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991.
992.
993.
《Green Chemistry Letters and Reviews》2013,6(2):185-193
Abstract A variety of 1,3,5-trisubstituted benzenes could be obtained upon heating enaminones in absence of solvent over montmorillonite-K-10. Heating mixtures of two different enaminones 2a–d have also afforded 1,3,5-trisubstituted benzenes 7b–d and 8b–d resulting from self-condensation of one enaminone with two molecules of the other enaminone. Heating enaminone 2b with ethyl propiolate afforded a mixture of triaroylbenzene 3b in addition to diaroylbenzoic acid esters 11 and 1,3,5-aroylbenzene dicarboxylate 12. On the other hand, reaction of enaminone derivative 2b with dimethyl acetylenedicarboxylate has afforded 2-oxopyran-4-carboxylic acid derivative 15. 2-Aminoprop-1-ene-1,1,3-tricarbonitrile 16 was reacted with enaminones to yield polysubstituted benzenes 19a–c. Likewise the reaction of 2-aminoprop-1-ene-1,1,3-tricarbonitrile 16 with benzylidenemalononitrile has afforded polysubstituted benzenes 24. 相似文献
994.
The ripeness of grapes at the harvest time is one of the most important parameters for obtaining high quality red wines. Traditionally the decision of harvesting is to be taken only after analysing sugar concentration, titratable acidity and pH of the grape juice (technological maturity). However, these parameters only provide information about the pulp ripeness and overlook the real degree of skins and seeds maturities (phenolic maturity). Both maturities, technological and phenolic, are not simultaneously reached, on the contrary they tend to separate depending on several factors: grape variety, cultivar, adverse weather conditions, soil, water availability and cultural practices. Besides, this divergence is increasing as a consequence of the climate change (larger quantities of CO2, less rain, and higher temperatures). 相似文献
995.
Xiaoying Wang Xiaobing Wang Xiaoning Wang Fentian Chen Kehui Zhu Qian Xu Meng Tang 《Analytica chimica acta》2013
A novel electrochemical biosensor based on functional composite nanofibers for sensitive hybridization detection of p53 tumor suppressor using methylene blue (MB) as an electrochemical indicator is developed. The carboxylated multi-walled carbon nanotubes (MWNTs) doped nylon 6 (PA6) composite nanofibers (MWNTs–PA6) was prepared using electrospinning, which served as the nanosized backbone for pyrrole (Py) electropolymerization. The functional composite nanofibers (MWNTs–PA6–PPy) used as supporting scaffolds for ssDNA immobilization can dramatically increase the amount of DNA attachment and the hybridization sensitivity. The biosensor displayed good sensitivity and specificity. The target wild type p53 sequence (wtp53) can be detected as low as 50 fM and the discrimination is up to 57.5% between the wtp53 and the mutant type p53 sequence (mtp53). It holds promise for the early diagnosis of cancer development and monitoring of patient therapy. 相似文献
996.
The use of a polymer inclusion membrane in a paper-based sensor for the selective determination of Cu(II) 总被引:1,自引:0,他引:1
B. Manori Jayawardane Lilibeth dlC. Coo Robert W. Cattrall Spas D. Kolev 《Analytica chimica acta》2013
A disposable paper-based sensor (PBS) is described for the determination of Cu(II) in natural and waste waters at approximately 2 cents per measurement. The device makes use of a polymer inclusion membrane (PIM) to provide the selectivity for Cu(II). The PIM consists of 40 wt% di(2-ethlyhexyl) phosphoric acid (D2EHPA) as the carrier, 10 wt% dioctyl phthalate (DOP) as a plasticizer, 49.5 wt% poly(vinyl chloride) (PVC) as the base polymer and 0.5 wt% (m m−1) 1-(2′-pyridylazo)-2-naphthol (PAN) as the colourimetric reagent. High selectivity under mildly acidic conditions (HCl, pH 2.0) is achieved for Cu(II) in the presence of frequently encountered metal ions in natural and waste waters such as Fe(III), Al(III), Zn(II), Cd(II), Pb(II), Ca(II), Mg(II), and Ni(II). 相似文献
997.
Saied Saeed Hosseiny Davarani Hamid Reza Moazami Ali Reza Keshtkar Mohammad Hossein Banitaba Saeed Nojavan 《Analytica chimica acta》2013
A novel method for the selective electromembrane extraction (EME) of U6+ prior to fluorometric determination has been proposed. The effect of extraction conditions including supported liquid membrane (SLM) composition, extraction time and extraction voltage were investigated. An SLM composition of 1% di-2-ethyl hexyl phosphonic acid in nitrophenyl octyl ether (NPOE) showed good selectivity, recovery and enrichment factor. The best performance was achieved at an extraction potential of 80 volts and an extraction time of 14 minutes Under the optimized conditions, a linear range from 1 to 1000 ng mL−1 and LOD of 0.1 ng mL−1 were obtained for the determination of U6+. The EME method showed good performance in sample cleanup and the reduction of the interfering effects of Mn2+, Zn2+, Cd2+, Ni2+, Fe3+, Co2+, Cu2+, Cl− and PO43− ions during fluorometric determination of uranium in real water samples. The recoveries above 54% and enrichment factors above 64.7 were obtained by the proposed method for real sample analysis. 相似文献
998.
Herein, synthesis of a series of naphtho[2,3-f]quinolin-13-one and naphtho[2,3-a]acridin-1(2H)-one derivatives directly by one-pot multi-component reaction of 1,3-dicarbonyl compounds (1,3-indanedione/1,3-cyclohexanedione), 2-aminoantharacene/2-naphthylamine and various substituted aldehydes under solvent-free conditions using heteropoly-11-molybdo-1-vanadophosphoric acid supported on montmorillonite K-10 clay catalyst (10% PVMoK-10) is reported. The successful formation of naphtho[2,3-f]quinolin-13-one and naphtho[2,3-a]acridin-1(2H)-one derivatives was confirmed by various spectroscopic techniques. This study offers a green approach for the synthesis of novel quinolinone derivatives. 相似文献
999.
An efficient, solid‐catalyst‐mediated Hantzsch synthesis of 1,4‐dihydropyridines is described. This procedure has such advantages as short reaction time, high yields, and simple workup. The catalyst could be reused several times and keeps its initial activity in the subsequent reactions. 相似文献
1000.
Different novel phthalazino[2,3‐b]phthalazine‐5,7,12,14‐tetraones were synthesized in a simple and environmentally benign method from the reaction of phthalic anhydrides with semicarbazide or thiosemicarbazide using montmorillonite K‐10 clay as solid heterogeneous acidic catalyst and microwaves under solvent‐free conditions in good yields and short reaction times. Products were characterized by the elemental analysis, IR, NMR, and mass spectrometry. 相似文献