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All total 1669 Articles be foundMagnetic Field Effects on and Mechanism of Photoredox Reaction of Aromatic Nitro Group
Mutai, Kiyoshi,Nakagaki, Ryoichi,Tukada, Hideyuki
, p. 920 - 926 (1993)
Photoredox reaction mechanism of a homologous series p-O2NC6H4O(CH2)nNHPh (1) in acetonitrile and benzene is studied.The major products are p-ONC6H4O(CH2)n-1CHO (3) and aniline derived from intramolecular reaction, but the presence of minor amounts of intermolecular reaction products, p-O2NC6H4O(CH2)n-1CHO (4) and p-ONC6H4O(CH2)nNHPh (5) is confirmed in the reaction mixture.In the presence of an external magnetic field, the yield of 3 is suppressed and those of 4 and 5 are correspondingly increased, while the rates of the disappearance of 1 and of the formation of aniline remain unchanged, suggesting the presence of biradical recombination process accompanied by intersystem crossing in a rate-determining step.On the basis of these observations, two reaction schemes are proposed.The magnetic field effects provide strong evidence for the presence of a transient species with (nitro)N(OH)-O-CHN group generally supposed for nitro oxygen transfer process in this type photoreaction.
Structure and Catalytic Activity of Cr-Doped BaTiO3 Nanocatalysts Synthesized by Conventional Oxalate and Microwave Assisted Hydrothermal Methods
Srilakshmi, Chilukoti,Saraf, Rohit,Prashanth,Rao, G. Mohan,Shivakumara
, p. 4795 - 4805 (2016)
In the present study synthesis of BaTi1-xCrxO3 nanocatalysts (x = 0.0 ≤ x ≤ 0.05) by conventional oxalate and microwave assisted hydrothermal synthesis methods was carried out to investigate the effect of synthesis methods on the physicochemical and catalytic properties of nanocatalysts. These catalysts were thoroughly characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 physisortion, and total acidity by pyridine adsorption method. Their catalytic performance was evaluated for the reduction of nitrobenzene using hydrazine hydrate as the hydrogen source. Structural parameters refined by Rietveld analysis using XRD powder data indicate that BaTi1-xCrxO3 conventional catalysts were crystallized in the tetragonal BaTiO3 structure with space group P4mm, and microwave catalysts crystallized in pure cubic BaTiO3 structure with space group Pm3μm. TEM analysis of the catalysts reveal spherical morphology of the particles, and these are uniformly dispersed in microwave catalysts whereas agglomeration of the particles was observed in conventional catalysts. Particle size of the microwave catalysts is found to be 20-35 nm compared to conventional catalysts (30-48 nm). XPS studies reveal that Cr is present in the 3+ and 6+ mixed valence state in all the catalysts. Microwave synthesized catalysts showed a 4-10-fold increase in surface area and pore volume compared to conventional catalysts. Acidity of the BaTiO3 catalysts improved with Cr dopant in the catalysts, and this could be due to an increase in the number of Lewis acid sites with an increase in Cr content of all the catalysts. Catalytic reduction of nitrobenzene to aniline studies reveals that BaTiO3 synthesized by microwave is very active and showed 99.3% nitrobenzene conversion with 98.2% aniline yield. The presence of Cr in the catalysts facilitates a faster reduction reaction in all the catalysts, and its effect is particularly notable in conventional synthesized catalysts.
Pd nanoparticles immobilized on halloysite decorated with a cyclodextrin modified melamine-based polymer: a promising heterogeneous catalyst for hydrogenation of nitroarenes
Sadjadi, Samahe,Akbari, Maryam,Monflier, Eric,Heravi, Majid M.,Leger, Bastien
, p. 15733 - 15742 (2018)
For the first time, a hybrid system composed of halloysite (Hal) and a cyclodextrin modified melamine-based polymer is developed and employed for immobilization of Pd(0) nanoparticles. The resulting catalytic hybrid system, Pd@HTMC, was then applied as a
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Nicol
, p. 211 (1882)
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Palladium nanoparticles supported on silicate-based nanohybrid material: highly active and eco-friendly catalyst for reduction of nitrobenzene at ambient conditions
Ebadati, Esmat,Aghabarari, Behzad,Bagheri, Mozhgan,Khanlarkhani, Ali,Martinez Huerta, Maria Victoria
, p. 569 - 578 (2021)
In this study, spent bleaching earth (SBE), a hazardous industrial waste was used as raw material to synthesis carbon/silicate nanohybrid material (CSNH) as support for mono and bimetallic palladium and nickel nanoparticles. The synthesized catalysts were
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Masilamani et al.
, p. 3687,3688, 3691 (1976)
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A Modification of the Sheverdina-Kocheshkov Amination: The Use of Methoxyamine-Methyllithium as a Convenient Synthetic Equivalent for NH2+
Beak, Peter,Kokko, Bruce J.
, p. 2822 - 2823 (1982)
Direct stoichiometric amination of organolithiums can be achieved in high yields by methoxyamine and methyllithium in hexane-ether.The synthetic advantages of this approach are noted.
Pd immobilized on polymeric network containing imidazolium salt, cyclodextrin and carbon nanotubes: Efficient and recyclable catalyst for the hydrogenation of nitroarenes in aqueous media
Sadjadi, Samahe,Koohestani, Fatemeh
, (2020)
A novel polymeric network benefiting from the chemistry of imidazolium salt (IL), cyclodextrin (CD) and carbon nanotube (CNT) is fabricated through a multi-step process, in which silica coated CNTs were vinyl functionalized and polymerized with poly (ethy
Synthesis of PVP-stabilized Pt/Ru colloidal nanoparticles by ethanol reduction and their catalytic properties for selective hydrogenation of ortho-chloronitrobenzene
Liu, Manhong,Zhang, Jin,Liu, Jinqiang,Yu, William W.
, p. 1 - 7 (2011)
Stable poly(N-vinyl-2-pyrrolidone)-stabilized Pt/Ru colloidal nanoparticles (PVP-Pt/Ru) were prepared via ethanol reduction of H2PtCl 66H2O and RuCl3nH2O. The average diameters of the nanoparticles with different molar ratio of Pt/Ru were in a range of 2.1-2.8 nm with narrow size distributions. X-ray photoelectron spectroscopy verified that both Pt and Ru were in the metallic state and Ru was rich on the surface. These nanoparticles were employed to selectively hydrogenate ortho-chloronitrobenzene at 298 K and 0.1 MPa hydrogen pressure. They showed high activity [TOF was in the range of 0.8-5.3 × 10 -2 molo-CNB/(molM,surface atom) s] and high selectivity (93-99%) to ortho-chloroaniline (o-CAN) for the reaction, which were composition-dependent. The selectivity to o-CAN monotonously increased, but the activity of the catalyst decreased with the increasing proportion of Ru in Pt/Ru colloidal catalysts. PVP-1Pt/4Ru nanoparticles exhibited the highest selectivity of 99.0% to o-CAN at a complete conversion.
Thermolysis of azobenzene
Budyka, M. F.,Kantor, M. M.
, p. 1495 - 1497 (1993)
Thermolysis of azobenzene in a melt and in solution results in the formation of aniline.The possible directions of the reaction are considered.Comparison of the enthalpies of the reaction proves that the cleavage of a ?-bond in the N=N group to form a biradical intermediate is thermodynamically more favorable than that of a C-N ?-bond.
Photochemical locking and unlocking of an acyl nitroso dienophile in the Diels-Alder reaction
Schultz, Kevin P.,Spivey, David W.,Loya, E. Kirkbride,Kellon, Jaclyn E.,Taylor, Lisa M.,McConville, Marie R.
, p. 1296 - 1299 (2016)
Photochromic Diels-Alder cycloadducts consisting of acyl nitroso dienophiles, which are known nitroxyl (HNO) donors, and dithienyldienes are presented. The dithienylethene-type photochromic cycloadducts were found to exhibit reversible electrocyclic ring closing and ring opening reactions to 'lock' or 'unlock' the retro Diels-Alder reaction, respectively. The release of an acyl nitroso dienophile via a retro Diels-Alder reaction at 92 °C was shown to occur only from the open or 'unlocked' form of a photochromic dithienylcyclopentene and not from the closed or 'locked' isomer.
Oxidation-reduction conversions of derivatives of 1,4-dihydropyridine and 4H-pyran on interaction of alicyclic 1,5-diketones with 4-aminoazobenzene
Maslov,Akimova,Kaminski
, p. 417 - 421 (2002)
The interaction of 2,2′-methylenedicyclohexanone and 2,2′-methylenedicyclopentanone with 4-aminoazobenzene in acetic acid leads to reduction of the azo group of 1,4-dihydropyridine and 4H-pyran derivatives formed as intermediates. The reduction products were isolated as the corresponding pyridinium salts.
Methylene blue sensitized photodechlorination of isomeric mono- and dichloroanilines via molecular complex formation mechanism
Pande,Dwivedi
, p. 1086 - 1093 (2011)
The photosensitized dechlorination of isomeric mono- and dichloroanilines has been studied using methylene blue as photosensitizer in alkaline medium. The dechlorination products have been identified and formation of molecular complex between aniline and methylene blue has been observed. The effects of the pH, concentration of the sensitizer, concentration of the substrate, the intensity of the light and the temperature on the rate of the reaction have been studied. The quantum efficiency of the photodechlorination has been evaluated. The mechanism of the photodechlorination has been suggested.
Trimethylsilyl Azide/Triflic Acid, a Highly Efficient Electrophilic Aromatic Amination Reagent
Olah, George A.,Ernst, Thomas D.
, p. 1203 - 1204 (1989)
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Features of the phenylhydroxylamine catalytic hydrogenation in water solutions of 2-propanole on skeletal nickel
Budanov,Lefedova,Ulitin,Kha, Nguen Tkhi Tkhu
, p. 1901 - 1904 (2010)
The kinetics of phenylhydroxylamine hydrogenation reaction on skeletal nickel catalyst in 2-propanole aqueous solutions was studied. It was shown that the value of phenylhydroxylamine and aniline adsorption increases with an increase in the molar fraction of water in the binary solvent 2-propanole-water. It was found experimentally that the hydrogenation reaction is of the first order with phenylhydroxilamine and of the zero order with hydrogen. It is noted that the amount of hydrogen absorbed in the reduction of phenylxydroxylamine in the initial phase of the reaction is considerably lower than the stehiometry of the reaction would indicate. The reasons for the effect of solvent on the features of phenylhydroxilamine hydrogenation are discussed.
Vilsmeier-Haack reagent-promoted formyloxylation of α-chloro-N-arylacetamides by formamide
Huang, Jiann-Jyh,Lu, Shi-Han,Chung, Yu Hsuan,Wong, Fung Fuh
, p. 35934 - 35939 (2015)
In this study, a Vilsmeier-Haack reagent-promoted formyloxylation of α-chloro-N-arylacetamides by formamide was developed. The reaction successfully provided the desired α-formyloxy-N-arylacetamides 4 and 7a-n in moderate to excellent yields (70-96%) by use of 3.0 equivalents of PBr3 at 80-90 °C and was applicable to substrates bearing electron-donating or withdrawing groups at the aryl moiety. For α-chloro-N-(naphthalenyl)acetamide (8a), α-chloro-N-(quinolin-8-yl)acetamide (8b), and α-chloro-N-(thiazol-2-yl)acetamide (8c) possessing the α-chloro group, the reaction also provided the desired formyloxylated products 9a-c in 70-87% yields. A plausible mechanism was proposed through the activation of α-chloroacetamide by the Vilsmeier-Haack reagent to account for the new transformation.
o-Phenylenediamine from sulfur, ammonia, and cyclohexane
Weigert
, p. 1936 - 1937 (1981)
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METAL-ASSISTED REACTIONS. PART 24: THE IMPORTANCE OF SOLVENTS IN LIQUID-PHASE HETEROGENEOUS CATALYTIC TRANSFER REDUCTION
Brigast, Amadeu F.,Johnstone, Robert A. W.
, p. 7735 - 7746 (1992)
In liquid-phase catalytic transfer reduction in which a hydrogen donor is used to effect hydrogenation of a substrate, reaction often proceeds sluggishly in single phase solvents but goes rapidly in biphasic solvent systems in which the catalyst usually resides in one or other of the phases.Depending on the nature of the substrate and donor, an excess of either can lead to the catalyst surface becoming saturated with one component, thereby preventing reaction.It is shown that the biphasic solvent system is, in practice, a simple means of controlling access to the catalyst by either the substrate or donor such that both are present on the surface in comparable amounts, leading to optimum or near optimum reaction rates.
NN bond cleavage of azobenzene: Via photocatalytic hydrogenation with Dy-doped Zn(O,S): The progress from hydrogen evolution to green chemical conversion
Abdullah, Hairus,Kuo, Dong-Hau,Gultom, Noto Susanto
, p. 2651 - 2663 (2019)
Hydrogen-evolved Dy-doped Zn(O,S) photocatalysts with different amounts of Dy precursor have been synthesized, characterized and further utilized for hydrogenation reactions. The Dy catalysts are first examined using electrochemical impedance spectroscopy, photo responsivity, and the hydrogen evolution reaction. Dy-doped Zn(O,S) with 10% Dy precursor shows the best photocatalyst performance with the highest H2 production rate of 8.160 mmol g-1 h-1. This catalyst is chosen for conducting the hydrogenation reaction. It is our intention to confirm the correlation between the photocatalytic H2 production rate and the hydrogenation reactions of 4-nitrophenol to 4-aminophenol and azobenzene to aniline, which is a step further in the hydrogenation reaction to challenge the NN bond cleavage of azobenzene. A 100% photo conversion of 60 ppm azobenzene to aniline in 6 h was confirmed under a low-power UV light illumination in a 10% ethanol solution. Kinetic steps and kinetic mechanisms are proposed, which involve the important reaction steps of solvation, adsorption, pinning, and surface hydrogenation reaction operating together.
7-Bromo-5-phenyl-1,2-dihydro-3H-1,3,5-benztriazepin-2-one
Vlasiuk,Pavlovsky,Andronati,Gdaniec,Simonov
, p. 1077 - 1085 (2000)
7-Bromo-5-phenyl-1,2-dihydro-3H-1,4-benztriazepin-2-one was obtained by thermolysis of the syn-4-phenylsemicarbazone of 2-aminobenzophenone. Its molecular and crystal structure were established by X-ray crystallography. The nature of the hydrogen bonds be
Study of dehalogenation of halogenoanilines using Raney Al-Ni alloy in aqueous medium at room temperature
Weidlich, Tomas,Krejcova, Anna,Prokes, Lubomir
, p. 1015 - 1020 (2010)
Dehalogenation of halogenated anilines by action of powdered aluminium-nickel alloy in aqueous alkaline solution at room temperature has been studied. The reaction course was monitored by means of1H nuclear magnetic resonance (NMR) spectroscopy. The rates of dehalogenation of 4-bromo-, 4-chloro-, 4-fluoro-and 3-chloroaniline were compared under conditions of minimum necessary excess of Al-Ni alloy as reducing agent in edetane buffer medium at pH 10.9. The dehalogenation rates of halogenated anilines decreased in the following order: 3-chloroaniline > 4-bromoaniline ≥ 4-chloroaniline >4-fluoroaniline. On the basis of the results obtained in buffers, the dehalogenation method of aqueous solutions of halogenoanilines was verified using NaOH as the base. Springer-Verlag 2010.
Synthesis of palladium nanoparticles over graphite oxide and carbon nanotubes by reduction in ethylene glycol and their catalytic performance on the chemoselective hydrogenation of para-chloronitrobenzene
Dongil,Pastor-Pérez,Fierro,Escalona,Sepúlveda-Escribano
, p. 89 - 97 (2016)
Pd nanoparticles have been synthesized over carbon nanotubes (CNT) and graphite oxide (GO) by reduction with ethylene glycol and by conventional impregnation method. The catalysts were tested on the chemoselective hydrogenation of p-chloronitrobenzene and the effect of the synthesis method and surface chemistry on their catalytic performance was evaluated. The catalysts were characterized by N2 adsorption/desorption isotherms at 77 K, TEM, powder X-ray diffraction, thermogravimetry, infrared and X-ray photoelectron spectroscopy and ICP-OES. It was observed that the synthesis of Pd nanoparticles employing ethylene glycol resulted in metallic palladium particles of smaller size compared to those prepared by the impregnation method and similar for both supports. The presence of oxygen groups on the support surface favored the activity and diminished the selectivity. It seems that ethylene glycol reacted with the surface groups of GO, this favoring the selectivity. The activity was higher over the CNT-based catalysts and both catalysts prepared by reduction in ethylene glycol were quite stable upon recycling.
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Cann et al.
, p. 3969 (1978)
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Functionalization of a plasmonic Au/TiO2 photocatalyst with an Ag co-catalyst for quantitative reduction of nitrobenzene to aniline in 2-propanol suspensions under irradiation of visible light
Tanaka, Atsuhiro,Nishino, Yuri,Sakaguchi, Satoshi,Yoshikawa, Takayuki,Imamura, Kazuya,Hashimoto, Keiji,Kominami, Hiroshi
, p. 2551 - 2553 (2013)
A functionalized plasmonic Au/TiO2 photocatalyst with an Ag co-catalyst was successfully prepared by the combination of two types of photodeposition methods, and it quantitatively converted nitrobenzene and 2-propanol to aniline and acetone under irradiation of visible light.
Kinetics of the hydrogenation of a mixture of nitrobenzene and azoxybenzene on skeletal nickel in an aqueous solution of propan-2-ol
Merkin,Latypova,Kha, Nguen Tkhi Tkhu,Lefedova
, p. 1772 - 1775 (2015)
The sequence of the reduction of nitro and azoxy groups in the combined hydrogenation of nitrobenzene and azoxybenzene on skeletal nickel in an aqueous azeotropic solution of propan-2-ol is considered. The time dependences of the rates and concentrations of the initial compound and reaction product for the hydrogenation of individual compounds (nitrobenzene and azoxybenzene) in the solvent of the indicated composition are discussed for comparative analysis. In all cases, the reactions proceed selectively to aniline without accumulating side products. The reduction of the nitro and azoxy groups involves hydrogen bound by the active sites of the catalyst surface. The competitive character of adsorption between the initial compounds and formed aniline is observed. Nitrobenzene is characterized by the highest adsorbability, whereas azoxybenzene and aniline are less adsorbable.
Palladated composite of Cu-BDC MOF and perlite as an efficient catalyst for hydrogenation of nitroarenes
Koohestani, Fatemeh,Sadjadi, Samahe
, (2021/11/04)
A novel composite of metal-organic framework and perlite is prepared through hydrothermal treatment of terephthalic acid and Cu(NO3)2·3H2O in the presence of perlite. The resulting composite was then utilized as a support for the immobilization of Pd nanoparticles. The obtained compound was characterized via XRD, TGA, ICP, FTIR, TEM, FE-SEM/EDS and elemental mapping analysis and applied as a catalyst for the hydrogenation of nitroarenes under mild reaction condition. The results approved that the catalyst could efficiently promote hydrogenation of various nitroarenes with different electronic densities and steric properties. Moreover, the catalyst showed high selectivity towards hydrogenation of nitro groups. Hot filtration test affirmed heterogeneous nature of catalysis. Furthermore, the present catalytic composite was highly recyclable with low Pd leaching. A comparative study also approved superior activity of the composite compared to palladated perlite and metal-organic framework.
Synthesis, thermal behavior in oxidative and pyrolysis conditions, spectroscopic and DFT studies of some alkaline earth metals p-aminobenzoate complexes using TG-DTA, DSC, PXRD and EGA (TG-FTIR) techniques
Caires, Flávio J.,Fernandes, Richard P.,Gaspari, Ana P. S.,Ionashiro, Massao,Isquibola, Guilherme,Machado, Antonio E. H.,Teixeira, José Augusto
, (2022/03/17)
p-aminobenzoic acid is a substance widely used in several areas, such as catalysis, biomarkers, magnetic materials, luminescent materials and biological applications. p-aminobenzoate complexes with alkaline earth metal were synthesized and the thermal and pyrolysis behavior was studied using thermoanalytical and spectroscopic techniques. Based on TG/DTG-DTA and EGA results, the thermal decomposition mechanisms of the compounds were proposed under both atmospheres studied. The main gaseous products identified by EGA in both study conditions were H2O, Aniline, CO and CO2. From DSC analysis, it was possible to measure the enthalpies of dehydration and evaluate the phase transitions of the magnesium complex. FTIR data suggest that metal-ligand coordination occurs through carboxylate group by different ways. The coordination modes suggested by experimental FTIR data were supported by DFT study. The X-ray diffraction powder patterns show that the barium compound was obtained in amorphous state, while the other compounds have a crystalline structure.
2-(4-Nitrophenyl)-1H-indolyl-3-methyl Chromophore: A Versatile Photocage that Responds to Visible-light One-photon and Near-infrared-light Two-photon Excitations
Abe, Manabu,Guo, Runzhao,Hamao, Kozue,Lin, Qianghua,Takagi, Ryukichi
supporting information, p. 153 - 156 (2022/02/14)
Due to cell damage caused by UV light, photoremovable protecting groups (PPGs) that are removed using visible or near-infrared light are attracting attention. A 2-(4-nitrophenyl)- 1H-indolyl-3-methyl chromophore (NPIM) was synthesized as a novel PPG. Various compounds were caged using this PPG and uncaged using visible or near-infrared light. Low cytotoxicity of NPIM indicates that it may be applied in physiological studies.
