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91.
Copper‐Catalyzed Difunctionalization of Activated Alkynes by Radical Oxidation–Tandem Cyclization/Dearomatization to Synthesize 3‐Trifluoromethyl Spiro[4.5]trienones 下载免费PDF全文
Dr. Hui‐Liang Hua Yu‐Tao He Yi‐Feng Qiu Ying‐Xiu Li Bo Song Pin Gao Xian‐Rong Song Dong‐Hui Guo Prof. Dr. Xue‐Yuan Liu Prof. Dr. Yong‐Min Liang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(4):1468-1473
A copper‐catalyzed difunctionalizing trifluoromethylation of activated alkynes with the cheap reagent sodium trifluoromethanesulfinate (NaSO2CF3 or Langlois’ reagent) has been developed incorporating a tandem cyclization/dearomatization process. This strategy affords a straightforward route to synthesis of 3‐(trifluoromethyl)‐spiro[4.5]trienones, and presents an example of difunctionalization of alkynes for simultaneous formation of two carbon–carbon single bonds and one carbon–oxygen double bond. 相似文献
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In Situ Synthesis and Characterization of Poly(aryleneethynylene)‐Grafted Reduced Graphene Oxide 下载免费PDF全文
Sai Sun Dr. Xiaodong Zhuang Prof. Dr. Bo Liu Luxing Wang Linfeng Gu Prof. Dr. Sannian Song Prof. Dr. Bin Zhang Prof. Dr. Yu Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2247-2252
Using highly soluble bromo‐functionalized reduced graphene oxide (RGBr) as a key graphene template for surface‐directing Sonogashira–Hagihara polymerization, a novel soluble poly(arylene‐ethynylene)‐grafted reduced graphene oxide, hereafter abbreviated as PAE‐g‐RGO, was prepared in situ. The entirely different electron distribution of LUMO and HOMO of PAE‐g‐RGO suggested the existence of a charge‐transfer (CT) state (PAE.?–RGO.+). The negative ΔGCS value (?2.57 eV) indicates that the occurrence of the charge separation via 1RGO* in o‐DCB is exothermic and favorable. Upon irradiation with 365 nm light, the light‐induced electron paramagnetic resonance (LEPR) spectrum of PAE‐g‐RGO showed a decrease in the spin‐state density owing to photoinduced intramolecular electron transfer events in this system. A sandwich‐type Al/PAE‐g‐RGO/ITO device showed representative bistable electrical switching behavior. The nonvolatile memory performance was attributed to the CT‐induced conductance changes, which was supported by molecular computation results and conductive atomic force microscopy (C‐AFM) images. 相似文献
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Tianrong Yu Yang Gao Bo Wang Xing Dai Wanrun Jiang Ruixia Song Prof. Zhanwen Zhang Prof. Mingxing Jin Prof. Yongjian Tang Prof. Zhigang Wang 《Chemphyschem》2015,16(15):3308-3312
The mechanism of depolymerization is one of the most essential issues in chemical engineering and materials science. In this work, we investigate the depolymerization reactions of three typical free‐radical poly(alpha‐methylstyrene) tetramers by using first‐principles density functional theory. The calculated results show that these reactions all need to overcome the energy barriers in the range of 0.58 to 0.77 eV, and that breaking the C?C bond at the chain end leads to the dissociation of alpha‐methylstyrene monomers from the polymers. Electronic‐structure analysis indicates that the reactions occur easily at the CR3 unsaturated end, and that the frontier molecular orbitals that participate in the reactions are mainly localized at the unsaturated ends. Meanwhile, spin population analysis presents the unique net spin‐transfer process in free‐radical depolymerization reactions. We hope the current findings can contribute to understanding the free‐radical depolymerization mechanism and help guide future experiments. 相似文献
98.
Theoretical and experimental research on the self‐assembled system of molecularly imprinted polymers formed by salbutamol and methacrylic acid 下载免费PDF全文
The quantum chemical method was applied for screening functional monomers in the rational design of salbutamol‐imprinted polymers. Salbutamol was the template molecule, and methacrylic acid was the single functional monomer. The LC‐WPBE/6–31G(d,p) method was used to investigate the geometry optimization, active sites, natural bond orbital charges, binding energies of the imprinted molecule, and solvation energy. The mechanism of action between salbutamol and methacrylic acid was also discussed. The theoretical results show that salbutamol interacts with functional monomers by hydrogen bonds, and the salbutamol‐imprinted polymers with a ratio of 1:4 (salbutamol/methacrylic acid) in acetonitrile had the highest stability. The salbutamol‐imprinted polymers were prepared by precipitation polymerization. The experimental results indicated that the maximum adsorption capacity for salbutamol toward molecularly imprinted polymers was 7.33 mg/g, and the molecularly imprinted polymers had a higher selectivity for salbutamol than for norepinephrine and terbutaline sulfate. Herein, the studies can provide theoretical and experimental references for the salbutamol molecular imprinted system. 相似文献
99.
Chemometrics for comprehensive analysis of nucleobases,nucleosides, and nucleotides in Siraitiae Fructus by hydrophilic interaction ultra high performance liquid chromatography coupled with triple‐quadrupole linear ion‐trap tandem mass spectrometry 下载免费PDF全文
Guisheng Zhou Mengyue Wang Renjie Xu Xiao‐Bo Li 《Journal of separation science》2015,38(20):3508-3515
A rapid and sensitive hydrophilic interaction ultra high performance liquid chromatography coupled with triple‐quadrupole linear ion‐trap tandem mass spectrometry method was validated for the simultaneous determination of 20 nucleobases, nucleosides, and nucleotides (within 3.5 min), and then was employed to test the functional food of Luo‐Han‐Guo samples. The analysis showed that the Luo‐Han‐Guo was rich in guanosine and uridine, but contained trace levels of the other target compounds. Chemometrics methods were employed to identify 40 batches of Luo‐Han‐Guo samples from different cultivated forms, regions and varieties. Unsupervised hierarchical cluster analysis and principal component analysis were used to classify Luo‐Han‐Guo samples based on the level of the 20 target compounds, and the supervised learning method of counter propagation artificial neural network was utilized to further separate clusters and validate the established model. As a result, the samples could be clustered into three primary groups, in which correlation with cultivated varieties was observed. The present strategy could be applied to the investigation of other edible plants containing nucleobases, nucleosides, or nucleotides. 相似文献
100.
以介孔分子筛MCM-48为前驱体,通过表面胺化和高温NH3氮化方法制备出两种碱性分子筛.采用X射线衍射(XRD)、N2-吸附脱附、透射电镜(TEM)、红外光谱(FT-IR)、热重分析(TG)和哈密特指示剂法对上述分子筛的结构及表面酸碱性进行了详细表征,并通过苯甲醛与丙二腈的Knoevenagel缩合反应对其碱催化活性及稳定性进行了考察和对比.结果表明,表面胺化和高温氮化的方法均可制备出碱性介孔分子筛,且均在Knoevenagel碱性探针反应中表现出较好的碱催化活性,但与后者相比,前者制备的碱性分子筛具有更强的表面碱性和更好的反应稳定性. 相似文献