Anaerobic Biotransformation of Nitro-Compounds to Amines by Bovine Rumen Fluid

Microorganims of the bovine rumen fluid biocatalyzed the reduction of nitro-compound substrates to yield the respective amines. This enzymatic process, using ruminal contents, has rarely been reported in associa- tion with the bioreduction of nitro groups. The biotransformation reactions catalyzed by this system were de- pendent of both the electronic characteristics and the area/volume of the nitro-substrates confirming the processes are enzymatic. The semi-preparative scale biotransformation went by in good yield showing the rumen fluid may be employed in the synthesis of amines under very mild conditions and, moreover, it may have application in the bioremediation of nitro-compounds.

水溶性钌络合物催化卤代芳香硝基化合物选择性加氢的研究

研究了水/有机两相催化体系中,水溶性钌络合物催化剂AC 1催化卤代芳香硝基化合物中硝基的选择性加氢反应.以对 氯硝基苯为底物,考察了表面活性剂种类及浓度、反应温度、氢压、催化剂浓度和反应时间等对反应转化率和选择性的影响.实验结果表明,阳离子表面活性剂对反应有明显的影响,其中以添加十六烷基三甲基溴化铵(CTAB)效果最好.当反应条件为90℃,氢压4.0MPa时,反应5h,对 氯硝基苯转化率可达100%,生成对 氯苯胺的选择性可达99.9%.该催化体系对其它卤代芳香硝基化合物的选择性加氢也具有很高的活性和选择性.

用环糊精毛细管色谱分离卤代芳烃位置异构体

采用一根以 β-CD环糊精衍生物为固定相的石英毛细管柱 ,在一定的气相色谱条件下 ,对氯甲苯、氟甲苯和二氯甲苯卤代芳烃位置异构体进行分离探索 ,取得了满意的效果。

Ni-B/SiO_2非晶态催化剂对卤代芳香硝基化合物的催化加氢性能

对Ni-B/SiO2 非晶态催化剂在卤代芳香硝基化合物加氢制卤芳胺反应中的催化活性和选择性进行了研究。研究表明 ,该催化剂不仅具有很高的催化活性 ,且反应中卤芳胺脱卤率低 ,反应选择性高 ,寿命长 ,优于RaneyNi催化剂。晶化导致催化剂失活。载体能提高催化剂的分散度 ,使催化剂的活性比表面积增大。将催化剂保存在乙醇溶液中可保持其活性不变。通过催化剂的表征结果 ,讨论了Ni-B/SiO2非晶态催化剂及RaneyNi催化剂的催化活性与其机构的关系。

Fe_xO_y@C负载Pt催化氯代硝基化合物加氢反应研究

以九水合硝酸铁为铁源,葡萄糖为炭源,通过水热法制备了FexOy@C复合材料。以该材料为载体,采用浸渍法制备了FexOy@C负载Pt催化剂,用于硝基化合物加氢制备相应苯胺。采用XRD和TEM对催化剂进行表征并探讨了催化剂的加入量、有机溶剂、混合溶剂体积比等因素对对氯硝基苯加氢制备对氯苯胺的影响。实验证明,该催化剂稳定性高,催化剂循环利用6次以后,其加氢活性仍可以达到100%,选择性可达99%以上。另外,该催化剂对其它硝基化合物也显示了较好的催化性能。

Vegetation Composition of Abu Tartur Mining Region （Western Desert, Egypt）： Biological and Phytochemical Survey of Some Studied Taxa

Groundwater in Egypt plays an important role in the country＇s water budget. South Western desert represent an arid of desert biome within world＇s net-work of the biosphere reserves. In this study, the plant wild vegetation were surveyed in Abu Tartur mining area located in the Southern part of Western depending essentially on the seepage from water line tubes which supplies water demands at Abu Tartur. The vegetation-environment relationships in Abu Tartur are described. Data sets （42 species in 38 plots） beside the pip-line enriched from 13 wells were analyzed, using multivariate procedures, i.e., two-way indicator species analysis （TW1NSPAN）, detrended correspondence analysis （DCA） and detrended canonical correspondence analysis （CCA）, to produce a classification of plant communities in the studied areas and to examine the relationships of that plant communities to certain edaphic factors. Five plant communities were identified. Astragalus vogelii, Chenopodium murale, Citrullus colocynthis, Fagonia arabica, Farsetia aegyptia, Hyoscyamus muticus, Morettia philaeana, Cynodon dactylon, Trichodesma africana, Tarnarix nilotica, Senna italica, Schouwia purpurea, Salsola volkensii and Phragmites australis were common in the study area. Phytochemical survey for nitroprpionic compounds in some taxa belonging to Fabaceae family showed the absence of these toxic compounds by using GC/MS analysis. Also some phytochemical components ofAstragalus vogalii were extracted and identified by GC/MS spectra. A biological activity, in this regard was the screening of methanol extracts for some wild taxa of Abu Tartur against natural Tetranychus urticae as acricidal activity and the methanol extracts of some taxa give high mortality results, like Farsetia aegyptia （86.6%） and Fagonia arabica Burm. f. （70.0%）.

Photocoupling Reactions of Haloaromatic Hydrocarbons With Aromatic Compounds——Synthesis and Mechanism

<正> An effective method of synthesizing polyaromatic hydrocarbons with high selectivity was developed through our research work on the photocoupling reactions between several haloaromatic hydrocarbons and aromatic compounds. The structures of polyaromatic hydrocarbons synthesized were determined by IR, UV, ~1H NMR, MS and elemental analysis, and the crystal structure of 3-(1-naphthyl)-coumarin was established by an crystallographic analysis. Further study of the regioselectivity, orientational effect of substituents, solvent effect, sensitizing and quenching effect supported the proposed mechanism of this type of reaction involving election transfer process under excited triplet state.

Photobiodegradation of halogenated aromatic pollutants

Release of wide range of compounds as a consequence of industrial development is now a serious environmental problem. Numerous hazardous waste sites have been generated worldwide resulting from the accumulation of xenobiotics in soil and water. Aromatic compounds constitute a large and diverse group of chemicals that are responsible for causing widespread environmental pollution. Among them halogenated aromatic hydrocarbons are very stable to undergo degradation due to resonance energy and inertness of carbon-halogen, carbon-hydrogen and carbon-carbon covalent bonds. The physico-chemical remedial strategies to clean up sites contaminated by these compounds are inadequate and economically inefficient. Therefore, research is increasingly being focused on development of biological approaches for their remediation. The hunt for the microorganisms degrading halogenated aromatic pollutants has been successful in discovering a diverse range of aerobic, anaerobic and phototrophic bacteria. The bacteria mineralize the toxic halogenated pollutants into harmless products thereby contributing towards conservation of the environment quality.

Two-dimensional porous Cu-CuO nanosheets: Integration of heterojunction and morphology engineering to achieve high-effective and stable reduction of the aromatic nitro-compounds

The morphology and heterojunction engineering are effective ways to boost the performance of Cubased catalysts. Herein, we have reported the designed synthesis of two-dimensional Cu-Cu O heterojunction nanosheets(2D Cu-Cu O NS) based on 3-aminopropyl-triethoxysilane(APTES, KH550) aided synthetic strategy. The APTES can act as both the ligand and alkali(-OH) source to guide the large-scale synthesis of 2D Cu-based precursor, which can transform into 2D Cu-Cu O NS by the controllable post-treatment.The Si species from APTES can protect the particles from the severe aggregation and growth, guaranteeing the formation of 2D sheets composed of small-sized Cu-Cu O heterojunction(about 20 nm). The heterojunction interfaces can provide plentiful active sites to boost the catalytic ability. The 2D sheets can provide large accessible surface, being conducive to the contact of the catalyst and reactants. Benefiting from above virtues, the 2D Cu-Cu O NS showed the superior catalytic performance for the reduction of a series of nitro compounds, being superior to most reported non-noble metal-based catalysts. Notably,it exhibited good re-cycled performance with no obvious performance degradation after 10 consecutive catalysis. The present study will be promising to promote the application of the Cu-based catalysts, due to its ability to control the morphology and potential for the large-scale synthesis.

Fabrication of hierarchical MXene-based AuNPs-containing core-shell nanocomposites for high efficient catalysts

MXene is a new type of layered two-dimensional transition metal carbide materials differing from graphene, demonstrating intriguing chemical/physical properties. Here the chemical modification of MXene and next fabrication of core-shell MXene-COOH@(PEI/PAA)_n composites have been investigated. The obtained MXene-based composites were treated with gold nanoparticles to form MXene—COOH@(PEI/PAA)_n@AuNPs nanocomposites, and their catalytic properties for nitro-compounds were studied. The prepared nanocomposites demonstrated good catalytic activity and reproducibility, showing potential applications in composite catalysts and environmental fields.

Fabrication of tunable hierarchical MXene@AuNPs nanocomposites constructed by self-reduction reactions with enhanced catalytic performances

MXene, a new type of two-dimensional layered transition metal carbide material differing from graphene, demonstrates intriguing chemical/physical properties and wide applications in recent years. Here, the preparation of the self-assembled MXene-gold nanoparticles （MXene@AuNPs） nanocomposites with tunable sizes is reported. The nano- composites are obtained via the self-reduction reactions of MXene material in a HAuCI4 solution at room temperature. The sizes of the Au particles can be well-controlled by reg- ulating the self-reduction reaction time. They can greatly in- fluence the catalytic behaviors of the MXene@AuNPs composites. MXene@AuNPs composites with optimized re- duction time show high catalytic performances and good cycle stability for model catalytic reactions of nRro-compounds, such as 2-nitrophenol and 4-nitrophenol. This work demon- strates a new approach for the preparation of tunable MXene- based self-assembled composites.

Synthesis, characterization and fluorescence quenching of conjugated polymer containing triphenylamine group

Poly(triphenylamine-p-phenylenevinylene)s with two different end-groups were obtained through a Wittig polycondensation.The structures of two copoly-mers were characterized.Ultraviolet and visible spectro-scopy(UV-Vis)and photoluminescence(PL)spectra show the end-capped polymer emits intensive green light in both solution and film state.Their applications in the detection of nitro compounds were investigated,and the results show high fluorescence quenching sensitivity of the end-capped polymer towards o-nitrotoluene(o-NT).When the concentration of o-NT was 21.5×10^(-3) mol/L,the fluorescence quenching reached 96%.Additionally,after the exposure of polymer film in three different quenchers such as dinitrotoluene(DNT),p-nitrobenzo-quinone(p-BQ)and p-nitrotoluene(p-NT)for 600 s,its fluorescence quenching reached 93.6%,11.5%and 77.9%,respectively.This kind of polymer has great advantages in preparation and may find applications in the detection of nitro explosives.