One-pot propagation of (Hetero)Arylamines: Modular synthesis of diverse Amino-di(hetero)arylamines

Formal propagation of (hetero)arylamine is achieved via a one-pot Buchwald–Hartwig C–N cross-coupling and nitro reduction sequence, enabling a rapid modular synthesis of diverse amino-di(hetero)arylamines from (hetero)arylamines and halogenated nitrobenzenes. Various functionalized aromatic amines with different electronic and steric environments can be efficiently prolongated to formally incorporate another arylamino fragments. This approach has been successfully applied in the synthesis of more than forty amino-di(hetero)arylamines. The applicability of this method has also been demonstrated in the synthesis of oligoanilines and the tyrosine-kinase inhibitor Imatinib.     

表面暴露活性位点的MoS_2纳米催化剂催化硝基化合物的非均相氢转移反应（英文）

MoS_2具有独特的二维层状结构,被广泛用于加氢脱硫过程以及HER反应,而且可以通过减少MoS_2的颗粒尺寸以及层数来进一步改善其催化活性.通过剥离方法得到的MoS_2纳米片虽然表现出优良的加氢脱硫活性,但容易团聚使其循环使用性能很差.如果通过引入纳米碳将单层的MoS_2纳米片进行有效"隔离",则可明显降低团聚的可能性,从而改善其催化性能和稳定性.本文通过一步水热法制备出了碳嵌入的MoS_2纳米颗粒(MoS_2@C),将其应用于硝基苯类化合物的氢转移反应中表现出了非常好的催化性能.进一步通过粉末X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)和在线质谱检测等手段研究了层间距增加的MoS_2催化剂在硝基苯类化合物的氢转移反应中催化性能提升的原因.XRD,SEM和TEM结果表明,通过引入碳材料可以明显增加MoS_2的层间距,同时减小其颗粒尺寸,而且使MoS_2表现出弯曲的(002)晶面.由于存在一定的曲率,这种(002)晶面也会表现出一定的催化能力.氮气物理吸附结果表明,这种MoS_2@C复合物具有较高的比表面积(89 m~2g~(-1))和明显的介孔结构(~20 nm),在催化反应中有利于底物扩散,进而改善催化性能.XPS结果显示,与体相的MoS_2相比,MoS_2@C表面暴露出更多的不饱和Mo原子(Mo/S=0.71(MoS_2@C)vs Mo/S=0.63(MoS_2)),形成了独特的S-Mo-O结构以及缺陷结构.在硝基苯类化合物的氢转移反应中,层间距增加的MoS_2@C由于暴露出更多的活性位和具有弯曲的(002)晶面,表现出了更高的催化活性–(TOF=3.66 s~(-1) vs 1.24 s~(-1)(MoS_2)).通过质谱对反应过程的追踪发现,在只有肼存在的条件下,MoS_2@C催化肼分解的主要气相产物是氨气.这说明MoS_2@C能够使肼发生N-N键的断裂.而当肼和硝基苯同时存在的条件下,质谱检测的气相产物主要是氮气,表明硝基苯的存在可以诱导肼逐步发生N-H键断裂,在催化剂表面形成活性的H物种,进而转移到硝基苯上使其还原得到苯胺.使用偶氮苯和氧化偶氮苯作为反应底物,发现MoS_2@C很难使其还原为苯胺,这说明在该催化体系中,硝基苯的还原过程主要是沿着直接路径(硝基苯-亚硝基苯-苯胺)进行的.     

顶空单液滴微萃取-气相色谱法测定水中苯系物

采用顶空单液滴微萃取样品处理方法分离富集水中苯系物,用气相色谱法进行测定.考察了不同萃取剂、萃取条件对检测结果的影响.苯、甲苯、对二甲苯的检出限分别为0.05,0.05,0.03 μg·L-1,三种苯同系物的相关系数分别为0.999 2,0.998 5和0.997 2,回收率分别为98.3%,101.9%和97.3%.     

Evidence for a SN2-type pathway for phosphine exchange in phosphine-phosphenium cations, [R2P--PR'3]+

Abstraction of a Cl(-) ion from the P-chlorophospholes, R4C4PCl (R=Me, Et), produced the P--P bonded cations [R4C4P--P(Cl)C4R4]+, which reacted with PPh3 to afford X-ray crystallographically characterised phosphine-phosphenium cations [R4C4P(PPh3)]+ (R=Me, Et). Examination of the 31P-{1H} NMR spectrum of a solution (CH2Cl(2)) of [Et4C4P-(PPh3)]+ and PPh3 revealed broadening of the resonances due to both free and coordinated PPh3, and importantly it proved possible to measure the rate of exchange between PPh3 and [Et4C4P-(PPh3)]+ by line shape analysis (gNMR programmes). The results established second-order kinetics with DeltaS( not equal)=(-106.3+/-6.7) J mol(-1) K(-1), DeltaH( not equal)=(14.9+/-1.6) kJ mol(-1) and DeltaG( not equal) (298.15 K)=(46.6+/-2.6) kJ mol(-1), values consistent with a SN2-type pathway for the exchange process. This result contrasts with the dominant dissociative (S(N)1-type) pathway reported for the analogous exchange reactions of the [ArNCH2CH2N(Ar)P(PMe3)]+ ion, and to understand in more detail the factors controlling these two different reaction pathways, we have analysed the potential energy surfaces using density functional theory (DFT). The calculations reveal that, whilst phosphine exchange in [Et4C4P(PPh3)]+ and [ArNCH2CH2N(Ar)P(PMe3)](+) is superficially similar, the two cations differ significantly in both their electronic and steric requirements. The high electrophilicity of the phosphorus center in [Et4C4P]+, combined with strong pi-pi interactions between the ring and the incoming and outgoing phenyl groups of PPh3, favours the SN2-type over the SN1-type pathway in [Et4C4P(PPh3)]+. Effective pi-donation from the amide groups reduces the intrinsic electrophilicity of [ArNCH2CH2N(Ar)P]+, which, when combined with the steric bulk of the aryl groups, shifts the mechanism in favour of a dissociative SN1-type pathway.     

超细Pd—B／SiO2非晶态合金加氢反应的催化活性

采用浸渍法并通过ＫＢＨ４还原制备超细Ｐｄ－Ｂ／ＳｉＯ２非晶态合金催化剂,以硝基苯加氢生成苯胺为目标反应,考察了上述催化剂的活性和选择性及热稳定性,并与晶态Ｐｄ－Ｂ／ＳｉＯ２和Ｐｄ／ＳｉＯ２催化剂及非负载型Ｐｄ－Ｂ非晶态合金催化剂进行了比较。     

[2,6‐(Trip)2H3C6 ](Cp*)Si: A Stable Monomeric Arylsilicon(II) Compound

Si takes a rest : A bulky σ‐bound terphenyl substituent and a π‐bound Cp* ligand enable the isolation and full characterization of the first aryl‐substituted, monomeric silicon(II) compound 1 , which can be regarded as the “resting state” of a true silylene containing a σ‐bound Cp* group. The conformation of the aryl group prevents aryl–Si π back‐bonding.

     

Biostimulation-enhanced Biodegradation of Nitrobenzene in Contaminated Groundwater

In this study, biostimulation technology was used for bioremediation of nitrobenzene-contaminated groundwater by adding a mixture of lactose and phosphate, peptone, and beef extract. During the process of biostimulation, the remediation effectiveness, microbial dehydrogenase activities and microbial densities were investigated; the varieties of microbial community structure and composition were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE) technique and the relative abundances of nitrobenzene-degrading gene(nbzA) were determined by fluorescence quantitative real-time PCR(RT-PCR). Findings show that the removal rate of nitrobenzene in groundwater could reach about 60% by biostimulation with lactose and phosphate, 70% with peptone and 68% with beef extract. The microbial dehydrogenase activities and microbial densities were all improved obviously via biostimulation. The results of PCR-DGGE show that the microbial diversities were improved, and more than ten kinds of dominant microorganisms were detected after biostimulation. RT-PCR results show that the relative abundances of nbzA gene of microbes in groundwater were increased significantly, which indicated that biostimulation actually enhanced the growth of nitrobenzene-degrading bacteria. Therefore, biostimulation is a cost-effective and feasible bioremediation technique for nitrobenzene-contaminated groundwater.     

Degradation of nitrobenzene in aqueous solution by dual-pulse ultrasound enhanced electrochemical process

The present work reports a novel dual-pulse ultrasound enhanced electrochemical degradation (US-ECD) process that synchronizes alternatively ultrasound pulses and potential pulses to degrade nitrobenzene in aqueous solution with a high percentage degradation and low energy consumption. In comparison to the test results generated from the conventional US-ECD and original electrochemical degradation (ECD) process, the dual-pulse US-ECD process increased degradation percentages to nitrobenzene by 2% and 17%, respectively, while energy used in the pulse process was only about 46.5% of that was used in the conventional US-ECD process. Test results demonstrated a superior performance of the dual-pulse US-ECD process over those of other conventional ones. Impacts of pulse mode, initial pH value, cell voltage, supporting electrolyte concentration and ultrasonic power on the process performances were investigated. With operation conditions optimized in the study at pH = 3.0, cell voltage = 10 V, ultrasonic power = 48.84 W, electrolyte concentration = 0.1 M and an experiment running time of 30 min, the percentage degradation of nitrobenzene could reach 80% (US pulse time = 50 ms and ECD pulse time = 50 ms). This process provided a reliable and effective technical approach to degrade nitrobenzene in aqueous solution and significantly reduced energy consumption in comparison to the conventional US-ECD or original ECD treatment.     

Synthesis and Tunable Reactivity of N‐Heterocyclic Germylene

Modifying the β‐diketimine ligand LH 1 (LH=[ArN?C(Me)? CH?C(Me)? NHAr], Ar=2,6‐iPr₂C₆H₃) through replacement of the proton in 3‐position by a benzyl group (Bz) leads to the new ^BzLH ligand 2, which could be isolated in 77 % yield. According to ¹H NMR spectroscopy, 2 is a mixture of the bis(imino) form [(ArN?C(Me)]₂CH(Bz) 2a and its tautomer [ArN?C(Me)? C(Bz)?C(Me)NHAr] 2b. Nevertheless, lithiation of the mixture of 2a and 2b affords solely the N‐lithiated β‐diketiminate [ArN?C(Me)? C(Bz)?C(Me)? NLiAr], ^BzLLi 3. The latter reacts readily with GeCl_2?dioxane to form the chlorogermylene ^BzLGeCl 4, which serves as a precursor for a new zwitterionic germylene by dehydrochlorination with LiN(SiMe₃)₂. This reaction leads to the zwitterionic germylene ^BzL′Ge: 5 (^BzL′=ArNC(?CH₂)C(Bz)?C(Me)NAr) which could be isolated in 83 % yield. The benzyl group has a distinct influence on the reactivity of zwitterionic 5 in comparison to its benzyl‐free analogue, as shown by the reaction of 5 with phenylacetylene, which yields solely the 1,4‐addition product 6, that is, the alkynyl germylene ^BzLGeCCPh. Compounds 2–8 have been fully characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses, and single‐crystal X‐ray diffraction analyses.     

Simultaneous Gas Chromatographic Determination of Nitrobenzene and 2,4-Dinitrophenol in Nitrobenzene Manufacturing Plant Wastewater

Abstract

A simple and rapid gas chromatographic procedure is described for the identification and quantification of pollutants in the nitrobenzene manufacturing plant wastewater. The samples were extracted with methylene chloride and subsequently nitrobenzene and 2,4-dinitrophenol were analysed by GC using FID. The method was found to be precise and accurate and applicable for monitoring the effluent treatment system at ppm levels.