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991.
We report the time courses of five solid-phase reactions obtained using single bead FTIR microspectroscopy. This time-resolved information aided in the determination of the required reaction time, the nature of the solid-phase reaction, and resin property, effectively assisting in the initial phase of our combinatorial chemistry efforts. Our results showed that solid-phase organic reactions proceed faster than generally speculated. In addition, we have shown that reactions on the surface and in the interior of the bead occur at the same rate for reactions studied. The reaction on the TentaGel resin was shown to be not faster than reactions on Wang resin, suggesting that the diffusion of the substrate into polystyrene bead copolymerized with 1% divinylbenzene is not rate-limiting. Finally, the capability of obtaining IR spectra from the partial surface of a single bead demonstrated the femtomolar detection limit of single bead FTIR microspectroscopy. 相似文献
992.
[Chemical reaction: see text] Polysubstituted furans and highly functionalized 2H-pyrans were prepared in good yields by DABCO-catalyzed reactions of alpha-halo carbonyl compounds with dimethyl acetylenedicarboxylate (DMAD) at room temperature. 相似文献
993.
Qiong Yu Lai Ji Zheng LuXiao Bo Su Xiao Yang Ji 《Journal of solid state chemistry》2002,165(2):312-316
Spinel compound LiNi1−xMnxVO4 (0≤x≤0.4) had been prepared by using the moist chemical method. X-ray diffraction spectra showed that the lattice constant increased with x in the LiNi1−xMnxVO4, XPS spectra indicating that Li1s had a chemical shift towards lesser binding energy, and manganese in LiNi1−xMnxVO4 existing as the mixed valence of Mn2+ and Mn3+. The electrochemical charge and discharge testing at a current density of 0.1 mA/cm2 between the potentials of 4.0 and 3.0 V vs Li/Li+ in 1 mol/dm3 LiPF6/EC+DEC (1:1 by volume) at 25°C showed that LiNi1−xMnxVO4 cell has a better rechargeability, but a lower cell voltage of 4.0 V vs Li/Li+ than that without the doping sample, and the capacity and the cycle efficiency of the Li/LiNi1−xMnxVO4 cells increased with x in the LiNi1−xMnxVO4. 相似文献
994.
A novel approach has been found and the first total synthesis of (±)-Salvirecognine was accomplished by using it. In which intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously to afford key intermediates for synthesis of aromatic tricyclic diterpenoids OMe PPA O O O OMe 1 2 Scheme 1 As shown in Scheme 1 intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously when compound 1 was treated by PPA at 125 ℃. In which the i-pr… 相似文献
995.
996.
The solubilities of four surfactants, sodium bis‐2‐ethylhexyl sulfosuccinate (AOT), cetyltrimethylammonium chloride, didodecyldimethylammonium bromide, and n‐dodecyltrimethylammonium chloride in liquid refrigerant 1,1,1,2‐tetrafluoroethane (R134a) modified with methanol, ethanol, and 2‐propanol were measured. The measurements were performed under 25 and 50 bar at 25 °C. The solubility of AOT was as high as 92 mM in R134a with addition of 2% ethanol. Cytochrome c molecules were then verified to be soluble in the AOT‐containing and ethanol‐modified R134a solution. Accordingly, liquid R134a is suggested as a potential extraction solvent for hydrophilic compounds. 相似文献
997.
The m6A‐RNA modification is a dynamic and reversible process, which has emerged as a new RNA code for the regulation of gene expression. The functional network of methyltransferases (writers), demethylases (erasers), and binding proteins (readers) modulate the level of m6A modification. Dysfunction of RNA methylation has been associated with various fundamental biological processes and human diseases. Herein, we briefly introduce an understanding‐enabled manipulation on m6A‐RNA modification with an emphasis on the use of small‐molecule intervention. 相似文献
998.
TaoJIANG BuXingHAN GuoYingZHAO ZhongHaoLI YanHongCHANG HaiXiangGAO JunChunLI 《中国化学快报》2004,15(3):296-299
The oxidation of styrene with molecular oxygen catalyzed by PdCl2 CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree. 相似文献
999.
Rama Acharyya Shie-Ming Peng Ren-Zhang Wang Samaresh Bhattacharya 《Journal of organometallic chemistry》2005,690(17):3908-3917
Reaction of 2-(2′,6′-dimethylphenylazo)-4-methylphenol with [Ir(PPh3)3Cl] in refluxing ethanol in the presence of a base (NEt3) affords an organoiridium complex 5, where the 2-(2′,6′-dimethylphenylazo)-4-methylphenol is coordinated to iridium, via C-H activation of a methyl group, as a dianionic tridentate C,N,O-donor. Two triphenylphosphines and a hydride are also coordinated to the metal center. A similar reaction carried out in toluene affords complex 5 along with a similar complex 7, where a chloride is coordinated to iridium instead of the hydride. Reaction of 2-(2′-methylphenylazo)-4-methylphenol with [Ir(PPh3)3Cl] in refluxing ethanol in the presence of a base (NEt3) affords an organoiridium complex 12, where the 2-(2′-methylphenylazo)-4-methylphenol is coordinated to iridium, via C-H activation at the ortho position of the phenyl group in the 2′-methylphenylazo fragment, as a dianionic tridentate C,N,O-donor. Two triphenylphosphines and a hydride are also coordinated to the metal center. A similar reaction carried out in toluene affords a complex 12 along with a similar complex 13, where a chloride is coordinated to iridium instead of the hydride. Structures of complexes 5, 12 and 13 have been determined by X-ray crystallography. In all these complexes, the two triphenylphosphines are trans. All these complexes show intense MLCT transitions in the visible region. Cyclic voltammetry on all the complexes shows an Ir(III)-Ir(IV) oxidation within 0.60-0.73 V vs. SCE, followed by an oxidation of the coordinated 2-(arylazo)phenolate ligand within 1.08-1.39 V vs. SCE. A reduction of the coordinated 2-(arylazo)phenolate ligand is observed within −1.10 to −1.26 V vs. SCE. 相似文献
1000.
XinYingZHANG XueSenFAN JianJiWANG YanZhenLI 《中国化学快报》2004,15(10):1170-1172
Quinoline derivatives were efficiently prepared through acid-catalyzed Friedlander reaction in ionic liquid ([bmim] [BF4]). It is shown that the proposed method is operationally simple and environmentally benign in that the reaction media and the catalyst can be recovered and be reused effectively for at least four times. 相似文献