- Theoretical and experimental NMR data of 3,5-dinitro-2-(2-phenylhydrazinyl) pyridine and of its 4- and 6-methyl derivatives
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3,5-Dinitro-2-(2-phenylhydrazinyl)pyridine and its methyl derivatives: 4-methyl-3,5-dinitro-2-(2-phenylhydrazinyl)pyridine and 6-methyl-3,5-dinitro-2- (2-phenylhydrazinyl)pyridine were synthesized and characterized by 1H NMR and 13C NMR. Calculations were also performed where the above molecules were optimized using the methods of density functional theory (DFT) with 6-31G(d,p) and 6-311G(d,p) basis sets. For all molecules studied, the lowest energy was obtained using the 6-311G(d,p) basis set. The GIAO/DFT (Gauge Invariant Atomic Orbitals/Density Functional Theory) calculations on the 6-311G and 6-311++G and 6-311G* basis sets were carried out to determine proton and carbon chemical shifts and to find they were close to the experimental values. It has been also found that intramolecular hydrogen bonding exists between hydrogen atom (in 2-NH group) and oxygen atom (pyridine-3-NO2). Moreover, resonances between pyridine ring and electron withdrawing 3-nitro group as well between that ring and the lone electron pair of NH group favor a co-planarity of the structure; this means a chelate ring created by above-mentioned intramolecular hydrogen bond is almost co-planar with pyridine ring.
- Wandas,Talik
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- Molecular and crystal structures, vibrational studies and quantum chemical calculations of 3 and 5-nitroderivatives of 2-amino-4-methylpyridine
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The crystal structures of 2-amino-4-methyl-3-nitropyridine (I), 2-amino-4-methyl-3,5-dinitropyridine (II) and 2-amino-4-methyl-5-nitropyridine (III) have been determined. The compounds crystallize in the monoclinic P2 1/n, triclinic P-1 and monoclinic C2/c space groups, respectively. These structures are stabilized by a combination of N-H···N and N-H···O hydrogen bonds and exhibit layered arrangement with a dimeric N-H···N motif in which the molecular units are related by inversion centre. The molecular structures of the studied compounds have been determined using the DFT B3LYP/6-311G(2d,2p) approach and compared to those derived from X-ray studies. The IR and Raman wavenumbers have been calculated from the optimized geometry of monomers and dimers formed in the unit cell and compared to the experimental values obtained from the spectra.
- Bryndal,Kucharska,Sasiadek,Wandas,Lis,Lorenc,Hanuza
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p. 952 - 962
(2012/11/07)
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- Synthesis of some fluorine-containing pyridinealdoximes of potential use for the treatment of organophosphorus nerve-agent poisoning
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Fluoroheterocyclic aldoximes were screened as therapeutic agents for the treatment of anticholinesterase poisoning. 2-Fluoropyridine-3- and -6-aldoxime, and 3-fluoropyridine-2- and -4-aldoxime, were synthesised. Attempts to obtain 3,5,6-trifluoropyridine-2,4-bis(aldoxime) and -2-aldoxime, however, proved unsuccessful. Pentafluorobenzaldoxime was prepared by oximation of pentafluorobenzaldehyde. Acid dissociation constants (pKa) and second-order rate constants (kox-) of the fluorinated pyridinealdoximes towards sarin were measured. 2,3,5,6-Tetrafluoropyridine-4- aldoxime had the best profile: its kox- approached that of the therapeutic oxime P2S (310 vs. 120 l mol-1 min-1), but its higher pKa (9.1 vs. 7.8) fell short of the target figure of 8 required for reactivation of inhibited acetylcholinesterase in vivo. N-alkylation of the fluorinated pyridine-aldoximes may reduce their pK a nearer to 8 and enhance their therapeutic potential. Crown Copyright
- Timperley, Christopher M.,Banks, R. Eric,Young, Ian M.,Haszeldine, Robert N.
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scheme or table
p. 541 - 547
(2011/09/15)
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- An alternate route to 2-amino-3-nitro-5-bromo-4-picoline: Regioselective pyridine synthesis via 2-nitramino-picoline intermediate
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The 2-nitramino functionality in 2-nitramino-4-picoline was successfully exploited not only as a protecting group but also as a directional handle to afford an efficient, atom-economic, and regioselective synthesis of 2-amino-5-bromo-3-nitro-4-picoline (4), a precursor for a drug candidate in development.
- Bhattacharya, Apurba,Purohit, Vikram C.,Deshpande, Prashant,Pullockaran, Annie,Grosso, John A.,DiMarco, John D.,Gougoutas, Jack Z.
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p. 885 - 888
(2012/12/30)
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- SYNTHESES WITH AROMATIC NITRAMINES, VI SUBSTITUENT EFFECT IN THE PHOTOLYTIC REARRANGEMENT OF NITRAMINOPYRIDINES
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All isomeric ring-substituted methyl-2-nitraminopyridines, both 3-nitro- and 5-nitro-2-nitraminopyridines, 5-chloro- and 3-carboxy-2-nitraminopyridines, as well as 3,5-dibromo-2-nitraminopyridine were photolyzed in methanol by irradiation with a low-pressure mercury lamp (253.7 nm).Preference was generally noted for the migration of the side-chain nitro group to the vicinal β-position. 3,5-Dibromo-2-nitraminopyridine gave both 2-amino-3,5-dibromopyridine and 3,5-dibromopyridine-2-one.The ratio of the preparative and quantum yields of the two products were 2.5 and 3.0, respectively.
- Sepiol, Jadwiga,Tomasik, Piotr
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p. 333 - 338
(2007/10/02)
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- The Effect of Acid Concentration on the Pyridine Nitramine Rearrangement: an N.M.R. Study
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The rearrangement of 2- and 4-nitraminopyridines in 70-95percent sulfuric acid has been investigated by n.m.r.Ring nitration is favoured by conditions leading to initial dissociation of the nitramine, and the results provide no support for an intramolecul
- Deady, Leslie W.,Korytsky, Olga L.
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p. 1159 - 1166
(2007/10/02)
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- Kinetic Studies of the Mechanism of the Nitraminopyridine Rearrangement
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Rate data are reported for the rearrangement, in 92percent sulfuric acid at 30 deg C, of a series of 4-X-2-nitraminopyridines (X=H, Me, Br, Cl, MeO, CO2H) and of 4-methyl-2-nitramino(3-D)-pyridine.Values of pKa for second protonation of the corresponding pyridin-2-amines were also measured and rate constants for nitration of the monoprotonated pyridinamines were thereby calculated.The results suggest that the rate-determining step occurs prior to formation of the appropriate 3- and 5-nitro ? complexes.The nature of this step is not clear, however, and a key role for the nitramine itself is not proven by the current evidence
- Deady, Leslie W.,Korytsky, Olga L.
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p. 2035 - 2040
(2007/10/02)
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