- Salicylic acid nitration by means of nitric acid/acetic acid system: Chemical and kinetic characterization
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The nitration of salicylic acid by means of HNO3/AcOH is investigated, and the results are compared with those obtained using different nitrating systems: HNO3/H2SO4/H2O (mixed acid), HNO3/Ac2O/AcOH, aqueous HNO3 (70% by weight) at 343 K. Little differences are found in terms of yield of the desired product (5-nitrosalicylic acid) among HNO3/AcOH mixture, mixed acid, and HNO3/Ac2O/AcOH systems, aqueous HNO 3 giving the poorest results. However according to the data collected during the present investigation the use of the system HNO3/AcOH presents some advantages with respect to the others for the separation and purity of desired product, waste minimization, and safety improvements. The reaction kinetics for the nitration of salicylic acid with this system is also investigated. A global second-order kinetic law (one for the substrate, one for nitric acid) is used in the analysis of the data collected for the formation of the two mononitroderivatives (3-nitro- and 5-nitrosalicylic acids) and of the side product 2-nitrophenol.
- Andreozzi, Roberto,Canterino, Marisa,Caprio, Vincenzo,Di Somma, Ilaria,Sanchirico, Roberto
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- Research on the decomposition kinetics and thermal hazards of aniline diazonium salt
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Diazotization reaction, strong exothermic characteristics and thermal instability of diazonium salts make the production process high risk. To research thermal hazards of aniline diazonium salt, dynamic experiments are carried out by the differential scanning calorimeter (DSC) to obtain thermodynamic parameters. Moreover, the kinetic parameters are analyzed by Advanced Kinetics and Technology Solutions (AKTS) software. Finally, the GC-MS and UV spectrum are used to further study the decomposition mechanism of the aniline diazonium salt. The results indicate that aniline diazonium salt is very easy to decompose. When the heating rate is 2 K/min, the onset decomposition temperature is only 27.21 ℃ (Tonset). The apparent activation energy of the decomposition process calculated by Friedman and Ozawa methods are respectively 98-85 kJ/mol and 110-100 kJ/mol. Under the ideal adiabatic conditions (φ = 1), the initial temperatures of TMRad for 24 h is only 6.2 ℃ (TD24), which is predicted by the AKTS software. The decomposition process of aniline diazonium salt is inconsistent with a single reaction mechanism.
- Du, Lei,Wang, Ben,Xie, Chuanxin,Yuan, Yucan
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- Benzene Hydroxylation by Bioinspired Copper(II) Complexes: Coordination Geometry versus Reactivity
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A series of bioinspired copper(II) complexes of N4-tripodal and sterically crowded diazepane-based ligands have been investigated as catalysts for functionalization of the aromatic C-H bond. The tripodal-ligand-based complexes exhibited distorted trigonal-bipyramidal (TBP) geometry (τ, 0.70) around the copper(II) center; however, diazepane-ligand-based complexes adopted square-pyramidal (SP) geometry (τ, 0.037). The Cu-NPy bonds (2.003-2.096 ?) are almost identical and shorter than Cu-Namine bonds (2.01-2.148 ?). Also, their Cu-O (Cu-Owater, 1.988 ? Cu-Otriflate, 2.33 ?) bond distances are slightly varied. All of the complexes exhibited Cu2+ → Cu+ redox couples in acetonitrile, where the redox potentials of TBP-based complexes (-0.251 to -0.383 V) are higher than those of SP-based complexes (-0.450 to -0.527 V). The d-d bands around 582-757 nm and axial patterns of electron paramagnetic resonance spectra [g∥, 2.200-2.251; A∥, (146-166) × 10-4 cm-1] of the complexes suggest the existence of five-coordination geometry. The bonding parameters showed K∥ > K∥ for all complexes, corresponding to out-of-plane πbonding. The complexes catalyzed direct hydroxylation of benzene using 30% H2O2 and afforded phenol exclusively. The complexes with TBP geometry exhibited the highest amount of phenol formation (37%) with selectivity (98%) superior to that of diazepane-based complexes (29%), which preferred to adopt SP-based geometry. Hydroxylation of benzene likely proceeded via a CuII-OOH key intermediate, and its formation has been established by electrospray ionization mass spectrometry, vibrational, and electronic spectra. Their formation constants have been calculated as (2.54-11.85) × 10-2 s-1 from the appearance of an O (π?σ) → Cu ligand-to-metal charge-transfer transition around 370-390 nm. The kinetic isotope effect (KIE) experiments showed values of 0.97-1.12 for all complexes, which further supports the crucial role of Cu-OOH in catalysis. The 18O-labeling studies using H218O2 showed a 92% incorporation of 18O into phenol, which confirms H2O2 as the key oxygen supplier. Overall, the coordination geometry of the complexes strongly influenced the catalytic efficiencies. The geometry of one of the CuII-OOH intermediates has been optimized by the density functional theory method, and its calculated electronic and vibrational spectra are almost similar to the experimentally observed values.
- Anandababu, Karunanithi,Mayilmurugan, Ramasamy,Muthuramalingam, Sethuraman,Velusamy, Marappan
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p. 5918 - 5928
(2020/04/20)
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- 3-(Ethoxycarbonyl)-1-(5-methyl-5-(nitrosooxy)hexyl)pyridin-1-ium cation: A green alternative to tert-butyl nitrite for synthesis of nitro-group-containing arenes and drugs at room temperature
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Due to their remarkable properties, task-specific ionic liquids have turned out to be progressively popular over the last few years in the field of green organic synthesis. Herein, for the first time, we report that a new task-specific nitrite-based ionic liquid such as 3-(ethoxycarbonyl)-1-(5-methyl-5-(nitrosooxy)hexyl)pyridin-1-ium bis(trifluoromethanesulfonyl)imides (TS-N-IL) derived from biodegradable ethyl nicotinate indeed acted as an efficient and eco-friendly reagent for the synthesis of highly valuable nitroaromatic compounds and drugs including nitroxynil, tolcapone, niclofolan, flutamide, niclosamide and nitrazepam. The bridging of an ionic liquid with nitrite group not only increases the yield and rate of direct C[sbnd]N bond formation reaction but also allows easy product separation and recyclability of a byproduct. Nonvolatile nature, easy synthesis, merely stoichiometric need and mildness are a portion of the extra focal points of TS-N-IL while contrasted with tert-butyl nitrite an outstanding and highly-flammable reagent utilized largely in organic synthesis.
- Chaudhary, Renu,Natarajan, Palani,Rani, Neetu,Sakshi,Venugopalan, Paloth
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supporting information
(2019/12/30)
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- Benzimidazolium-based high temperature ionic liquid-in-oil microemulsion for regioselective nitration reaction
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Owing to the fascinating applications of ionic liquids (ILs) based non-aqueous microemulsions (MEs) in the field of chemical reactions due to their high thermal stability compared to that of aqueous MEs and requirement of water-free environment, we design
- Kar, Barnali,Ghosh, Prasanjit,Kundu, Kaushik,Bardhan, Soumik,Paul, Bidyut K.,Das, Sajal
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p. 122 - 130
(2018/07/25)
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- Silica-supported perchloric acid and potassium bisulfate as reusable green catalysts for nitration of aromatics under solvent-free microwave conditions
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Silica-supported perchloric acid and bisulfate (SiO2/HClO4 and SiO2/KHSO4) have been developed as reusable green catalysts for nitration of aromatic compounds using NaNO2 in acetonitrile medium under conventional and solvent-free microwave conditions. The reaction times under microwave irradiation are significantly shorter than conventional method even though the yields obtained in microwave-assisted reactions are comparable with those obtained under reflux conditions.
- Kumar, M. Satish,Sriram, Y. Hemanth,Venkateswarlu,Rajanna,Sudhakar, M. Sai,Venkanna, Purugula,Saiprakash
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supporting information
p. 59 - 67
(2017/12/26)
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- Visible-Light-Mediated Nitration of Protected Anilines
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The photocatalytic nitration of protected anilines proceeds with riboflavin tetraacetate as an organic photoredox catalyst. Sodium nitrite serves as the NO2 source in this visible-light-driven room temperature reaction. Various nitroanilines are obtained in moderate to good yields without the addition of acid or stoichiometric oxidation agents. The catalytic cycle is closed by aerial oxygen as the terminal oxidant.
- Düsel, Simon J. S.,K?nig, Burkhard
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supporting information
p. 2802 - 2807
(2018/03/09)
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- Rapid photocatalytic degradation of nitrobenzene under the simultaneous illumination of UV and microwave radiation fields with a TiO2 ball catalyst
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To use the microwave/ML/TiO2 hybrid system as an advanced treatment of nitrobenzene (NB), a series of experiments were performed to examine the effects of microwave irradiation and auxiliary oxidants. The degradation of NB was carried out using different combinations of five-unit treatment techniques. The NB degradation rate increased with increasing microwave intensity. The circulation fluid velocity, concentration of H2O2, and the rate of O2 gas injection showed the highest rate of degradation under optimal conditions. A significant synergistic effect was observed when H2O2 addition was combined with the microwave/ML/TiO2 hybrid process.
- Jeong, Sangmin,Lee, Heon,Park, Hyunwoong,Jeon, Ki-Joon,Park, Young-Kwon,Jung, Sang-Chul
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- Nitrogen Oxides and Nitric Acid Enable the Sustainable Hydroxylation and Nitrohydroxylation of Benzenes under Visible Light Irradiation
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A new type of waste recycling strategy is described in which nitrogen oxides or nitric acid are directly employed in photocatalyzed hydroxylations and nitrohydroxylations of benzenes. Through these transformations, otherwise costly denitrification can be combined with the synthesis of valuable compounds for various applications.
- Hofmann, Laura Elena,Mach, Leonard,Heinrich, Markus R.
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supporting information
p. 431 - 436
(2017/12/15)
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- Sc3+ (or HClO4) Activation of a Nonheme FeIII-OOH Intermediate for the Rapid Hydroxylation of Cyclohexane and Benzene
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[Fe(β-BPMCN)(CH3CN)2]2+ (1, BPMCN = N,N′-bis(pyridyl-2-methyl)-N,N′-dimethyl-trans-1,2-diaminocyclo-hexane) is a relatively poor catalyst for cyclohexane oxidation by H2O2 and cannot perform benzene hydroxylation. However, addition of Sc3+ activates the 1/H2O2 reaction mixture to be able to hydroxylate cyclohexane and benzene within seconds at -40 °C. A metastable S = 1/2 FeIII-(η1-OOH) intermediate 2 is trapped at -40 °C, which undergoes rapid decay upon addition of Sc3+ at rates independent of [substrate] but linearly dependent on [Sc3+]. HClO4 elicits comparable reactivity as Sc3+ at the same concentration. We thus postulate that these additives both facilitate O-O bond heterolysis of 2 to form a common highly electrophilic FeVO oxidant that is comparably reactive to the fastest nonheme high-valent iron-oxo oxidants found to date.
- Kal, Subhasree,Draksharapu, Apparao,Que, Lawrence
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supporting information
p. 5798 - 5804
(2018/05/09)
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- Method for preparing nitro compound by using graphene to catalyze nitric oxide
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The invention discloses a method for preparing a nitro compound by using graphene to catalyze nitric oxide. A graphene oxide carbon material is used for catalysis of a reaction of nitric oxide and a nitrification substrate such as an aromatic compound to prepare the nitro compound. The method is used for replacing a traditional nitric acid/sulfur acid method to prepare the nitro compound, so thatthe atom utilization rate of the reaction is increased, the energy is saved, and the emission is reduced; and the method has the characteristic of atom economy during industrial preparation of the nitro compound.
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Paragraph 0033; 0034
(2018/06/16)
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- Room-Temperature, Water-Promoted, Radical-Coupling Reactions of Phenols with tert -Butyl Nitrite
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A radical-radical cross-coupling reaction of phenols with tert -butyl nitrite has been developed with the use of water as an additive. This method allows the construction of C-N bonds under an air atmosphere at room temperature, providing the ortho -nitrated phenol derivative in moderate to good yields.
- Wei, Wen-Ting,Zhu, Wen-Ming,Liang, Weida,Wu, Yi,Huang, Hui-Yan,Huang, Yi-Ling,Luo, Junfei,Liang, Hongze
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supporting information
p. 2153 - 2156
(2017/09/26)
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- Potassium Periodate/NaNO2/KHSO4-Mediated Nitration of Aromatic Compounds and Kinetic Study of Nitration of Phenols in Aqueous Acetonitrile
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Synthesis and kinetics of potassium periodate(KIO4)/NaNO2/KHSO4)-initiated nitration of aromatic compounds have been studied in aqueous acetonitrile medium. Synthesis of nitroaromatic compounds is achieved under conventional and solvent-free microwave conditions. Reaction times in microwave-assisted reaction are comparatively less than in conventional reaction. The reaction kinetics for the nitration of phenols in aqueous bisulfate and acetonitrile medium indicated first-order dependence on [phenol], [NaNO2], and [KIO4]. An increase in [KHSO4] accelerated the rate of nitration under otherwise similar conditions. The rate of nitration increased in the solvent of high dielectric media (solvents with high dielectric constant (D)). Observed results were in accordance with Amis and Kirkwood plots [log k′ vs. (1/D) and [(D ? 1)/(2D + 1)]. These observations probably indicate the participation of anionic species and molecular or (dipolar) species in the rate-determining step. In addition, the plots of (log k′) versus volume% of organic solvent were also linear, which probably indicate the importance of both electrostatic and nonelectrostatic forces, solvent–solute interactions during nitration of phenols. Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups, but results could not be quantitatively correlated with Hammett's equation and depicted deviations from linearity. These deviations could probably be attributed to cumulative effects arising inductive, resonance, and steric effects. Leffler's plot (ΔH# vs. ΔS#) was found linear indicating the compensation (cumulative) effect of both enthalpy and entropy parameters in controlling the mechanism of nitration.
- Sriram, Y. Hemanth,Fatima, Touheeth,Rajanna,Kumar, M. Satish,Raju, R. Madhusudan
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supporting information
p. 622 - 632
(2017/06/30)
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- Yttrium Nitrate mediated Nitration of Phenols at room temperature in Glacial Acetic acid
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Rapid nitration of electron rich phenols using Y(NO 3) 3.6H 2O in glacial acetic acid at room temperature was observed with good yield. The method allows nitration of phenols without oxidation, and isolation of nitration product in a rapid and simple way. The described method is selective for phenols. [Figure not available: see fulltext.]
- Mondal, Mohabul A,Mandal, Debashis,Mitra, Kanchan
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- A phenol compound green nitration method and application
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The invention discloses a green nitrification method and application for a phenolic compound, belonging to the technical field of organic synthesis. The method provided by the invention comprises the following steps: with the phenolic compound as a raw material, dissolving the phenolic compound into a solvent at room temperature, adding sodium nitrite, then dropwise adding hydrogen peroxide into the obtained reaction solution, adding water-soluble metalloporphyrin at room temperature and starting reaction, carrying out nitrification reaction under stirring, then carrying out extraction by using an organic solvent, and carrying out vacuum concentration and column chromatographic separation so as to obtain a target product. The nitrification method provided by the invention has the advantages of mild reaction conditions, no need of heating, convenient operation and easy treatment of products. The green nitrification reaction is suitable for the phenolic compound.
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Paragraph 0038; 0039; 0040; 0041; 0042; 0043; 0044-0047
(2017/08/24)
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- A promising catalyst for exclusive: Para hydroxylation of substituted aromatic hydrocarbons under UV light
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Herein, we describe a waterborne polymer/carbon dot nanocomposite system as an efficient, resourceful and sustainable photocatalyst for para-selective hydroxylation of substituted aromatic compounds using H2O2 under UV light. The polymer matrix and carbon dot generate a synergistic catalytic system. A unique structural attribute of the functionalities in this catalytic system attracts the aromatic substrates into close proximity and activates them. Additionally, the flexible molecular box-like structure of the hyperbranched polymer provides the ability for favorable three-point interaction with several substrates having various sizes by means of their multiple force networks and the increased accessibility of the active sites. The catalyst can be stored on the bench top for months and is reusable without considerable loss in its activity. The reaction was exclusively selective toward para hydroxylation irrespective of the nature of the substituents (electron donating or electron withdrawing) in the aromatic hydrocarbons. Hence, it is one of the most promising catalysts for selective hydroxylation of substituted aromatic hydrocarbons.
- Das, Vijay Kumar,Gogoi, Satyabrat,Choudary, Boyapati Manoranjan,Karak, Niranjan
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p. 4278 - 4283
(2017/09/29)
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- 8,10,12 as nanoreactors for non-enzymatic introduction of: Ortho, meta or para -hydroxyl groups to aromatic molecules
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Traditional electrophilic bromination follows long established "rules": electron-withdrawing substituents cause bromination selective for meta positions, whereas electron-donating substituents favor ortho and para bromination. In contrast, in the [PhSiO1.5]8,10,12 silsesquioxanes, the cages act as bulky, electron withdrawing groups equivalent to CF3; yet bromination under mild conditions, without a catalyst, greatly favors ortho substitution. Surprisingly, ICl iodination without a catalyst favors (>90%) para substitution [p-IC6H4SiO1.5]8,10,12. Finally, nitration and Friedel-Crafts acylation and sulfonylation are highly meta selective, >80%. In principle, the two halogenation formats coupled with the traditional electrophilic reactions provide selective functionalization at each position on the aromatic ring. Furthermore, halogenation serves as a starting point for the synthesis of two structural isomers of practical utility, i.e. in drug prospecting. The o-bromo and p-iodo compounds are easily modified by catalytic cross-coupling to append diverse functional groups. Thereafter, F-/H2O2 treatment cleaves the Si-C bonds replacing Si with OH. This represents a rare opportunity to introduce hydroxyl groups to aromatic rings, a process not easily accomplished using traditional organic synthesis methods. The as-produced phenol provides additional opportunities for modification. Each cage can be considered a nanoreactor generating 8-12 product molecules. Examples given include syntheses of 4,2′-R,OH-stilbenes and 4,4′-R,OH-stilbenes (R = Me, CN). Unoptimized cleavage of the Br/I derivatives yields 55-85% phenol. Unoptimized cleavage of the stilbene derivatives yields 35-40% (3-5 equivalents of phenol) in the preliminary studies presented here. In contrast, meta R-phenol yields are 80% (7-10 mol per cage).
- Bahrami, Mozhgan,Zhang, Xingwen,Ehsani, Morteza,Jahani, Yousef,Laine, Richard M.
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supporting information
p. 8797 - 8808
(2017/07/22)
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- Aqueous Oxidations Started by TiO2 Photoinduced Holes Can Be a Rate-Determining Step
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In aqueous TiO2 photocatalytic hydroxylation of weakly polar aromatics, a series of inverse H/D KIEs of 0.7–0.8 were observed, which is different than the normal H/D kinetic isotope effects (KIEs) usually observed for polar aromatics. This result indicated that the oxidation started by photo-induced hvb + can be the rate-determining step.
- Gong, Yuanzheng,Yang, Chun,Ji, Hongwei,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
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supporting information
p. 2048 - 2051
(2017/08/23)
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- A dinuclear iron(II) complex bearing multidentate pyridinyl ligand: Synthesis, characterization and its catalysis on the hydroxylation of aromatic compounds
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A dinuclear iron(II) complex Fe2L2(μ2-Cl)2Cl2 (L = N,N-bis(pyridin-2-ylmethyl)prop-2-yn-1-amine) was prepared and fully characterized by UV–Vis spectroscopy, elemental analysis, electrochemical analysis and X-ray single crystal diffraction analysis. The catalytic activity of the complex was assessed for the hydroxylation of aromatic compounds by using aqueous H2O2 as an oxidant in acetonitrile. The catalytic system was applicable in a wide range of substrates including aromatic compounds with both electron-donating and electron-withdrawing substituents and showed moderate to good catalytic activity and selectivity in the oxidation reactions. Particularly, in the case of benzene the selectivity of phenol achieve to 74% with the reaction conversion of 24.8%.
- Gu, Erxing,Zhong, Wei,Ma, Hongxia,Xu, Beibei,Wang, Hailong,Liu, Xiaoming
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p. 159 - 165
(2018/03/29)
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- Tertiary Butyl Nitrite Triggered Nitration of Phenols: Solvent- and Structure-Dependent Kinetic Study
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Nitration of phenols with tertiary butyl nitrite (TBN) obeyed second-order kinetics with a first-order dependence on [TBN] and [phenol] under acid-free conditions. Reaction rates were significantly altered by a change in the dielectric constant and other physical properties of solvent. The rate of nitration increased with an increase in temperature (303-323 K) in different solvent media (acetonitrile, dichloroethane, CCl4, dimethyl formamide (DMF), and toluene). The rates of nitration (log k) could not fit into either Amis or Kirkwood plots [log k' vs. (1/D) or [(D - 1)/(2D + 1)], but the trends were better explained by the basic form of multivariate linear solvent energy relationships (MLSER) suggested by the Koppel and Palm approach on the one hand and the Kamlet and Taft approach on the other hand. These observations probably substantiate that cumulative contributions of basic solvent parameters (equilibrium as well as frictional solvent effects) and solvent-solute interactions for solvation of transition state during nitration of phenols. Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups. Accordingly, the reactivity of structurally different phenols was found to follow the following sequence: p-OH > p-MeO > p-Me > H > m-Me > p-Cl > p-Br > m-Cl > p-NO2 > m-OH. The results are interpreted by Hammett's theory of linear free energy relationship. The reaction constant (Hammett's ρ) is a measure of the sensitivity of the reaction toward the electronic effects of the substituent. The rho (ρ) values obtained from the present experiments are fairly large negative values (ρ CH3) versus σ? or, Es or combined Taft's relationship. However, Charton's MLRA of the log k with polar, resonance, steric, hydrophobicity, and molar refractivity showing a very good linear relationship was obtained. It is of interest to note that when log kexp values are correlated with log kcal a perfect linearity is obtained with a correlation coefficient of unity, indicating the consonance between experimental and calculated rate constants in the present work.
- Kumar, M. Satish,Rajanna,Venkateswarlu,Rao, K. Lakshman
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supporting information
p. 171 - 196
(2016/04/09)
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- Environment-friendly bionic catalytic nitration method for phenolic compound
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The invention discloses an environment-friendly bionic catalytic nitration method for a phenolic compound and belongs to the technical field of organic synthesis. The method provided by the invention comprises the steps of dissolving the phenolic compound, which serves as a raw material, in a solvent at normal temperature, adding sodium nitrite into the solution, then, dropwise adding hydrogen peroxide into the reaction solution, adding metal-doped Al-MCM-41 molecular sieves into the reaction solution at normal temperature so as to start a reaction, carrying out stirring so as to carry out a nitration reaction, and then, carrying out suction filtration, organic solvent extraction, depressurized concentration and column chromatography separation, thereby obtaining a target product. According to the nitration method disclosed by the invention, the reaction conditions are mild, heating is not required, the operation is convenient, and the product is easy to treat. The nitration method is applicable to an environment-friendly bionic catalytic nitration reaction for phenolic compounds.
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Paragraph 0031-0032
(2017/06/19)
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- Solvent-free one-step photochemical hydroxylation of benzene derivatives by the singlet excited state of 2,3-dichloro-5,6-dicyano-p-benzoquinone acting as a super oxidant
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Photoinduced hydroxylation of neat deaerated benzene to phenol occurred under visible-light irradiation of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), which acts as a super photooxidant in the presence of water. Photocatalytic solvent-free hydroxylation of benzene derivatives with electron-withdrawing substituents such as benzonitrile, nitrobenzene, and trifluoromethylbenzene used as neat solvents has been achieved for the first time by using DDQ as a super photooxidant to yield the corresponding phenol derivatives and 2,3-dichloro-5,6-dicyanohydroquinone (DDQH2) in the presence of water under deaerated conditions. In the presence of dioxygen and tert-butyl nitrite, the photocatalytic hydroxylation of neat benzene occurred with DDQ as a photocatalyst to produce phenol. The photocatalytic reactions are initiated by oxidation of benzene derivatives with the singlet and triplet excited states of DDQ to form the corresponding radical cations, which associate with benzene derivatives to produce the dimer radical cations, which were detected by the femto- and nanosecond laser flash photolysis measurements to clarify the photocatalytic reaction mechanisms. Radical cations of benzene derivatives react with water to yield the OH-adduct radicals. On the other hand, DDQC?- produced by the photoinduced electron transfer from benzene derivatives reacts with the OH-adduct radicals to yield the corresponding phenol derivatives and DDQH2. DDQ is recovered by the reaction of DDQH2 with tert-butyl nitrite when DDQ acts as a photocatalyst for the hydroxylation of benzene derivatives by dioxygen.
- Ohkubo, Kei,Hirose, Kensaku,Fukuzumi, Shunichi
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supporting information
p. 2855 - 2861
(2015/02/05)
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- Direct hydroxylation of arenes with O2 catalyzed by V@CN catalyst
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A vanadium doped graphitic carbon nitride catalyst has been prepared and used for the direct hydroxylation of arenes with O2. Substituted arenes with electron-withdrawing groups such as CN, NO2, COOH, CF3, and COCH3 were oxygenated to the corresponding phenols in moderate yields. The catalyst also proved applicable for the hydroxylation of aromatic halides (F, Cl, and Br) with O2.
- Li, Yan,Li, Bing,Chen, Ting,Zhou, Zhicheng,Wang, Jun,Huang, Jun
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p. 1086 - 1092
(2015/07/01)
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- The Hydroxylation of Aromatics with Oxygen by Vanadium Catalysts Supported on N-doped Carbon Materials
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Vanadium catalysts supported on N-doped carbon materials (CN) were prepared and the catalyst VOSiW showed high activity for the hydroxylation of various aromatics with O2. Aromatics with electron-withdrawing groups such as CN, NO2, COOH, CF3, COCH3 and aromatic halides (F, Cl and Br) were oxygenated to the corresponding phenols in considerable yields. The CN materials were not only indispensable for the reusability of the vanadium catalyst VOSiW, but also favorable to the high catalytic activity. The VOSiW catalyst is ready for the hydroxylation of aromatics with O2 as both V4+ and V5+ species are coexisted in the VOSiW catalyst.
- Li, Yan,Li, Bing,Geng, Longfei,Wang, Jun,Wang, Yong,Huang, Jun
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p. 1014 - 1021
(2015/08/04)
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- Regioselective nitration of phenols and phenyl ethers using aluminium nitrate on silica as a nitrating system
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Silica supported aluminum nitrate (Al(NO3)3·9H2O) was found to be an excellent reagent for the nitration of phenols and phenyl ethers. This procedure works efficiently on most of the examples at room temperature yielding nitro derivatives in fair to good yields with high regioselectivity. The present methodology evidenced a considerable enhancement in the reaction rate along with high o-selectivity, excellent yields, ease of handling and the simplicity in work up.
- Patil, Mahadeo R.,Mohite, Pravinkumar H.,Shisodia, Suresh,Keri, Rangappa S.
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p. 129 - 135
(2015/06/23)
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- N-methyl-2-chloropyridinium iodide/NaNO2/Wet SiO2: Neutral reagent system for the nitration of activated aromatic compounds under very mild conditions
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Mononitration of activated aromatic compounds using N-methyl-2-chloro-pyridinium iodide (Mukaiyama reagent)/NaNO2/wet SiO2 reagent system under neutral, very mild and environmentally safer reaction condition has been developed. Various structurally diverse aromatic rings are subjected in this condition and the corresponding nitro-aromatic compounds are prepared in moderately high yields.
- Azadi, Roya,Nazari-Far, Zahra
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p. 136 - 140
(2015/06/22)
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- Biomimetic Nitration of Phenols Using Metalloporphyrins/H2O2/NO2 -
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An efficient metalloporphyrins/H2O2/NO2 - nitration of phenols has been developed. The total yield of nitrophenol could reach up to 55.1 %, which is about 4 and sixfold higher than that of horse radish peroxidase catalysis and peroxynitrite nitration, respectively. Furthermore, the nitration system attained an enhanced regioselectivity of 1.0 o/p ratio, and exhibited a good substrate scope of monophenols. This protocol is environmentally friendly compared with HNO3/H2SO4 nitration, and stable, inexpensive and organic solvent tolerant compared with enzyme catalytic nitration and peroxynitrite nitration reaction. Graphical Abstract: [Figure not available: see fulltext.]
- Sun, Weizhi,Liu, Yaojie,Zhang, Haibo,Xian, Mo,Liu, Huizhou
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p. 1991 - 1999
(2015/12/24)
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- Nitration of phenol in 1,4-dioxane
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The nitration of phenol with excess nitric acid in aqueous dioxane, in contrast to the nitration in aqueous ethanol, yields exclusively 2,4-dintrophenol, whereas at equimolar ratio of phenol and nitric acid the major reaction products are mononitrophenols (99%), among which the p-isomer prevails.
- Khabarov,Lakhmanov,Kosyakov,Ul'Yanovskii,Veshnyakov,Nekrasova
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p. 1783 - 1787
(2016/03/05)
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- NITRATING AGENT AND METHOD FOR PRODUCING NITRO COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for producing a nitrating agent not necessarily requiring the use of a large quantity of acid, and a method for producing a nitro compound. SOLUTION: Provided is a nitrating agent including: an inorganic porous member; and a nitrate carried on the inorganic porous member. As the inorganic porous member, a silica gel can be given. As the nitrate, an alkaline-earth metal nitrate can be given. In the method for producing a nitro compound, the nitrating agent and an organic compound are contacted, and heating is performed. As the organic compound, an aromatic compound can be given. The temperature upon the heating is preferably set in 70 to 170°C. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0042-1145
(2017/01/02)
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- Reactions of p-substituted phenols with nitrous acid in aqueous solution
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The reaction of phenols with nitrite (nitrous acid HONO, or its conjugated base, NO2-) is of importance in stomach fluids (low pH) and in atmospheric hydrometeors (mild acid and basic pH). The initial reaction associated with the oxidation/nitration of 4-substitued phenols promoted by HONO/NO2 depends on the pH of the solution. At low pH, the initial step involves the reaction between HONO and phenol, whereas at basic conditions this involves an electron transfer from the phenoxy anion to nitrogen dioxide (NO2) producing the nitrite anion. The rate of both processes is determined by the donor capacity of the substituent at the 4-position of the phenol, and the data obtained at pH 2.3 follow a linear Hammett-type correlation with a slope equal to -1.23. The partition of the gaseous intermediates (NO and NO2) makes the rate of HONO-mediated oxidation dependent on their gas-liquid distribution. At low pH, the main process is phenol oxidation, even in oxygen-free conditions, and the presence of any 4-substituted phenol decreases the rate of HONO auto-oxidation.
- Rubio, Maria A.,Lissi, Eduardo,Olivera, Nicol,Reyes, Jael L.,Lopez-Alarcon, Camilo
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p. 143 - 150
(2014/02/14)
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- An efficient method on nitration of eugenol using NH4NO3 and KHSO4
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The main objective of this research was to find new method for the synthesis of nitro-eugenol. Nitro-eugenol is of considerable importance in the production of other fine chemicals such as amino-eugenol for further chemical synthesis and has also been reported to possess antibacterial, antioxidant and anticancer properties. In an attempt to synthesize nitro-eugenol in high yield, some different nitration methods of eugenol have been applied. An efficient method using NH4NO3 in the presence of KHSO4 as a catalyst has been found to give nitro-eugenol in good yield.
- Sudarma,Wazni,Wildawaty,Yuanita,Suana
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p. 173 - 175
(2014/03/21)
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- Phosphoric acid modified montmorillonite clay: A new heterogeneous catalyst for nitration of arenes
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The easily available montmorillonite clay is treated with phosphoric acid and 10 wt.% is found to be the optimum concentration of phosphoric acid that can be adsorbed chemically on the surface of the clay. Acidity of this phosphoric acid treated montmorillonite clay (PAM) is determined by volumetric as well as potentiometric titration and characterized. Catalytic efficacy of PAM in nitration of various aromatic compounds is reported.
- Bharadwaj, Saitanya K.,Boruah, Purna K.,Gogoi, Pradip K.
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p. 124 - 128
(2014/12/11)
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- Photocatalytic ozonation for degradation of 2-sec-butyl-4,6-dinitrophenol (DNBP) using titanium dioxide: Effect of operational parameters and wastewater treatment
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The results of degradation efficiency of 2-sec-butyl-4,6-dinitrophenol (DNBP) in a batch system by various advanced oxidation processes revealed the order of TiO2/UV/O3 > TiO2/O3 > UV/O3 > O3 > UV/TiO2. All processes followed pseudo-first order kinetics. The influence of operational parameters such as initial pH, initial concentration of DNBP, ozone and catalyst dosage on the TiO2/UV/O3 process, which was the most significant investigated method. The ozone dosage was found to have the noticeable impact on the process; however, initial pH and TiO2 dosage were less effective. The mineralization of 40 mg/L of DNBP and petrochemical wastewater under the obtained optimal conditions was monitored by total organic carbon and chemical oxygen demand, respectively. The results demonstrated that the TiO 2/UV/O3 process was a very effective method for degradation and mineralization of DNBP in aqueous solutions and industrial wastewater. The degradation intermediates were identified by GC-MS.
- Mousanejad,Khosravi,Tabatabaii,Khataee,Zare
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p. 711 - 722
(2014/02/14)
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- Preparation of heteropoly acid based amphiphilic salts supported by nano oxides and their catalytic performance in the nitration of aromatics
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A series of Keggin heteropoly acid anion based amphiphilic salts supported by nano oxides were synthesized and used as catalysts in the nitration of aromatic compounds with HNO3. The reaction conditions in the nitration of toluene were optimized and both 92.6% conversion and good para selectivity (ortho:para = 1.09) were obtained.
- Wang, Peng-Cheng,Yao, Kai,Lu, Ming
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p. 2197 - 2202
(2013/03/14)
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- Chemoselective nitration of aromatic sulfonamides with tert-butyl nitrite
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A methodology for the efficient conversion of aromatic sulfonamides into their mono-nitro derivatives using tert-butyl nitrite is reported. The reaction exhibits a high degree of chemoselectivity for sulfonamide functionalized aryl systems, even in the presence of other sensitive or potentially reactive functionalities.
- Kilpatrick, Brenden,Heller, Markus,Arns, Steve
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p. 514 - 516
(2013/02/25)
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- Ultrasonic and microwave-assisted synthesis of β-nitro styrenes and nitro phenols with tertiary butyl nitrite under acid-free conditions
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Tertiary butyl nitrite (TBN) is an acid-free and safe nitrating agent that provides preferentially β-nitrostyrenes with cinnamic acids and corresponding nitro derivatives with phenols in good yields under classical conditions. However, ultrasonic and microwave-assisted reactions reduced the reaction times substantially and enhanced the yields from good to excellent. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- Kumar, M. Satish,Rajanna,Reddy, K. Rajendar,Venkateswarlu,Venkanna
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supporting information
p. 2672 - 2677
(2013/07/26)
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- Preparation, catalytic performance and theoretical study of porous sulfated binary metal oxides shell (SO42 -/M1xO y-M2xOy) using pollen grain templates
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Porous micro-sized particles of binary metal oxide (SO4 2 -/M1xOy-M2xOy) shell were prepared by template-directed synthesis method employing HCl-treated pollen grains. With 150 m2/g high surface area, these solid acids could provide more acid sites and thus obtain better catalytic activity. Using aromatic nitration as the typical reaction, their catalytic performances were evaluated and showed a significant improvement in both conversion and regioselectivity. Then, with chlorobenzene as substrate, theoretical studies were performed to investigate the interaction between transition metals and chlorobenzene. The results showed that the excellent para-selectivity was closely relative to the metal ion in these solid acids.
- Wang, Peng Cheng,Yao, Kai,Zhu, Jie,Liu, Xiang,Lu, Ting Ting,Lu, Ming
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- Identification of rice β-glucosidase with high hydrolytic activity towards salicylic acid β-d-glucoside
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β-Glucosidases (EC 3.2.1.21) split β-glucosidic linkages at the non-reducing end of glucosides and oligosaccharides to release β-D-glucose. One of the important functions of plant β-glucosidase is deglucosylation of inactive glucosides of phytohormones to regulate levels of active hormones. Tuberonic acid is a jasmonaterelated compound that shows tuber-inducing activity in the potato. We have identified two enzymes, OsTAGG1 and OsTAGG2, that have hydrolytic activity towards tuberonic acid β-D-glucoside in rice (Oryza sativa L.). The expression of OsTAGG2 is upregulated by wounding and by methyl jasmonate, suggesting that this isozyme is involved in responses to biotic stresses and wounding, but the physiological substrate of OsTAGG2 remains ambiguous. In this study, we produced recombinant OsTAGG2 in Pichia pastoris (rOsTAGG2P), and investigated its substrate specificity in detail. From 1L of culture medium, 2.1mg of purified recombinant enzyme was obtained by ammonium sulfate precipitation and Ni-chelating column chromatography. The specific activity of rOsTAGG2P (182 U/mg) was close to that of the native enzyme (171 U/mg), unlike recombinant OsTAGG2 produced in Escherichia coli, which had approximately 3-fold lower specific activity than the native enzyme. The optimum pH and temperature for rOsTAGG2P were pH 3.4 and 60 βC. After pH and heat treatments, the enzyme retained its original activity in a pH range of 3.4-9.8 and below 55 βC. Native OsTAGG2 and rOsTAGG2P showed 4.5-4.7-fold higher activities towards salicylic acid β-D-glucoside, an inactive storageform of salicylic acid, than towards tuberonic acid β-Dglucoside (TAG), although OsTAGG2 was originally isolated from rice based on TAG-hydrolytic activity.
- Himeno, Nami,Saburi, Wataru,Wakuta, Shinji,Takeda, Ryosuke,Matsuura, Hideyuki,Nabeta, Kensuke,Sansenya, Sompong,Ketudat Cairns, James R.,Mori, Haruhide,Imai, Ryozo,Matsui, Hirokazu
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p. 934 - 939
(2013/07/27)
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- Nitrosation of aryl and heteroaryltrifluoroborates with nitrosonium tetrafluoroborate
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Organotrifluoroborates have emerged as an alternative to toxic and air- and moisture-sensitive organometallic species for the synthesis of functionalized aryl and heteroaryl compounds. It has been shown that the trifluoroborate moiety can be easily converted into a variety of different substituents in a late synthetic stage. In this paper, we disclose a mild, selective, and convenient method for the ipso-nitrosation of organotrifluoroborates using nitrosonium tetrafluoroborate (NOBF4). Aryl- and heteroaryltrifluoroborates were converted into the corresponding nitroso products in good to excellent yields. This method proved to be tolerant of a broad range of functional groups.
- Molander, Gary A.,Cavalcanti, Livia N.
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experimental part
p. 4402 - 4413
(2012/06/18)
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- Aromatic nitration under neutral conditions using N-bromosuccinimide/ silver(I) nitrate
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The use of N-bromosuccinimide and silver nitrate as a convenient reagent system for the nitration of aromatic compounds under neutral and environmentally safer reaction conditions is described.
- Nowrouzi, Najmeh,Mehranpour, Abdol Mohammad,Bashiri, Elham,Shayan, Zohre
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experimental part
p. 4841 - 4842
(2012/09/22)
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- HIGH-EFFICIENCY CATALYSTS, PREPARATION AND USE THEREOF
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Disclosed are new molecules, on a peptide-porphyrin base, with a low molecular weight (2000-5000 amu), optionally in covalent association with biomolecules, which are able to catalyse peroxidation, oxidation, hydroxylation, phenol nitration and inert comp
- -
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Page/Page column 42-43
(2012/05/20)
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- Nitration of phenol over silica supported H4PW 11VO40 catalyst
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Vanadium incorporated tungstophosphoric acid (TPAV1) supported on silica was synthesized and characterized by BET-surface area, Fourier transform infrared spectroscopy, X-ray diffraction and Laser Raman techniques. Nitration of phenol was studied at room temperature (25 °C) using HNO 3 in the presence of 0-20 wt.% TPAV1/SiO2 catalysts taking 1, 2-dichloroethane as solvent. The effects of various parameters such as phenol/HNO3 mole ratio, reaction time, catalyst weight, and stirring speed on the catalyst activity were studied. 8 wt.% TPAV1/SiO2 has shown the best activity, regioselectivity and reusability in the nitration of phenol, with a conversion of 92.6% and o-nitrophenol selectivity of 97.9%.
- Kumar, A. Sri Hari,Rao, K.T. Venkateswara,Upendar,Sailu, Ch.,Lingaiah,Prasad, P.S. Sai
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- Molecular cloning and high-level expression of a β-galactosidase gene from Paecilomyces aerugineus in Pichia pastoris
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A β-galactosidase gene (designated PaGalA) was cloned for the first time from Paecilomyces aerugineus and expressed in Pichia pastoris under the control of the AOX1 promoter. The coding region of 3036 bp encoded a protein of 1011 amino acids with a deduced molecular mass of 108.7 kDa. The PaGalA without the signal peptide was cloned into a vector pPIC9K and was expressed successfully in P. pastoris as active extracellular β-galactosidase. The recombinant β-galactosidase (PaGalA) was secreted into the medium at an extremely high levels of 22 mg ml-1 having an activity of 9500 U ml-1 from high density fermentation culture, which is by far the highest yield obtained for a β-galactosidase. The purified enzyme with a high specific activity of 820 U mg-1 had a molecular mass of 120 kDa on SDS-PAGE. PaGalA was optimally active at pH 4.5 and a temperature of 60 °C. The recombinant β-galactosidase was able to hydrolyze lactose efficiently at pH 5.0 and 50 °C. It also possessed transglycosylation activities at high concentrations of lactose. PaGalA exhibited better lactose hydrolysis efficiency in whey than two other widely used commercial lactases. The extremely high expression levels coupled with favorable biochemical properties make this enzyme highly suitable for commercial purposes in the hydrolysis of lactose in milk or whey.
- Katrolia, Priti,Yan, Qiaojuan,Jia, Huiyong,Li, Yinan,Jiang, Zhengqiang,Song, Chunlei
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experimental part
p. 112 - 119
(2012/01/19)
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- Highly efficient nitration of phenolic compounds using some nitrates and oxalic acid under solvent-free conditions
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Nitrophenols can be obtained by direct nitration of phenols with some nitrates and oxalic acid at room temperature in moderate to high yields under solvent-free conditions. A small amount of water proved to be important in the initial period of the reaction.
- Ji, Li,Qian, Chao,Liu, Mei-Xin,Chen, Xin-Zhi
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experimental part
p. 101 - 103
(2011/07/29)
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- Nitration of aromatic compounds under neutral conditions using the Ph 2PCl/I2/AgNO3 reagent system
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Aromatic compounds were nitrated efficiently under essentially neutral conditions by employing Ph2PCl in the presence of I2 and AgNO3. This method minimizes waste products compared to traditional methods and gives the corresponding mononitro derivatives in good to excellent yields in dichloromethane at room temperature.
- Nowrouzi, Najmeh,Zareh Jonaghani, Mohammad
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experimental part
p. 5081 - 5082
(2011/10/09)
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- Nitration of phenolic compounds and oxidation of hydroquinones using tetrabutylammonium chromate and dichromate under aprotic conditions
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In this work, we have reported a mild, efficient and selective method for the mononitration of phenolic compounds using sodium nitrite in the presence of tetrabutylammonium dichromate (TBAD) and oxidation of hydroquinones to quinones with TBAD in CH2Cl2. Using this method, high yields of nitrophenols and quinones were obtained under neutral aprotic conditions. Tetrabutylammonium chromate (TBAC) can also be used as oxidant at same conditions. Indian Academy of Sciences.
- Pourali, Ali Reza,Goli, Arezou
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scheme or table
p. 63 - 67
(2012/01/13)
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- Ethylammonium nitrate (EAN)/Tf2O and EAN/TFAA: Ionic liquid based systems for aromatic nitration
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Acting as in situ sources of triflyl nitrate (TfONO2) and trifluoroacetyl nitrate (CF3COONO2), the EAN/Tf 2O and EAN/TFAA systems, generated via metathesis in the readily available ethylammonium nitrate (EAN) ionic liquid as solvent, are powerful electrophilic nitrating reagents for a wide variety of aromatic and heteroaromatic compounds. Comparative nitration experiments indicate that EAN/Tf2O is superior to EAN/TFAA for nitration of strongly deactivated systems. Both systems exhibit low substrate selectivity (K T/KB = 5-10) in (Figure presented) between values reported for covalent nitrates and preformed nitronium salts.
- Aridoss, Gopalakrishnan,Laali, Kenneth K.
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experimental part
p. 8088 - 8094
(2011/11/13)
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- On the effect of 2-propanol on phenol photonitration upon nitrate photolysis
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It is shown that the enhancement by 2-propanol of the nitration of phenol upon nitrate photolysis is compatible with the inhibition by the alcohol of in-cage recombination between O- and NO2. This effect would increase the availabili
- Vione, Davide,Sur, Babita,Dutta, Binay K.,Maurino, Valter,Minero, Claudio
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scheme or table
p. 68 - 70
(2012/05/04)
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- The stability and reactivity of activated acryloylcarbamates as reagents for the synthesis of N-1 substituted thymine and uracil - An NMR and DFT study
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The mechanism of the decomposition of acryloylcarbamates 7a-b yielding highly reactive isocyanates 3a-b was proposed based on NMR measurements and quantum chemical calculations. A good agreement between the experimental kinetic data and DFT calculations allowed us to demonstrate that the stability of 7a-d depends on the presence of methyl in the acryloyl moiety and the position of the nitro group in the nitrophenolic part of the molecule. Furthermore, the reactivity of 7a-d with weakly nucleophilic and sterically hindered 2,4,6-tri-tert-butylaniline was explored by 1H NMR demonstrating the usefulness of reagents 7a-d offering access to a variety of 1-N-substituted uracils and thymines with potentially interesting biological properties. Copyright
- Pohl, Radek,Rulisek, Lubomir,Rejman, Dominik
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supporting information; scheme or table
p. 423 - 430
(2011/11/14)
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- Enhanced mechanism of catalytic ozonation by ultrasound with orthogonal dual frequencies for the degradation of nitrobenzene in aqueous solution
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The experiments have been performed with a semi-continuous batch reactor to investigate the degradation efficiency of nitrobenzene in aqueous solution by ultrasound with the different orthogonal dual frequencies catalytic ozonation. The introduction of ultrasound can enhance the degradation efficiency of nitrobenzene compared to the results obtained from the processes of ozonation alone and ultrasound alone. The degradation of nitrobenzene is found to be zero-order in the two systems of ultrasound alone, and the reactions follow the pseudo-first-order kinetic model in the processes of ozone alone and ozone/ultrasound. The investigation confirms that the degradation of nitrobenzene follows the mechanism of hydroxyl radical (?OH) oxidation, and the enhancement function is even more pronounced in the presence of ultrasound with the greater difference between the orthogonal dual frequencies due to the obvious synergetic effect between ozone and ultrasound, which increases the utilization efficiency of ozone, and accelerates the initiation of ?OH and the formation of H2O2, resulting in the rapid formation of an increasing diversity of byproducts and the advancement degree of mineralization of total organic carbon (TOC). The oxidative byproducts have been, respectively identified in the different processes selected, including o, p, m-nitrophenols, phenol, malonic acid, 4-nitrocatechol, nitrate ion, maleic acid, oxalic acid, hydroquinone, p-quinone, 1,2,3-trihydroxy-5-nitrobenzene and acetic acid.
- Zhao, Lei,Ma, Jun,Zhai, Xuedong
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experimental part
p. 84 - 91
(2010/11/18)
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- Influence of activated carbons on the kinetics and mechanisms of aromatic molecules ozonation
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Companies have been looking for new methods for treating toxic or refractory wastewaters; which can mainly be used prior to or after or in connexion with biological treatment processes. This paper compares conventional ozone oxidation with activated carbon (AC) promoted ozone oxidation, which helps developing a mechanism involving HO{radical dot} radical. For a compound which is quite easy to oxidise, like 2,4-dichlorophenol (2,4-DCP) conventional ozonation is efficient enough to remove the initial molecule. The mechanism involved mainly consists of an electrophilic attack on the aromatic ring, which is activated by the donor effect of the -OH group, then followed by a 1,3 dipolar cycloaddition (Criegee mechanism) that leads to aliphatic species, mainly carboxylic acids. Yet, the addition of AC, through the presence of HO{radical dot} radical, enhances the removal of these species which are more refractory. For a refractory compound like nitrobenzene (NB), with a de-activated aromatic ring because of the attractive effect of -NO2, conventional ozonation is inefficient. On the contrary, this molecule can be quite easily removed with AC promoted oxidation and it is found that the mechanism (electrophilic attack followed by a 1,3 dipolar cycloaddition) is quite similar to the one corresponding to conventional ozonation, but with less selectivity. For both molecules, a mass balance has established that the by-products accounting for more than 75% of the remaining COD can be quantified. A significant part is composed of carboxylic acids (acetic, oxalic, etc.), which could afterwards be easily removed in an industrial wastewater treatment process followed by a final biological treatment step.
- Merle,Pic,Manero,Mathé,Debellefontaine
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experimental part
p. 166 - 172
(2010/08/20)
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