or carboxylic acid functionalities also remain intact. The nitroarene to aniline reduction pathway does not require nitrosoarenes as intermediate products. Copyright
- Vasilikogiannaki, Eleni,Gryparis, Charis,Kotzabasaki, Vasiliki,Lykakis, Ioannis N.,Stratakis, Manolis
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supporting information
p. 907 - 911
(2013/05/08)
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- Ramoplanin derivatives possessing antibacterial activity
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Novel ramoplanin derivatives are disclosed. These ramoplanin derivatives exhibit antibacterial activity. As the compounds of the subject invention exhibit potent activities against gram positive bacteria, they are useful antimicrobial agents. Methods of synthesis and of use of the compounds are also disclosed.
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Page/Page column 69
(2010/11/23)
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- 1,3-Dihydroxybenzene derivatives and colorants containing said compounds
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1,3-Dihydroxybenzene derivatives of general formula (I) or (Ia) or physiologically tolerated, water-soluble thereof wherein R′1 denotes substituted pyridyl group, a pyrimidyl group, a group of formula (IIa) or (IIIa) and the dyeing agents for keratin fibers containing these compounds.
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- Indium Mediated Reduction of Nitro and Azide Groups in the Presence of HCl in Aqueous Media
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Indium mediated reduction of azide and nitro groups in the presence of HCl (1.5 equiv based on indium) at room temperature in aqueous THF successfully provided the corresponding amine in high to quantitative yields. Under the some reaction conditions, selective reduction of azide and nitro group in the presence of vinyl group could be accomplished.
- Lee, Jung Gyu,Choi, Kyung Il,Koh, Hun Yeong,Kim, Youseung,Kang, Yonghan,Cho, Yong Seo
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- Process for the preparation of 2-amino-5-alkyl-phenols
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2-Amino-5-alkyl-phenols, which are suitable as intermediates in the production of crop-protection agents or photographic couplers, can be prepared by subjecting 2-amino-5-alkyl-benzenesulphonic acids or their salts to alkaline hydrolysis.
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- 3-substituted para-aminophenols
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The invention concerns the use of a 3-substituted para-aminophenol as an oxidation dye precursor for dyeing keratinous fibres, in particular human hair. The 3-substituted para-aminophenol has formula: STR1 where R1 represents alkyl, alkenyl, mono- or polyhydroxyalkyl, nitrile, cyanoalkyl, halogenoalkyl, aminoalkyl or alkoxyalkyl and R2 represents hydrogen, alkyl or mono- or polyhydroxyalkyl, provided that when R2 is hydrogen R1 is not methyl or trifluoromethyl, and to addition salts thereof with an acid. The invention also concerns dye compositions containing compound (I). The invention further concerns novel 3-substituted para-aminophenols.
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- Keratinous fiber dye composition containing a 2-substituted amino-5-alkylphenol derivative coupler
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A keratinous fiber dye composition comprising a developer and a coupler, wherein the coupler is a 2-substituted amino-5-alkylphenol derivative represented by the following formula (1): STR1 wherein the all symbols are defined in the disclosure, is disclosed. The keratinous fiber dye composition imparts a color tone of a high chroma and is excellent in coloring power and fastness.
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- A NEW CONCISE APPROACH TO THE ENANTIOSELECTIVE SYNTHESIS OF THE HYDROXYAMINO ACID MOIETY OF AI-77-B
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The hydroxyamino acid moiety of AI-77-B has been prepared from D-ribose in an optically pure form via stereoselective alkylation of N-acylpyrrolidinium ion intermediates as the key step.
- Kotsuki, Hiyoshizo,Iwasaki, Mitsuhiro,Ochi, Masamitsu
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- Acid-catalyzed amino-migration of O-phenylhydroxylamines
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The mechanism of amino-migration of O-phenylhydroxylamine (1a) was studied. It was found that 1 rearranges to give 2-aminophenol (50%) and 4-aminophenol (7%) in trifluoroacetic acid (TFA). The predominance of the ortho rearrangement of 1 clearly distinguishes this process from the Bamberger rearrangement. From cross-coupling experiments employing stable isotopes, it was clarified that the ortho rearrangement proceeds intramolecularly and the para rearrangement involves both intra- and intermolecular processes. Good first-order kinetics were obtained for the rearrangement. The Hammett plot (σ+) with a large negative slope (ρ = -7.8) indicates that initial heterolytic N-O bond cleavage of 1 occurs and generates a positive charge on the oxygen atom with considerable delocalization into the aromatic ring. An ion-molecule pair involving a phenoxenium ion and an ammonia molecule as an intermediate rationalizes all of the results. In this pair, intramolecular combination to the ortho position proceeds preferentially over that to the para position. Formation of catechol and hydroquinone can be explained in terms of nucleophilic attack of TFA on the phenoxenium ion in a solvent-separated pair.
- Haga, Naoki,Endo, Yasuyuki,Kataoka, Ken-Ichiro,Yamaguchi, Kentaro,Shudo, Koichi
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p. 9795 - 9806
(2007/10/02)
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- Pyridopyrrolobenzoxazine
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Compounds of the formula: STR1 where 2 THE R's are the same or different and are H or CH3, and one of them can be C2 -C9 alkyl or phenyl; R1 is hydrogen, C1 -C4 alkyl, C3 -C6 cycloalkyl, C2l -C4 alkoxycarbonyl, or substituted C1 -C4 alkyl where the substituent is C3 -C6 cycloalkyl or phenyl; and Z is H, Cl or CH3 ; and their pharmaceutically suitable salts. The compounds are useful as sedatives; some of them also exhibit antidepressant activity.
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