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61.
Chan Sik Cho Tae Kyung Kim Bok Tae Kim Tae-Jeong Kim Sang Chul Shim 《Journal of organometallic chemistry》2002,650(1-2):65-68
Nitroarenes react with trialkylamines in the presence of a catalytic amount of a ruthenium catalyst together with tin(II) chloride dihydrate at 180 °C in an aqueous medium (toluene–H2O) to afford the corresponding quinolines in moderate to good yields. The catalytic pathway seems to be proceeded via a sequence involving initial reduction of nitroarenes to anilines, alkyl group transfer from alkylamines to anilines to form an imine, dimerization of imine, and heterocyclization. 相似文献
62.
We synthesized the new photosensitive oligomer containing a chalcone moiety in the main chain by end-capping reaction of diepoxide compound with methacrylic acid. The chalcone-epoxy oligomeric compound was synthesized with 4,4′-dihydroxychalcone and epichlorohydrin. Investigation of the photosensitivity of the newly synthesized chalcone oligomer was carried out by using UV-Vis absorption and infrared spectroscopies under UV exposure. We observed the photodimerization behavior under UV irradiation. At the same time, we could also observe the photopolymerization of the compound with a trace amount of dimethoxyphenyl acetophenone. Thermal properties of UV-cured dimethacrylate compounds were also studied. 相似文献
63.
A method for fast in situ measurement of adsorption kinetics based on a finite bath was developed. We modified the conventional finite bath by replacing the external loop by a dip probe which enables in situ measurement of the concentration change in the contactor. Deposition of adsorbent particles on the reflection surface of the dip probe compromised measurements. Different membranes, a polyamide, a polypropylene and a nylon membrane were tested to protect the internal reflection surface of the dip probe from fouling with adsorbent particles. The nylon membrane provided efficient protection and high mass transfer evaluated by response time experiments. Unspecific adsorption of the model protein on the membrane could also be excluded. To corroborate the measurements of the dip probe the results were compared to a conventional finite bath and to a shallow-bed. The uptake curves for human polyclonal IgG at different concentrationes (0.1-3 g/l) on rProtein A Sepharose FF and MabSelect were used as model system. The effective diffusion coefficients were determined using a pore diffusion model. These values were in good agreement for all methods. 相似文献
64.
W.John Albery David Clark Humphrey J.J. Drummond Anthony J.M. Coombs William K. Young Clive E.W. Hahn 《Journal of Electroanalytical Chemistry》1992,340(1-2)
A novel electrochemical sensor for the determination of CO2 in expired breath is described. The sensor works by generating
from the reduction of O2 in dimethyl sulphoxide (DMSO) in a generating pulse. There is a rapid titration reaction between the
and any CO2 present. In the recovery pulse the amount of unreacted
is determined. The larger the concentration of CO2 the less
is found in the recovery pulse. The solubilities and diffusion coefficients of O2 and CO2 in DMSO have been determined using rotating disc voltammetry and rotation speed step experiments. The stoichiometry, the product, and the rate constant of the titration reaction have been determined using ring—disc voltammetry and laser Raman spectroscopy. The operation and the effect of adventitious water on the sensor are described. Results are presented which show that the sensor can indeed measure the breath-by-breath rhythm of expired CO2 from a human subject. 相似文献
65.
The goal of this study was to investigate the effect of photothermal laser irradiation on rat breast tumor (DMBA-4) vascular contents. An 805-nm diode laser was used in our experiment with a power density ranging from 0.32 to 1.27 W/cm2. The dynamic changes of oxygenated hemoglobin and total hemoglobin concentrations, delta[HbO2] and delta[Hb]total, in rat tumors during photothermal irradiation were noninvasively monitored by a near-infrared spectroscopy system. A multichannel thermal detection system was also used simultaneously to record temperatures at different locations within the tumors. Our experimental results showed that: (1) photoirradiation did have the ability to induce hyperthermic effects inside the rat breast tumors in a single exponential trend; (2) the significant changes (P < 0.005) of delta[HbO2] and delta[Hb]total in response to a low dosage of laser irradiation (0.32 W/cm2) have a single exponential increasing trend, similar to that seen in the tumor interior temperature; and (3) the increase in magnitude of delta[HbO2] is nearly two times greater than that of delta[Hb]total, suggesting that photoirradiation may enhance tumor vascular oxygenation. The last observation may be important to reveal the hidden mechanism of photoirradiation on tumors, leading to improvement of tumor treatment efficiency. 相似文献
66.
Contributions to the Chemistry of Phosphorus. 105. 1,2,34-Tetraphenyl-1,4-bis(trimethylsilyl)-tetraphosphane and 1,2,3,4-Tetraphenyltetraphosphane 1,2,3,4-Tetraphenyl-1,4-bis(trimethylsilyl)-tetraphosphane, Me3Si? (PPh)4? SiMe3 ( 1 ), is obtained by reacting K2(PPh)4 with trimethylchlorosilane under suitable conditions. Compound 1 disproportionates almost easier than the corresponding triphosphane (Me3Si)2(PPH)3. Of the six possible diastereomers only 1a (erythro, meso, erythro), 1b (erythro, d,l, erythro), 1 d (threo, d,l, threo), and 1 f (erythro, threo, threo) can be detected in solution by 31P-NMR spectroscopy. In consequence of rapid inversion at the P atoms a dynamic equilibrium exists between the different isomers. The assignment of the 31P-NMR-spectroscopically observed spin systems to the corresponding diastereomers results from the dependence of the 1JPP-coupling constants on the dihedral angle between vicinal free electron pairs as well as on the observed frequency distribution. In the alcoholysis of 1 the corresponding hydride H? (PPh)4? H ( 2 ) is formed as the main product. It could be isolated in spite of its instability. At room temperature 2 disproportionates rapidly forming mainly (PPh)4 and H2(PPh)2 (ratio 1:2) at first; later on also H2(PPh)3, H2PPh, and (PPh)5 are found. The corresponding rearrangements follow a four-center mechanism involving predominantly P? P bonds. 相似文献
67.
The cationic ruthenium hydride complex [(PCy(3))(2)(CO)(CH(3)CN)(2)RuH](+)BF(4)(-) was found to be a highly effective catalyst for the C-H bond activation reaction of arylamines and terminal alkynes. The regioselective catalytic synthesis of substituted quinoline and quinoxaline derivatives was achieved from the ortho-C-H bond activation reaction of arylamines and terminal alkynes by using the catalyst Ru(3)(CO)(12)/HBF(4).OEt(2). The normal isotope effect (k(CH)/k(CD) = 2.5) was observed for the reaction of C(6)H(5)NH(2) and C(6)D(5)NH(2) with propyne. A highly negative Hammett value (rho = -4.4) was obtained from the correlation of the relative rates from a series of meta-substituted anilines, m-XC(6)H(4)NH(2), with sigma(p) in the presence of Ru(3)(CO)(12)/HBF(4).OEt(2) (3 mol % Ru, 1:3 molar ratio). The deuterium labeling studies from the reactions of both indoline and acyclic arylamines with DCCPh showed that the alkyne C-H bond activation step is reversible. The crossover experiment from the reaction of 1-(2-amino-1-phenyl)pyrrole with DCCPh and HCCC(6)H(4)-p-OMe led to preferential deuterium incorporation to the phenyl-substituted quinoline product. A mechanism involving rate-determining ortho-C-H bond activation and intramolecular C-N bond formation steps via an unsaturated cationic ruthenium acetylide complex has been proposed. 相似文献
68.
M. H. Baik W. J. Cho P. S. Hahn 《Journal of Radioanalytical and Nuclear Chemistry》2004,260(3):495-502
Surface sorption experiments of U(VI) onto the surfaces of a Korean granite rock are carried out in order to investigate the
kinetics and reversibility of U(VI) sorption as a function of pH and surface types such as fresh intact surfaces and natural
fracture surfaces. It was shown that the effect of pH is significant in the sorption of U(VI) onto both types of the granite
surfaces. However the sorption rates do not greatly depend upon the pH regardless of the surface types. A two-step first order
kinetic behavior dominates onto both the intact surfaces and natural fracture surfaces of granite and that the linearization
approach of the kinetic model agrees well with experimental sorption data. The desorption results showed that the sorption
process of U(VI) was a little irreversible for the two types of granite surfaces regardless of pH and surface types. This
kinetic approach could give a better understanding of U(VI) sorption onto granite surfaces depending on pH and surface types.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
69.
Grotjahn DB Van S Combs D Lev DA Schneider C Incarvito CD Lam KC Rossi G Rheingold AL Rideout M Meyer C Hernandez G Mejorado L 《Inorganic chemistry》2003,42(10):3347-3355
Inter- and intramolecular hydrogen bonding of an N-H group in pyrazole complexes was studied using ligands with two different groups at pyrazole C-3 and C-5. At C-5, groups such as methyl, i-propyl, phenyl, or tert-butyl were present. At C-3, side chains L-CH(2)- and L-CH(2)CH(2)- (L = thioether or phosphine) ensured formation of chelates to a cis-dichloropalladium(II) fragment through side-chain atom L and the pyrazole nitrogen closest to the side chain. The significance of the ligands is that by placing a ligating side chain on a ring carbon (C-3), rather than on a ring nitrogen, the ring nitrogen not bound to the metal and its attached proton are available for hydrogen bonding. As desired, seven chelate complexes examined by X-ray diffraction all showed intramolecular hydrogen bonding between the pyrazole N-H and a chloride ligand in the cis position. In addition, however, intermolecular hydrogen bonding could be controlled by the substituent at C-5: complexes with either a methyl at C-5 or no substituent there showed significant intermolecular hydrogen bonding interactions, which were completely avoided by placing a tert-butyl group at C-5. The acidity of two complexes in acetonitrile solutions was estimated to be closer to that of pyridinium ion than those of imidazolium or triethylammonium ions. 相似文献
70.
S. Kallus A. Hahn G. Golemme C. Algieri P. Timmins J.D.F. Ramsay 《Journal of Sol-Gel Science and Technology》2003,26(1-3):721-725
The synthesis of zeolite membranes and thin films using the secondary growth process is briefly described. In this process colloidal zeolite particles (sols) are prepared hydrothermally and then subsequently deposited on substrates to produce uniform layers of controlled thickness, as illustrated with silicalite and zeolite-A. The formation and growth of the zeolite sols has been investigated in situ by small angle neutron scattering (SANS). SANS measurements on silicalite sols at progressively higher concentrations have provided details of the colloid interactions which lead to zeolite gel-layer structures which are uniform and free of defects. 相似文献