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排序方式: 共有174条查询结果,搜索用时 15 毫秒
31.
Vitale M Lecourt T Sheldon CG Aggarwal VK 《Journal of the American Chemical Society》2006,128(8):2524-2525
The reaction of lithiated trimethylsilyldiazomethane (LTMSD) with aldehydes and subsequent quenching with TMSCl furnished relatively stable alpha-silylated diazocompounds. Upon treatment of the alpha-silylated diazocompounds with Rh2(OAc)4 in refluxing toluene, alpha-silyl silyl enol ethers were formed from unbranched and branched aliphatic aldehydes through predominantly 1,2-migration of the C-H bond. In contrast, treatment of the alpha-silylated diazocompounds with Rh2(tfa)4 at room temperature gave alpha-silyl silyl enol ethers through exclusive and unusual 1,2-migration of the C-C bond. The origin of the selectivity observed from the two catalysts is discussed in relation to early and late transition states. 相似文献
32.
Bioactive indolo[3,2-j]phenanthridine alkaloids, calothrixin B and its N-oxide derivative calothrixin A have been synthesized via an oxidative free radical reaction. Calothrixin B is generated from the commercially available 2,4,5-trimethoxybenzaldehyde in only seven steps. The key step in this synthesis is the Mn(OAc)3 mediated oxidative free radical reaction of 9-(benzylamino)phenanthridine-7,10-dione with cyclohexenone to form 12-benzyl-12H-indolo[3,2-j]phenanthridine-7,13-dione. 相似文献
33.
34.
S. A. Vitale K. Hadidi D. R. Cohn P. Falkos 《Plasma Chemistry and Plasma Processing》1997,17(1):59-78
The effect of a carbon-carbon double bond on the energy required for decomposition in an electron beam-generated plasma reactor
is studied by comparing the decomposition of trichloroethylene and 1,1,1-trichloroethane. A reaction mechanism for TCE decomposition
based on a chlorine radical chain reaction is presented which accounts for the formation of all of the experimentally observed
reaction products. TCE decomposition is autocatalyzed by reaction products, whereas TCA decomposition is inhibited. The rate
expression for the decomposition of TCE in the reactor is determined to be r=−[T](15.07[T0]−0.40+0.006{[T0]−[T]}), where [T] and [T0] are both in ppm, and r is in ppm Mrad−1. The energy expense ɛ for TCE decomposition is determined as a function of inlet concentration. For 99% decomposition of
100 ppm TCE in air, ɛ=28 eV/molecule, and ɛ=2.5 eV/molecule at 3000 ppm. This is only 2.5–5% of the amount of energy required
to decompose a similar amount of TCA as reported by the authors in a previous study. By comparing the energy requirements
for TCE decomposition to those for TCA decomposition, the TCE reaction chain length is determined to increase from approximately
20 at 100 ppm initial TCE concentration, to 40 at 3000 ppm.
This work was supported by the Contaminant Plume Containment and Remediation Focus Area, Office of Environmental Management,
U.S. Department of Energy. 相似文献
35.
36.
Annalisa Chiavaroli Simonetta Cristina Di Simone Alessandra Acquaviva Maria Loreta Libero Claudia Campana Lucia Recinella Sheila Leone Luigi Brunetti Giustino Orlando Nilofar Irene Vitale Stefania Cesa Gokhan Zengin Luigi Menghini Claudio Ferrante 《Molecules (Basel, Switzerland)》2022,27(19)
Pollen extract represents an innovative approach for the management of the clinical symptoms related to prostatitis and pelvic inflammatory disease (PID). In this context, the aims of the present work were to analyze the phenolic composition of a hydroalcoholic extract of PollenAid Plus soft gel capsules, and to evaluate the extract’s cytotoxic effects, in human prostate cancer PC3 cells and human ovary cancer OVCAR-3 cells. Additionally, protective effects were investigated in isolated prostate and ovary specimens exposed to lipopolysaccharide (LPS). The phytochemical investigation identified catechin, chlorogenic acid, gentisic acid, and 3-hydroxytyrosol as the prominent phenolics. The extract did not exert a relevant cytotoxic effect on PC3 and OVCAR-3 cells. However, the extract showed a dose-dependent inhibition of pro-inflammatory IL-6 and TNF-α gene expression in prostate and ovary specimens, and the extract was effective in preventing the LPS-induced upregulation of CAT and SOD gene expression, which are deeply involved in tissue antioxidant defense systems. Finally, a docking approach suggested the capability of catechin and chlorogenic acid to interact with the TRPV1 receptor, playing a master role in prostate inflammation. Overall, the present findings demonstrated anti-inflammatory and antioxidant effects of this formulation; thus, suggesting its capability in the management of the clinical symptoms related to prostatitis and PID. 相似文献
37.
38.
Dr. Giuseppe Dilauro Dr. Cosimo Luccarelli Dr. Andrea F. Quivelli Prof. Paola Vitale Prof. Filippo M. Perna Prof. Vito Capriati 《Angewandte Chemie (International ed. in English)》2023,62(30):e202304720
Advancing the development of perfecting the use of polar organometallics in bio-inspired solvents, we report on the effective generation in batch of organosodium compounds, by the oxidative addition of a C−Cl bond to sodium, a halogen/sodium exchange, or by direct sodiation, when using sodium bricks or neopentylsodium in hexane as sodium sources. C(sp3)-, C(sp2)-, and C(sp)-hybridized alkyl and (hetero)aryl sodiated species have been chemoselectively trapped (in competition with protonolysis), with a variety of electrophiles when working “on water”, or in biodegradable choline chloride/urea or L-proline/glycerol eutectic mixtures, under hydrous conditions and at room temperature. Additional benefits include a very short reaction time (20 s), a wide substrate scope, and good to excellent yields (up to 98 %) of the desired adducts. The practicality of the proposed protocol was demonstrated by setting up a sodium-mediated multigram-scale synthesis of the anticholinergic drug orphenadrine. 相似文献
39.
Rahman GM Kingston HM Towns TG Vitale RJ Clay KR 《Analytical and bioanalytical chemistry》2005,382(4):1111-1120
Precise and accurate determination of hexavalent chromium in different types of solid environmental sample is regarded as a technical challenge with significant potential error if historically accepted methods are used. Microwave-assisted alkaline extraction (0.5 mol L–1 NaOH+0.28 mol L–1 Na2CO3) followed by anion-exchange chromatographic separation and inductively coupled plasma mass spectrophotometric detection has been shown to provide accurate and precise results. To obtain a better understanding of potential species conversion during and/or after extraction steps, speciated isotope-dilution mass spectrometry (SIDMS) (EPA Method 6800) metrology has been successfully applied as a diagnostic tool with the modified accompanying extraction version of EPA Method 3060A. In our study, aggregate materials distributed over a large area of a major western US state were found to contain a high concentration of total chromium (195±13 to 709±19 g g–1) and significant amounts of Cr6+ (141±6 to 341±29 g g–1) which are at least three orders of magnitude higher than the US EPA threshold limit (0.5 g g–1). Sediment samples from a major western US state, studied independently, were found to contain less (1.77±0.34 g g–1) or no Cr6+ in the presence of significant total chromium. 相似文献
40.
Extensive new high-temperature, high-resolution FTIR emission spectroscopy measurements for the five common isotopomers of GeO are combined with previous diode laser and microwave measurements in combined isotopomer analyses. New Dunham expansion parameters and an accurate analytical potential energy function are determined for the ground X1Sigma+ state. Copyright 1999 Academic Press. 相似文献