- Nitration of some di- and tri-nitrohalobenzenes with solid sodium nitrite in the presence of 18 crown 6
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1-Halo-4-R1-6-R2-2-nitrobenzenes 1a-d (where a : hal = F, R1 = NO2, R2=H; b: hal = Cl, R1 = NO2, R2 = H; c: hal = Cl, R1 = H, R2 = NO2 ; d: hal = Cl, R1 = CF3, R2 = NO2; ) and 1-chloro-2,4,6-trinitrobezene 1e were nitrated in methylene chloride with solid sodium nitrite in the presence of 18C6, and afforded the corresponding nitroderivatives 4-R1-6-R2-1,2-dinitrobenzenes 3a-c (where a: R1 = NO2, R2 = H; b: R1 = H, R2 = NO2; c: R1 = CF3, R2 = NO2; ) and 1,2,3,5-tetranitrobenzene 3d, respectively. The yields of this nucleophilic process depended on the number of nitro substituents and on the halogene type. UV-VIS and NMR spectra, TLC behaviour and pH-depending repartition in biphasic system water/methylene chloride of the synthecized compounds 3a-d are presented.
- Badea, Florin,Stoica, Alice,Ioni?ǎ, Petre,Cǎproiu, Miron T.,Constantinescu, Titus
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p. 351 - 356
(2007/10/03)
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- The Reaction of Nitrobenzenes with Sodium Borohydride; a Novel Reductive Coupling to Diphenylamine Derivatives
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The reduction of mono-, di-, and trinitro-substituted benzenes by NaBH4 in hydroxylic solvents gives very different products depending on structure and reaction conditions.In addition to known reactions, such as formation of azoxybenzene and azobenzene derivatives, displacement of nitro groups by hydrogen, and ring reduction, a novel coupling reaction with loss of one nitro group was observed.From 1,3-dinitrobenzene and 1,3,5-trinitrobenzene, diphenylamine derivatives were obtained in reactions that are clean and of preparative value when the nitro compound is present in exess.From 1,2-dinitrobenzene the diphenylhydroxylamine derivative was obtained in a much slower, but equally clean reaction.Possible mechanisms are discussed, and an aromatic ipso radical substitution of a nitro group by a phenylnitroxide intermediate is proposed.
- Dale, Johannes,Vikersveen, Line
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p. 354 - 361
(2007/10/02)
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- Cyano and Nitro Group Effect on the Rate of Methoxy Denitration Reaction in the Pyrrole and Benzene Ring
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In both the pyrrole and benzene ring the methoxy denitration reaction is accelerated by a nitro or a cyano group flanking the reaction center.However, because of the different geometry of the rings, in the pyrrole ring a nitro group is more effective than a cyano group, at variance whit what is observed in the benzene ring.
- Bazzano, Francesca,Mencarelli, Paolo,Stegel, Franco
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p. 2375 - 2377
(2007/10/02)
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- 1,2,4-TRINITROBENZENE AS A THIOL REAGENT
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The 2,4-dinitrophenylation of thiol or amino group with 1,2,4-trinitrobenzene proceeded quantitatively at pH 8.5 and 30 deg C.The rate of S-dinitrophenylation was ca. 1E4 times faster than that of N-dinitrophenylation.So this reaction can be used for both the determination of thiol even in the presence of large excess amine and the specific modification of thiol in proteins.
- Takahashi, Seitaro,Kokubo, Masayuki,Satake, Kazuo
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p. 1445 - 1448
(2007/10/02)
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- OXIDATION AT NITROGEN IN BENZO- BENZODI- AND BENZOTRIFUROXANS
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Hydrogen peroxide in sulfuric acid oxidized 5-nitrobenzofuroxan into 1,2,4-trinitrobenzene and completed the oxidation of a mixture from benzodifuroxan and hydrogen peroxide in polyphosphoric acid into 1,2,3,4-tetranitrobenzene.The incompletely oxidized m
- Boyer, Joseph H.,Huang, Chorngbao
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p. 285 - 289
(2007/10/02)
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