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Mikhail A Varfolomeev - One of the best experts on this subject based on the ideXlab platform.
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enthalpies of solution and enthalpies of solvation of chloro and nitro substituted benzenes in 1 butyl 3 methyl imidazolium based ionic liquids at 298 15k additivity of group contributions
Thermochimica Acta, 2016Co-Authors: Artashes A Khachatrian, Ziliya I Shamsutdinova, Mikhail A VarfolomeevAbstract:Abstract In this work thermochemistry of solution and solvation of mono- and di-substituted chloro- and nitro-benzenes in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][TfO]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]) ionic liquids was studied. Enthalpies of solution at infinite dilution of benzene, chlorobenzene, nitrobenzene, 1,2-, 1,3-, 1,4-dichlorobenzenes, 1,2-, 1,3-, 1,4-dinitrobenzenes, 1-chloro-2-nitrobenzene, 1-chloro-3-nitrobenzene, and 1-chloro-4-nitrobenzene in three ionic liquids were measured at 298.15 K. On the basis of experimental data enthalpies of solvation of substituted benzenes in ionic solvents were calculated. Values of Cl and NO2 group contributions to the enthalpies of solvation were derived and compared with molecular solvents. Enthalpies of solvation of each series of dichlorobenzenes, chloronitrobenzenes and dinitrobenzenes in studied ionic liquids are equal and do not depend on the mutual position of substituents. This fact shows that dipole moment does not affect the enthalpy of solvation of organic solutes in ionic liquids. Enthalpies of solvation of disubstituted benzenes in ionic liquids calculated through group contribution approach were in good agreement with experimental data.
Shuangjiang Liu - One of the best experts on this subject based on the ideXlab platform.
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assimilation of aromatic compounds by comamonas testosteroni characterization and spreadability of protocatechuate 4 5 cleavage pathway in bacteria
Applied Microbiology and Biotechnology, 2013Co-Authors: Yun Zhang, Dongwei Chen, Baojun Wang, Shuangjiang LiuAbstract:Comamonas testosteroni strain CNB-1 was isolated from activated sludge and has been investigated for its ability to degrade 4-chloronitrobenzene. Results from this study showed that strain CNB-1 grew on phenol, gentisate, vanillate, 3-hydroxybenzoate (3HB), and 4-hydroxybenzoate (4HB) as carbon and energy sources. Proteomic data and enzyme activity assays suggested that vanillate, 3HB, and 4HB were degraded in strain CNB-1 via protocatechuate (PCA) 4,5-cleavage pathway. The genetics and biochemistry of the PCA 4,5-cleavage pathway were investigated. Results showed that the 4-oxalomesaconate (OMA) hydratase from C. testosteroni takes only enol-OMA as substrate. A previously functionally unknown gene pmdU encodes an OMA tautomerase and catalyzes conversion of OMAketo into OMAenol. The 4-carboxy-4-hydroxy-2-oxoadipate (CHA) aldolase is encoded by pmdF and catalyzes the last step of the PCA 4,5-cleavage pathway. We explored the 1,183 microbial genomes at GenBank for potential PCA 4,5-cleavage pathways, and 33 putative pmd clusters were found. Results suggest that PCA 4,5-cleavage pathways are mainly distributed in α- and β-Proteobacteria.
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proteomic and molecular investigation on the physiological adaptation of comamonas sp strain cnb 1 growing on 4 chloronitrobenzene
Biodegradation, 2009Co-Authors: Yun Zhang, Josef Zeyer, Lei Liu, Chengying Jiang, Bo Meng, Siqi Liu, Shuangjiang LiuAbstract:Comamonas sp. strain CNB-1 can utilize 4-chloronitrobenzene (4CNB) as sole carbon and nitrogen source for growth. Previous studies were focused on 4CNB degradative pathway and have showed that CNB-1 contained a plasmid pCNB1 harboring the genes (cnbABCaCbDEFGH, cnbZ) for the enzymes involving in 4CNB degradation, but only three gene products (CnbCa, CnbCb, and CnbZ) were identified in CNB-1 cells. Comamonas strain CNB-2 that lost pCNB1 was not able to grow on 4CNB. In this study, physiological adaptation to 4CNB by CNB-1 was investigated with proteomic and molecular tools. Comparative proteomes of strains CNB-1 and CNB-2 grown on 4CNB and/or succinate revealed that adaptation to 4CNB by CNB-1 included specific degradative pathway and general physiological responses: (1) Seven gene products (CnbA, CnbCa, CnbCb, CnbD, CnbE, CnbF, and CnbZ) for 4CNB degradation were identified in 4CNB-grown cells, and they were constitutively synthesized in CNB-1. Two genes cnbE and cnbF were cloned and simultaneously expressed in E. coli. The CnbE and CnbF together catalyzed the conversion of 2-oxohex-4-ene-5-chloro-1,6-dioate into 2-oxo-4-hydroxy-5-chloro-valeric acid; (2) Enzymes involving in glycolysis, tricarboxylic acid cycle, and synthesis of glutamate increased their abundances in 4CNB-grown cells.
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responses to arsenate stress by comamonas sp strain cnb 1 at genetic and proteomic levels
Microbiology, 2007Co-Authors: Yun Zhang, Bo Meng, Siqi Liu, Muhammad Tausif Chaudhry, Shuangjiang LiuAbstract:Comamonas sp. strain CNB-1, a chloronitrobenzene-degrading bacterium, was demonstrated to possess higher arsenate tolerance as compared with the mutant strain CNB-2. pCNB1, a plasmid harboured by CNB-1 but not CNB-2, contained the genetic cluster ars(RPBC)Com , which putatively encodes arsenate-resistance regulator, family II arsenate reductase, arsenite efflux pump and family I arsenate reductase, respectively, in Comamonas strain CNB-1. The arsC-negative Escherichia coli could gain arsenate resistance by transformation with arsPCom or arsCCom , indicating that these two genes might express functional forms of arsenate reductases. Intriguingly, when CNB-1 cells were exposed to arsenate, the transcription of arsPCom and arsCCom was measurable by RT-PCR, but only ArsP Com was detectable at protein level. To explore the proteins responding to arsenate stress, CNB-1 cells were cultured with and without arsenate and differential proteomics was carried out by two-dimensional PAGE (2-DE) and MALDI-TOF MS. A total of 31 differential 2-DE spots were defined upon image analysis and 23 proteins were identified to be responsive specifically to arsenate. Of these spots, 18 were unique proteins. These proteins were identified to be phosphate transporters, heat-shock proteins involved in protein refolding, and enzymes participating in carbon and energy metabolism.
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a novel deaminase involved in chloronitrobenzene and nitrobenzene degradation with comamonas sp strain cnb 1
Journal of Bacteriology, 2007Co-Authors: Lei Liu, Shengyue Wang, Guoping Zhao, Shuangjiang LiuAbstract:Comamonas sp. strain CNB-1 degrades nitrobenzene and chloronitrobenzene via the intermediates 2-aminomuconate and 2-amino-5-chloromuconate, respectively. Deamination of these two compounds results in the release of ammonia, which is used as a source of nitrogen for bacterial growth. In this study, a novel deaminase was purified from Comamonas strain CNB-1, and the gene (cnbZ) encoding this enzyme was cloned. The N-terminal sequence and peptide fingerprints of this deaminase were determined, and BLAST searches revealed no match with significant similarity to any functionally characterized proteins. The purified deaminase is a monomer (30 kDa), and its Vmax values for 2-aminomuconate and 2-amino-5-chloromuconate were 147 μmol·min−1·mg−1 and 196 μmol·min−1·mg−1, respectively. Its catalytic products from 2-aminomuconate and 2-amino-5-chloromuconate were 2-hydroxymuconate and 2-hydroxy-5-chloromuconate, respectively, which are different from those previously reported for the deaminases of Pseudomonas species. In the catalytic mechanism proposed, the α-carbon and nitrogen atoms (of both 2-aminomuconate and 2-amino-5-chloromuconate) were simultaneously attacked by a hydroxyl group and a proton, respectively. Homologs of cnbZ were identified in the genomes of Bradyrhizobium japonicum, Rhodopseudomonas palustris, and Roseiflexus sp. strain RS-1; these genes were previously annotated as encoding hypothetical proteins of unknown function. It is concluded that CnbZ represents a novel enzyme that deaminates xenobiotic compounds and/or α-amino acids.
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plant microbe association for rhizoremediation of chloronitroaromatic pollutants with comamonas sp strain cnb 1
Environmental Microbiology, 2007Co-Authors: Lei Liu, Chengying Jiang, Xingyu Liu, Jigang Han, Shuangjiang LiuAbstract:Comamonas sp. strain CNB-1, isolated from activated sludge and having a strong ability to degrade 4-chloronitrobenzene (4CNB), was applied for rhizoremediation of 4CNB-polluted soil through association with alfalfa. Confocal laser scanning microscopy revealed that strain CNB-1 successfully colonized alfalfa roots. Determination of strain CNB-1 populations by cultivation method and by quantitative competitive PCR technique targeting the chloronitrobenzene nitroreductase gene showed that the population of strain CNB-1 in the rhizosphere was about 10-100 times higher than that in the bulk soil. Gnotobiotic and outdoor experiments showed that pollutant 4CNB was completely removed within 1 or 2 days after 4CNB application into soil, and that its phytotoxicity to alfalfa was eliminated by inoculation of strain CNB-1. Results from PCR-denaturing gradient gel electrophoresis and analysis of 16S rRNA gene libraries revealed that the indigenous soil microbial community mainly consisted of alphaproteobacteria, betaproteobacteria, gammaproteobacteria, the CFB bacteria (Cytophaga-Flavabacterium-Bacteriodes), and Acidobacteria. This microbial community was not significantly influenced by inoculation of strain CNB-1. Thus, this study has developed a Comamonas-alfalfa system for rhizoremediation of 4CNB.
Chin-ping Yang - One of the best experts on this subject based on the ideXlab platform.
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synthesis and properties of soluble alternating copoly amide imide s based on 1 2 bis 4 trimellitimidophenoxy 4 t butylbenzene and various aromatic diamines
Polymer, 2001Co-Authors: Chin-ping Yang, Chishu WeiAbstract:Abstract A new diimide dicarboxylic acid, 1,2-bis(4-trimellitimidophenoxy)-4- t -butylbenzene ( I ), was prepared by the condensation of 1,2-bis(4-aminophenoxy)-4- t -butylbenzene (1,2-BAP- t BB) and trimellitic anhydride (TMA) at 1:2 molar ratio. The diamine 1,2-BAP- t BB was first synthesized from 4- t -butylcatechol and p -chloronitrobenzene in the presence of potassium carbonate (K 2 CO 3 ) and then reduced by H 2 NNH 2 and Pd/C. A series of novel poly(amide–imide)s (PAIs) III a –III k with inherent viscosities of 0.83–1.73 dl/g was prepared from the diimide–diacid I with various aromatic diamines (II a –II k ) by direct polycondensation in a medium consisting of N -methyl-2-pyrrolidone (NMP) (as a solvent), triphenyl phosphite/pyridine (as condensing agents), and calcium chloride. Most of the polymers show excellent solubility in amide-type solvents such as NMP and N , N -dimethylacetamide (DMAc) and formed a tough, transparent, and flexible film by casting from DMAc solution. The films have tensile strengths of 87–108 MPa, elongations at break of 8–17%, and initial moduli of 2.1–2.6 GPa. The glass transition temperature of these polymers is in the range of 234–276°C and the 10% weight loss temperature is above 475°C in air or in nitrogen.
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synthesis and characterization of aromatic polyamides based on a bis ether carboxylic acid or a dietheramine derived from tert butylhydroquinone
Macromolecular Chemistry and Physics, 1999Co-Authors: Chin-ping Yang, Sheng-huei Hsiao, Huei-wen YangAbstract:1,4-Bis(4-carboxyphenoxy)-2-tert-butylbenzene (2a) and 1,4-bis(4-aminophenoxy)-2-tert-butylbenzene (2b) were synthesized in two steps starting from the nucleophilic aromatic substitution reaction of p-fluorobenzonitrile and p-chloronitrobenzene, respectively, with tert-butylhydroquinone in the presence of potassium carbonate in N,N-dimethylformamide (DMF). Aromatic polyamides were synthesized by direct polycondensation from diacid 2a with various diamines or from diamine 2b with various diacids, by means of triphenyl phosphite and pyridine in N-methyl-2-pyrrolidone solution containing calcium chloride. Inherent viscosities of the polyamides ranged from 0.64 to 1.04 dL/g. Almost all the polyamides are readily soluble in various organic solvents and afford transparent and tough films by solvent casting. The polyamides display T g values of 209-267°C and 10% weight loss values above 460°C in nitrogen and 439°C in air. A comparative study of some polyamides with an isomeric repeating unit is also presented.
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preparation and properties of polyamide imides derived from 1 3 bis 4 aminophenoxy benzene trimellitic anhydride and various aromatic diamines
Journal of Polymer Research, 1994Co-Authors: Chin-ping Yang, Sheng-huei Hsiao, Chingder ChenAbstract:A diamine, 1,3-bis(4-aminophenoxy) benzene (II), was synthesized in two steps; fist from the condensation of resorcinol with p-chloronitrobenzene in the presence of potassium carbonate, producing I ,3-bis(4-nitrophenoxy) benzene (I), followed by hydrazine hydrate/Pd-C reduction. A two imide rings-preformed dicarboxylic acid, 1,3-bis(4-trimellitimidophenoxy)benzene (III), was prepared from the condensation of diamine II and trimellitic anhydride in 1:2 molar ratio. A series of structurally new polyamide-imides (Va-p) were directly synthesized from the diacid III and various aromatic diamines (IVa-p). The resultant polyamide-imides had inherent viscosities between 0.56–1.39 dl/g. All polymers, except some derived from diamines with p-phenoxy structure, showed excellent solubility. Some polymer resulted in tough or flexible transparent films. Dynamic TG data indicated that all polymers possess excellent thermal stability with no significant weight loss up to the temperature of approximately 450 °C in nitrogen, and their 10% weight loss temperature was recorded in the range of 489–577 °C. Measurements of wide-angle X-ray diffraction revealed that some polymers derived from p-phenoxy group-containing diamines showed crystalline patterns.
Artashes A Khachatrian - One of the best experts on this subject based on the ideXlab platform.
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enthalpies of solution and enthalpies of solvation of chloro and nitro substituted benzenes in 1 butyl 3 methyl imidazolium based ionic liquids at 298 15k additivity of group contributions
Thermochimica Acta, 2016Co-Authors: Artashes A Khachatrian, Ziliya I Shamsutdinova, Mikhail A VarfolomeevAbstract:Abstract In this work thermochemistry of solution and solvation of mono- and di-substituted chloro- and nitro-benzenes in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][TfO]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]) ionic liquids was studied. Enthalpies of solution at infinite dilution of benzene, chlorobenzene, nitrobenzene, 1,2-, 1,3-, 1,4-dichlorobenzenes, 1,2-, 1,3-, 1,4-dinitrobenzenes, 1-chloro-2-nitrobenzene, 1-chloro-3-nitrobenzene, and 1-chloro-4-nitrobenzene in three ionic liquids were measured at 298.15 K. On the basis of experimental data enthalpies of solvation of substituted benzenes in ionic solvents were calculated. Values of Cl and NO2 group contributions to the enthalpies of solvation were derived and compared with molecular solvents. Enthalpies of solvation of each series of dichlorobenzenes, chloronitrobenzenes and dinitrobenzenes in studied ionic liquids are equal and do not depend on the mutual position of substituents. This fact shows that dipole moment does not affect the enthalpy of solvation of organic solutes in ionic liquids. Enthalpies of solvation of disubstituted benzenes in ionic liquids calculated through group contribution approach were in good agreement with experimental data.
Mark A Keane - One of the best experts on this subject based on the ideXlab platform.
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selective gas phase hydrogenation of p chloronitrobenzene over pd catalysts role of the support
ACS Catalysis, 2013Co-Authors: Fernando Cardenaslizana, Yufen Hao, Xiaodong Wang, Mark A Keane, Micaela Crespoquesada, Igor Yuranov, Lioubov KiwiminskerAbstract:The gas phase (1 atm, 453 K) hydrogenation of p-chloronitrobenzene (p-CNB) over a series of laboratory-synthesized and commercial Pd (1–10% wt) supported on activated carbon (AC) and non-reducible (SiO2 and Al2O3) and reducible (ZnO) oxides has been examined. Reaction over these catalysts generated the target p-chloroaniline (p-CAN) (via selective hydrogenation) and nitrobenzene (NB)/aniline (AN) as a result of a combined hydrodechlorination/hydrogenation. A range of Pd nanoparticles with mean sizes 2.4–12.6 nm (from HRTEM and H2/CO chemisorption) were generated. Both the p-CNB transformation rate and H2 chemisorption increased with decreasing Pd size. Residual Mo (from the stabilizer used in the synthesis of Pd colloids) suppressed activity, but this was circumvented by the use of poly(N-vinyl-2-pyrrolidone) (PVP). Pd/AC generated p-CAN and AN as principal products, Pd on SiO2 and Al2O3 exhibited hydrodechlorination character generating AN and NB, and Pd/ZnO promoted the sole formation of p-CAN at all le...
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the role of hydrogen partial pressure in the gas phase hydrogenation of p chloronitrobenzene over alumina supported au and pd a consideration of reaction thermodynamics and kinetics
Chemical Engineering Journal, 2012Co-Authors: Xiaodong Wang, Noemie Perret, Mark A KeaneAbstract:The gas phase hydrogenation of p-chloronitrobenzene (p-CNB) over alumina supported Au and Pd has been subjected to thermodynamic and kinetic analyses where the H2 partial pressure was varied from excess (H2/p-CNB up to 2300) to lean (stoichiometric) conditions. The catalysts have been characterised by temperature-programmed reduction (TPR), H2 chemisorption/temperature-programmed desorption (TPD), BET surface area/porosity, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) measurements. Both catalysts exhibited nano-scale metal particles (mean diameter = 4.5 nm (Au) and 2.4 nm (Pd)) with the formation (from XPS analysis) of electron-rich Pdδ− but no significant electron transfer between Au and Al2O3. Under thermodynamic control, cyclohexane is the only product where H2/p-CNB ⩾ 10 with product (p-chloroaniline, aniline, chlorobenzene, benzene and cyclohexane) dependence on H2/p-CNB in the range 1–8; at a given H2/p-CNB, reaction temperature (373–473 K) has a negligible effect. Under conditions of catalytic control, Au/Al2O3 generated p-chloroaniline as the sole product while Pd/Al2O3 promoted hydrodechlorination to nitrobenzene and hydrogenation to aniline. A kinetic model is presented that accounts for the rate dependence on H2 partial pressure, where the maximum turnover frequency delivered by Au/Al2O3 (with a lower H2 adsorption coefficient) was an order magnitude lower than that recorded for Pd/Al2O3. Adsorption of p-CNB on Pdδ− via the aromatic ring is proposed that serves to activate both –NO2 and –Cl for attack whereas Au/Al2O3 selectively activates –NO2, leading to exclusive production of p-chloroaniline.
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exclusive production of chloroaniline from chloronitrobenzene over au tio2 and au al2o3
Chemsuschem, 2008Co-Authors: Fernando Cardenaslizana, Santiago Gomezquero, Mark A KeaneAbstract:The gas-phase continuous hydrogenation of p-chloronitrobenzene (p-CNB) over 1 mol % Au/TiO2 and Au/Al2O3 was compared for the first time. Both catalysts exhibit 100 % selectivity in terms of -NO2 group reduction, resulting in the sole formation of p-chloroaniline (p-CAN). Au/TiO2 exhibited a narrower particle size (1–10 nm) distribution than Au/Al2O3 (1–20 nm) and a smaller surface-area-weighted mean Au size (6 nm versus 9 nm). Au/TiO2 delivered a higher specific hydrogenation rate (by a factor of up to four), a response that is discussed in terms of Au particle size and a possible contribution of the support to p-CNB activation. A CNB isomer reactivity sequence was established, that is, o>p>m, which is attributed to resonance stabilisation effects. The results presented establish a basis for the development of a sustainable alternative route for the production of haloamines.