APPLIED CATALYSIS B-ENVIRONMENTAL
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2016
·
IF 8.328
Yanghe Fu,Long Sun,Huan Yang,Lai Xu,Fumin Zhang,Weidong Zhu
The Ni-doped NH 2 -MIL-125(Ti) catalyst was developed for the photocatalytic aerobic oxidation of aromatic alcohols upon visible light irradiation. The results show that different aromatic alcohols can be effectively transformed to their corresponding aldehydes with almost absolute selectivity using O 2 as the oxidant over Ni-doped NH 2 -MIL-125(Ti) upon visible light irradiation. Compared with the parent catalyst NH 2 -MIL-125(Ti), Ni-doped NH 2 -MIL-125(Ti) exhibits a significantly enhanced photocatalytic activity for the selective oxidation of aromatic alcohols. Preliminary studies indicate that the doping of Ni nanoparticles into NH 2 -MIL-125(Ti) could improve the visible-light harvesting, charge-separation, and electron-transport of the resultant catalyst, leading to the enhanced photocatalytic activity. The current work provides some guidance in the development of MOF-based photocatalysts for organic syntheses.
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CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2017
·Vol. 96
·期 3
·739-748
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IF 1.356
Chun Xi Qin,Cheng Lin,Jie Tang,Zhen Hao Xi,Ling Zhao
Nylon 6 extract concentrate, namely, wastewater produced from industrial nylon 6 extraction unit, was hydrolyzed in subcritical water to efficiently decrease the cyclic dimer (CD) content. The CD equilibrium conversion reached a maximum when the initial water content ranged from 0.40 to 0.45 g/g; specifically, a CD conversion of 94.3 % was achieved at the hydrolysis temperature of 543 K and an initial water content of 0.40 g/g. A kinetic model including both acid- and base-catalyzed mechanisms was developed. The model predictions were in good agreement with the experimental results. The hydrolysis reaction constants increased significantly with increasing subcritical water content. By considering the effects of subcritical water on the individual reaction constants, the kinetic model could reproduce the experimental results over a wide range of initial water contents. Hopefully, the developed kinetic model will be applied in the design of a novel nylon 6 extract liquor recycling process.
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GREEN CHEMISTRY
·
2016
·Vol. 18
·期 12
·3628-3639
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IF 8.506
Xiaofeng Ning,Sugang Meng,Xianliang Fu,Xiangju Ye,Shifu Chen
In this study, a nanoparticle structure of CdS with cubic phase (CdS-G) was prepared by a facile solid-state reaction at room temperature for the first time. CdS-G can be used as a highly active photocatalyst for selective oxidation of p-methoxybenzyl alcohol (pMBA) to p-methoxybenzaldehyde (pMBAD) and reduction of nitrobenzene (NB) to aniline (AL) in a coupled reaction system under green mild reaction conditions through visible light irradiation. Compared with the counterparts prepared by the conventional precipitation method (CdS-P) and hydrothermal method (CdS-H), the photocatalytic performance of CdS-G is greatly improved owing to the unique features of the nanostructure, the high surface area, pore volume, visible light absorption and photoelectric properties. The yield of pMBAD (AL) over CdS-G is about 1.6 (5.2) and 1.9 (20.8) times higher than that over CdS-P and CdS-H, respectively. The CdS-G sample exhibits excellent selectivity and stability because its valence band (VB) and conduction band (CB) positions matched well with the redox potentials of pMBA/pMBAD and NB/AL. Furthermore, the photogenerated holes and electrons can be efficiently and directly reacted with pMBA and NB, respectively. The photocatalytic selective oxidation and reduction reaction is a synergistic reaction via producing and consuming protons. The photogenerated holes and electrons could be utilized thoroughly to produce pMBAD and AL, respectively. The molar ratio of pMBA and NB was 3 : 1, and the yield of pMBAD and AL could be successfully achieved at a theoretical ratio of 1 : 1. This work highlights the promising scope for selective organic synthesis in one reaction system under mild conditions using photogenerated electrons and holes directly and simultaneously.
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RSC Advances
·
2016
·Vol. 6
·期 115
·114519-114531
·
IF 3.289
Hui-Kang Yang,Meng Qi,Lei Mo,Rui-Meng Yang,Xiang-Dong Xu,Jun-Fang Bao,Wen-Jie Tang,Jian-Tao Lin,Li-Ming Zhang,Xin-Qing Jiang
Reduction-sensitive, amphiphilic dextran derivatives were developed from disulfide-linked dextran-g-poly-(N-ε-carbobenzyloxy-L-lysine) graft polymer (Dex-g-SS-PZLL), and used as theranostic nanocarriers for chemotherapy and MR imaging. Dex-g-SS-PZLLs were synthesized by click conjugation between azidized dextran (Dex-N3, 40 kD) and α-alkyne-SS-PZLL (degree of polymerization = 10, 15 and 25). The chemical structures of dextran derivatives were characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance analyses. Owing to their amphiphilic nature, these copolymers can self-assemble into spherical nanosized micelles in an aqueous medium, as confirmed by fluorometry, transmission electron microscopy and dynamic light scattering. Interestingly, the hydrodynamic radii of the micelles (65–100 nm in diameter) were dependent on the block length of PZLL, and their critical micelle concentrations were in the range of 0.020–0.007 mg mL−1, which decreased as the length of PZLL increased. The anticancer drug doxorubicin (DOX) and superparamagnetic iron oxide (SPIO) nanoparticles (NPs), as the magnetic resonance imaging (MRI) contrast agent, were simultaneously encapsulated in the hydrophobic core of the micelles by the dialysis method. The release profiles of encapsulated DOX from SPIO/DOX-loaded micelles were shown to be rapid in the presence of 10 mM glutathione (GSH) within 24 h, whereas less than 30% DOX was released from reduction insensitive Dex-g-PZLL micelles in 48 h. Only about 35% DOX was released from Dex-g-SS-PZLL micelles in the same timeframe. According to the in vitro cytotoxicity test, it was found that reduction-sensitive micelles showed higher toxicity to HepG2 cancer cells than the reduction-insensitive micelles incubated with equivalent DOX concentration. Flow cytometry and fluorescence microscopy analyses further demonstrated that the reduction-sensitive micelles exhibited faster drug release behavior than reduction-insensitive micelles, which also led to higher cytotoxicity. The SPIO/DOX-loaded micelles demonstrated excellent MRI contrast enhancement, and the r2 relaxivity values of the SPIO/DOX-loaded micelles were up to 261.3 Fe mM−1 s−1. Consequently, these reduction-sensitive amphiphilic dextran derivatives are promising theranostic nanocarriers for MR imaging and chemotherapy.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2016
·
IF 8.328
Zhiwang Yang,Xueqing Xu,Xixi Liang,Cheng Lei,Yuhan Cui,Wenhua Wu,Yaoxia Yang,Zhe Zhang,Ziqiang Lei
Photocatalytic synthesis using visible light is a desirable chemical process because of its potential to utilize sunlight. A heterostructured MIL-125/Ag/g-C 3 N 4 nanocomposite was implemented as an efficient bifunctional visible-light response catalyst for the photoreduction of nitrocompounds and the oxidation of alcohols. The photocatalyst was prepared via an accessible method and characterized by XRD, SEM, TEM, XPS, FT-IR, N 2 adsorption–desorption isotherm, UV–vis DRS, PL and EIS. The reactive efficiency of the photocatalyst depends on two primary factors, one is the light adsorption of catalysts, Ag nanoparticles (NPs) were photodeposited on the surface of g-C 3 N 4 and MIL-125 to increase visible-light absorption via the surface plasmon resonance. And the other is the separation efficiency of the photogenerated charge carrier. As an electron-conduction bridge in the interface between MIL-125 and g-C 3 N 4 , Ag NPs could facilitate the direct migration of photoinduced electrons from g-C 3 N 4 to MIL-125 and retard the recombination of electron-holes. Therefore, the MIL-125/Ag/g-C 3 N 4 sample shows highest photocatalytic activity compared with MIL-125, g-C 3 N 4 , MIL-125/Ag and MIL-125/g-C 3 N 4 . A corresponding photocatalytic mechanism of these reactions was discussed in detail. Moreover, the photoreduction of nitrocompounds and oxidation of the alcohols with superior conversions and selectivities were obtained, and the catalyst can be recycled four times. It is concluded that MIL-125/Ag/g-C 3 N 4 would be a promising visible light photocatalyst in the field of selective organic transformations.
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GREEN CHEMISTRY
·
2016
·Vol. 19
·期 4
·1109-1116
·
IF 8.506
Huan Liu,Dong-Liang Wang,Xia Chen,Yong Lu,Xiao-Li Zhao,Ye Liu
Mono-phosphines (L1 and L2) and diphosphines (L3 and L4) with typical π-acceptor character were prepared and applied in Ir(I)-catalyzed N-alkylation of amines with alcohols. It was found that the π-acceptor character of the applied phosphines is closely correlated to the catalytic efficiency of the [Ir(COD)Cl]2 complex for this green reaction. Compared to PPh3 as the typical σ-donor (i.e. with poor π-acceptor character), L1–L4 all resulted in the efficient N-alkylation of aniline to benzyl-aniline. While L1–L4 coordinated to the Ir(I)-catalyst, the consolidated Ir–P linkages due to π-backdonation could well protect the Ir-catalyst against deactivation, giving rise to the N-alkylation of aniline. On the other hand, the stabilized Ir-catalyst with the involvement of L2 could be recycled successfully for at least 4 runs in the ionic liquid of [MePh3P]Br without the detectable leaching of Ir and P elements in the organic products.
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CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2016
·Vol. 32
·期 4
·586-593
·
IF 1.086
Zhang Guofu,Zhang Guihua,Lei Jie,Li Shasha,Xu Shengjun,Ding Chengrong,Shan Shang
A facile, practical and scalable catalyst system for alcohols ammoxidation into nitriles is developed using amino acid as ligand, oxygen as terminal oxidant and copper iodide(CuI) as catalyst. The catalyst system shows excellent functional groups compatibility for a wide range of testing substrates, even the substrates bearing oxidation-sensitive groups such as MeS—, alkenyl and —NH 2 can also work well. In addition, the protocol is readily scaled up to more than 20 g and the product can be obtained just through filtration or distillation without conventional column chromatography.
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POLYMER DEGRADATION AND STABILITY
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2016
·
IF 3.12
Shijie Hou,Yong Jian Zhang,Pingkai Jiang
Phosphonium sulfonates (PhSs) as flame retardants have been synthesized from organic sulfonates and triphenylphosphine as starting materials. The PhSs revealed good thermal stability and efficient flame retardancy for polycarbonate (PC). The LOI values increased with the increase of PhS-1 contents to PC and reached 33.7 when the PhS-1 content is 10 phr, and the V-0 rating can be achieved when only 5 phr PhSs are added. The cone calorimeter analysis indicated that the HRR and THR were reduced with the addition of PhSs to the PC matrix. The PhS bearing alkene group revealed highest LOI values and lowest peak HRR (pHRR) values for PC. The morphology of the residual chars after LOI test and the element content of the chars after CONE test were also investigated by SEM and EDX .
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2016
·
IF 8.328
Zhiwang Yang,Xueqing Xu,Xixi Liang,Cheng Lei,Yuli Wei,Peiqi He,Bolin Lv,Hengchang Ma,Ziqiang Lei
A series of MIL-53(Fe)-graphene nanocomposite photocatalysts were synthesized by a facile one-pot solvothermal reaction. All materials have been thoroughly characterized by FT-IR, SEM, TEM, PXRD, UV–vis DRS and PL analysis. It was demonstrated that the introducing of graphene on the MIL-53(Fe) would minimize the recombination of photogenerated electron-hole pairs, thus, leading to the enhancement of photocatalytic activity. MIL-53(Fe)-graphene nanocomposite was an efficient catalyst towards the photocatalytic selectively oxidation of alcohols to the corresponding aldehydes or ketones under visible light and ambient conditions. High selectivity of the aldehydes or ketones (99%) were obtained. Meanwhile, the catalyst can be recycled at least four times without loss of catalytic efficiency. A possible photocatalytic reaction mechanism involving a direct photogenerated hole-oxidation process was also investigated in detail by the active species trapping experiments and the related electrochemical analysis.
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Analytical Methods
·
2016
·Vol. 8
·期 23
·4727-4735
·
IF 1.915
Chaojun He,Xiangmeng Guo,Yumin Yang,Yanfu Xie,Fengyang Ju,Wenbo Guo
Aroma volatiles from zijuan and pu-erh green teas were extracted by headspace solid-phase microextraction (HS-SPME). They were then characterized and identified using gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). The conditions of HS-SPME, including fiber selection and optimization of sampling conditions, have been previously investigated. Under optimal conditions, 51 and 42 aroma-active compounds were detected and characterized in zijuan and pu-erh green tea samples, respectively. Alcohols, ketones, and hydrocarbons were qualitatively the most dominant aroma-active compounds in zijuan and pu-erh green teas. The aroma-active compounds with similar sensory descriptors were grouped into the same category, and the sum of individual aroma intensity values within each category showed that the “floral” aroma, “woody” aroma, and “fruity” aroma in both zijuan and pu-erh green teas were the major aroma categories. These aroma notes were closely related to the characteristics of green tea aroma and its sensory perception.
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TALANTA
·
2016
·
IF 4.035
Xiyue Xiong,Haiqin He,Yan Shu,Yuxin Li,Zihui Yang,Yingzhuang Chen,Ming Ma,Bo Chen
A facile, flexible process was developed for the preparation of surface-glycosylated porous monolithic columns via aqueous two-phase graft copolymerization of polyethylene glycol diacrylate (PEGDA) and water-soluble dextran (dextran sulfate). The formation of poly(PEGDA) porous skeletons and surface glycosylation were achieved via a one-step process without pre-modification of the dextran. The synthesis conditions were thoroughly optimized. The optimal monolithic column exhibited a large dry state surface area (greater than 400 m 2 /g), and it was evaluated as a hydrophilic liquid chromatography (HILIC) stationary phase. A typical HILIC mechanism was observed at high organic solvent content (≥65% acetonitrile). In addition, the resulting monolithic column demonstrated the potential use in analysis of complex biological sample and enviroment water.
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PubMed
高影响因子
JOURNAL OF ORGANOMETALLIC CHEMISTRY
·
2016
·
IF 2.336
Xiang-Xin Zheng,Zhong-Xia Wang
Di(aminomethylpyrrolyl)methane derivatives [2-{5-R′ 2 NCH 2 (C 4 H 2 NH)}] 2 CR 2 ( 2a R = Et, R′ = Me; 2b R = Ph, R′ = Me; 2c R = Ph, R′ = Et; 2d R 2 = 1,1′-biphenyl-2,2′-diyl, R′ = Me; 2e R 2 = 1,1′-biphenyl-2,2′-diyl, R′ 2 = (CH 2 ) 4 ) were prepared through reaction of di(1 H -pyrrol-2-yl)methane derivatives (2-C 4 H 3 NH) 2 CR 2 ( 1a R = Et; 1b R = Ph; 1c R 2 = 1,1′-biphenyl-2,2′-diyl) with formaldehyde and amines. Treatment of 2a with 3 equiv. of ZnEt 2 in toluene afforded trinuclear zinc conplex 3a , while respective reaction of 2b - 2e with 3 equiv. of ZnEt 2 in toluene or THF produced dinuclear zinc complexes 3b - 3e . Each of the complexes was characterized by 1 H and 13 C NMR spectroscopy and elemental analysis . Structures of complexes 3a and 3b were additionally characterized by single crystal X-ray diffraction. Catalysis of complexes 3a - 3e toward the ROP of rac -lactides was evaluated in both toluene and THF. Each complex was active in the catalysis in the presence of benzyl alcohol (BnOH). 3a showed the highest activity in toluene and 3c was the most active in THF. Kinetic study of complexes 3a and 3e was carried out and the results showed that the polymerization catalyzed by 3e /BnOH follows a first-order kinetics, while 3a /BnOH-catalyzed polymerization followed neither first-order nor second-order kinetics.
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