T:Toxic;
108-95-2Relevant articles and documents
Chlorine-nickel interactions in gas phase catalytic hydrodechlorination: Catalyst deactivation and the nature of reactive hydrogen
Shin, Eun-Jae,Spiller, Andreas,Tavoularis, George,Keane, Mark A.
, p. 3173 - 3181 (1999)
The gas phase hydrodechlorination of chlorobenzene and 3-chlorophenol (where 473 K ≤ T ≤ 573 K) has been studied using a 1.5% w/w Ni/SiO2 catalyst which was also employed to promote the hydrogenation of benzene, cyclohexene and phenol. In the former two instances the catalyst was 100% selective in removing the chlorine substituent, leaving the aromatic ring intact. While the dechlorination of chlorobenzene readily attained steady state with no appreciable deactivation, the turnover of 3-chlorophenol to phenol was characterised by both a short and a long term loss of activity. Chlorine coverage of the catalyst surface under reaction conditions was probed indirectly by monitoring, via pH changes in an aqueous NaOH trap, HCI desorption after completion of the catalytic step. Contacting the catalyst with the chlorinated reactants was found to severely limit and, depending on the degree of contact, completely inhibit aromatic ring reduction although a high level of hydrodechlorination activity was maintained. Hydrogen temperature programmed desorption (TPD) reveals the existence of three forms of surface hydrogen which are tentatively assigned as: (i) hydrogen bound to the surface nickel; (ii) hydrogen at the nickel/silica interface; (iii) spillover hydrogen on the silica support. The effect of chlorine-nickel interactions on the resultant TPD profiles is presented and discussed. The (assigned) spillover hydrogen appears to be hydrogenolytic in nature and is responsible for promoting hydrodechlorination while the hydrogen that is taken to be chemisorbed on, and remains associated with, the surface nickel metal participates in aromatic hydrogenation. Hydrodechlorination proceeds via an electrophilic mechanism, possibly involving spillover hydronium ions. The experimental catalytic data are adequately represented by a kinetic model involving non-competitive adsorption between hydrogen and the chloroaromatic, where incoming chloroaromatic must displace the HCI that remains on the surface after the dechlorination step. Kinetic parameters extracted from the model reveal that chlorophenol has a higher affinity than chlorobenzene for the catalyst surface but the stronger interaction leads to a greater displacement of electron density at the metal site and this ultimately leads to catalyst deactivation.
Gordon,Miller,Day
, (1949)
Baxendale,Magee
, p. 160 (1953)
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Kupferberg
, p. 442 (1877)
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Debromination of 2,4,6-tribromophenol coupled with biodegradation
Weidlich, Tomas,Prokes, Lubomir,Pospisilova, Dagmar
, p. 979 - 987 (2013)
The application effect of aluminium and their alloys and mixtures with nickel was studied for the complete hydrodebromination of 2,4,6-tribromophenol (TBP) to phenol in aqueous NaOH solution at room temperature. It was found that the Raney Al-Ni alloy can
Photocatalytic degradation of 2,4-dichlorophenol with V2O5-TiO2 catalysts: Effect of catalyst support and surfactant additives
Sinirtas, Eda,Isleyen, Meltem,Soylu, Gulin Selda Pozan
, p. 607 - 615 (2016)
Binary oxide catalysts with various weight percentage V2O5 loadings were prepared by solid-state dispersion and the nanocomposites were modified with surfactants. The catalysts were analyzed using X-ray diffraction, diffuse-reflectance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and N2 adsorption-desorption. The photocatalytic activities of the catalysts were evaluated in the degradation of 2,4-dichlorophenol under ultraviolet irradiation. The photocatalytic activity of 50 wt% V2O5-TiO2 (50V2O5-TiO2) was higher than those of pure V2O5, TiO2, and P25. Interactions between V2O5 and TiO2 affected the photocatalytic efficiencies of the binary oxide catalysts. Cetyltrimethylammonium bromide (CTAB) and hexadecyltrimethylammonium bromide (HTAB) significantly enhanced the efficiency of the 50V2O5-TiO2 catalyst. The highest percentage of 2,4-dichlorophenol degradation (100%) and highest reaction rate (2.22 mg/(L·min)) were obtained in 30 min with the (50V2O5-TiO2)-CTAB catalyst. It is concluded that the addition of a surfactant to the binary oxide significantly enhanced the photocatalytic activity by modifying the optical and electronic properties of V2O5 and TiO2.
Spectroscopic and QM/MM investigations of Chloroperoxidase catalyzed degradation of orange G
Zhang, Rui,He, Qinghao,Huang, Yi,Wang, Xiaotang
, p. 1 - 9 (2016)
Chloroperoxidase (CPO), a heme-thiolate protein, from Caldariomyces fumago catalyzes a plethora of reactions including halogenation, dismutation, epoxidation, and oxidation. Although all CPO-catalyzed reactions go through a common intermediate, compound I, different mechanisms are followed in subsequent transformations. To understand the mechanism of CPO-catalyzed halide-dependent degradation of orange G, the role of halide and pH was systematically investigated. It is revealed that formation and protonation of compound X, a long-sought after hypochlorite heme adduct intermediate existed during CPO-catalyzed halide-dependent reactions, significantly lowers the reaction barrier and increases the efficiency of CPO-catalyzed orange G degradation. The extremely acidic optimal reaction pH suggests the protonation of a residue, presumably, Glu 183 in CPO catalysis. Halide dependent studies showed that Kcat is higher in the presence of Br- than in the presence of Cl-. The degradation products of orange G indicate the cleavage at a single position of orange G, demonstrating a high regioselectivity of CPO-catalyzed degradation. Based on our kinetic, NMR and QM/MM studies, the mechanism of CPO-catalyzed orange G degradation was proposed.
Solvent-Induced Single Crystal-Single Crystal Transformation of an Interpenetrated Three-Dimensional Copper Triazole Catalytic Framework
Wang, Ying,Meng, Shan-Shan,Lin, Peng-Xiang,Xiao, Yi-Wei,Ma, Qing-Qing,Xie, Qiong,Chen, Yuan-Yuan,Zhao, Xiao-Jun,Chen, Jun
, p. 4069 - 4071 (2016)
The 2-fold interpenetrated 3D framework 1 can be solvent-induced to noninterpenetrated framework 1′ in a reversible single crystal-single crystal transformation fashion. In addition, 1′ represents the first catalyst based on triazole to catalyze the aerobic homocoupling of various substituted arylboronic acids.
Photo-Fries rearrangement of 1-pyrenyl esters
Maeda, Hajime,Akai, Tomomi,Segi, Masahito
, p. 4377 - 4380 (2017)
Photo-Fries rearrangement reactions of 1-pyrenyl esters were investigated. Photoreaction of 1-pyrenyl benzoate in benzene generates 1-hydroxy-2-pyrenyl phenyl ketone along with 1-pyrenol. The exceptionally down field 1H NMR chemical shift of OH proton in the photoproduct indicates the existence of intramolecular hydrogen bonding. Photorearrangements of analogs that have electron-withdrawing or electron-releasing group on the phenyl ring, and related heteroaromatic carboxylates also take place to form the corresponding ketones. However, photoreactions of 1-pyrenyl aliphatic carboxylate esters do not occur. The results of spectroscopic and theoretical studies suggest the mechanistic pathway for this process is initiated by homolytic C–O bond cleavage in an aroyl group localized 1(π → π?) excited state of the 1-pyrenyl esters. The radical pair generated in this fashion then undergoes in-solvent-cage coupling to yield the 1-hydroxy-2-pyrenyl aryl ketone selectively.
Selective enzymatic hydrolysis of phenolic acetates
Basavaiah,Raju
, p. 467 - 473 (1994)
Phenolic acetates are selectively hydrolyzed in the presence of alkyl acetates, methyl esters and cinnamates with pig liver acetone powder (PLAP).
Vanadium oxyacetylacetonate grafted on UiO-66-NH2 for hydroxylation of benzene to phenol with molecular oxygen
Wang, Weitao,Li, Na,Tang, Hao,Ma, Yangmin,Yang, Xiufang
, p. 113 - 120 (2018)
V/UiO-66-NH2 was prepared by the vanadium oxyacetylacetonate grafted on UiO-66-NH2. The catalytic performance of V/UiO-66-NH2 was investigated for the hydroxylation of benzene to phenol using O2. It can give the
Bronsted acid-functionalized choline chloride-butane sultone for the catalytic decomposition of cumene hydroperoxide to phenol
Padma priya,Rajarajeswari
, (2018)
Abstract: Choline chloride and 1,4-butane sultone were combined to obtain a sulphonic acid-functionalized ionic liquid. The structural properties of the ionic liquid were evaluated with AT-IR, NMR, mass and elemental analysis. The Bronsted acidity of the
Long-Lived Photoexcited State of a Mn(IV)-Oxo Complex Binding Scandium Ions That is Capable of Hydroxylating Benzene
Sharma, Namita,Jung, Jieun,Ohkubo, Kei,Lee, Yong-Min,El-Khouly, Mohamed E.,Nam, Wonwoo,Fukuzumi, Shunichi
, p. 8405 - 8409 (2018)
Photoexcitation of a MnIV-oxo complex binding scandium ions ([(Bn-TPEN)MnIV(O)]2+-(Sc(OTf)3)2) in a solvent mixture of trifluoroethanol and acetonitrile (v/v = 1:1) resulted in formation of the long-l
Trapping hydrogen sulfide (H2S) with diselenides: The application in the design of fluorescent probes
Peng, Bo,Zhang, Caihong,Marutani, Eizo,Pacheco, Armando,Chen, Wei,Ichinose, Fumito,Xian, Ming
, p. 1541 - 1544 (2015)
Here we report a unique reaction between phenyl diselenide-ester substrates and H2S to form 1,2-benzothiaselenol-3-one. This reaction proceeded rapidly under mild conditions. Thiols could also react with the diselenide substrates. However, the resulted S-Se intermediate retained high reactivity toward H2S and eventually led to the same cyclized product 1,2-benzothiaselenol-3-one. Based on this reaction two fluorescent probes were developed and showed high selectivity and sensitivity for H2S. The presence of thiols was found not to interfere with the detection process.
Reductive dechlorination of 2,4-dichlorophenol by Pd/Fe nanoparticles prepared in the presence of ultrasonic irradiation
Zhao, Deming,Li, Min,Zhang, Dexing,Baig, Shams Ali,Xu, Xinhua
, p. 864 - 871 (2013)
Palladium/Iron (Pd/Fe) nanoparticles were prepared by using ultrasound strengthened liquid phase reductive method to enhance dispersion and avoid agglomeration. The dechlorination of 2,4-dichlorophenol (2,4-DCP) by Pd/Fe nanoparticles was investigated to understand its feasibility for an in situ remediation of contaminated groundwater. Results showed that 2,4-DCP was first adsorbed by Pd/Fe nanoparticles, then quickly reduced to o-chlorophenol (o-CP), p-chlorophenol (p-CP), and finally to phenol (P). The induction of ultrasound during the preparation of Pd/Fe nanoparticles further enhanced the removal efficiency of 2,4-DCP, as a result, the phenol production rates increased from 65% (in the absence of ultrasonic irradiation) to 91% (in the presence of ultrasonic irradiation) within 2 h. Our data suggested that the dechlorination rate was dependent on various factors including Pd loading percentage over Fe0, Pd/Fe nanoparticles availability, temperature, mechanical stirring speed, and initial pH values. Up to 99.2% of 2,4-DCP was removed after 300 min reaction with these conditions: Pd loading percentage over Fe 0 0.3 wt.%, initial 2,4-DCP concentration 20 mg L-1, Pd/Fe dosage 3 g L-1, initial pH value 3.0, and reaction temperature 25 °C. The degradation of 2,4-DCP followed pseudo-first-order kinetics reaction and the apparent pseudo-first-order kinetics constant was 0.0468 min -1.
Efficient visible-light-induced photocatalytic activity on gold-nanoparticle-supported layered titanate
Ide, Yusuke,Matsuoka, Mizuki,Ogawa, Makoto
, p. 16762 - 16764 (2010)
The visible-light-induced photocatalytic conversion of aqueous benzene to phenol on Au-nanoparticle-supported layered titanate was accelerated when the reaction was conducted in the presence of aqueous phenol.
Preparation of salicylic nitrile through direct catalytic dehydration of salicylamide with immobilized phosphoric acid as catalyst
Yao, Shu-Feng,Cai, Zhao-Sheng,Huang, Xu-Juan,Song, Lan-Xuan
, p. 1082 - 1086 (2020)
Salicylic nitrile was prepared through direct catalytic dehydration of salicylamide under high temperature using immobilized phosphoric acid as catalyst. The catalytic performances of different catalysts were evaluated according to the analytic results of
Cu(II) catalyzed reaction between phenyl hydrazine and toluidine blue - dual role of acid
Jonnalagadda,Nattar
, p. 271 - 276 (1999)
The detailed kinetics of Cu(II) catalyzed reduction of toluidine blue (TB+) by phenyl hydrazine (Pz) in aqueous solution is studied. Toluidine white (TBH) and the diazonium ions are the main products of the reaction. The diazonium ion further decomposes to phenol (PhOH) and nitrogen. At low concentrations of acid, H+ ion autocatalyzes the uncatalyzed reaction and hampers the Cu(II) catalyzed reaction. At high concentrations, H+ hinders both the uncatalyzed and Cu(II) catalyzed reactions. Cu(II) catalyzed had stoichiometry similar to the uncatalyzed reaction, Pz+2 TB++H2O = PhOH+2 TBH+2 H++N2. Cu(II) catalyzed reaction occurs possibly through ternary complex formation between the unprotonated toluidine blue and phenyl hydrazine and catalyst. The rate coefficient for the Cu(II) catalyzed reaction is 2.1×104 M-2 s-1. A detailed 13-step mechanistic scheme for the Cu(II) catalyzed reaction is proposed, which is supported by simulations.
UV-controlled shape memory hydrogels triggered by photoacid generator
Feng, Wei,Zhou, Wanfu,Zhang, Shidong,Fan, Yujiao,Yasin, Akram,Yang, Haiyang
, p. 81784 - 81789 (2015)
Light-induced shape memory polymers represent a class of stimuli-responsive materials that can recover their permanent shapes from temporarily trapped ones upon exposure to light illumination. Although much effort has been devoted to developing various light-responsive shape memory polymers, fabrication of such a light-responsive shape memory hydrogel still remains a challenge compared to neat polymers in their dry state. Herein, we developed a facile and general strategy to endow conventional hydrogel systems with ultraviolet (UV)-controlled shape memory performance simply using a photoacid generator (PAG) as a trigger. The process involves shape fixity through coordination interaction between imidazole groups and metal ions, and shape recovery by switching off the complexation via PAG photolysis reaction which leads to the protonation of imidazole groups. Furthermore, this convenient strategy is proved to be applicable to other pre-existing hydrogels such as a boronate ester cross-linked melamine-poly(vinyl alcohol) (PVA) hydrogel. We believe this method could provide a new opportunity with regard to the design and practical application of light-controlled shape memory hydrogels.
Catalytic dechlorination of chlorophenols in water by palladium/iron
Liu, Yihui,Yang, Fenglin,Yue, Po Lock,Chen, Guohua
, p. 1887 - 1890 (2001)
Three isomer chlorophenols, o-, m-, p-chlorophenol, were dechlorinated by palladium/iron powder in water through catalytic reduction. The dechlorinated reaction is believed to take place on the surface site of the catalyst in a pseudo-first-order reaction. The reduction product for all the three isomers is phenol. The dechlorination rate increases with increase of bulk loading of palladium due to the increase of both the surface loading of palladium and the total surface area. The molecular structure also has an effect on the dechlorination rate. For conditions with 0.048% Pd/Fe, the rate constants are 0.0215, 0.0155 and 0.0112min-1 for o-, m-, p-chlorophenol, respectively. Almost complete dechlorination is achieved within 5h. Copyright
Photochemical Reactions in the Benzophenone/tert-Butyl Alcohol/Oxygen System. Some Unexpected Results
Gramain, Jean-Claude,Remuson, Roland
, p. 1120 - 1122 (1985)
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Stable N-functionalised 'pincer' bis carbene ligands and their ruthenium complexes; synthesis and catalytic studies
Danopoulos, Andreas A.,Winston, Scott,Motherwell, William B.
, p. 1376 - 1377 (2002)
Deprotonation of 2,6-bis(arylimidazolium)pyridine dibromide with KN(SiMe3)2 gave thermally stable 2,6-bis(arylimidazol-2-ylidene)pyridine, which was further used to prepare ruthenium 'pincer' complexes; the latter show catalytic activity in transfer hydrogenation of carbonyl compounds.
Ionic-liquid-functionalized polyoxometalates for heterogeneously catalyzing the aerobic oxidation of benzene to phenol: Raising efficacy through specific design
Long, Zhouyang,Zhou, Yu,Ge, Weilin,Chen, Guojian,Xie, Jingyan,Wang, Qian,Wang, Jun
, p. 1590 - 1596 (2014)
By combining nitrile-tethered pyridinium-based ionic liquid dication with the polyoxometalate anion of Keggin H5PMo10V2O40 (PMoV2) through precipitation in aqueous solution, an organic-inorganic hybri
Hydroxylation of benzene to phenol by molecular oxygen over an organic-inorganic hybrid catalyst: Schiff base manganese complex attached to molybdovanadophosphoric heteropolyacid
Zhou, Changjiang,Wang, Jun,Leng, Yan,Ge, Hanqing
, p. 120 - 125 (2010)
The organic-inorganic hybrid catalyst L-Mn-PMoV was prepared simply by combining a schiff base Mn complex (L-Mn, L: N,N-disalicylidene-1, 6-hexanediamine) with the Keggin-structured molybdovanadophosphoric heteropolyacid (PMoV). The proposed composition and structure of the catalyst were evidenced by TG, elemental analysis, FT-IR, and UV-Vis characterizations. Its catalytic performance was evaluated in the direct hydroxylation of benzene to phenol by molecular oxygen with ascorbic acid as the reducing agent. Various reaction parameters were changed to attain the optimal conditions. The hybrid catalyst has a formula [{Mn(C20H22N2O 2)(Cl)}2(H4PMo11VO40)], with the two terminal oxygen atoms in the PMoV Keggin structure coordinately linked to the two Mn(III) ions in two L-Mn units, respectively. It exhibits a remarkably enhanced yield to phenol compared to the pure PMoV due to the synergy effect between the Schiff-base manganese complex and PMoV. Graphical Abstract: [Figure not available: see fulltext.]
Active species formed in a Fenton-like system in the medium of triethylammonium acetate ionic liquid for hydroxylation of benzene to phenol
Hu, Xiaoke,Zhu, Liangfang,Wang, Xueqin,Guo, Bin,Xu, Jiaquan,Li, Guiying,Hu, Changwei
, p. 41 - 49 (2011)
High-valent iron(IV)-oxo species was proved to be the main oxidizing species for hydroxylation of benzene to phenol by a Fenton-like reagent in triethylammonium acetate ionic liquid via UV-vis and ESI-MS characterization, while hydroxyl radical was excluded by detailed investigations. It was found that the formation of hydroxyl radical was prohibited by the reduction of redox potential of Fe(III)/Fe(II) couple in triethylammonium acetate medium, leading to a decreased over-oxidation of benzene than that in aqueous solution. The reaction mechanisms for hydroxylation of benzene, as well as for over-oxidation of phenol by iron(IV)-oxo species were proposed. The latter is partly prohibited by the hydrogen-bond interaction between as-produced phenol and acetate anion of the ionic liquid.
Steady-state kinetic analysis of human cholinesterases over wide concentration ranges of competing substrates
Mukhametgalieva, Aliya R.,Lushchekina, Sofya V.,Aglyamova, Aliya R.,Masson, Patrick
, (2021/10/22)
Substrate competition for human acetylcholinesterase (AChE) and human butyrylcholinesterase (BChE) was studies under steady-state conditions using wide range of substrate concentrations. Competing couples of substates were acetyl-(thio)esters. Phenyl acetate (PhA) was the reporter substrate and competitor were either acetylcholine (ACh) or acetylthiocholine (ATC). The common point between investigated substrates is that the acyl moiety is acetate, i.e. same deacylation rate constant for reporter and competitor substrate. Steady-state kinetics of cholinesterase-catalyzed hydrolysis of PhA in the presence of ACh or ATC revealed 3 phases of inhibition as concentration of competitor increased: a) competitive inhibition, b) partially mixed inhibition, c) partially uncompetitive inhibition for AChE and partially uncompetitive activation for BChE. This sequence reflects binding of competitor in the active centrer at low concentration and on the peripheral anionic site (PAS) at high concentration. In particular, it showed that binding of a competing ligand on PAS may affect the catalytic behavior of AChE and BChE in an opposite way, i.e. inhibition of AChE and activation of BChE, regardless the nature of the reporter substrate. For both enzymes, progress curves for hydrolysis of PhA at very low concentration (?Km) in the presence of increasing concentration of ATC showed that: a) the competing substrate and the reporter substrate are hydrolyzed at the same time, b) complete hydrolysis of PhA cannot be reached above 1 mM competing substrate. This likely results from accumulation of hydrolysis products (P) of competing substrate and/or accumulation of acetylated enzyme·P complex that inhibit hydrolysis of the reporter substrate.
A highly efficient transformation from cumene to cumyl hydroperoxide via catalytic aerobic oxidation at room temperature and investigations into solvent effects, reaction networks and mechanisms
Chen, Chong,Ji, Lijun,Lu, Qiuting,Shi, Guojun,Yuan, Enxian,Zhou, Hongyu
, (2021/12/04)
Cumyl hydroperoxide (CHP) is an important intermediate for the production of phenol/acetone, but suffers from severe reaction conditions and a low yield industrially. Here, an efficient transformation from cumene to CHP was developed. Different solvents were modulated for cumene oxidation catalyzed by NHPI/Co, and reaction network and mechanisms were investigated methodically. Hexafluoroisopropanol (HFIP) markedly promoted the transformation from cumene to CHP compared to other solvents at room temperature. A cumene conversion high up to 64.3% were observed with a selectivity to CHP of 71.7%. The solvent HFIP exhibited a significant promotion on cumene oxidation due to its contribution to the enhancement of the concentration of PINO radicals. Moreover, cumyl, cumyl oxyl and methyl radicals were captured by TEMPO and analyzed by HRMS, and the reaction paths and mechanisms from cumene to products were inferred. The preparation method discovered in this work may open an access to the production of CHP.
Coordination Polymers as a Functional Material for the Selective Molecular Recognition of Nitroaromatics and ipso-Hydroxylation of Arylboronic Acids
Rani, Pooja,Husain, Ahmad,Bhasin,Kumar, Girijesh
, (2021/12/06)
We report the synthesis and structural characterization of two coordination polymers (CPs), namely; [{Zn(L)(DMF)4} ? 2BF4]α (1) and [{Cd(L)2(Cl)2} ? 2H2O]α (2) (where L=N2,N6-di(pyridin-4-yl)naphthalene-2,6-dicarboxamide). Crystal packing of 1 reveals the existence of channels running along the b- and c-axis filled by the ligated DMF and lattice anions, respectively. Whereas, crystal packing of 2 reveals that the metallacycles of each 1D chain are intercalating into the groove of adjacent metallacycles resulting in the stacking of 1D loop-chains to form a sheet-like architecture. In addition, both 1 and 2 were exploited as multifunctional materials for the detection of nitroaromatic compounds (NACs) as well as a catalyst in the ipso-hydroxylation of aryl/heteroarylboronic acids. Remarkably, 1 and 2 showed high fluorescence stability in an aqueous medium and displayed a maximum 88% and 97% quenching efficiency for 4-NPH, respectively among all the investigated NACs. The mechanistic investigation of NACs recognition suggested that the fluorescence quenching occurred via electron as well as energy transfer process. Furthermore, the ipso-hydroxylation of aryl/heteroarylboronic acids in presence of 1 and 2 gave up to 99% desired product yield within 15 min in our established protocol. In both cases, 1 and 2 are recyclable upto five cycles without any significant loss in their efficiency.
