- Preparation and catalytic performance of active metal sintered membrane reactor anchored with Pt atoms
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In the chemical industry, reactors are typically designed and filled with supported catalyst particles. However, the intrinsic problems associated with the internal/external diffusion effect and catalyst separation/loss in these traditional reactors can be very challenging to mitigate. To address these issues, herein, an active metal sintered membrane reactor anchored with Pt atoms was successfully developed, and applied into continuous, liquid-phase, hydrogenation processes. The catalyzing reactions transpired on the active sites that were fastened onto the surface of the reactor's microchannels. As a result, the mass transfer at the gas-liquid-solid three-phase was greatly enhanced, and an incredibly high reaction efficiency was obtained. The novel, active reactor demonstrated a superior catalytic performance and stability to nitrobenzene (NB) hydrogenation at 120 °C and 0.5 MPa H2, which enabled an aniline (ANI) yield of 19.28 molANI h-1 L-1. This work opens a new window for the design of high-performance gas-liquid-solid reactor toward multiphase catalytic reactions. This journal is
- Ren, Xiaoliang,Wang, Shufang,Ding, Xiaoshu,Zhang, Dongsheng,Wang, Yanji
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p. 2848 - 2853
(2021/01/28)
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- Synthesis, spectroscopic characterization, structural studies, thermal analysis and molecular docking of N-(2-methyl-5-nitrophenyl)-4-(pyridin-2-yl)pyrimidin-2-amine, a precursor for drug design against chronic myeloid leukemia
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The synthesis, crystal structure and spectroscopic and electronic properties of N-(2-methyl-5-nitrophenyl)-4-(pyridin-2-yl)pyrimidin-2-amine (NPPA), C16H13-N5O2, a potential template for drug design against chronic myelogenous leukemia (CML), is reported. The design and construction of the target molecule were carried out starting from the guanidinium nitrate salt (previously synthesized) and the corresponding enaminone. X-ray diffraction analysis and a study of the Hirshfeld surfaces revealed important interactions between the nitro-group O atoms and the H atoms of the pyridine and pyrimidine rings. A crystalline ordering in layers, by the stacking of rings through interactions of the π-π type, was observed and confirmed by a study of the shape-index surfaces and dispersion energy calculations. Quantitative electrostatic potential studies revealed the most positive value of the molecule on regions close to the N-H groups (34.8 kcal mol-1); nevertheless, steric impediments and the planarity of the molecule do not allow the formation of hydrogen bonds from this group. This interaction is however activated when the molecule takes on a new extended conformation in the active pocket of the enzyme kinase (PDB ID 2hyy), interacting with protein residues that are fundamental in the inhibition process of CML. The most negative values of the molecule are seen in regions close to the nitro group (-35.4 and -34.0 kcal mol-1). A molecular docking study revealed an energy affinity of ΔG = -10.3 kcal mol-1for NPPA which, despite not having a more negative value than the control molecule (Imatinib; ΔG = -12.8 kcal mol-1), shows great potential to be used as a template for new drugs against CML.
- Arango-Daravi?a, Kevin,Kennedy, Alan R.,Moreno-Fuquen, Rodolfo
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p. 621 - 632
(2021/10/12)
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- A polyamine dendritic polymer-copper complex: A reusable catalyst for the additive-free amination of aryl bromides, and iodides
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A porphyrin-initiated amine-functionalized polyepichlorohydrin dendritic polymer (PPECH-Amine) was effectively synthesized, and its water-soluble copper complex (PPECH-Amine-Cu) was developed by treating it with copper acetate. PPECH-Amine and PPECH-Amine-Cu were characterised by different spectroscopic and microscopic techniques. PPECH-Amine-Cu was identified as a reusable catalyst for the amination of bromo- and iodo-benzene derivatives in aqueous media. Due to the presence of residual amino groups in the PPECH-Amine-Cu catalyst, the protocol does not need any additional base additive, as ammonia itself acts as a base and a coupling partner. Due to the good water-soluble nature of this catalyst, it can be easily separated and reused up to six reaction cycles without any loss in its activity.
- Avudaiappan,Palmurukan,Unnikrishnan,Sreekumar
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p. 1477 - 1484
(2020/02/05)
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- Highly Selective Room Temperature Monoreduction of Dinitro-arenes by Hydrogen Sulfide under Liquid–Liquid Biphasic Catalysis
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Selective reduction of one of the nitro group present in dinitro aromatic compounds by a novel Zinin reagent, H2S-laden N-methyldiethanolamine (MDEA) solution, has been explored in the presence of tetra-n-butyl phosphonium bromide as a phase transfer catalyst under the liquid–liquid mode of reaction. Under the room temperature reaction condition, reduction of 2,4-dinitrotoluene (2,4-DNT) with H2S-laden MDEA leads to the selective reduction of one nitro group present either at the fourth position to obtain 4-amino-2-nitrotoluene (4A2NT) or at the second position to get 2-amino-4-nitrotoluene (2A4NT). The reaction was very fast to achieve 100% conversion, and the selectivity of 4A2NT is much higher than the 2A4NT. A detailed parametric study was performed to analyze the effect of parameters on 2,4-DNT conversion and selectivity of both the isomers. The apparent activation energy was found to be as high as 46.25 kJ/mol, and the reaction was found to be kinetically controlled. An empirical kinetic model has been developed to correlate with the conversion version time data obtained experimentally. The present system dealt with an industrial problem in dealing with H2S, present in by-product gaseous streams of many petroleum and natural gas industries. Novelties in the selective monoreduction lie in that fact that the reaction was done at room temperature (303 K), with a novel reagent, H2S-laden MDEA solution. Therefore waste-minimization was effected to yield value-added fine chemicals, that is, amines.
- Mondal, Ujjal,Sen, Sujit
-
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- RAF-DEGRADING CONJUGATE COMPOUNDS
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The present disclosure provides, inter alia, RAF-Degrading Conjugate Compounds that are useful in the treatment of cancer and other RAF related diseases. Also provided are, pharmaceutical compositions, methods of treatment, and kits comprising a RAF- Degrading Conjugate Compound.
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-
Paragraph 0209; 0229
(2018/11/22)
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- Novel fast scarlet base G production process
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The invention relates to a novel fast scarlet base G production process. A fast scarlet base G is an important constituent of an insoluble azo dyestuff and is mainly used for dyeing and printing a cotton fabric; the fast scarlet base G is coupled with azoic coupling component AS or AS-D to dye fast scarlet (Chinese red), can also be used for dyeing silk, viscose and nylon fabrics and is also used as an intermediate of an organic dyestuff. In a nitrification process, nitric acid and sulfuric acid are mixed at the ratio of 1 to 1.3 and then are nitrified; 50 percent of the sulfuric acid is cyclically utilized so that the flowability and conduction of a system are improved; liquid ammonia is used for neutralizing to obtain a byproduct with relatively high additional value; at a nitrification phase, the size of a kettle is enlarged and the kettle is made of 316L; meanwhile, a 5m built-in coiled pipe is additionally arranged in the kettle when a jacket is used for cooling, so that the cooling speed is greatly improved. The novel fast scarlet base G production process has the advantages of no pollution, high yield, low energy consumption, cyclic utilization of the byproducts, high additional value of the byproducts and the like; the novel fast scarlet base G production process has extremely high economic benefits and environment benefits.
- -
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Paragraph 0010
(2017/05/12)
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- A highly active non-precious metal catalyst based on Fe-N-C@CNTs for nitroarene reduction
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Research on transition metal-nitrogen-carbon (M-N-C) materials revealed their potential as catalysts in several important traditional reactions. However, the activity of M-N-C still needs to be further improved and the real active center of M-N-C catalysts is still under debate. In this work, an efficient Fe-N-C@CNTs for the hydrogenation of nitroarenes was prepared by pyrolysis of FeCl3, phenanthroline and CNTs. Fe-N-C supported on CNTs is much more active than that supported on activated carbon, showing the promotion effect of CNTs. The characterization results suggest that the high activity of Fe-N-C is mainly attributed to the formation of ?-Fe3N, which is the active site for the hydrogenation reaction. Nitrogen/carbon atoms contacted to the active centers could serve as bridges to transport the dissociated hydrogen atoms via spillover effect. The catalytic performance of Fe-N-C was also tested on fixed bed reactor under continuous flow condition for the first time and could smoothly catalyze the reaction for over 300 hours.
- Chen, Jian,Yao, Yi,Zhao, Jiao,Zhao, Yaopeng,Zheng, Yuanyuan,Li, Mingrun,Yang, Qihua
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p. 96203 - 96209
(2016/10/22)
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- Altering the regioselectivity of a nitroreductase in the synthesis of arylhydroxylamines by structure-based engineering
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Nitroreductases have great potential for the highly efficient reduction of aryl nitro compounds to arylhydroxylamines. However, regioselective reduction of the desired nitro group in polynitroarenes is still a challenge. Here, we describe the structure-based engineering of Escherichia coli nitroreductase NfsB to alter its regioselectivity, in order to achieve reduction of a target nitro group. When 2,4-dinitrotoluene was used as the substrate, the wild-type enzyme regioselectively reduced the 4-NO2 group, but the T41L/N71S/F124W mutant primarily reduced the 2-NO2 group, without loss of activity. The crystal structure of T41L/N71S/F124W and docking experiments indicated that the regioselectivity change (from 4-NO2 to 2-NO2) might result from the increased hydrophobicity of residues 41 and 124 (proximal to FMN) and conformational changes in residues 70 and 124. The regioselectivity of nitroreductase NfsB from E. coli toward 2,4-dinitrotoluene was shifted from the 4-NO2 group to the 2-NO2 group without loss of activity, by introducing three mutations: T41L, N71S, and F124W. This study provides an example of a tailored enzyme for regioselective synthesis of the target arylhydroxylamines.
- Bai, Jing,Zhou, Yong,Chen, Qi,Yang, Qing,Yang, Jun
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p. 1219 - 1225
(2015/05/27)
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- Gold supported on titania for specific monohydrogenation of dinitroaromatics in the liquid phase
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Liquid-phase selective monohydrogenation of various substituted dinitroaromatics to the corresponding valuable nitroanilines was investigated on gold-based catalysts. Special attention was paid to the effect of Au particle size on this monoreduction reaction. Interestingly, TiO2 supported gold catalysts containing a relatively larger mean Au particle size (>5 nm) showed far superior chemoselectivity for specific mono-hydrogenation of dinitroaromatics, with the highest performance attainable for the catalyst bearing Au particles of ca. 7.5 nm. Results in the intermolecular competitive hydrogenation showed that the intrinsic higher accumulation rates of the desired nitroanilines associated with the catalyst possessing larger Au particles were responsible for the high chemoselectivity observed. the Partner Organisations 2014.
- Liu, Shuang-Shuang,Liu, Xiang,Yu, Lei,Liu, Yong-Mei,He, He-Yong,Cao, Yong
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p. 4162 - 4169
(2014/09/29)
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- Discovery and synthesis of N2,N4-substitued- cycloalkyl[d]pyrimidine-2,4-diamine analogs: The first examples of small-molecular FGFR-1 activator
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A series of novel, cycloalkyl-modified pazopanib analogs 2 and 3 were designed and synthesized. Their kinase modulatory effects on FGFR-1, VEGFR-2, PDGFR-β, and c-KIT were evaluated by the caliper mobility shift assay. Introduction of cycloalkyl into the pyrimidine linker of pazopanib almost abolished the four kinases inhibitory potency of compounds 2 and 3, but surprisingly, resulted in good activation effects on FGFR-1. Compounds 3d and 3g showed double-digit, nanomolar, selective activation effects on FGFR-1, and could be classified as first-generation small molecular activators of FGFR-1 kinase.
- Li, Bao-Li,Xiao, Fang,Lu, Wen-Chao,Sun, Yu-Yun,Zhu, Jin,Li, Jian
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p. 989 - 994
(2014/08/18)
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- One-pot aromatic amination based on carbon-nitrogen coupling reaction between aryl halides and azido compounds
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An efficient copper-mediated C-N coupling reaction between various aryl halides and azido compounds to produce the corresponding aromatic primary amines was established. The present amination is apparently involved in both the reduction of an azido functionality to the corresponding primary amino group and its cross-coupling reaction with aryl halides in a one-pot manner. The present amination could be applied to the synthesis of procaine, a local anesthetic drug. A mechanistic study indicated that 2-aminoethanol could work as a major hydrogen donor and the reaction would proceed without the formation of the intermediary aryl azide.
- Maejima, Toshihide,Shimoda, Yutaka,Nozaki, Kei,Mori, Shigeki,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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experimental part
p. 1712 - 1722
(2012/03/08)
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- Synthesis and antimicrobial activity of 2-methyl-5-nitroaniline derivatives: A structure-activity relationship study
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A series of 2-methyl-5-nitroaniline derivatives, 5a-5k and 6a-6f, were synthesized in order to determine their in vitro antimicrobial activity. The chemical structures of the synthesized compounds were confirmed by elemental analyses, UV-visible, FT-IR, 1H NMR and 13C NMR spectral studies. The structure-activity relationships of the synthesized compounds were also discussed. Among the synthesized compounds, 5f, 5d, 6b and 6e showed good antimicrobial activity compared to standard drugs. A series of novel 2-methyl-5-nitroaniline derivatives were synthesized and their antimicrobial efficacy was tested. Among the synthesized compounds, 5f and 5d showed good antimicrobial activity. Copyright
- Lingappa, Mallesha,Kikkeri, N. Mohana,Devaraju, Rakshith,Sreedharamurthy, Satish
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scheme or table
p. 102 - 108
(2012/04/17)
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- Copper-mediated reductive amination of aryl halides with trimethylsilyl azide
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(Chemical equation presented) Look, no azide! Trimethylsilyl azide was reductively cross-coupled with a variety of aryl halides in the presence of a copper species and amines, such as triethylamine or aminoethanol, to give the corresponding primary aryl amine in good yields without the formation of the expected aryl azide (see scheme).
- Monguchi, Yasunari,Maejima, Toshihide,Mori, Shigeki,Maegawa, Tomohiro,Sajiki, Hironao
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supporting information; experimental part
p. 7372 - 7375
(2010/08/20)
-
- Design and synthesis of novel 2-phenylaminopyrimidine (PAP) derivatives and their antiproliferative effects in human chronic myeloid leukemia cells
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A series of novel 2-phenylaminopyrimidine (PAP) derivatives structurally related to STI-571 were designed and synthesized. The abilities of these compounds to inhibit proliferation were tested in human chronic myeloid leukemia K562 cells. (E)-3-(2-bromophenyl)-N-[4-methyl-3-(4-pyridin-3-yl-pyrimidin-2- ylamino)phenyl]acrylamide( 12d) was the most effective cell growth inhibitor and was 3-fold more potent than STI-571.
- Chang, Sheng,Yin, Shi-Liang,Wang, Jian,Jing, Yong-Kui,Dong, Jin-Hua
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experimental part
p. 4166 - 4179
(2009/12/28)
-
- Reactivity of metal-containing monomers 66.* Hydrogenation of nitrotoluene derivatives in the presence of polymer-immobilized Pd nanoparticles
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A new approach to the synthesis of immobilized catalysts of the mixed type was developed: frontal polymerization of metal-containing monomers in the presence of a highly dispersed inorganic support. The synthesis of the acrylamide complex of PdII nitrate on the SiO2 surface followed by polymerization and reduction results in the formation of a polymer-inorganic composite with inclusions of Pd nanoparticles stabilized by the polymer matrix on the support surface. The study of the catalytic properties in the hydrogenation of nitrotoluene derivatives showed that the polymer-immobilized Pd nanoparticles on the inorganic support are efficient catalysts for the reduction of the nitrocompounds.
- Dzhardimalieva,Dorokhov,Golubeva,Pomogailo,Lyakhovich,Savchenko,Pomogailo
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experimental part
p. 2070 - 2076
(2011/01/06)
-
- Selective partial hydrogenation of dinitrobenzenes to nitroanilines catalyzed by Ru/C
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Ru/C was found to be a highly effective catalyst for the selective partial hydrogenation of a range of dinitrobenzenes to their corresponding nitroanilines with excellent selectivity under mild conditions. Furthermore, the effect from other substitute groups of dinitrobenzenes on partial hydrogenation was also explored in this study. Copyright
- Hou, Jie,Ma, Yonghuan,Li, Yuhan,Guo, Fang,Lu, Lianhai
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scheme or table
p. 974 - 975
(2009/04/06)
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- Effect of the electronic structure of the radical anions of 4-substituted 1,2-and 1,3-dinitrobenzenes on the regioselectivity of reduction of the nitro groups
-
Theoretical and experimental regularities of the regioselectivity of the reduction of one of the two nitro groups in unsymmetrical dinitrobenzenes were studied. It was found that the regioselectivity of the formation of isomeric nitroanilines depends on the structure of the substrate and the nature of the reducing agent. The reduction regioselectivity model was verified, according to which radical anion protonation is the major reaction direction. Pleiades Publishing, Inc. 2006.
- Orlov,Begunov,Demidova,Rusakov
-
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- Palladium colloids from an organometallic route: Redox reaction between [VCp2] and [Pd(η3-allyl)2Cl]2. Catalytic application to the hydrogenation of aromatic nitro compounds
-
[Pd(η3-C3H5)2Cl] 2 reacts in THF in the presence of poly(vinylpyrrolidone) (PVP), with the 15-electron complex vanadocene [V(C5H5) 2], to give PVP-protected palladium particles. High resolution electron microscopy (HREM) and wide angle X-ray scattering (WAXS) experiments were carried out on the PVP-protected palladium particles as obtained when exposed to H2 and O2 and after hydrogenation catalysis. In each case, the particles display the fee lattice of bulk palladium and a narrow size distribution centred near 2-3 nm. Catalytic hydrogenation reactions of nitrotoluene and 2,4-dinitrotoluene into their corresponding aniline and 2,4-diaminotoluene were performed in CH2Cl2 and in H 2O/CH2Cl2 biphasic conditions. The catalytic reactions were found to be zero order with respect to the substrate and first order with respect to dihydrogen and catalyst.
- Pellegatta, Jean-Louis,Blandy, Claudine,Choukroun, Robert,Lorber, Christian,Chaudret, Bruno,Lecante, Pierre,Snoeck, Etienne
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p. 1528 - 1532
(2007/10/03)
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- SUBSTITUTED QUINAZOLINE DERIVATIVES AND THEIR USE AS INHIBITORS
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The use of a compound of formula (I) 1 or a salt, ester or amide thereof; where X is O, or S, S(O) or S(O)2, or NR6 where R6 is hydrogen or C1-6 alkyl,; R5 is an optionally substituted 5-membered heteroaromatic ring, R1, R2 ,R3, R4 are independently selected from various specified moieties, in the preparation of a medicament for use in the inhibition of aurora 2 kinase. Certain compounds are novel and these, together with pharmaceutical compositions containing them are also described and claimed
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- Surfactant-assisted UV-photolysis of nitroarenes
-
Photochemical transformations (λ = 254 nm) of 2,4-dinitrotoluene (2,4-DNT) in aqueous solutions containing the cationic surfactant cetyltrimethylammonium (CTA) and the anionic nucleophile borohydride (BH4-) were investigated. The ove
- Diehl, Claude A.,Jafvert, Chad T,Marley, Karen A.,Larson, Richard A.
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p. 553 - 560
(2007/10/03)
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- Electrochemical treatment of 2,4,6-trinitrotoluene and related compounds
-
This work involves electrolysis of nitrotoluene congeners, which are persistent pollutants that enter the environment as a consequence of their manufacture and use as explosives. Reduction to aminotoluenes occurred with high current efficiency at a variety of cathodes, at potentials -0.5 to -1 V vs SCE. The products were formed in high chemical yield and with excellent mass balance. Preliminary experiments were also carried out to find methods of removing the electrolysis products from solution by oxidative oligomerization. The most satisfactory method was partial reoxidation at a Ti/IrO2 anode, suggesting an overall remediation technology in which reduction is followed by reoxidation of the spent catholyte in the anode compartment of the same electrolytic cell. This work involves electrolysis of nitrotoluene congeners, which are persistent pollutants that enter the environment as a consequence of their manufacture and use as explosives. Reduction to aminotoluenes occurred with high current efficiency at a variety of cathodes, at potentials -0.5 to -1 V vs SCE. The products were formed in high chemical yield and with excellent mass balance. Preliminary experiments were also carried out to find methods of removing the electrolysis products from solution by oxidative oligomerization. The most satisfactory method was partial reoxidation at a Ti/IrO2 anode, suggesting an overall remediation technology in which reduction is followed by reoxidation of the spent catholyte in the anode compartment of the same electrolytic cell.
- Rodgers, James D.,Bunce, Nigel J.
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p. 406 - 410
(2007/10/03)
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- Reductive carbonylation of aromatic dinitro compounds with a palladium(phenanthroline)2(triflate)2 catalyst and an aromatic carboxylic acid as cocatalyst
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Reductive carbonylation of aromatic dinitro compounds to afford valuable dicarbamates proceeds at reasonable rates and with high selectivities under the influence of a Pd(phenanthroline)2(triflate)2 catalyst in combination with an aromatic carboxylic acid as cocatalyst.
- Wehman, Petra,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.
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p. 217 - 218
(2007/10/03)
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- Factors controlling regioselectivity in the reduction of polynitroaromatics in aqueous solution
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Regioselectivities in the bisulfide reduction of 10 polynitroaromatics (PNAs) to monoamine products have been determined; four of these compounds have also been reduced by anoxic sediments in heterogeneous aqueous solution, and the same regioselectivities are observed. Analyses of Austin Model 1- Solvation Model 2 electrostatic potential surfaces for the radical anions of these polynitroaromatic compounds provides a reliable method of predicting the regioselectivity of their reduction. In particular, at their minimum- energy geometries in aqueous solution, it is the more negative nitro group that is selectively reduced. This is consistent with a mechanism where regioselection occurs upon kinetic protonation at the site of maximum negative charge in the radical anion formed after the first electron transfer to the neutral PNA. Inclusion of solvation effects is critical in order to confidently predict the electrostatic preference for the reduction of one nitro group over the others. Sterically uncongested nitroaromatic radical anions have gas-phase geometries in which the nitro group is coplanar with the aromatic ring. However, ortho substituents and solvation effects both oppose this tendency and can lead to nitro groups that are rotated out of the ring plane and pyramidalized.
- Barrows, Susan E.,Cramer, Christopher J.,Truhlar, Donald G.,Elovitz, Michael S.,Weber, Eric J.
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p. 3028 - 3038
(2007/10/03)
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- Pd-Fe/SiO2 Catalysts in the Hydrogenation of 2,4-Dinitrotoluene
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Pd-Fe/SiO2 bimetallic catalysts with a constant amount of Pd and a different Fe/Pd ratio were prepared by sequential wet impregnation and the hydrogenation of 2,4-dinitrotoluene was carried out at 25 deg C in a batch reactor.The presence of Fe enhances the Pd catalytic activity.The formation of a dispersed Pd-Fe alloy was evidenced through X-ray powder diffraction and is consisted with the data observed by FTIR analysis, TPR, and chemisorption features.The increase of the Fe total content of the catalysts results in the increase of the dispersion of the metallic phase and in the presence of partially oxidized Fe species.FTIR analysis shows that nitrocompounds chemisorb mainly on the support rather than on the metal surface.It is suggested that the Pd-Fe alloy formation is responsible for the increase of the catalytic activity because of a cooperative effect of Fe in the hydrogen transfer step.
- Pinna, F.,Selva, M.,Signoretto, M.,Strukul, G.,Boccuzzi, F.,et al.
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p. 356 - 367
(2007/10/02)
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- Formamidine as a versatile protecting group for primary amines: A mild procedure for hydrolytic removal
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A mild, zinc chloride-promoted cleavage of N,N,-dimethyl-formamidine derivatives of primary amines to the free amines is described. Under slightly different hydrolytic conditions the corresponding N-formyl derivatives can be isolated.
- Toste,McNulty,Still
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p. 1617 - 1624
(2007/10/02)
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- Regioselective Reduction of Substituted Dinitroarenes Using Baker's Yeast
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A range of substituted dinitroaromatic compounds have been reduced using baker's yeast (Saccharamyces cerevisiae), in some cases with very high selectivity.A model is presented to account for the origin of the selectivity together with a possible mechanism for the reduction.
- Davey, Claire L.,Powell, Lawson W.,Turner, Nicholas J.,Wells, Andrew
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p. 7867 - 7870
(2007/10/02)
-
- RADICAL-ANIONS OF AROMATIC COMPOUNDS. XVI. ELECTRONIC STRUCTURE OF RADICAL-ANIONS AND THE DIRECTION OF PARTIAL REDUCTION OF DISUBSTITUTED DERIVATIVES OF m-DINITROBENZENE: THE RELATIVE EFFECTS OF THE SUBSTITUENTS
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It was shown by means of compounds labeled with the 15N isotope that the radical-anions of a wide range of 1,5-disubstituted 2,4-dinitrobenzenes are in most cases characterized by localization of the density of the unpaired electron at one of the nitro groups.It was concluded that the substituents can be arranged in the following order according to their ability to stabilize the form with the negatively charged nitro group at the para position: CO2- > CH3 Br > Cl N(C2H5)2 > CN > OCH3; CO2- > I.The relative effectiveness of the substituents which stabilize the form of the radical-anions with the negatively charged nitro group at the ortho position was determined theoretically as follows: OCH3 +C5H5 +H(C2H5)2.The position of the substituents in the series given above are determined by the combined effect of such factors as the effective volume, the electronic effect transmitted through the skeleton, the field effect, and the ability to form intramolecular hydrogen bonds.It was shown that the direction of partial reduction of the derivatives of m-dinitrobenzene can be predicted on the basis of data on the electronic structure of their radical-anions, which are probable key intermediates of the processes.
- Uskov, S. I.,Bilkis, I. I.,Shteingarts, V. D.
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- Intestinal metabolism of 2,4-dinitrotoluene in rats
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2,4-Dinitrotoluene (2,4-DNT), which is an industrial chemical of importance in the production of urethane foams and elastomers, is a hepatocarcinogen in rats. 2,4-Diaminotoluene (2,4-DAT), one of the urinary and hepatic metabolites of 2,4-DNT, is also carcinogenic in rats. We have studied the pathways of metabolism of 2,4-DNT in the cecal microflora of rats. 2,4-DNT was not metabolized by this preparation in the presence of oxygen. Under anaerobic conditions, an ordered sequence of reductive metabolism was observed. 2,4-DNT was reduced to 2-amino-4-nitrotoluene (2A4NT) and 4-amino-2-nitrotoluene (4A2NT) via 2-hydroxylamino-4-nitrotoluene (2HA4NT) and 4-hydroxylamino-2-nitrotoluene (4HA2NT), which were identified by mass spectral (MS) comparison with authentic materials. The two aminonitrotoluenes were then reduced to 2,4-DAT. No intermediates in this sequence could be isolated. These findings indicate that rat intestinal microflora catalyze the reductive metabolism of 2,4-DNT and suggest that the reduction of 2,4-DNT to 2,4-DAT may play a role in the carcinogenicity of 2,4-DNT.
- Mori,Kudo,Nunozawa,Miyahara,Kozuka
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p. 327 - 332
(2007/10/02)
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- Electron Rich Heterocycles as Donor Groups in Fluorescent Dyes
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The synthesis of N-methylphthalimides substituted with the donor groups pyrazole, triazole, benzotriazole, and naphthotriazole in position 4 is described (17, 18, 14, 12).The substituent constants of these groups are obtained by alkaline hydrolysis of the corresponding phthalimide dyes.Their solvatochromism in absorption and fluorescence gives information about charge distribution in ground- and excited state.
- Fritzsche, Katharina,Langhals, Heinz
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p. 2275 - 2286
(2007/10/02)
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- PARTIAL REDUCTION OF DINITROARENES TO NITROANILINES WITH HYDRAZINE HYDRATE.
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Dinitroarenes containing substituents such as hydroxyl and amine groups could be conveniently reduced with 3 molar equivalents of hydrazine hydrate in presence of Raney nickel catalyst in ethanol/1,2-dichloro-ethane solvent mixture to give a product wherein one of the two nitro groups was reduced to the amino group. The yields of the partial reduction products are good. Under similar conditions alkoxyl substitutes in the o,p-position to the nitro groups were displaced by the hydrazine to give 2,4-dinitrophenyl-hydrazine as the main product. The details of the reduction reaction are described.
- Avyyangar,Kalkote,Lugade,Nikrad,Sharma
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p. 3159 - 3164
(2007/10/02)
-
- Azo pigments derived from 2-hydroxy-3-carboxynaphthalene containing a substituted or unsubstituted phthalimide
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Azo pigments derived from 2-hydroxy-3-carboxy-naphthalene and containing a substituted or unsubstituted phthalimide radical. The majority give red colorations and due to their excellent fastness properties are particularly valuable for use in surface coatings and resins.
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