- Theoretical and experimental evidence of the photonitration pathway of phenol and 4-chlorophenol: A mechanistic study of environmental significance
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Light-induced nitration pathways of phenols are important processes for the transformation of pesticide-derived secondary pollutants into toxic derivatives in surface waters and for the formation of phytotoxic compounds in the atmosphere. Moreover, phenols can be used as NO2 probes in irradiated aqueous solutions. This paper shows that the nitration of 4-chlorophenol (4CP) into 2-nitro-4-chlorophenol (NCP) in the presence of irradiated nitrate and nitrite in aqueous solution involves the radical NO2. The experimental data allow exclusion of an alternative nitration pathway by OH + NO2. Quantum mechanical calculations suggest that the nitration of both phenol and 4CP involves, as a first pathway, the abstraction of the phenolic hydrogen by NO2, which yields HNO2 and the corresponding phenoxy radical. Reaction of phenoxyl with another NO2 follows to finally produce the corresponding nitrated phenol. Such a pathway also correctly predicts that 4CP undergoes nitration more easily than phenol, because the ring Cl atom increases the acidity of the phenolic hydrogen of 4CP. This favours the H-abstraction process to give the corresponding phenoxy radical. In contrast, an alternative nitration pathway that involves NO 2 addition to the ring followed by H-abstraction by oxygen (or by NO2 or OH) is energetically unfavoured and erroneously predicts faster nitration for phenol than for 4CP.
- Bedini, Andrea,Maurino, Valter,Minero, Claudio,Vione, Davide
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Read Online
- Light-Controlled Tyrosine Nitration of Proteins
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Tyrosine nitration of proteins is one of the most important oxidative post-translational modifications in vivo. A major obstacle for its biochemical and physiological studies is the lack of efficient and chemoselective protein tyrosine nitration reagents. Herein, we report a generalizable strategy for light-controlled protein tyrosine nitration by employing biocompatible dinitroimidazole reagents. Upon 390 nm irradiation, dinitroimidazoles efficiently convert tyrosine residues into 3-nitrotyrosine residues in peptides and proteins with fast kinetics and high chemoselectivity under neutral aqueous buffer conditions. The incorporation of 3-nitrotyrosine residues enhances the thermostability of lasso peptide natural products and endows murine tumor necrosis factor-α with strong immunogenicity to break self-tolerance. The light-controlled time resolution of this method allows the investigation of the impact of tyrosine nitration on the self-assembly behavior of α-synuclein.
- Long, Tengfang,Liu, Lei,Tao, Youqi,Zhang, Wanli,Quan, Jiale,Zheng, Jie,Hegemann, Julian D.,Uesugi, Motonari,Yao, Wenbing,Tian, Hong,Wang, Huan
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supporting information
p. 13414 - 13422
(2021/05/12)
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- Copper-mediated nitrosation: 2-nitrosophenolato complexes and their use in the synthesis of heterocycles
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A simple protocol yielding ortho-substituted nitrosophenols from phenols is demonstrated, in the form of copper(II) bis(nitrosophenolato) complexes. The developed methodology was applied to a range of substrates, confirming the role of the copper in both the formation and protection of the challenging 1, 2-substitution pattern. Using polymer supported thiourea, the Cu could be stripped from the complexes and thus enabled the isolation or identification of the uncoordinated ligands and their decomposition products, in yields generally low in line with the intrinsic high reactivity of 2-nitrosophenols. The product complexes are useful intermediates as demonstrated in revisiting a formal [4 + 2] cycloaddition with dimethylacetylene dicarboxylate to synthesise bicyclic products in variable yields, revealing the product has a novel structure different from those previously reported in the literature.
- Nicholls, Alexander J.,Batsanov, Andrei S.,Baxendale, Ian R.
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- Nitration method for aryl phenol or aryl ether derivative
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The invention relates to a nitration method for an aryl phenol or aryl ether derivative. The method comprises the steps of stirring an aryl phenol or aryl ether compound, nitrate, trimethylchlorosilane (TMSCl) and a copper salt in an acetonitrile solution in air at room temperature, simultaneously, monitoring extent of reaction through a TLC dot plate, removing a solvent from a mixture by a rotaryevaporator after a substrate is consumed completely, and carrying out purification through a silica-gel column, thereby obtaining a nitroolefin derivative. Meanwhile, the selective mono-nitration orbis-nitration of the substrate can be achieved through controlling equivalent weight of the nitrate. Compared with the prior art, the nitration method disclosed by the invention has the advantages that the consumption of strong-acid substances is avoided, the reaction conditions are mild, the yield is high, the applicable range of the substrate is wide, reaction activity is free of obvious attenuation after an amplified reaction, and an excellent yield is still obtained, so that the method has an obvious industrial application value.
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Paragraph 0050-0058
(2020/01/03)
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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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- Iodine(III)-Catalyzed Electrophilic Nitration of Phenols via Non-Br?nsted Acidic NO2+ Generation
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The first catalytic procedure for the electrophilic nitration of phenols was developed using iodosylbenzene as an organocatalyst based on iodine(III) and aluminum nitrate as a nitro group source. This atom-economic protocol occurs under mild, non-Br?nsted acidic and open-flask reaction conditions with a broad functional-group tolerance including several heterocycles. Density functional theory (DFT) calculations at the (SMD:MeCN)Mo8-HX/(LANLo8+f,6-311+G) level indicated that the reaction proceeds through a cationic pathway that efficiently generates the NO2+ ion, which is the nitrating species under neutral conditions.
- Juárez-Ornelas, Kevin A.,Jiménez-Halla, J. Oscar C.,Kato, Terumasa,Solorio-Alvarado, César R.,Maruoka, Keiji
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supporting information
p. 1315 - 1319
(2019/03/07)
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- Kinetics and mechanism of trichloroisocyanuric acid/NaNO2-triggered nitration of aromatic compounds under acid-free and Vilsmeier-Haack conditions
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Kinetics and mechanism of nitration of aromatic compounds using trichloroisocyanuric acid (TCCA)/NaNO2, TCCA-N,N-dimethyl formamide (TCCA-DMF)/NaNO2, and TCCA-N,N-dimethyl acetamide (TCCA-DMA)/NaNO2 under acid-free and Vilsmeier-Haack conditions. Reactions followed second-order kinetics with a first-order dependence on [Phenol] and [Nitrating agent] ([TCCA], [(TCCA-DMF)], or [(TCCA-DMA)] >> [NaNO2]). Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups, but did not fit well into the Hammett's theory of linear free energy relationship or its modified forms like Brown-Okamoto or Yukawa-Tsuno equations. Rate data were analyzed by Charton's multiple linear regression analysis. Isokinetic temperature (β) values, obtained from Exner's theory for different protocols, are 403.7?K (TCCA-NaNO2), 365.8?K (TCCA-DMF)/NaNO2, and 358?K (TCCA-DMA)/NaNO2. These values are far above the experimental temperature range (303-323?K), indicating that the enthalpy factors are probably more important in controlling the reaction.
- Bhooshan,Rajanna,Govardhan,Venkanna,Satish Kumar
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p. 445 - 462
(2019/04/10)
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- Sodium perborate/NaNO2/KHSO4-triggered synthesis and kinetics of nitration of aromatic compounds
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Sodium perborate (SPB) was used as efficient green catalyst for NaNO2/KHSO4-mediated nitration of aromatic compounds in aqueous acetonitrile medium. Synthesis of nitroaromatic compounds was achieved under both conventional and solvent-free microwave conditions. Reaction times were comparatively shorter in the microwave-assisted than conventional reaction. The reaction kinetics for nitration of phenols in aqueous bisulfate and acetonitrile medium indicated first-order dependence on [Phenol], [NaNO2], and [SPB]. Reaction rates accelerated with introduction of electron-donating groups but retarded with electron-withdrawing groups. Kinetic results did not fit well quantitatively with Hammett’s equation. Observed deviations from linearity were addressed in terms of exalted Hammett’s constants (σˉ or σeff), para resonance interaction energy (ΔΔGp) parameter, and Yukawa–Tsuno parameter (r). This term provides a measure of the extent of resonance stabilization for a reactive structure that builds up charge (positive) in its transition state. The observed negative entropy of activation (?ΔS#) suggests greater solvation and/or cyclic transition state before yielding products.
- Rajanna,Muppidi, Suresh,Pasnoori, Srinivas,Saiprakash
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p. 6023 - 6038
(2018/09/21)
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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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- Highly efficient protocol for the aromatic compounds nitration catalyzed by magnetically recyclable core/shell nanocomposite
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An efficient protocol for the nitration of aromatic compounds in the presence of a catalytic amount of sulfuric acid-functionalized silica-based magnetic core/shell nanocomposite was reported. The designed products were obtained in high yields in relatively short reaction times at room temperature under solvent-free conditions. The nanocatalyst was simply recovered from the reaction mixture by using an external magnet and efficiently reused for several times. The characterization of particle size, morphology and elemental analysis of the nanocatalyst were provided by scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses, respectively.
- Maleki, Ali,Aghaei, Morteza,Paydar, Reza
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p. 485 - 490
(2017/01/10)
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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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- Prussian Blue/NaNO2 as an Efficient Reagent for the Nitration of Phenols in Aqueous Bisulfate and Acetonitrile Medium: Synthetic and Kinetic Study
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The reaction kinetics of Prussian blue (PB)/NaNO2 initiated for the nitration of phenols by in aqueous bisulfate and acetonitrile medium indicated first-order dependence on [phenol], [NaNO2], and [PB]. An increase in [KHSO4] accelerated the rate of nitration under otherwise similar conditions. The rate of nitration was faster in the solvent of higher dielectric constant (D). Observed results were in accordance with Amis and Kirkwood plots [log k′ vs. (1/D) and [(D ? 1)/(2D + 1)]. These findings together with the linearity of plots, log k′ versus (vol% of acetonitrile (ACN)) and mole fraction of (nx) ACN, probably indicate the importance of both eloctrostatic and nonelctrostatic forces, solvent–solute interactions during nitration of phenols. Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups, which are interpreted by Hammett's theory of linear free energy relationship. Hammett's reaction constant (ρ) is a fairly large negative (ρ 0) value, indicating attack of an electrophile on the aromatic ring. Furthermore, an increase in temperature decreased the reaction constant (ρ) values. This trend was useful in obtaining isokinetic temperature (β) from Exner's plot of ρ versus 1/T. Observed β value (337.8 K) is above the experimental temperature range (303–323 K), indicating that the enthalpy factors are probably more important in controlling the reaction.
- Srinivas, Pasnoori,Suresh, Muppidi,Rajanna,Krishnaiah
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supporting information
p. 209 - 218
(2017/02/05)
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- A preparation process of chlorazol method (by machine translation)
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The invention provides a preparation process of chlorazol method, the method adopts the first hydrolysis, re-hydrogenation reduction, ring-in-one pot reaction, a total reaction through the two-step synthesis method of generating [...]sha Zong, mainly through the raw material 2, 5 - dichloro nitrobenzene in strong alkali aqueous solution heated in the hydrolyzed to obtain the hydrolysis product. In the filtering, drying can get the purity as _AOMARKENCODEGTX0AO _ 99% of 4 - chloro - 2 - nitro-phenol, the invention the whole of the synthetic route is a total of two step, step II of the reduction reaction and ring-closure reaction are combined into a step, not only effectively improves the overall yield, but also shortens the reaction period. The reduction of 2 - amino - 4 - chlorophenol dwell time, avoiding the separated compounds are oxidized and deteriorated. (by machine translation)
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Paragraph 0033; 0034; 0035; 0036; 0037
(2017/03/21)
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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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- Nitration of arenes by 1-sulfopyridinium nitrate as an ionic liquid and reagent by in situ generation of NO2
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1-Sulfopyridinium nitrate was synthesized as a potent nitrating agent for the nitration of arenes without the need for any co-catalysts. A variety of nitro compounds were synthesized and fully characterized by IR, 1H NMR, 13C NMR, thermal gravimetric analysis (TGA), differential thermal gravimetry (DTG), CHN analysis and mass spectroscopy. Mechanistically, in situ generated nitrogen dioxide as a radical from the reagent is proposed for the presented nitration protocol.
- Moosavi-Zare, Ahmad Reza,Zolfigol, Mohammad Ali,Zarei, Mahmoud,Noroozizadeh, Ehsan,Beyzavi, M. Hassan
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p. 89572 - 89577
(2016/10/03)
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- Conformations, equilibrium thermodynamics and rotational barriers of secondary thiobenzanilides
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The article deals with conformational behaviour of 2-methoxy-2′-hydroxythiobenzanilides. The CS-NH group of these compounds preferentially adopts the Z-conformation. Entropy favours the Z-conformer over the E-conformer, whereas enthalpy slightly favours the E-conformer over the Z-conformer. The rotational barrier about the CS-NH bond was determined to be (81.5±0.4) kJ/mol. No significant rotational barrier was found on the Ar-CS and Ar-NH bonds. All experimental outcomes are compared with the results of quantum-chemical calculations.
- Kozic, Ján,Novák, Zdeněk,?ímal, Václav,Profant, Václav,Kune?, Ji?í,Vin?ová, Jarmila
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p. 2072 - 2083
(2016/04/09)
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- Production method of 4-chloro-2-aminophenol
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The invention provides a production method of 4-chloro-2-aminophenol. After a nitrification-catalytic reduction reaction is carried out according to a hydrazine hydrate catalytic reduction method, the 4-chloro-2-aminophenol product with the product purity being 97% or above and the product yield capable of reaching 86% or so is obtained. Meanwhile, raw materials adopted in the production method are easy to obtain, synthesis conditions are simple, the product yield is high, and the production method is suitable for industrial production.
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Paragraph 0032
(2017/03/14)
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- Effect of chloride ion concentration on rapid kinetics of chlorination of regioisomers of nitrophenol by molecular chlorine in aqueous medium using rotating platinum electrode
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The rapid kinetics of chlorination of regioisomers of the nitrophenol by molecular chlorine in the presence of chloride ion in aqueous solution has been studied using rotating platinum electrode (RPE). The chloride ion has a catalytic effect on the chlorination reaction. The mechanism suggested explaining the catalytic effect of chloride ion postulates a longer mean life for Cl-Cl dipole induced by the aromatic substrate by electron rearrangement with the chloride ion, which facilitate the electrophilic attack of Cl-Cl on the aromatic substrate in rate determining step. Hence the specific reaction rate varies linearly with the concentration of chloride ion.
- Sukul,Bonde,Bhadane,Dangat
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p. 2159 - 2163
(2016/02/27)
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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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- Kinetic study on aminolysis of y-substituted-phenyl x-substituted- benzoates: Effects of substituents x and y on reactivity and reaction mechanism
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A kinetic study on aminolysis of 2-chloro-4-nitrophenyl X-substituted-benzoates (2a-k) in 80 mol % H2O/20 mol % DMSO at 25.0 oC is reported. The Bronsted-type plot for the reactions of 2-chloro-4-nitrophenyl benzoate (2g) with a series of cyclic secondary amines curves downward (e.g., β1 = 0.25, β2 = 0.85 and pKa o = 10.3), which is typical of reactions reported to proceed through a stepwise mechanism with a change in ratedetermining step (RDS). The Hammett plot for the reactions of 2a-k with piperidine consists of two intersecting straight lines, while the corresponding Yukawa-Tsuno plot exhibits an excellent linear correlation with ρX = 1.15 and r = 0.59. Thus, it has been concluded that the nonlinear Hammett plot is not due to a change in RDS but is caused by stabilization of substrates through resonance interactions between the electron-donating substituent and the C=O bond. Substrates possessing a substituent at the 2-position of the leaving aryloxide deviate negatively from the curved Bronsted-type plot for the reactions of Y-substituted-phenyl benzoates (3ai), implying that the steric hindrance exerted by the substituent at the 2-position is an important factor which governs the reactivity of Y-substituted-phenyl benzoates.
- Jeon, Seong Hoon,Kim, Hyun Soo,Han, Young Joon,Kim, Min-Young,Um, Ik-Hwan
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p. 471 - 476
(2014/03/21)
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- A practical approach for regioselective mono-nitration of phenols under mild conditions
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Cu(NO3)2.3H2O was demonstrated to be an efficient, regioselective and inexpensive nitrating reagent for the synthesis of mono-nitro substituted phenolic compounds. 12 examples of different phenols were examined. Good yields (67-90%) have been achieved. ARKAT-USA, Inc.
- Chen, Ling-Yan,Liu, Tao,Zhou, Xiaokun,Sun, Zhihua
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- Vanadium pentoxide as a catalyst for regioselective nitration of organic compounds under conventional and nonconventional conditions
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Vanadium pentoxide is used as an efficient catalyst for regioselective nitration of aromatic compounds under conventional and nonconventional conditions such as ultrasonically assisted (USAR) and microwave-assisted reactions (MWAR). The reactions underwent smoothly and afforded good yields of products with high regioselectivity. Observed longer reaction times (about 8 h) in V2O5 catalyzed reactions reduced to (0.5/30 min) under sonication and (90 s) in the case of MWAR. When ortho position is blocked, para derivatives are obtained as end products while ortho nitro products are obtained when para position is blocked.
- Venkatesham,Reddy, K. Rajendar,Rajanna,Veerasomaiah
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p. 921 - 926
(2014/04/03)
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- Microwave assisted synthesis of nitro phenols from the reaction of phenols with urea nitrate under acid-free conditions
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Urea nitrate was found to be an inexpensive, acid-free, and safe nitrating agent that provides mononitration of phenols and substituted phenols in excellent yields with exclusive ortho-selectivity under microwave irradiation. Microwave assisted reactions reduced the reaction times substantially and enhanced the product yields from good to excellent within shorter reaction times.
- Verma, Sanny,Pandita, Sangeeta,Jain, Suman L.
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p. 1320 - 1322
(2014/03/21)
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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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- Oxalylchloride/DMF as an efficient reagent for nitration of aromatic compounds and nitro decarboxylation of cinnamic acids in presence of KNO 3 or NaNO2 under conventional and nonconventional conditions
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Nitration of aromatic compounds and cinnamic acids with oxalylchloride/DMF afforded the corresponding nitro derivatives in the presence of KNO3 or NaNO2 under conventional and nonconventional (ultrasonic and microwave) conditions. The present methodology offers several benefits such as excellent yields, simple work-up procedure, and short reaction times. The yields obtained under present methodology are comparable with those obtained from (POCl3/DMF/KNO3 or NaNO2) and (SOCl 2/DMF/KNO3 or NaNO2) systems followed by shorter reaction times. The reaction times of sonication and microwave conditions are very shorter than those of the conventional conditions.
- Kumar, M. Satish,Reddy, K. Rajendar,Rajanna,Venkanna,Krishnaiah
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p. 977 - 983
(2013/06/05)
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- Cu-Mn spinel oxide catalyzed regioselective halogenation of phenols and N-heteroarenes
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A novel simple, mild chemo- and regioselective method has been developed for the halogenation of phenols using Cu-Mn spinel oxide as a catalyst and N-halosuccinimide as halogenating agent. In the presence of Cu-Mn spinel oxide B, both electron-withdrawing and electron-donating groups bearing phenols gave monohalogenated products in good to excellent yields with highest para-selectivity. The para-substituted phenol gave monohalogenated product with good yield and ortho-selectivity. N-Heteroarenes such as indoles and imidazoles also gave monohalogenated products with high selectivity. Unlike the copper-catalyzed halogenation, the present method works well with electron-withdrawing group bearing phenols and gives comparatively better yields and selectivity. The Cu-Mn spinel catalyst is robust and reused three times under optimized conditions without any loss in catalytic activity. Nonphenolics did not undergo this transformation.
- Singh, Parvinder Pal,Thatikonda, Thanusha,Kumar, K. A. Aravinda,Sawant, Sanghapal D.,Singh, Baldev,Sharma, Amit Kumar,Sharma,Singh, Deepika,Vishwakarma, Ram A.
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scheme or table
p. 5823 - 5828
(2012/09/05)
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- Sodium lauryl sulfate-catalyzed oxidative chlorination of aromatic compounds
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Chlorination of commercially important aromatic compounds using sodium chloride as chlorine source and sodium periodate as oxidant in acidic medium catalyzed by sodium lauryl sulfate (SLS) led to the chloro-substituted aromatics in good yields and purity. Addition of sodium lauryl sulfate led to increased chlorination rate, better yield, excellent purity, and better quality of end product. The advantages of the present method are greater yield, excellent purity, and shorter reaction time at room temperature. Also dichlorinated product can be obtained by increasing the amount of sodium chloride and sodium periodate at slightly higher temperature (40C).
- Mahajan, Tanu,Kumar, Lalit,Dwivedi, K.,Agarwal, D. D.
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p. 3655 - 3663,9
(2020/08/31)
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- A new method for the mononitration of phenol derivatives by poly(4-vinylpyridinium nitrate) and silica sulfuric acid under mild conditions
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This procedure works efficiently for high selective mono nitration of phenol and substituted phenol to corresponding nitro compounds in moderate to high yield using poly(4-vinylpyridinium nitrate) and silica sulfuric acid in dichloromethane at room temperature.
- Goudarziafshar, Hamid
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experimental part
p. 458 - 461
(2012/06/18)
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- Selective reduction of nitroaromatic compounds on silver nanoparticles by visible light
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For the first time, we report experimentally and theoretically that nitroaromatic compounds, 2,4-dinitrobenzenethiol and 4-chloro-2- nitrobenzenethiol, on silver sols can be selectively reduced to 2-amino-4-nitrobenzenethiol and 2-amino-4-chlorobenzenethiol simply by irradiating with a visible light in ambient conditions, and the selective photoreduction is a very facile process. The results of quantum chemical calculations are in good agreement with our experimental data. Copyright
- Xia, Lixin,Hu, Xinhu,Sun, Mengtao,Li, Jushi,Yang, Donghui,Wang, Xiaofang,Xu, Hongxing
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p. 1024 - 1028
(2012/10/29)
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- PIPERIDINECARBOXAMIDES AS MPGES - 1 INHIBITORS
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The invention relates to piperidinecarboxamides of formula (I), to their use in medicine as mPGES-1 inhibitors for the treatment of pain, to compositions containing them, to processes for their preparation and to intermediates used in such processes.
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(2011/07/09)
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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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- 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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- Cellulose-supported Ni(NO3)2.6H2O/2,4,6- trichloro-1,3,5-triazine (TCT) as a mild, selective, and biodegradable system for nitration of phenols
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Nitration of certain phenols and naphthols in the presence of biodegradable cellulose-supported Ni(NO3)2.6H2O/2,4,6- trichloro-1,3,5-triazine was carried out in acetonitrile at room temperature. Ortho nitrated phenols were obtained regioselectively within a short reaction time with good yields. The reaction condition was mild, and the employed cellulose could be recovered several times for further use. Copyright
- Nemati, Firouzeh,Kiani, Hossein,Hayeniaz, Yaser Saeidi
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experimental part
p. 2985 - 2992
(2011/08/22)
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- Melamine-(H2SO4)3 and PVP-(H 2SO4)n as solid acids: Synthesis and application in the first mono- and di-nitration of bisphenol A and other phenols
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Melamine and poly vinylpyrrolidone (PVP) reacted with neat sulfuric acid readily to form two new organic solid acids namely melamine-(H 2SO4)3 and PVP-(H2SO 4)n. These solid acids were used for the first nitration of bisphenol A as well as other phenols in the presence of NH4NO 3. Mono- and di-nitro bisphenol A have been characterized with IR and 1H NMR techniques.
- Chehardoli, Gholamabbas,Zolfigol, Mohammad Ali,Azimi, Seyedeh Bahareh,Alizadeh, Ebadollah
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experimental part
p. 827 - 830
(2012/02/14)
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- A mild procedure for the preparation of o-nitrophenols by nitro urea or ammonium nitrate in the presence of silica sulfuric acid (SiO 2-OSO3H)
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A mixture of ammonium nitrate or nitro urea and silica sulfuric acid was found to be efficient and environmentally friendly nitrating media for the preparation of orto-nitro phenols in dichloromethane at room temperature. A mixture of ammonium nitrate or nitro urea and silica sulfuric acid was found to be efficient and environmentally friendly nitrating media for the preparation of orto-nitro phenols in dichloromethane at room temperature.
- Ghorbani-Choghamarani, Arash,Nikoorazm, Mohsen,Goudarziafshar, Hamid,Naserifar, Zahra,Zamani, Parisa
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experimental part
p. 731 - 734
(2011/11/12)
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- Mononitration of phenol derivatives by guanidinium nitrate and silica sulfuric acid under mild conditions
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A mixture of guanidinium nitrate and silica sulfuric acid acts as mild and heterogeneous media for the efficient mono nitration of phenolic compounds in dichloromethane at room temperature.
- Ghorbani-Choghamarani, Arash,Goudarziafshar, Hamid,Nikoorazm, Mohsen,Naseri, Zahra
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experimental part
p. 1431 - 1434
(2012/06/01)
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- Regiospecific oxyhalogenation of aromatics over SBA-15-supported nanoparticle group IV-VI metal oxides
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TiOx, VOx, MoOx and WOx supported on SBA-15 exhibit efficient catalytic activity for oxyhalogenation of aromatics with the H2O2-halide ion system. Unlike the hitherto known solid catalysts, these reusable catalysts yield the para-halogenated product with 100% selectivity at 298 K and moderate acidic pH (3-5). The catalytic activity was enhanced by five orders of magnitude when supported on SBA-15. Springer Science+Business Media, LLC 2010.
- Saikia,Rajesh,Srinivas,Ratnasamy
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scheme or table
p. 190 - 201
(2010/11/05)
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- Zn(NO3)2·6H2O/2,4,6-trichloro-1,3,5-triazine (TCT) a mild and selective system for nitration of phenols
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Certain phenols and naphthols were nitrated regioselectively with Zn(NO3)2·6H2O/TCT in acetonitrile as solvent at room temperature and short reaction time in good yields. The reaction condition was mild. TCT is a cheap and commercially available reagent. It performed as an acid catalyst in this transformation.
- Nemati, Firouzeh,Kiani, Hossein
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experimental part
p. 403 - 406
(2010/12/24)
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- Selective nitration of phenols using bismuth subnitrate/charcoal in the presence of trichloroisocyanuric acid under aprotic conditions
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A mild, efficient and regioselective method for the mononitration of phenolic compounds is described using bismuth subnitrate/charcoal in the presence of trichloroisocyanuric acid in CH2Cl2 at room temperature.
- Pourali, Ali Reza,Fatemi, Fatemeh
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experimental part
p. 1283 - 1286
(2011/10/05)
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- Bromodimethylsulfonium bromide/tetrabutylammonium nitrite: An efficient catalyst mixture for the nitration of phenols
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Nitrophenols were obtained via direct nitration of phenols with tetrabutylammonium nitrite in the presence of bromodimethylsulfonium bromide at room temperature in high yields under aprotic conditions. TUeBITAK.
- Akhlaghinia, Batool,Pourali, Alireza
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experimental part
p. 753 - 759
(2010/12/18)
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- Efficient and facile method for the nitration of aromatic compounds by nitric acid in micellar media
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Aromatic compounds were efficiently nitrated under mild reaction conditions by employing HNO3 in the presence of anionic (sodium dodecyl sulfate, SDS), cationic (cetyl trimethyl ammonium bromide, CTAB), and nonionic (Triton-X 100) micelles. The reaction rapidly afforded corresponding mononitro derivatives in fair to good yields with high regioselectivity. This new method offers an environmentally safe reaction condition to minimize the waste products.
- Sana,Tasneem,Ali, M. Moazzam,Rajanna,Saiprakash
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experimental part
p. 2949 - 2953
(2009/12/03)
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- Aluminum nitrate and silica sulfuric acid as efficient nitrating media for the mononitration of phenols under mild and heterogeneous conditions
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A variety of phenol derivatives were successfully nitrated via combination of Al(NO3)3-9H2O and silica sulfuric acid in the presence of wet SiO2 (50% w/w) in dichloromethane at room temperature with moderate-to-good yields.
- Ghorbani-Choghamarani, Arash,Goudarziafshar, Hamid,Nikoorazm, Mohsen,Yousefi, Somaieh
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experimental part
p. 1144 - 1147
(2009/10/23)
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- A simple DNase model system comprising a dinuclear Zn(II) complex in methanol accelerates the cleavage of a series of methyl aryl phosphate diesters by 1011-1013
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The di-Zn(II) complex of 1,3-bis[N1,N′1-(1,5,9- triazacyclododecyl)]propane with an associated methoxide (3:Zn(II) 2:-OCH3) was prepared and its catalysis of the methanolysis of a series of fourteen methyl aryl phosphate diesters (6) was studied at sspH 9.8 in methanol at 25.0 ± 0.1°C. Plots of kobs vs [3:Zn(II)2: -OCH3]free for all members of 6 show saturation behavior from which KM and kcatmax were determined. The second order rate constants for the catalyzed reactions (k catmax/KM) for each substrate are larger than the corresponding methoxide catalyzed reaction (k2-OMe) by 1.4 × 108 to 3 × 109-fold. The values of kcatmax for all members of 6 are between 4 × 10 11 and 3 × 1013 times larger than the solution reaction at sspH 9.8, with the largest accelerations being given for substrates where the departing aryloxy unit contains ortho-NO 2 or C(=O)OCH3 groups. Based on the linear Bronsted plots of kcatmax vs sspK aof the phenol, βIg values of -0.57 and -0.34 are determined respectively for the catalyzed methanolysis of regular substrates that do not contain the ortho-NO2 or C(=O)OCH3 groups, and those substrates that do. The data are consistent with a two step mechanism for the catalyzed reaction with rate limiting formation of a catalyst-coordinated phosphorane intermediate, followed by fast loss of the aryloxy leaving group. A detailed energetics calculation indicates that the catalyst binds the transition state comprising [CH3O -:6]?, giving a hypothetical [3:Zn(II) 2:CH3O-:6]? complex, by -21.4 to -24.5 kcal/mol, with the strongest binding being for those substrates having the ortho-NO2 or C(=O)OCH3 groups.
- Neverov, Alexei A.,Liu, C. Tony,Bunn, Shannon E.,Edwards, David,White, Christopher J.,Melnychuk, Stephanie A.,Brown, R. Stan
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p. 6639 - 6649
(2008/12/23)
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- PEG-N2O4: An efficient nitrating agent for the selective mono- and dinitration of phenols under mild conditions
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N2O4 was easily impregnated on polyethyleneglycol to give a stable reagent. The polyethyleneglycol-N2O4 (PEG-N2O4) system was used as an effective nitrating agent for the nitration of phenols. Mono- and dinitrophenols can be obtained via direct nitration of phenols in the presence of PEG-N2O4 at room temperature in moderate to high yields. Copyright Taylor & Francis Group, LLC.
- Zolfigol, Mohammad Ali,Madrakian, Elaheh,Ghaemi, Ezat,Niknam, Khodabakhsh
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p. 3366 - 3374
(2008/12/22)
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- AI203/MeS03H (AMA) as a novel heterogeneous system for the nitration of aromatic compounds by magnesium nitrate hexahydrate
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Mg(NO3)2-6H2O was an efficient nitrating agent in the presence of a mixture of AI2O3/MeSO 3H (AMA) as a novel heterogeneous system for the nitration of aromatic compounds without use of any organic solvents and with high selectivity. The reaction proceeds at room temperature for the nitration of highly reactive aromatic compounds such as phenols and anilines.
- Hosseini-Sarvari, Mona,Tavakolian, Mina
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experimental part
p. 722 - 724
(2009/10/02)
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- Tribromoisocyanuric acid/NaNO2: A new reagent for mononitration of phenols under mild and heterogeneous conditions
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Nitrophenols can be obtained via direct nitration of phenols with tribromoisocyanuric acid, NaNO2 and wet SiO2 at room temperature in good to high yields.
- Niknam, Khodabakhsh,Zolfigol, Mohammad Ali,Madrakian, Elaheh,Ghaemi, Ezat
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p. 109 - 112
(2008/09/17)
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- Mild and selective nitration of phenols by zeofen
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Certain phenols and naphthols were nitrated regioselectively with zeofen in dichloromethane as solvent at room temperature and in a short reaction time to give good yields. Copyright Taylor & Francis Group, LLC.
- Bigdeli, Mohammad A.,Heravi, Majid M.,Nemati, Firouzeh
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p. 2225 - 2230
(2008/02/07)
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- Catalysis and inhibition of ester hydrolysis in the presence of resorcinarene hosts functionalized with dimethylamino groups
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Complexation and catalysis of two calixresorcinarene (RES) derivatives with nucleophilic N,N-dimethylamino functions attached to their upper rims in the hydrolysis of carboxylate and sulfonate esters of 4-nitrophenol and 2,4-dinitrophenol have been investigated. Rate constants obey the complexation equation: kobs = kb × Ks + k c[Host]/Ks + [Host] Values of the dissociation constant (Ks) of the complexes are within the range exhibited by other systems such as cyclodextrins-ester complexes. The reactions of sulfonate esters only exhibit inhibition by the macrocyclic hosts. The reactions of the carboxylate esters exhibit catalysis and inhibition depending on the pH of the system. It is proposed that the dimethylamino function in RES3 and RES5 behaves as a nucleophile to form a reactive acylammonium species which subsequently decomposes and regenerates the catalytic amine. In the reaction of substituted phenyl acetates with RES3 the effective charge on the leaving oxygen in the complexed state (+0.88) is slightly more positive than that in the free ester (+0.70). The effective charge on the leaving oxygen in the transition structure is substantially more positive (+0.04 units) than in a model intramolecular reaction of tertiary dimethylamines with aryl esters (-0.53 units). The influence of the host on the reaction in the complex includes an electronic component which is ascribed to solvation of the transition structure of the rate-limiting step by water molecules located within the cavity of the host. It is suggested that this solvation is stronger than that occurring in the transition state for the model intramolecular reaction. Copyright
- Cevasco, Giorgio,Thea, Sergio,Vigo, Daniele,Williams, Andrew,Zaman, Flora
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p. 630 - 636
(2008/02/08)
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- 1,3-Dihalo-5,5-dimethylhydantoin or citric acid/NaNO2 as a heterogeneous system for the selective mononitration of phenols under mild conditions
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Direct nitration of phenols was performed using 1,3-dichloro-5,5- dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin or citric acid/NaNO 2 in the presence of wet SiO2 at room temperature.
- Zolfigol, Mohammad A.,Ghaemi, Ezat,Madrakian, Elaheh,Choghamarani, Arash G.
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