- Catalytic Activities of Mono- and Bimetallic (Gold/Silver) Nanoshell-Coated Gold Nanocubes toward Catalytic Reduction of Nitroaromatics
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A new class of core-shell metallic nanostructures with tunable near-surface composition and surface morphology with excellent catalytic activity is reported. Very thin shells of metal nanoassemblies such as monolayer (Ag and Au), bilayer of Ag or Au, and AgAu alloy layer with controlled size and morphology were deposited onto a gold nanocube (AuNC) core. UV-vis absorption spectroscopy and high-resolution transmission electron microscopy analyses along with selected-area electron diffraction, energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometer, and X-ray diffraction techniques were used to characterize the prepared core-shell nanocubes. High-angle annular dark field scanning transmission electron microscopy-energy dispersive X-ray spectroscopy mapping images were recorded for the bilayer shell and alloy layer shell in the core-shell nanostructures. Reduction of 4-nitroaniline in the presence of sodium borohydride was chosen to validate the catalytic activity of the prepared core-shell metal nanocubes. Interestingly, the AgAu alloy shell layer over the AuNC (AuNC1@Ag0.25Au0.25) showed excellent catalytic activity compared with the pristine AuNC and monolayer and bilayer core-shell nanostructures.
- Sundarapandi, Manickam,Viswanathan, Perumal,Sivakumar, Shanmugam,Ramaraj, Ramasamy
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- Pd nanoparticles partially embedded in the inner wall of nitrogen-doped carbon hollow spheres as nanoreactors for catalytic reduction of 4-nitrophenol
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Pd@nitrogen-doped carbon nanoreactors (Pd@NC) were synthesized by partially embedding small Pd nanoparticles in the inner wall of the nitrogen-doped carbon shells. Such embedment is critical for improving catalytic activity and stability.
- Bian, Shao-Wei,Liu, Si,Guo, Mei-Xia,Xu, Ling-Li,Chang, Lan
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- Nitrogen-doped carbon supported iron oxide as efficient catalysts for chemoselective hydrogenation of nitroarenes
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Chemoselective hydrogenation has been widely used in the production of fine chemicals, and developing heterogeneous catalysts with high activity and chemoselectivity is always a challenging topic. Herein, we report a new type of catalysts synthesized from biomass-derived chitosan and non-noble iron, which is denoted as nitrogen-doped carbon supported iron (Fe/N-C). TEM and XRD characterization indicate the presence of iron species. Interestingly, the Fe/N-C catalysts exhibited excellent catalytic performances in the hydrogenation of nitroarenes, and excellent yields of target aniline products could be obtained under industrially viable conditions.
- Xu, Shaodan,Yu, Deqing,Liao, Shangfu,Ye, Tao,Sheng, Huadong
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- Record-high catalytic hydrogenated activity in nitroarenes reduction derived from in-situ nascent active metals enabled by constructing bimetallic phosphate
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Herein, we report an excellent in-situ exsolution triggered hydrogenated catalyst F-Ni/Cu-P-RT started from bimetallic phosphate Ni/Cu-P-RT, affording an ultrafast catalytic hydrogenated rate (20 s even 5 s) in nitrophenol reduction. In the first catalytic cycle, we proved the enhanced catalytic reduction activity of bimetallic Ni/Cu-P-RT within 50 s compared to monometallic counterparts. The kinetics results revealed Ni/Cu-P-RT affords the reaction rate K of 2.85/4.23/6.6 min?1 at 20, 30, and 40 °C with the activation energy 32 kJ/mol. Impressively, the involved reaction induction period is visibly observed and interpreted by reconstruction and evolution of active metal during the reaction, but was eliminated through integrating two metal Cu-Ni by regulation of electronic band energy of phosphate from 4.1–3.5 eV. The nascent Cu and Ni nanoparticles as reaction-preferred active species were in-situ exsolved partially after adding NaBH4, triggering the resulted higher active and stable F-Ni/Cu-P-RT(20 s, 14.1 min?1) in later multiple cycles.
- Yang, Fu,Wang, Jin,Gao, Shuying,Zhou, Shijian,Kong, Yan
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- Pd-Co catalysts prepared from palladium-doped cobalt titanate precursors for chemoselective hydrogenation of halonitroarenes
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Bimetallic Pd-Co catalysts supported on the mixed oxides CoTiO3-CoO-TiO2 (CTO) were synthesized via the thermal reduction of Pd-doped cobalt titanates PdxCo1-xTiO3 and evaluated for the chemoselective hydrogenation of halonitroarenes to haloarene-amines. The nominal Pd mass percentage of the Pd-Co/CTO systems was varied from 0.0 to 0.50. After the thermal reduction of PdxCo1-xTiO3 at 500 °C for 3 h, Pd was completely reduced and Co was partially reduced, producing a mixture of ionic Co, metallic Co, and TiO2-rutile species to give the supported bimetallic catalysts. The metallic cobalt content increased with the Pd content of the precursor. The catalytic activity toward 4-chloronitrobenzene increased with the Pd content; however, >0.1 mass% Pd decreased the chemoselectivity toward 4-chloroaniline due to the formation of the hydrodehalogenation product—aniline. The 0.1Pd-Co/CTO system was used as a model catalyst to produce haloarene-amine building blocks for linezolid, loxapine, lapatinib, and sorafenib with >98% conversion, 96% chemoselectivity, and no hydrohalogenation products. Finally, recycling tests of the 0.1Pd-Co/CTO catalyst showed loss of activity and selectivity during the third cycle due to catalyst deactivation. Regeneration treatments, every two catalytic cycles, allowed six operation cycles without loss of chemoselectivity and only a slight decrease in catalytic activity during the last cycle.
- Bustamante, Tatiana M.,Dinamarca, Robinson,Torres, Cecilia C.,Pecchi, Gina,Campos, Cristian H.
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- Ultrafine silver nanoparticles supported on a covalent carbazole framework as high-efficiency nanocatalysts for nitrophenol reduction
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A novel conjugated microporous polymer (CMP) material CZ-TEB was synthesized with a carbazole analogue and 1,3,5-triethynylbenzene. It possessed a high specific surface area, excellent thermal stability and layered-sheet morphology. Furthermore, ultrafine silver nanoparticles were successfully immobilized on CZ-TEB, thus preparing a nanocatalyst Ag0@CZ-TEB. To evaluate its catalytic performance, Ag0@CZ-TEB was exploited in the reduction reaction of nitrophenols, a family of priority pollutants. Ag0@CZ-TEB exhibited high catalytic ability, convenient recovery and excellent reusability. Strikingly, the normalized rate constant (knor) of the reduction reaction of 4-NP to 4-AP is as high as 21.49 mmol-1 s-1. This result shows a significant improvement over all previously reported work. We purposed to use a "capture-release" model to explain the high catalytic ability of Ag0@CZ-TEB. This explanation is supported by further experimental results that agree well with the "capture-release" model.
- Gong, Wei,Wu, Qianqian,Jiang, Guoxing,Li, Guangji
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supporting information
p. 13449 - 13454
(2019/06/13)
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- Fe-Catalyzed Amination of (Hetero)Arenes with a Redox-Active Aminating Reagent under Mild Conditions
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A novel and efficient Fe-catalyzed direct C?H amination (NH2) of arenes is reported using a new redox-active aminating reagent. The reaction is simple, and can be performed under air, mild, and redox-neutral conditions. This protocol has a broad substrate scope and could be used in the late-stage modification of bioactive compounds. Mechanistic studies demonstrate that a radical pathway could be involved in this transformation.
- Liu, Jianzhong,Wu, Kai,Shen, Tao,Liang, Yujie,Zou, Miancheng,Zhu, Yuchao,Li, Xinwei,Li, Xinyao,Jiao, Ning
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supporting information
p. 563 - 567
(2017/01/18)
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- Zwitterionic Surfactant stabilized palladium nanoparticles as catalysts in aromatic nitro compound reductions
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Palladium nanoparticles (NPs) stabilized by ImS3-14, a zwitterionic surfactant structurally related to ionic liquids, are revealed here to be good catalysts for the reduction of a large number of substituted aromatic nitro compounds. Our mass spectrometry results are consistent with the formation of amino products in a direct route, where the aromatic nitro compounds are initially reduced to nitroso compounds, which are then reduced to the hydroxylamine derivatives and finally to the anilines. Activation parameters showed that for most Pd catalysts reported in the literature, the mechanism seems to be similar, with lower enthalpy of activation (ΔH?) being compensated by more negative entropy of activation (ΔS?). As a result, the reaction is thermally compensated and the rate constants for most reactions rather similar. Furthermore, Pd NPs stabilized by ImS3-14 showed efficient catalytic activities for the reduction of aromatic nitro compounds, with high conversion and good selectivity even using very low loadings of metal.
- Souza, Franciane D.,Fiedler, Haidi,Nome, Faruk
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p. 372 - 381
(2016/03/19)
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- Activity and Selectivity in Nitroarene Hydrogenation over Au Nanoparticles on the Edge/Corner of Anatase
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Highly selective hydrogenation of molecules containing more than one reducible group is always challenging. Here we report an efficient strategy for rational preparation of highly selective gold-based catalysts in the hydrogenation of substituted nitroarenes by positioning gold nanoparticles on the edge/corner sites of anatase. Mechanistic studies reveal that the catalyst with gold nanoparticles on the edge/corner sites of anatase could form unique sites for selective adsorption and activation of nitro groups, thus leading to high activity and selectivity. This strategy for preparation of supported gold catalysts opens a new door for the design of highly efficient heterogeneous catalysts in the future.
- Wang, Liang,Zhang, Jian,Wang, Hong,Shao, Yi,Liu, Xiaohui,Wang, Yan-Qin,Lewis, James P.,Xiao, Feng-Shou
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p. 4110 - 4116
(2016/07/12)
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- Monodispersed Ag nanoparticles as catalyst: Preparation based on crystalline supramolecular hybrid of decamethylcucurbit[5]uril and silver ions
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Monodispersed silver nanoparticles (Ag0 NPs) have been first prepared on the basis of a postsynthesis via mild reduction from a new crystalline supramolecular hybrid solid assembled from Ag+ ions and decamethylcucurbit[5]uril (Me10CB[5]). Uniform growth of nearly spherical Ag0 NPs with an average size of ca. 4.4 nm was observed on the organic Me10CB[5] support to form Ag@Me10CB[5] composite material. The as-synthesized composite material was characterized by a range of physical measurements (PXRD, TGA, XPS, ICP, TEM, etc.) and was further exploited as a heterogeneous catalyst for the reduction of various nitrophenols in the presence of NaBH4. The kinetics of the reduction process was monitored under various experimental conditions. The Ag@Me10CB[5] composite material showed excellent catalytic performance over the reduction reactions and remained active after several consecutive cycles.
- Li, Hong-Fang,Lue, Jian,Lin, Jing-Xiang,Cao, Rong
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p. 5692 - 5697
(2014/06/23)
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- 4′-Alkoxyl substitution enhancing the anti-mitotic effect of 5-(3′,4′,5′-substituted)anilino-4-hydroxy-8-nitroquinazolines as a novel class of anti-microtubule agents
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Mitosis inhibitors are powerful anticancer drugs. Based on a novel anti-microtubule agent of 5-(4′-methoxy)anilino-4-hydroxy-8-nitroquinazoline, a series of 5-(3′,4′,5′-substituted)anilino-4-hydroxy-8- nitroquinazolines were designed and synthesized to investigate the effect of the substitution on the inhibitory activity against mitotic progression of tumor cells. The large alkoxyl substitution on the 4′-position of 5-anilino ring is beneficial for the potency. The 5-(3′,4′,5′-trimethoxy)anilino-8-nitroquinazoline (1h) displays an overwhelming activity in arresting the cells at the G2/M phase, providing a promising new template for further development of potent microtubule-targeted anti-mitotic drugs.
- Jin, Yi,Zhou, Zu-Yu,Tian, Wei,Yu, Qiang,Long, Ya-Qiu
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p. 5864 - 5869
(2007/10/03)
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- One step hair coloring compositions using salts
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A hair coloring composition comprising the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an amino phenol, a naphthol, a polyhydric phenol, a catechol and mixtures thereof; wherein the composition comprising one or more oxidative hair coloring agents further comprises al least one water soluble carbonate releasing salts; and optionally a water soluble ammonium salt, is described.
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- Transition metal complexes as dye forming catalysts in hair coloring compositions
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A hair coloring composition comprising a first composition which comprises: (a) a dye forming transition metal salt or complex; which is first applied to the hair; and a second composition which comprises the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an aminophenol, a polyhydric phenol a catechol and mixtures thereof.
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- Hair colouring and conditioning compositions
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A hair colouring and conditioning composition comprising: (a) a hair colouring agent; and (b) a hair conditioning agent; wherein the composition provides an Average Combing Index Value of greater than 1.2 as measured by the Combing Technical Test Method. The products can provide excellent hair colouring together with excellent conditioning, reduced hair damage, brittleness and dryness, and is convenient and easy to use.
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- Enhanced color deposition for hair with sequestering agents
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Hair coloring compositions which comprise: (A) non-nitrogenous chelating agents from the group consisting of polyphosphate; phosphonates; hydroxycarboxylates; polyacrylates; zeolite; and mixtures thereof; (B) an oxidative dye primary intermediate; and (C) an oxidative dye coupler; (D) and water are described. The present invention also relates to a method for coloring hair which comprises contacting said hair with a hair coloring composition as described above.
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- Hair conditioning compositions and their use in hair colouring compositions
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The present invention relates to a hair care composition comprising a aminofunctional polysiloxane having a specified average effective particle size which provides improved durable conditioning particularly when utilised in conjunction with a hair colouring composition.
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- HAIR COLORING COMPOSITIONS
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A hair coloring composition comprising: (a) from about 0.0003 moles (per 100 g of composition) to less than about 0.09 moles (per 100 g of composition) of an inorganic peroxygen oxidizing agent; and (b) an oxidative hair coloring agent; wherein the pH of each of (a) and (b) is in the range of from about 1 to about 6 and wherein the combined mixture of (a) and (b) has a pH in the range of from about 1 to about 6. The products can provide excellent hair coloring and in-use efficacy benefits including excellent initial color and good wash fastness in combination with reduced hair damage at low pH.
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- HAIR COLORING COMPOSITIONS
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A hair coloring composition comprising: (a) a preformed organic peroxyacid oxidising agent; and (b) an oxidative hair coloring agent; wherein the pH of each of components (a) and (b) is in the range of from about pH 1 to less than about pH 7 and wherein the pH of the composition is in the range of from about pH 1 to less than about pH 7. The products can provide excellent hair coloring and in-use efficacy benefits including excellent initial color and good wash fastness in combination with reduced hair damage at low pH.
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- Therapeutic amines
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Compounds of formula I, and their pharmaceutically acceptable salts, STR1 in which R1 and R2 are hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenylalkyl or alkenyl; or NR1 R2 is a heterocyclic group; A is trimethylene optionally substituted by alkyl and the phenyl ring is optionally substituted by substituents such as halogeno, alkenyl, amino, cyano, ureido, alkyl, carbamoylalkyl, alkanoylamino, alkoxycarbonyl, N-alkyl-alkanoylamino, alkanoyl and amines thereof; are inhibitors of squalene synthese and hence useful in treating diseases in which a lowering of cholesterol is desirable. As well as the use of these compounds in medicine, novel compounds, processes for their preparation and pharmaceutical compositions are also referred to.
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- Methods for dyeing keratinous fibers with compositions which contain aminoindole couplers, oxidation dye precursors, and oxidizing agents at acid pHs
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A method for dyeing keratin fibers, wherein a composition is applied to said fibers which contains, in a suitable dyeing medium, at least one coupler having formula (I) STR1 wherein R1 is hydrogen or alkyl; R2 and R3 are hydrogen, alkyl, COOR', where R' is alkyl or hydrogen; R4 is hydrogen, hydroxyalkyl, alkyl, polyhydroxyalkyl or acetyl or aminoalkyl wherein the amine may be mono- or disubstituted by alkyl; Z1 and Z2 are hydrogen, alkyl, hydroxy, halogen, alkoxy or a salt thereof; at least one precursor of an oxidation hair dye; and at least one oxidizing agent, the pH of the composition applied to the fibers being less than 7.
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- Process for dyeing keratinous fibers with 2,4-diamino-1,3-dimethoxybenzene at an acid ph and compositions employed
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Process for dyeing keratinous fibres, especially human keratinous fibres such as the hair, characterised in that a composition containing, in a medium suitable for dyeing, at least 2,4-diamino-1,3-dimethoxybenzene as a coupler; an oxidation dye precursor; and an oxidising agent; is applied to these fibres, the pH of the composition applied to the fibres being less than 7.
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- Substituted ortho-aminophenols, process for preparing them and their use for the oxidatin dyeing of keratinous fibres
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5-Substituted ortho-aminophenols of formula: STR1 in which: R1 denotes a hydrogen atom, an alkyl radical having 1 to 4 carbon atoms or a hydroxyalkyl radical having 1 to 4 carbon atoms; and R2 denotes, independently of R1, an alkyl radical having 1 to 4 carbon atoms, an alkoxy radical having 1 to 4 carbon atoms or a benzyl radical; the addition salts with an acid and the phenates, and dyeing composition containing a compound of formula (I) or a salt or a phenate of such a compound. The 5-substituted ortho-aminophenols enable hair to be dyed in a rich spectrum of hues having good durability.
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- Hydrogenation of halonitrobenzenes without dehalogenation
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A method for inhibiting dehalogenation of fluorinated and chlorinated benzenoid nitro compounds during catalytic hydrogenation to make the corresponding substituted anilines by conducting the hydrogenation reaction in the presence of an acidic catalytic medium.
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- 2-substituted para-aminophenols and their use for dyeing keratinous fibres
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2-Substituted para-aminophenols of general formula: STR1 where Y denotes oxygen or sulphur and R denotes a C1 -C6 alkyl, C1 -C6 hydroxyalkyl or C1 -C6 haloalkyl or a C2 -C6 polyhydroxyalkyl, provided that when Y=O, R is not methyl or ethyl and when Y=S, R is not ethyl; and dye composition containing one or more compounds of formula (I) where Y denotes an oxygen or sulphur atom and R is C1 -C6 alkyl, C1 -C6 hydroxyalkyl, C1 -C6 haloalkyl or C2 -C6 polyhydroxyalkyl.
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- THERMOTROPIC LIQUID CRYSTAL BEHAVIOR IN SOME AROMATIC ESTERAMIDES.
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Ester-amide analogs of p-phenylene di-p-substituted benzoates have been synthesized and the thermotropic liquid crystal properties of the two series are compared. The crystalline, smectic, and nematic phases are all more thermally stable in the ester-amides than in the diesters. In the corresponding series of 4-alkoxybenzoyl compounds, as the alkyl chain length increases the difference in nematic phase stability also increases, but the difference in smectic phase stability decreases. Introduction of a methyl substituent into the central ring reduces the stability of all three phases, and increases the sensitivity of smectic phase stability, but not of crystalline or nematic phase stability, to alkyl chain length.
- Kalyvas,McIntyre
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p. 105 - 118
(2007/10/02)
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- Kinetics and Mechanisms of the Bamberger Rearrangement. Part 3. Rearrangement of Phenylhydroxylamines to p-Aminophenols in Aqueous Sulphuric Acid Solutions
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The rates of Bamberger-type rearrangement of phenylhydroxylamine (1a) and its derivatives (1b-d) to the corresponding p-aminophenols were determined in sulphuric acid solution.Plots if the pseudo-first-order rate constants against pH (or H0) indicate that the active species at +H2) which exists in equilibrium with the N-protonated species (ArN+H2OH), while the diprotonated species (ArN+H2O+H2) contributes significantly to the observed reaction rate at > 1.00 N (H0 region).The slope of Hammett plots (ρ) which was obtained by plotting kobs at 1.00 N against the Hammett ? values was -3.19.It was also established that the ΔS* values for the four substrates are all positive.These results suggest that the Bamberger rearrangement occurs by an SN1 mechanism and that the elimination of water from ArNHO+H2 is rate determining.
- Sone, Takaaki,Tokuda, Yuuji,Sakai, Toshimi,Shinkai, Seiji,Manabe, Osamu
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p. 298 - 302
(2007/10/02)
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- Enzyme-activated oxidative process for coloring hair
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An enzyme-based oxidative process for coloring hair wherein the hair is exposed to a solution having a pH of about 4 to about 10 and containing hydrogen peroxide, soybean peroxidase enzyme and one or more oxidation dye precursors.
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