- Photochemical nitration by tetranitromethane. Part 36. Adduct formation in the photochemical reactions of 4-fluoroanisole and 4-fluoro-3-methylanisole
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The photolysis of the charge transfer (CT) complex of tetranitromethane and 4-fluoroanisole 2 in dichloromethane at -20 deg C gives the epimeric 1-fluoro-4-methoxy-5-nitro-6-trinitromethylcyclohexa-1,3-dienes 9 and 9, the epimeric 1-fluoro-4-methoxy-3-nitro-6-trinitromethylcyclohexa-1,4-dienes 10 and 12, the epimeric 1-fluoro-4-methoxy-6-nitro-3-trinitromethylcyclohexa-1,4-dienes 11 and 13, a 1-fluoro-6-hydroxy-4-methoxy-3-trinitromethylcyclohexa-1,4-diene 14, together with 4-fluoro-2-trinitromethylanisole 3,4-fluoro-2-nitroanisole 4 and 3-fluoro-6-hydroxy-5-nitrobenzoic acid 15.In acetonitrile at 20 or -20 deg C, only minor amounts of adducts 13 and 14 are formed, together with aromatic compounds 3, 4 and 16.The photolysis of the CT complex of tetranitromethane and 4-fluoro-3-methylanisole 7 in dichloromethane at -20 deg C gives the epimeric 1-fluoro-4-methoxy-6-methyl-6-nitro-3-trinitromethylcyclo-hexa-1,4-dienes 23 and 24, 1-fluoro-4-methoxy-2-methyl-r-5-nitro-c-6-trinitromethylcyclohexa-1,3-diene 25 and predominatly 4-fluoro-5-methyl-2-trinitromethylanisole 19.In acetonitrile a similar reaction of 4-fluoro-3-methylanisole 7 gives only adduct 25, lesser amounts of the trinitromethyl compound 19 and increased amounts of 4-fluoro-5-methyl-2-nitroanisole 22.Photolysis reactions with tetranitromethane of either 2 or 7 in 1,1,1,3,3,3-hexafluoropropan-2-ol are slow and yield the nitroanisoles 4, or 20 and 22, respectively.X-Ray crystal structures are reported for 4-fluoro-5-methyl-2-trinitromethylanisole 19 and 4-fluoro-5-methyl-2-nitroanisole 22.
- Butts, Craig P.,Eberson, Lennart,Hartshorn, Michael P.,Robinson, Ward T.
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p. 1877 - 1888
(2007/10/03)
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- 13C NMR Spectra of Substituted o-Nitroanisoles and n-Butyl o-Nitrophenyl Ethers
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13C NMR analyses of substituted o-nitroanisoles and n-butyl o-nitrophenyl ethers are reported. Key Words: 13C NMR - o-Nitroanisoles - n-Butyl o-nitrophenyl ethers
- Zeegers, Petrus J.,Thompson, Malcolm J.
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p. 497 - 499
(2007/10/02)
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- 4,5,6,7-trisubstituted benzoxazolones
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Certain 6-aryl- or 6-heteroaryl- alkylaminobenzoxazolones, and their pharmaceutically-acceptable salts, are dual inhibitors of lipoxygenase and cyclooxygenase enzymes, and so are useful as antiallergy and antiinflammatory agents.
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- REGIOSPECIFIC SYNTHESIS OF CERTAIN 1,2,3,4-TETRASUBSTITUTED BENZENES IN ONE STEP VIA A BENZENE CYCLIZATION
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Tetrasubstituted benzenes of type 3 are obtained regiospecifically in a single step by the treatment of 1-fluoro-4-methoxy-5-carbo-tert-butoxy aniline with tert-butyllithium followed by reaction with an elecrophile.
- Fisher, Lawrence E.,Caroon, Joan M.
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p. 233 - 238
(2007/10/02)
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- ipso Nitration in p-halophenyl ethers
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Addition of nitronium ion ipso to halogen occurs on nitration of the p-haloanisoles in acetic anhydride at -60 deg C.In the cases of p-fluoro- and p-chloro-anisole, addition of the nitronium ion is reversible and only small amounts of ipso products are obtained.With p-bromoanisole nitrodebromination occurs.When p-halophenyl ethers containing a trapping substituent, e.g., 2-(4-chlorophenoxy)-2-methylpropanoic acid, are used as substrates, substantial amounts of the spiro diene with nitro ipso to halogen, e.g., 3,3-dimethyl-8-chloro-8-nitro-1,4-dioxaspirodeca-6,9-dien-2-one, can be isolated.The results demonstrate that extensive ipso attack at the halogen-substituted position is general in the nitration of p-halophenyl ethers.Key words: ipso nitration, ether, diene, p-haloanisole.
- Clewley, Robin G.,Fischer, Alfred,Henderson, George N.
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p. 1472 - 1479
(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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