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91.
The first intermolecular Friedel-Crafts acylation of a variety of aromatic substrates with azetidinones is described. The Friedel-Crafts acylations are performed under very mild conditions, using trifluoromethanesulfonic acid to produce beta-amino aromatic ketones in excellent yields. 相似文献
92.
The reactions of various fluoroaromatics, C6F6?xHx, and C6F5X (X = C6F6, Cl, Me, NO2, CF3, COCl, CH2Br, OMe, and NH2) with lead(II) benzenethiolate in DMF have been examined. Lead thiolate acted as an excellent source of benzenethiolate anions and displacement of fluorine, chlorine or the nitro group was observed. The new products have been characterized by elemental analysis, and NMR (H?1 and F?19), infrared and mass spectroscopy. 相似文献
93.
94.
This study compared H2S adsorption kinetic parameters in both grain adsorption and column adsorption systems. Results indicated that when the nondimensional mass transfer parameter for adsorption column design was included, the axial dispersion (Pe > 1, < 1) and external film resistance (B 1) could be neglected, the fluid viscosity effect was small (Sc = 0.76), and the adsorbate affinity was fine (). Surface and pore diffusion controlled the adsorbent and fluid mass transfer. In addition, spent activated carbon could be treated by a thermal process and then impregnated with NaOH. After the pretreatment, the spent activated carbon could be used for H2S adsorption. Furthermore, we also propose that the H2S adsorption reaction on the carbon is due to the formation of sulfur crystals. 相似文献
95.
Janak KE Tanski JM Churchill DG Parkin G 《Journal of the American Chemical Society》2002,124(16):4182-4183
Mo(PMe3)6 reacts with thiophene to give the eta5-thiophene complex (eta5-C4H4S)Mo(PMe3)3 and the eta5-butadiene-thiolate complex (eta5-C4H5S)Mo(PMe3)2(eta2-CH2PMe2), which are the first examples of (i) eta5-thiophene coordination and (ii) C-S cleavage and hydrogenation by a molybdenum compound. Deuterium labeling studies suggest that the hydrogenation of thiophene may involve an alkylidene intermediate, an observation that has ramifications for the mechanisms of hydrodesulfurization. 相似文献
96.
Metal (M) oxide (M: Ir, Os, Pd, Pt, Rh, Ru) together with MaO2 and MnO2 alone, were coated on SnO2 films and the anode behavior was examined in 1.0 N H2SO4, 1.0 N NaOH and 1.0, N NaCl aqueous solutions at 25°. The results are compared with those of DSA and of metallic Pt. 相似文献
97.
Plieger PG Ehler DS Duran BL Taylor TP John KD Keizer TS McCleskey TM Burrell AK Kampf JW Haase T Rasmussen PG Karr J 《Inorganic chemistry》2005,44(16):5761-5769
The ligand 4,5-dicarboxyimidazole (H(2)DCI) and its methyl derivative 1-methyl-4,5-dicarboxyimidazole (H(2)MDCI) have been shown to bind to Be(II) forming a zwitterionic species that has been structurally characterized. A new dicarboxyimidazole-based polymer has been prepared and its Be-binding properties have been studied using NMR ((1)H and (9)Be) and fluorescence spectroscopy; it represents a rare example of beryllium binding to a polymer. Models of the mononuclear and polymeric Be(II)-binding sites have been studied using density functional theory (DFT), and the (9)Be NMR chemical shifts of these model materials have been calculated for the purpose of direct comparison to experimentally observed values. Differences in the binding modes of the mononuclear and polymeric species are discussed. 相似文献
98.
Simulation of the Adhesion of Particles to Surfaces 总被引:1,自引:0,他引:1
The removal of micrometer and submicrometer particles from dielectric and metal films represents a challenge in postchemical mechanical polishing cleaning. Proper modeling of the adhesive force between contaminant particles and these films is needed to develop optimal solutions to postchemical mechanical polishing cleaning. We have previously developed and experimentally validated a model to describe the adhesion between spherical particles and thin films. This simulation expands previous models to characterize the adhesive interaction between asymmetrical particles, characteristic of a polishing slurry, and various films. Our simulation accounts for the contact area between particles and substrates, as well as the morphology of the surfaces. Previous models fail to accurately describe the contact of asymmetrical particles interacting with surfaces. By properly accounting for nonideal and geometry and morphology, the simulation predicts a more accurate adhesive force than predictions based upon an ideal van der Waals model. The simulation is compared to experimental data taken for both semi-ideal particle-substrate systems (polystyrene latex spheres in contact with silicon films) and asymmetrical systems (alumina particles in contact with various films). Copyright 2001 Academic Press. 相似文献
99.
A MALDI TOF-TOF instrument was optimized and evaluated for intact protein analysis by tandem mass spectrometry. Ion source voltages and delay times were adjusted to affect an up to a 10-fold improvement in fragment ion yield compared to data obtained using default settings employed in peptide analysis. For large peptides (3-4.5 kDa), up to 90% of all possible b- and y-fragment ions were observed, which provides sufficient information for de novo sequencing and unambiguous protein identification. Product ion signals associated with preferential cleavages C-terminal to aspartic acid and glutamic acid residues and N-terminal to proline residues became dominant with increased protein molecular weight. Matrix effects were also evaluated and, among the eight matrices examined, alpha-cyano-4-hydroxycinnamic acid (CHCA) was found to produce the best intact protein tandem mass spectra for proteins up to 12 kDa. Optimized performance yielded detection limits of 50-125 fmol for proteins of 4 and 12 kDa, respectively. This improved performance has yielded an instrument with potential to be a useful tool in proteomic investigations via analysis of intact proteins. 相似文献
100.
Klapars A Waldman JH Campos KR Jensen MS McLaughlin M Chung JY Cvetovich RJ Chen CY 《The Journal of organic chemistry》2005,70(24):10186-10189
[reaction: see text] A mild and transition-metal-free method for the alpha-arylation of aliphatic nitriles with activated heteroaryl halides was developed using NaHMDS or KHMDS as base at ambient temperature. The key to the success of this method is generation of the nitrile anion in the presence of the heteroaryl halide. The method is applicable to both primary and secondary carbonitriles and a wide range of heteroaryl halides. Selective monoarylation was observed with primary carbonitriles. The operational simplicity and the mild reaction conditions add to the value of this method as a practical alternative to the preparation of alpha-heteroaryl carbonitriles. 相似文献