- Kinetics and product distribution of 1-adamantyl picrate heterolysis in acetonitrile in the presence of triphenylverdazyls
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The reaction of triphenylverdazyls with strong acids in acetonitrile in the presence of salts with chloride anion is reversible. The observed rate of the heterolysis of 1-adamantyl picrate in the presence of triphenylverdazyls does not depend on the subst
- Serebryakov,Moiseeva
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- General-Base Catalysis in the Reaction of Water with Activated Aromatic Substrates. The Hydrolysis of 3-Methyl-1-picrylimidazolium Ion
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The rate of hydrolysis of 3-methyl-1-picrylimidazolium ion was investigated between pH 1.7 and 9.3 in the presence of several buffer bases at various concentrations.The reaction is strongly catalyzed by oxygen bases.The catalytic constants including water and OH- are spread over a range of ten powers of ten and show a good Broensted correlation with β=0.62.The kinetic solvent isotopic effect for the water-, acetate-, and OH--catalyzed reactions are 2, 0.86, and 0.84, respectively.The mechanism of catalysis is discussed, and it is concluded that it represents concerted addition of water to the aromatic ring.
- Rossi, Rita H. de,Veglia, Alicia
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- Medium effect on the reaction of N-butyl-2,4,6-trinitroaniline with NaOH
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The kinetics of the reaction of N-butyl-2,4,6-trinitroaniline (3) with NaOH have been studied in 10 and 60% 1,4-dioxane/H2O at 25 °C. In both cases, several processes were observed. In 10% 1,4-dioxane/H2O the only product formed was 2,4,6-trinitrophenol (4), whereas in 60% 1,4-dioxane/ H2O a mixture of 4 and 5,7-dinitro-2-propyl-1H-benzimid- azole 3-oxide (5) was observed in ratios that depend on the HO- concentration. A mechanism involving the formation of a complexes through the addition of one or two HO- anions to unsubstituted ring positions is proposed for 2,4,6-trinitrophenol formation. The presence of these complexes was confirmed by NMR studies in 60% [D8]1,4-dioxane/D2O. The mechanism suggested for the formation of the N-oxide includes the cyclization of an N-alkylidene-2-nitrosoaniline-type intermediate as the rate-determining step. The decrease in solvent polarity produces a decrease in the observed rate constant for the formation of 4 of about one order of magnitude making the cyclization reaction a competitive pathway. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Salum, Maria Laura,De Rossi, Rita H.,Bujan, Elba I.
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- Supramolecular structure of 2,4,6-trinitrophenol
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The compound 2,4,6-trinitrophenol with the molecular formula C6H3N3O7, crystallizes with two crystallographically independent but chemically identical molecules in the asymmetric unit. The dihedral angle formed by the two benzene rings is about 67.49. The
- Sun, Yin-Xia,Ren, Zong-Li,Meng, Wei-Sheng
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- Nitration of aromatics with dinitrogen pentoxide in a liquefied 1,1,1,2-tetrafluoroethane medium
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Regardless of the sustainable development path, today, there are highly demanded chemical productions still operating that bear environmental and technological risks inherited from the previous century. The fabrication of nitro compounds, and nitroarenes in particular, is traditionally associated with acidic wastes formed in nitration reactions exploiting mixed acids. However, nitroarenes are indispensable for industrial and military applications. We faced the challenge and developed a greener, safer, and yet effective method for the production of nitroaromatics. The proposed approach comprises the application of an eco-friendly nitrating agent, namely dinitrogen pentoxide (DNP), in the medium of liquefied 1,1,1,2-tetrafluoroethane (TFE) - one of the most non-hazardous Freons. Importantly, the used TFE is not emitted into the atmosphere but is effortlessly recondensed and returned into the process. DNP is obtainedviathe oxidation of dinitrogen tetroxide with ozone. The elaborated method is characterized by high yields of the targeted nitro arenes, mild reaction conditions, and minimal amount of easy-to-utilize wastes.
- Fauziev, Ruslan V.,Kharchenko, Alexandr K.,Kuchurov, Ilya V.,Zharkov, Mikhail N.,Zlotin, Sergei G.
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p. 25841 - 25847
(2021/08/09)
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- Visible-Light-Induced Radical Polynitration of Arylboronic Acids: Synthesis of Polynitrophenols
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We report a visible light-assisted one-pot method for the synthesis of polynitrophenols through radical tandem hydroxylation and nitration of arylboronic acids by utilizing copper(II) nitrate tri-nitydrate as the nitro source. This method features mild conditions, a simple procedure, and good functional group tolerance. Compared to conventional methods, this work provides a straightforward approach for the polynitration of aromatic compounds.
- Zhang, Qi,Raveendra Babu, Kaki,Huang, Zhouliang,Song, Jinna,Bi, Xihe
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p. 2891 - 2896
(2018/06/20)
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- Effect of medium acidity on the efficiency of oxidation of 2,4,6-trinitrotoluene to 2,4,6-trinitrobenzoic acid
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An effect of boric acid additives on oxidation of 2,4,6-trinitrotoluene (TNT) to 2,4,6-trinitrobenzoic acid (TNBA) with chromic anhydride in concentrated (96—100%) H2SO4 has been studied. In the presence of tetrahydrosulfatoboric acid HB(HSO4)4 formed in situ (up to 5 mol.%) or added as a preliminary prepared solution (up to 1 mol. %), TNT is selectively oxidized to TNBA in the yields up to 95—99%. The mechanism including formation of TNT dication as a key step of its oxidation at the methyl group has been suggested.
- Мikhalchenko,Leibzon,Leonova, M. Yu.,Gultyai
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p. 2216 - 2219
(2017/05/12)
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- O-Phenylisourea Synthesis and Deprotonation: Carbodiimide Elimination Precludes the Reported Chapman Rearrangement
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The kinetics of the addition of phenol to diisopropylcarbodiimide, and reaction of the resulting N,N′-diisopropyl-O-phenylisourea with hydroxide, are reported. The isourea is generated by a slow overall termolecular equilibrium process, inhibited by isourea–phenol salt generation. In contrast to an earlier report, reaction of the isourea with hydroxide does not induce a synthetically useful 1,3-O–N (Chapman) rearrangement. Instead, deprotonation results in solvolysis by carbodiimide elimination.
- Tate, Joseph A.,Hodges, George,Lloyd-Jones, Guy C.
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p. 2821 - 2827
(2016/07/07)
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- Tuning the intramolecular charge transfer (ICT) process in push-pull systems: Effect of nitro groups
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The intramolecular charge transfer (ICT) process in donor-acceptor systems has tremendous importance in various physical and biological systems. Three nitrophenolate salts were synthesized and studied here. The ICT and π → π? transition processes were identified in these derivatives using UV-Vis spectroscopy and theoretical calculations. It was observed that by simple substitution with nitro groups, one can generate and control the ICT process by regulating the charge distribution over the molecule. While for a monosubstitute nitro derivative, only one ICT band was observed, additional ICT processes can be generated at will by introducing a second nitro group. The intensity of this second ICT channel can be regulated with introduction of a third nitro group. Further, the association constants and solvation processes for these potassium nitrophenolate derivatives were found to be drastically dependent on the number of ICT channels present in the molecule. Theoretical studies (MEP analysis) support the experimental observations presented here. The results show that by simply introducing additional acceptor groups to the system, one can tune the ICT band efficiently in a conjugate system.
- Panja, Sumit Kumar,Dwivedi, Nidhi,Saha, Satyen
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p. 105786 - 105794
(2016/11/18)
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- Spectroscopic and thermal investigations on the charge transfer interaction between risperidone as a schizophrenia drug with some traditional π-acceptors: Part 2
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The focus of present investigation was to assess the utility of non-expensive techniques in the evaluation of risperidone (Ris) in solid and solution states with different traditional π-acceptors and subsequent incorporation of the analytical determination into pharmaceutical formulation for a faster release of risperidone. Charge-transfer complexes (CTC) of risperidone with picric acid (PA), 2,3-dichloro-5,6-dicyano-p-benzoquinon (DDQ), tetracyanoquinodimethane (TCNQ), tetracyano ethylene (TCNE), tetrabromo-p-quinon (BL) and tetrachloro-p-quinon (CL) have been studied spectrophotometrically in absolute methanol at room temperature. The stoichiometries of the complexes were found to be 1:1 ratio by the photometric molar ratio between risperidone and the π-acceptors. The equilibrium constants, molar extinction coefficient (εCT) and spectroscopic-physical parameters (standard free energy (ΔGo), oscillator strength (f), transition dipole moment (μ), resonance energy (RN) and ionization potential (ID)) of the complexes were determined upon the modified Benesi-Hildebrand equation. Risperidone in pure form was applied in this study. The results indicate that the formation constants for the complexes depend on the nature of electron acceptors and donor, and also the spectral studies of the complexes were determined by (infrared, Raman, and 1H NMR) spectra and X-ray powder diffraction (XRD). The most stable mono-protonated form of Ris is characterized by the formation of +NH (pyrimidine ring) intramolecular hydrogen bonded. In the high-wavenumber spectral region ~3400 cm-1, the bands of the +NH stretching vibrations and of the pyrimidine nitrogen atom could be potentially useful to discriminate the investigated forms of Ris. The infrared spectra of both Ris complexes are confirming the participation of +NH pyrimidine ring in the donor-acceptor interaction.
- El-Habeeb, Abeer A.,Al-Saif, Foziah A.,Refat, Moamen S.
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p. 464 - 477
(2013/04/23)
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- IR, 1H-NMR, UV-Vis and thermal studies on the rhodamine 6G chargetransfer complexes
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Charge-transfer (CT) complexes formed between Rhodamine 6G (Rh6G) as donor with iodine, CLA and PA as acceptors have been studied spectrophotometrically. The synthesis and characterization of Rhodamine 6G CT-complexes of iodine, [(Rh6G)2]I+.I3-, chloranilic acid (CLA), [(Rh6G)(CLA)] and picric acid (PA) [(Rh6G)(PA)] were described. These complexes are readily prepared from the reaction of Rh6G with I2, CLA and PA with CHCl3 solvent. Mid and far IR, 1H-NMR, UV-Vis techniques, elemental analyses (CHN) and thermal studies, characterize the three new Rhodamine 6G charge-transfer complexes. Modified Benesi-Hildebrand method was applied to the determination of association constant and molar extinction coefficient.
- Refat, Moamen S.,Killa, Hamada M.A.,El-Sayed
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experimental part
p. 137 - 146
(2012/05/31)
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- Reactivity of α-amino acids in the N-acylation with benzoic acid esters in aqueous dioxane
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The effect of the nitro group as a substituent in the phenoxide part of phenyl benzoate on the rate of N-acylation of glycine, L-proline,and L-valine in the water (40 wt %)-dioxane solvent was studied. The activation parameters of glycine reactions with the esters were measured. The existence of compensation effect and the linear relation of the logarithms of the acylation constants to the Hammett constants were revealed. The energy of the LUMO of esters can serve as the descriptors of the easters reactivity. Pleiades Publishing, Ltd., 2010.
- Ishkulova,Oparina,Kochetova,Kustova,Kalinina,Kuritsin
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experimental part
p. 964 - 967
(2011/01/07)
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- Reaction of poly-L-lysine with aryl acetates and aryl methyl carbonates. A mechanistic study
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The pH profile (log k vs. pH) of the reactions of poly-L-lysine (PL) with a series of aryl acetates and aryl methyl carbonates in aqueous solution show the same conformational changes as those determined by potentiometric titrations. When PL is a random coil, the most probable mechanism for the reactions studied is through the formation of a tetrahedral intermediate and its breakdown to products as the rate-determining step. The tetrahedral intermediate is stabilized by a hydrogen bond interaction between the nitro groups in the substrate and the NH group of the principal chain or some NH2 groups of the lateral chains. Copyright
- Castro, Enrique A.,Echevarria, Gerardo R.,Opazo, Alejandra,Robert, Paz S.,Santos, Jose G.
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- Kinetics and mechanism of the reactions of polyallylamine with aryl acetates and aryl methyl carbonates
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The reactions of polyallylamine (PAA) with 4-nitrophenyl acetate (NPA), 2,4-dinitrophenyl acetate (DNPA), 2,4,6-trinitrophenyl acetate (TNPA), 4-nitrophenyl methyl carbonate (NPC), 2,4-dinitrophenyl methyl carbonate (DNPC) and 2,4,6-trinitrophenyl methyl carbonate (TNPC) at pH 7.0-11.5 were subjected to a kinetic investigation in aqueous solution at 25.0°C and an ionic strength of 0.1 M (KC1). Potentiometric titration curves were obtained at different polymer concentrations under the same conditions as for the kinetic measurements. The degree of dissociation (a) and pKapp values for PAA at each pH were found from the titration curves. The shape of these curves shows a conformational change of the polymer at α > 0.7. Similar behavior was observed through the dependence of logkN on either pH or a, where kN is the second-order rate constant for the title reactions. The KN value is influenced by the electrostatic interactions in the polymer chain and the conformational changes that PAA undergoes in solution. The Bronsted-type plots (logkN vs pkapp) are linear with slopes (β values) of 0.5, 0.4, 0.5, 0.7, 0.6 and 0.7 for the reactions of PAA with NPA, DNPA, TNPA, NPC, DNPC and TNPC, respectively. These data are consistent with concerted mechanisms. The k N values increase in the sequence TNPA > DNPA > NPA and TNPC > DNPC > NPC. These results are in accordance with those found for the reactions with monomeric amines, which are due to the increasing nucleofugality of the leaving groups, and also the increasing electrophilic character of the carbonyl carbon, as more nitro groups are added to the substrate. Acetates are more reactive than the corresponding methyl carbonates, which can be explained by the larger electron-releasing effect exerted by MeO relative to Me. PAA destabilizes the putative tetrahedral intermediate relative to the monomeric amines and the stability of tetrahedral intermediates would decrease in the sequence pyridines > anilines > secondary alicyclic amines > quinuclidines > PAA. Copyright
- Castro, Enrique A.,Echevarria, Gerardo R.,Opazo, Alejandra,Robert, Paz S.,Santos, Jose G.
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p. 129 - 135
(2007/10/03)
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- Nitration of aromatic compounds by Zn(NO3)2· 2N2O4 and its charcoal-supported system
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Zn(NO3)2·N2O4 and its charcoal supported system were found to be efficient nitrating agents. Mononitration of aromatic compounds such as benzene, alkyl benzenes, halobenzenes, nitrobenzene, anisol, and the highly selective mono-, di-, and trinitration of phenol, and dinitraion of substituted phenols were also performed in the presence of these reagents.
- Iranpoor, Nasser,Firouzabadi, Habib,Heydari, Reza,Shiri, Morteza
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p. 263 - 270
(2007/10/03)
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- Microwave assisted synthesis of an unusual dinitro phytochemical
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A novel dinitro secondary metabolite, 2-nitro-4-(2′-nitroethenyl) phenol has been isolated from a marine source. This metabolite was synthesized first (in 1964 in Japan) and discovered later (in 1991 in India) as a natural product. We describe here a new synthesis via highly accelerated, microwave assisted, nitration reactions using mild reagents. ipso-Substitution of a carboxy group by a nitro group is discussed.
- Bose, Ajay K.,Ganguly, Subhendu N.,Manhas, Maghar S.,Srirajan, Vaidyanathan,Bhattacharjee, Ashoke,Rumthao, Sochanchingwung,Sharma, Anju H.
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p. 1179 - 1181
(2007/10/03)
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- Synthesis of condensed nitrofuroxanes using hydroxylamine
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The possibility of preparing condensed nitrofuroxanes using hydroxylamine was examined.
- Klyuchnikov,Starovoitov,Khairutdinov,Golovin
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p. 853 - 854
(2007/10/03)
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- Silica-acetate complex of N2O4: A heterogeneous reagent for the selective nitration of phenols and nitrosation of thiols
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Complexation of gaseous N2O4 with acylated silica gel affords an addition compound, which is an efficient heterogeneous reagent for the selective mono- and dinitration of phenol, substituted phenols and nitrosation of thiols.
- Iranpoor,Firouzabadi,Heydari
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p. 703 - 710
(2007/10/03)
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- Method for the synthesis of pyrrole and imidazole carboxamides on a solid support
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The present invention describes a novel method for the solid phase synthesis of polyamides containing imidazole and pyrrole carboxamides. The polyamides are prepared on a solid support from aromatic carboxylic acids and aromatic amines with high stepwise coupling yields (>99%), providing milligram quantities of highly pure polyamides. The present invention also describes the synthesis of analogs of the natural products Netropsin and Distamycin A, two antiviral antibiotics. The present invention also describes a novel method for the solid phase synthesis of imidazole and pyrrole carboxamide polyamide-oligonucleotide conjugates. This methodology will greatly increase both the complexity and quantity of minor-groove binding polyamides and minor-groove binding polyamide-oligonucleotide conjugates which can be synthesized and tested.
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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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- Kinetics and mechanism of reactions between 2,4,6-trinitrofluorobenzene and alcohols
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The kinetics of formation of some ethers from alcohols and 2,4,6-trinitrofluorobenzene were studied under first order conditions ([ROH]o > [TNFB]o). In CCl4, k (in dm3 s-1 mol-1) values are increased on increasing the values of the initial concentrations of the alcohols. This anomalous kinetic behaviour parallels that of reactions between amines and activated aromatic fluoro derivatives. The presence of a substrate-alcohol interaction which precedes the substitution process explains the kinetic behaviour of the alcohols.
- Forlani, Luciano,Boga, Carla,Forconi, Marcello
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p. 1455 - 1458
(2007/10/03)
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- From N-n-butyl-2,6-dinitroaniline to a fused heterocyclic N-oxide
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The reaction of N-n-butyl-2,6-dinitroaniline with NaOH in 60% dioxane-water at reflux gives 7-nitro-2-n-propylbenzimidazole-3-oxide quantitatively.
- De Vargas, Elba Bujan,Canas, A. Irene
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p. 767 - 770
(2007/10/03)
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- Thermal Stability Studies on a Homologous Series of Nitroarenes
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The thermal stabilities of a number of nitroarenes were examined in solution and in condensed phase.In general, increasing the number of nitro groups decreased thermal stability.Changing the substituent on 1-X-2,4,6-trinitrobenzene from X = H to NH2 to CH3 to OH accelerated decomposition; this effect was attributed to increased ease of intramolecular proton transfer to an ortho nitro group, thus weakening the carbon-nitrogen bond.In solution, the effect of increasing substitution from n = 1 to n = 3 on Xn(NO2)3C6H3-n was uniformly that of decreasing the thermal stability of the species.However, in condensed phase, results suggested that crystal habit may be more important than molecular structure; for X = Br, CH3, and NH2, the more substituted species was the more stable.
- Oxley, Jimmie C.,Smith, James L.,Ye, Hong,McKenney, Robert L.,Bolduc, Paul R.
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p. 9593 - 9602
(2007/10/02)
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- Photochemical Nitration by Tetranitromethane. XV. Formation of Adducts and their Secondary Products in the Photochemical Reaction between Benzene and Tetranitromethane
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Photolysis of benzene/tetranitromethane in dichloromethane or acetonitrile with light of λ>435 nm gives four main product categories, namely, in dichloromethane at +20 deg C (relative yield, products): adducts 1 of hydroxy/trinitromethyl type (total 54percent, see below), nitro substitution products (total 8percent, nitrobenzene, 1,3-dinitrobenzene and 1,3,5-trinitrobenzene), trinitromethyl substitution products (26percent, trinitromethylbenzene, 1-nitro-4-trinitromethylbenzene, 1,3-dinitro-5-trinitromethylbenzene) and phenols (total 12percent, 2,4- and 2,6-dinitrophenol, 2,4,6-trinitrophenol). In acetonitrile at +20 deg C the same product groups comprised 15, 24, 39 and 18percent, respectively, and, in addition, a low yield (1.7percent) of what is formally a cycloaddition product between 4-nitrobenzonitrile N-oxide and acetonitrile, 5-methyl-3-(4-nitrophenyl)-1,2,4-oxadiazole 2. The structure of 2 was determined by single crystal X-ray analysis. The main adducts were assigned the structures of a cis/trans pair of 1-hydroxy-4-trinitromethylcyclohexa-2,5-diene (NMR). Their formation in both dichloromethane and acetonitrile shows that adduct formation from photolysis of tetranitromethane/aromatics is not only confined to polycyclic aromatics but can occur with a maximally resonance-stabilized system, like benzene itself. The high complexity of the product mixture can be explained partly by elimination reactions of adducts, combined with further thermal and photochemical transformations.
- Eberson, Lennart,Calvert, Jane L.,Hartshorn, Michael P.,Robinson, Ward T.
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p. 347 - 355
(2007/10/02)
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- 14N-15N Exchange at an Aromatic Nitro Group During Nitration with Acetyl Nitrate
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Acetyl nitrate prepared from nitric acid and acetic anhydride react with 2,6-dinitrophenol 1 and with 2,4,6-trinitrophenol 2.If 15N -labelled nitric acid is used to prepare the reagent, the label is found at all nitro groups of the products.These results demonstrated isotopic exchange of the nitro groups, and suggest that the reaction may occur by ipso substitution at the existing nitro groups of the aromatic substrates. isotopic exchange, nitration, 15N NMR
- Konior, R.J.,Walter, R.I.,Bologa, U.L.,Caproiu, M.T.,Balaban, A.T.
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p. 2451 - 2454
(2007/10/02)
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- Kinetic and Equilibrium Studies of ?-Adduct Formation and Nucleophilic Substitution in the Reactions of Hydroxide Ions with 2,4,6-Trinitrophenyl Sulfides and Ethers
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Kinetic and equlibrium data are reported for reaction of hydroxide ions in 20/80 DMSO/water (v/v) with a series of 4'-substituted phenyl 2,4,6-trinitrophenyl sulfides, 1, and with ethyl thiopicrate, 2, ethyl picrate, 3, phenyl picrate, 4, and 1,3,5-trinitrobenzene, 5.In each case a rapid reaction is observed involving reversible hydroxide addition at an unsubstituted ring-position.In the case of 1-4 this is followed by slower, irreversible attack at the 1-position leading to the formation of picric acid.The Hammett ρ value for equilibrium addition of hydroxide to the 3-position of 1 is 0.98, and the ρ value for rate constants for attack at the 1-position is 0.62.The results are discussed in terms of the electronic and steric effects of the 1-substituents.Comparison of 1-5 indicates that changing from an OR to SR group introduces additional steric crowding.However for the reactions studied changing from R = Et to R = Ph has little steric consequence.
- Chamberlin, Rachel,Crampton, Michael R.,Knight, Roland L.
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p. 2986 - 2998
(2007/10/02)
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- Vicarious Nucleophilic Hydroxylation of Aromatic Nitro Compounds with Organic Hydroperoxides
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Nitrobenzene, α-nitronaphthalene, m-dinitrobenzene, 1,3,5-trinitrobenzene, m-nitrobenzophenone, m-nitrobenzonitrile, methyl m-nitrobenzoate and m-nitro diphenylsulphone can be hydroxylated with cumene or tert-butyl hydroperoxide in dipolar aprotic solvents in the presence of strong bases.The hydroxyl group is introduced preferably in p-position to the nitro group.Attempts to hydroxylate benzophenone, anthraquinone, 2-ethyl anthraquinone, anthraquinone 2-sulphonate, benzonitrile and diphenyl sulphone under the same conditions failed. 1-Nitroanthraquinone delivered 1-hydroxy, 1,2-dihydroxy and 1,4-dihydroxy anthraquinone.
- Brose, Thomas,Holzscheiter, Felix,Mattersteig, Gunter,Pritzkow, Wilhelm,Voerckel, Volkmar
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p. 497 - 504
(2007/10/02)
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- Ullmann reaction of picryl bromide in the presence of ultrasound
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Ultrasonic irradiation was found to promote the Ullman coupling of picryl bromide at or below room temperature. In the presence of excess copper, a long-lived intermediate is formed that is quenched upon work-up affording variable mixtures of trinitrobenzene and picric acid.
- Nelson,Adolph
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p. 293 - 305
(2007/10/02)
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- SPECTROPHOTOMETRIC INVESTIGATIONS OF THE REACTION OF PICRIC ACID WITH SOME ANILINE DERIVATIVES IN ACETONITRILE
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Using the spectrophotometric method UV-VIS the reaction of picric acid with some monosubstituted aniline derivatives in acetonitrile has been investigated.Overall equilibrium picrate formation constants KBHA and molar fraction of the molecular product B...HA in equilibrium have been calculated.
- Smagowski, Henryk
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p. 175 - 181
(2007/10/02)
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- POTENTIOMETRIC STUDIES ON THE REACTION OF PICRIC ACID WITH SOME AROMATIC AMINES IN METHYL ISOBUTYL KETONE
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The reaction between picric acid and some aniline and pyridine derivatives has been investigated in methyl isobutyl ketone by the potentiometric method.Overall picrate formation constants KBHA, ammonium cationic acid dissociation constants KBH+ and apparent ion-pair formation Ki* and dissociation Kd* constants have been determined.
- Smagowski, Henryk,Bartnicka, Halina
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p. 201 - 209
(2007/10/02)
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- Reaction Between 2-Aminoazoles and Picryl Derivatives: Products and Structures
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The reactions of some 2-pyridinamine derivatives with 2,4,6-trinitro-chlorobenzene (or -fluorobenzene) afford products of condensation on the exocyclic nitrogen. 2-Thiazolamine derivatives react with picryl halides with both nitrogen atoms, exocyclic and endocyclic and, in some cases, with the carbon in position 5 of the thiazole ring.The structures of some of the products of the reactions reported in the literature are revised and corrected (also by X-ray diffraction) for both thiazole and pyridine systems.The difference in behaviour of two aminoazoles is explained by differences in the electron-releasing power of the amino group toward the nitrogen which is more effective in withdrawing electrons in the thiazole system thanin the pyridine one.The regioselectivity of the attack of the electrophiles to 2-thiazolamine is explained by the different polarizability requirements of the three centres involved, and by their different steric reguirements.From 1H NMR spectral data, it is possible to state that N-picryl-2-thiazolamine is mainly in the imino form in polar solvents, while the amino form predominates in apolar solvents.
- Forlani, Luciano,Guastadisegni, Grazia,Raffellini, Luca,Todesco, Paolo E.,Foresti, Elisabetta
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p. 493 - 499
(2007/10/02)
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- Kinetic and Thermodynamic Preferences in the Reactions of Thiolate Ions with 1-Substituted-2,,4,6-trinitrobenzene
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Kinetic and equilibrium data are reported for reaction in water of ethanethiolate, thioglycolate, and thiomalate ions with 1-X-2,4,6-trinitrobenzenes (X=H, SEt, OEt, and Cl).The thiolate ions show strong kinetic preference for attack at unsubstituted ring positions.However, the isomeric 1:1 adducts formed by attack at substituted and unsubstituted positions have similar thermodynamic stabilities.The latter is in marked contrast with corresponding reactions of alkoxides.Adducts of stoicheiometry thiolate:nitro compound (2:1) are formed by thiolate attack at two unsubstituted ring positions and are stabilised in water by the good solvation of negative charge localised on the nitro groups.A 3:1 adduct has been identified by reaction of ethanethiolate ions with 1,3,5-trinitrobenzene and the kinetic data recorded.Comparison of nucleophilic attack by thiolate ions and by hydroxide ions indicates that the kinetic barrier to reaction with thiolates is considerably lower than for reaction with the oxygen base; a consequence is that (5; X=OEt) is an observable intermediate during nucleophilic substitution. 1H NMR measurements in DMSO have been used to examine the structures of intermediates and reaction products; they show the irreversible displacement of nitro groups by thiolate ions.
- Crampton, Michael R.,Stevens, J. Andrew
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p. 1097 - 1103
(2007/10/02)
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- Isotopic Fractionation Factor of the Hydrogen-Bonded Complex AcO(1-)...(HOAc)n and Kinetic and Equilibrium Solvent Isotope Effects on Reactions of Acetate Ion in Acetic Acid
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A value of φ 0.58+/-0.05 has been obtained for the deuterium fractionation factor of the hydrogen-bonded complex AcO(1-)...(HOAc)n from (1)H n.m.r. studies of solutions of potassium acetate in AcOH and 97percent AcOD-3percent AcOH.The result is used to account for the kinetic solvent isotope effect 0.66+/-0.10 measured for formation of acetic anhydride from 2,4,6-trinitrophenyl acetate in AcOH and AcOD in the presence of potassium acetate.The equilibrium solvent isotope effect on complex formation between 2,4,6-trinitrophenol and acetate ion in AcOH and 97percent AcOD-3percent AcOH KAcOH/KAcOD 0.83+/-0.1, leads to a value φ ca. 0.7 for the complex (1-).
- Clark, David R.,Emsley, John,Hibbert, Frank
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p. 919 - 922
(2007/10/02)
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- REACTIONS OF PICRIC ACID WITH AROMATIC AMINES IN ACETONITRILE MEDIUM
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Resorting to the potentiometric method studies were carried out on the reaction between picric acid and some aniline derivatives in acetonitrile medium.General equilibrium constants of the reaction, KBHA were determined, as well as the constants of formation (K*i) and dissociation (K*d) of ion pair BH+A- in this medium.
- Smagowski, Henryk
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p. 449 - 455
(2007/10/02)
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- INTRAMOLECULAR ELECTROPHILIC DISPLACEMENT OF ACYL BY NITRO GROUP DURING ATTEMPTED SYNTHESIS OF 3-NITROCOUMARINS
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2-Hydroxyacetophenones undergo upon nitration in acetic acid a substitution of the acyl by nitro group followed by an intramolecular 1,3-acyl shift reminescent of a retro-Fries rearrangement to yield phenyl esters.
- Benedikt, George M.,Traynor, Lee
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p. 763 - 766
(2007/10/02)
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- LIQUID-PHASE OXIDATION OF o-NITROTOLUENE BY NITRIC ACID.
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The kinetics of oxidation of o-nitrotoluene were investigated and methods of optimizing the process, directed toward increasing the yield of o-nitrobenzoic acid and decreasing the concentration of picric acid in the products of the reaction, were sought in the present study. The mechanism of oxidation of the methyl group in o-nitrotoluene includes elimination of the hydrogen atom in the methyl group under the effect of free radicals, and this stage apparently limits the rate of the entire process. The results obtained indicate that o-nitrobenzoic and picric acid are formed in both cases, and the rate of these reactions is much higher than the rate of oxidation of o-nitrotoluene. The anomalous character of oxidation of o-nitrotoluene in comparison to o-, m-, p-chloro- and m-p-nitrotoluenes is due to the additional reaction of the nitro group with the partially oxidized methyl fragment.
- Sushchev,Dolmatov,Aleksenskii,V'yunov
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p. 1022 - 1026
(2007/10/02)
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- A Computerised Least Square Method for Determination of Stability Constants of 1:1 Molecular Complexes and Chemical Shift of Pure Complexes from Nuclear Magnetic Resonance Data
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A computerised method utilising nuclear magnetic resonance data has been developed for the determination of stability constants of 1:1 molecular complexes.It is based on the principle of least squares in which the coefficients are adjusted under a constraint with the help of Lagrange's method of undetermined multipliers.The method utilises the complete expression for equilibrium constant and is mathematically rigorous, straightforward, non-iterative and requires very little computer time.
- Seal, B. K.,Mukherjee, A. K.
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p. 413 - 415
(2007/10/02)
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- Mechanism of the Uncatalysed Path of Aromatic Nucleophilic Substitution in Dipolar Aprotic Solvents when Primary and Secondary Amines are the Nucleophiles; a Search for Electrophilic Catalysis of these Reactions
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The kinetics of the reactions of 1-chloro- and 1-fluoro-2,4-dinitrobenzene with morpholine have been studied in dimethyl sulphoxide, dimethylformamide, and nitromethane.The results confirm that the decomposition of the intermediate to products by the uncatalysed path takes place by a unimolecular mechanism.The kinetics of the reactions of 2,4-dinitroanisole with n-butylamine and piperidine in dipolar aprotic solvents have been determined.They show that when primary amines are the nucleophiles, reaction by the uncatalysed path does not occur by the unimolecular mechanism, but by the specific base-general acid (SB-GA) route.The reactions in dimethyl sulphoxide give another example of secondary amines reacting by a base catalysis mechanism whereas the corresponding reaction of a primary amine of the same basicity is not base-catalysed.In a search for electrophilic catalysis the effects of lithium, trialkylammonium, and tetraalkylammonium ions on the reactions of piperidine with 2,4-dinitroanisole and of morpholine with 2,4-dinitrophenyl phenyl ether in dimethyl sulphoxide were investigated.No catalysis was found and a tentative reason is given.When aniline reacts with 2,4,6-trinitrophenyl methyl ether in dimethyl sulphoxide, 82percent of the reaction occurs at the methyl carbon atom, and when the substrate is 2,4,6-trinitrophenyl phenyl ether the reaction is not base-catalysed.The first two observations of the change from base-catalysed to uncatalysed aromatic nucleophilic substitution reactions brought about by a change from protic to dipolar aprotic solvent are recorded.
- Hirst, Jack,Hussain, Ghazanfar,Onyido, Ikenna
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p. 397 - 404
(2007/10/02)
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- POLYPHENOLS FROM DIPTEROCARP SPECIES. VATICAFFINOL AND &ε-VINIFERIN
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A dipterocarp endemic to Sri Lanka, Vatica affinis, yielded three phenols.Two of them showed antibacterial properties and have been shown to be the dimer and tetramer of 3,5,4'-trihydroxystilbene.
- Sotheeswaran, Subramaniam,Sultanbawa, M. Uvais S.,Surendrakumar, Sivagnanasundram,Balasubramaiam, Sinnathamby,Bladon, Peter
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p. 159 - 162
(2007/10/02)
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- POTENTIOMETRIC STUDIES ON PICRIC ACID REACTION WITH SOME ANILINE DERIVATIVES IN NITROMETHANE
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The reaction between picric acid and some aniline derivatives in nitromethane has been investigated by the potentiometric method.Constants of forming picrates (KBHA), dissociation constants of anilinium ions (KBH+) and ion-pairs formation and dissociation constants (K*i and K*d) have been determined.
- Smagowski, Henryk
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p. 305 - 310
(2007/10/02)
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- A STUDY OF REACTION OF AROMATIC POLYNITRO COMPOUNDS WITH TRIBUTYLSTANNYL HYDRIDE
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1H, 13C, 15N, and 119Sn NMR spectra have been used to study composition and structure of reaction products from 1,3,5-trinitrobenzene, methyl 2,4,6-trinitrobenzoate, 1-dimethylamino-2,4,6-trinitrobenzene, 1-methoxy-2,4,6-trinitrobenzene, 1-chloro-2,4,6-trinitrobenzene, 2,4,6-trinitrotoluene, 3,5-dinitrobenzonitrile and methyl 3,5-dinitrobenzoate with tributylstannyl hydride in the presence of tetramethylammonium bromide.
- Machacek, Vladimir,Lycka, Antonin,Nadvornik, Milan
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p. 2598 - 2606
(2007/10/02)
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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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- KINETICS OF REACTION OF 1-CHLORO-2,4,6-TRINITROBENZENE WITH ENOLATE IONS OF 2,4-PENTANEDIONE AND METHYL 3-OXOBUTANOATE
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Reaction of 1-chloro-2,4,6-trinitrobenzene (I) with anions of 2,4-pentanedione (II) and methyl 3-oxobutanoate (III) produces 3-(2,4,6-trinitrophenyl)-2,4-pentanedione (IV) and methyl 2-(2,4,6-trinitrophenyl)-3-oxobutanoate (V), respectively, besides 2,4,6-trinitrophenol (VI).Amount of 2,4,6-trinitrophenol decreases with increasing amount of dimethyl sulphoxide and 2,4-pentanedione in methanol.A mechanism of formation of 2,4,6-trinitrophenol is suggested.Rate constant of formation of 3-(2,4,6-trinitrophenyl)-2,4-pentanedione in methanol-dimethyl sulphoxide mixtures increases with increasing content of dimethyl sulphoxide and decreases with increasing LiCl concentration.In methanol, 1-chloro-2,4,6-trinitrobenzene reacts with anion of 2,4-pentanedione about 20x slower than with anion of methyl 3-oxobutanoate.
- Machacek, Vladimir,Andrle, Jaroslav,Sterba, Vojeslav
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p. 1608 - 1617
(2007/10/02)
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- 9-ACETOXYANTHRACENE DERIVATIVES. PART VIII. THE MECHANISM OF DEGRADATION OF 9-ACETOXY-10-ARYLANTHRACENES TO ANTHRAQUINONE
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The mechanism of degradation of 9-acetoxy-10-arylanthracenes to anthraquinone with the use of HNO3 in AcOH has been reported.This was proved by way of example on 9-acetoxy-10-(4'-acetoxyphenyl)anthracene (1) by means of separation and identification of intermediate products 2, 3 and 4.
- Gronowska, Janina,Dzielendziak, Adam
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p. 5575 - 5578
(2007/10/02)
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