- New N-methoxy-dinitro-aniline derivatives: Synthesis, structure and pKa values
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New N-methoxy-trisubstituted compounds 11-n (where: 1, R2 = NO2, R3 = H, R4 = CN; j, R2 = CF3, R3 = H, R4 = NO2; k, R2 = CN, R3 = H, R
- Covaci, Irina,Constantinescu, Titus,Cǎproiu, Miron T.,Dumitra?cu, Florea,Luca, Constantin,Balaban, Alexandru T.
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p. 531 - 537
(2007/10/03)
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- A new nitration process of N-methoxy-dinitroaniline and triarylhydrazine derivatives with sodium nitrite in the presence of crown ethers
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We studied the reaction between solid sodium nitrite and derivatives of N-methoxy-4-R1-2,6-dinitroaniline 1a-f (where: a R1 = H; b, R1 =CH3; c, R1 =CF3; d, R1 = COOH; e, R1 = COOCH3; f, R1 = CN), of N-methoxy-6-R2-2,4-dinitroaniline 1g-k (where: g, R2 = H; h, R2 = CF3; i, R2 = CN; j, R2 = COOH; k, R2 = COOCH3) or of 2-(p-R2-phenyl)-2-phenyl-1-(2,6-dinitro-4-R 1-phenyl)-hydrazine 2a,b,d (where: a, R1 =NO2, R2 = H; b, R1,= = R2, = NO2; d, R1, = COOH, R2, = H) in the presence of crown ethers. It was observed that: compounds 1a-1e and 1g were nitrated leading to N-methoxy-2,4,6-trinitroaniline 11 (compounds 1b - 1e being formed by ipso-substitution); compounds 2 were nitrated as follows: 2a → 2b, 2b → 2c [2,2-(bis-p-nitrophenyl)-1-picrylhydrazine] and 2d → 2a (by ipso-substitution). The nitration is due to acid-base processes that occur in methylene chloride leading to the formation of nitrous acid and the corresponding anions of 1 and 2, followed by a redox homolytic process due to the NO2 free radical, formed by disproportionation of nitrous acid, which oxidizes the anions to the coresponding free radicals, and finally by a radical + radical coupling yielding the new nitroderivatives by selective nitration.
- Covaci, Irina Cristina,Constantinescu, Titus,Ioni?ǎ, Petre,Cǎproiu, Miron Teodor,Zarnǎ, Nicolae,Luca, Constantin,Balaban, Alexandru T.
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p. 823 - 829
(2007/10/03)
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- Self-nitration of N-alkoxy-dinitroanilines by oxidation
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N-Alkoxydinitroanilines 1-6 are self-nitrated by oxidation (with Ag2O, Ph(OAc)4, or with air, thermally or photochemically) to N-alkoxy-trinitroanilines 7. The yield depends on the type of the oxidation process and especially on the nature of the substituents. In the first stage of this process, the corresponding aminyl free radicals are formed.
- Stanciuc, Gabriela,Constantinescu, Titus,Cǎproiu, Miron T.,Zarnǎ, Nicolae,Caragheorgheopol, Agneta,Cǎldǎraru, Horia,Balaban, Alexandru T.
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p. 395 - 400
(2007/10/03)
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- Nucleophilic Reactivity: Nucleophilic Aromatic Substitution Reactions of 2,4-Dinitrochlorobenzene and Picryl Chloride in Aqueous and Methanol Solutions
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Rate constants for nucleophilic aromatic substitution reactions of picryl chloride, I, with acetate ion and a series of amine nucleophiles, including primary, secondary, tertiary (quinuclidines), and amines which show the α-effect, in aqueous and methanol
- Gandler, Joseph R.,Setiarahardjo, Irianto U.,Tufon, Chrisanthus,Chen, Chinpan
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p. 4169 - 4173
(2007/10/02)
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- Factors Affecting the Stability and Equilibria of Free Radicals. XIII. N-Alkoxy- and N-Aralkoxypicrylamines and ESR Spectra of the Corresponding Capto-Dative Persistent Aminyls
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Five O-alkylhydroxylamines and three aralkylhydroxylamines have been picrylated to give O-alkyl-N-picrylhydroxylamines.These were converted to the corresponding N-(ar)alkoxy-picryl-aminyl radicals in toluene solution, and the ESR spectra were recorded.Simulations of the spectra with reasonable parameters and g values confirm the expected radical structures.Hyperfine coupling constants for nuclei in the picryl (acceptor) ring are smaller than those for the (ar)alkoxy group.This indication of competitive electron pair delocalization to the picryl ring, together with the long lifetimes of these radicals (compared with the symmetrically substituted diphenylaminyls), both support the concept of captodative stabilization.
- Stanciuc, Gabriela,Caproiu, M. Teodor,Caragheorgheopol, Agneta,Caldararu, Horia,Balaban, Alexandru T.,Walter, Robert I.
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- Synthesis of Polynitrobenzenes. Oxidation of Polynitroanilines and Their N-Hydroxy, N-Methoxy, and N-Acetyl Derivatives
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Nitro-substituted arylhydroxylamines and alkyloxyamines have been oxidized to polynitroaryl compounds by utilizing ozone.Polynitroanilines have been oxidized to polynitroaromatics by peroxydisulfuric acid generated in situ from SO3 and ozone.Thus N-hydroxy-2,4,6-trinitroaniline (1a) or N-methoxy-2,4,6-trinitroaniline (1b) was cleanly oxidized to 1,2,3,5-tetranitrobenzene (2) by reaction with ozone in methylene chloride.Weakly basic amines such as pentanitroaniline (10) can conveniently be oxidized to hexanitrobenzene (11) in high yields by simply dissolving the amine in oleum and introducing ozone.A variety of substituted arylamines have been oxidized to polynitroaromatic compounds by using these two oxidation techniques.
- Atkins, Ronald L.,Nielsen, Arnold T.,Bergens, Cynthia,Wilson, William S.
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p. 503 - 507
(2007/10/02)
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