- 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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- Preparation method of pentachloride intermediate 2, 4 - dichloro -6 - nitrophenol (by machine translation)
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To the preparation method, 2, 4 - dichlorophenol sulfuric acid solution and nitric acid solution are respectively added to a continuous flow micro-channel reactor, and subjected to preheating, mixing, nitration reaction to obtain -6 - 2 dichloro 4 -6 - 4 - 2 -nitrophenol. The method comprises the following steps of: preheating, mixing and nitration reaction, and carrying out nitrification reaction. The method has the advantages of being convenient, safe, efficient, small in process environment pollution and the like, and can effectively avoid the generation. (by machine translation)
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Paragraph 0042; 0045-0049; 0050; 0052-0053; 0054; 0056-0057
(2019/08/06)
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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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- 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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- 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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- 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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- 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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- 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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- 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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- Highly efficient, para-selective oxychlorination of aromatic compounds using potassium chloride and Oxone
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A highly efficient, regioselective method for oxychlorination of aromatic compounds is possible through electrophilic substitution of chlorine generated in situ from KCl as a chlorine source and Oxone as an oxidant for the first time.
- Narender,Srinivasu,Kulkarni,Raghavan
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p. 279 - 286
(2007/10/03)
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- Novel stabilized activated derivatives of carbamic acid, their process of preparation and their use for the preparation of ureas
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Process for the preparation of stable activated derivatives of carbamic acid, comprising at least one protected amino group and an activated carbamic acid function, from an amino acid derivative in which the amino group is protected. The process includes: a) a step of transformation of the —COOH group of the amino acid derivative into a —CON3 group to obtain an acyl azide; b) a step of transformation of the —CON3 group of the acyl azide into a —NCO group to obtain an isocyanate; c) a step of treating the isocyanate to obtain a stable derivative of carbamic acid.
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- Kinetic studies of the reactions of some phenols and alkyl aryl ethers with dinitrogen pentoxide in perfluorocarbon solvents
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The reaction of dinitrogen pentoxide in perfluorocarbon solvents with phenols and alkyl aryl ethers carrying halogeno ring-substituents results in nitrodehydrogenation. Rate measurements show that the preferred orientation of nitration is ortho > para > meta to the hydroxy group; the kinetic isotope effect, kH/kD, has a value close to unity. Phenols show considerably higher reactivity than similarly substituted alkyl phenyl ethers, and a mechanism is suggested involving initial interaction of N2O5 with the hydroxy function followed by reaction via cyclic transition states.
- Crampton,Gibbons,Millar
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p. 1662 - 1665
(2007/10/03)
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- Ionic complex of N2O4 with 18-crown-6: A highly efficient and selective reagent for nitration of phenols
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Interaction of gaseous N2O4 with 18-crown-6 affords the stable crystalline complex of NO+ · 18-crown-6 · H(NO3)2· This ionic complex is an efficient nitrating agent for the selective mono-, di-, and trinitration of phenol and also for the selective mono-, and dinitration of substituted phenols.
- Iranpoor,Firouzabadi,Heydari
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p. 3295 - 3302
(2007/10/03)
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- Formation of 4-Halo-4-nitrocyclohexa-2,5-dienones on Nitration of p-Halophenols and p-Halophenyl Acetates.
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Nitration of p-chloro-, p-fluoro-, and p-bromo-phenol or the corresponding p-halophenyl acetates at -40 deg C and below gives the 4-halo-4-nitrocyclohexa-2,5-dienones in addition to the 4-halo-2-nitrophenols.The dienones isomerize to the nitrophenols at temperatures between -40 deg C and 0 deg C.Nitration of 4-chloro-2-methylphenol or its acetate gives both 4-chloro-2-methyl-4-nitrocyclohexa-2,5-dienone and 4-chloro-6-methyl-6-nitrocyclohexa-2,4-dienone. 4-Chloro-3-methylphenol and its acetate give 4-chloro-3-methyl-4-nitrocyclohexa-2,5-dienone.
- Clewley, Robin G.,Cross, Gordon G.,Fischer, Alfred,Henderson, George N.
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p. 1299 - 1310
(2007/10/02)
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- Electrophilic Aromatic Substitution. Part 28. The Mechanism of Nitration of Some 4-Substituted Anisoles and Phenols, and of Rearrangement of the Intermediate 4-Nitro-4-substituted-cyclohexa-2,5-dienones
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The kinetics of nitration in sulphuric acid of 2-chloro-4-methyl-, 4-chloro-, 2,4-dichloro-, and 4-fluoroanisole and of the corresponding phenols have been determined.The reaction products from the anisoles and from 2-chloro-4-methyl- and 4-fluoro-phenol have been determined.Results for 4-methylanisole supplementary to earlier ones are also reported.Generally the anisoles give the 2-nitro-derivatives and the 2-nitrophenols, and from 2-chloro-4-methylanisole, 2-chloro-4-methyl-4-nitrocyclohexa-2,5-dienone was formed as an intermediate.The decomposition of this dienone in sulphuric acid, like those of others, changes from a non-acid-catalysed to an acid-catalysed form with increasing acidity.The first form is regarded as a decomposition into an aryloxyl radical and nitrogen dioxide which can recombine to give the 2-nitrophenol.The formation of a small amount of 2-(4-fluorophenoxy)-4-fluorophenol in the nitration of 4-fluorophenol is seen as support for this view.The acid-catalysed form is regarded as the decomposition of the protonated dienone into a phenol-nitronium ion encounter-pair which can give the nitrophenol.A consequence of the mechanism is that if the phenol were nitrated at less than the encounter rate, the phenol itself would in appropriate conditions be a product of the ipso-nitration of the original anisole. 4-Methyl-, 2-chloro-4-methyl-, and 4-chloro-phenol have been so identified.Quantitative analysis of the results allows evaluation of the partitioning of dienone decomposition between the two modes.The mechanism accounts for the formation from 2,4-dichloro-anisole of both 2,4-dichloro-6- and 2,4-dichloro-5-nitroanisole, but only 2,4-dichloro-6-nitrophenol.
- Bloomfield, Colin,Manglik, Ajay K.,Moodie, Roy B.,Schofield, Kenneth,Tobin, Geoffrey D.
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