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971.
The mixture of silver iodide and ferrocene is used to prepare the membrane of iodide ion-selective electrode. The interference of sulfide can be reduced by the addition of cupric ion in the test solution. Ethylene glycol is determined by potentiometric titration using iodine ion-selective electrode as an indicator electrode. 相似文献
972.
Li Ting Chai Yang Zhou Li Wei Wei Wang Quan Rui Wang Feng Gang Tao 《中国化学快报》2007,18(12):1460-1462
Nation-Teflon bimembrane was used as an efficient support for the preparation and application of heterogeneous palladium catalysts.The supported palladium catalysts exhibit high activity and stability in the Suzuki cross-coupling of aryl bromides with arylboronic acids to afford the corresponding biaryls in good to excellent yields,and can be readily recovered and reused several times without significant loss of activity. 相似文献
973.
Two novel sesquiterpene dimers, compounds 1 and 2 , were isolated from the rhizome of Ligularia virgaurea, together with the six known sesquiterpenoids 3 – 8 . Their structures were established by physico‐chemical and spectroscopic methods, especially by means of 1D‐ and 2D‐NMR as well as HR‐MS analyses. A mechanism based on a classical Diels–Alder cyclization is proposed for the formation of the dimer 1 from the precursors 8 and the quinone form of 6 (Scheme). 相似文献
974.
Ramin Ghorbani‐Vaghei Mohammad Ali Zolfigol Nasrin Moshfeghifar Nadiya Koukabi Gholamabbas Chehardoli 《中国化学会会志》2007,54(3):791-794
An efficient method for the oxidative coupling of thiols to their corresponding disulfides by new reagents poly(N‐bromobenzene‐1,3‐disulfonylamide) PBBS , N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonylamide TBBDA and DABCO‐bromine complex is described. The reaction was applicable to a variety of thiols with high chemoselectivity. 相似文献
975.
Mohammad Ali Zolfigol Khodabakhsh Niknam Mojtaba Bagherzadeh Arash Ghorbani‐Choghamarani Nadiya Koukabi Maryam Hajjami Eskandar Kolvari 《中国化学会会志》2007,54(5):1115-1118
Tribromoisocyanuric acid (TBCA) and Oxone®‐MX systems were used as effective oxidizing agents for the oxidation of thiols to their corresponding disulfides under mild conditions at room temperature with good to excellent yields. 相似文献
976.
The three new lignanoids 1 – 3 and the five new phyllocladane diterpenoids 7 – 11 were isolated from the leaves of Callicarpa furfuraceae, together with two known lignanoids, lariciresinol ( 4 ) and (+)‐sesamin ( 5 ), and five known diterpenoids, 17‐norphyllocladane‐3,16‐dion ( 6 ), calliterpenone ( 12 ), calliterpenone 17‐acetate ( 13 ), (3β,16α)‐phyllocladane‐3,16,17‐triol ( 14 ), and (3β,16α)‐phyllocladane‐3,16,17‐triol 17‐acetate ( 15 ). Their structures were established by spectral‐data interpretation. 相似文献
977.
A new catalytic kinetic spectrophotometric method has been developed for the determination of trace amount of manganese (II) in nonionic microemulsion medium. The method is based on the catalytic effect of manganese (II) on the oxidation of dahlia violet by potassium periodate with nitrilotriacetic acid as an activitor in the presence of nonionic microemulsion. Under the optimum conditions, the calibration graph is linear in the range of 0.0004-0.0056 μg ml−1 of manganese (II) at 580 nm. The detection limit achieved is 3.75×10−5 μg ml−1. Manganese (II) in foodstuff samples was determined with satisfactory results. 相似文献
978.
Roland Wilberger Holger Piotrowski Marcus Warchhold Ingo‐Peter Lorenz 《无机化学与普通化学杂志》2003,629(14):2485-2492
Novel Neutral and Cationic Mono‐Aziridine Complexes of the Type [CpMn(CO)2Az], [CpCr(NO)2Az]+, and [(Ph3P)(CO)4ReAz]+ via CO‐, Hydride‐, and Chloride‐Elimination Reactions The monoaziridine complexes 1 — 5 are obtained by three differently induced substitution reactions. The photolytically induced CO substitution reaction of [CpMn(CO)3] with 2, 2‐dimethylaziridine leads to the neutral N‐coordinate aziridine complex [Cp(CO)2Mn{$\overline{N(H)CMe2C}$ H2}] ( 1 ). The protonation of [(Ph3P)(CO)4ReH] with CF3SO3H and consecutive treatment with 2, 2‐dimethylaziridine or 2‐ethylaziridine gives the salt‐like aziridine complexes [(Ph3P)(CO)4Re{$\overline{N(H)CMe2C}$ H2}](CF3SO3) ( 2 ) or [(Ph3P)(CO)4Re{ H2}](CF3SO3) ( 3 ) by hydride elimination reactions. The like‐wise salt‐like complexes [Cp(NO)2Cr{$\overline{N(H)CMe2C}$ H2}](BF4) ( 4 ) and [Cp(NO)2Cr{ H2}](CF3SO3) ( 5 ) are synthesized from [CpCr(NO)2Cl] by chloride elimination with AgX (X = BF4, CF3SO3) in the presence of 2, 2‐dimethylaziridine or 2‐ethylaziridine, respectively. As a result of X‐ray structure analyses, the metal atoms are trigonal pyramidally ( 1, 4, 5 ) or octahedrally ( 2, 3 , cis‐position) configurated; the intact three‐membered rings coordinate through the distorted tetrahedrally configurated N atoms. All compounds 1‐5 are stable with respect to the directed thermal alkene elimination to give the corresponding nitrene complexes; the IR, 1H‐ and 13C{1H}‐NMR, and MS spectra are reported and discussed. 相似文献
979.
Silica nanoparticles for separation of biologically active amines by capillary electrophoresis with laser-induced native fluorescence detection 总被引:1,自引:0,他引:1
This paper describes the analysis of biologically active amines by capillary electrophoresis (CE) in conjunction with laser-induced native fluorescence detection. In order to simultaneously analyze amines and acids as well as to achieve high sensitivity, 10 mM formic acid solutions (pH < 4.0) containing silica nanoparticles (SiNPs) were chosen as the background electrolytes. With increasing SiNP concentration, the migration times for seven analytes decrease as a result of increase in electroosmotic flow (EOF) and decrease in their electrophoretic mobilities against EOF. A small EOF generated at pH 3.0 reveals adsorption of SiNPs on the deactivated capillary wall. The decreases in electrophoretic mobilities with increasing SiNP concentration up to 0.3x indicate the interactions between the analytes and the SiNPs. Having a great sensitivity (the limits of detection at a signal-to-noise ratio (S/N) = 3 of 0.09 nM for tryptamine (TA)), high efficiency, and excellent reproducibility (less than 2.4% of the migration times), this developed method has been applied to the analysis of urinal samples with the concentrations of 0.50 +/- 0.02 microM, 0.49 +/- 0.04 microM, and 74 +/- 2 microM for TA, 5-hydroxytryptamine, and tryptophan, respectively. The successful examples demonstrated in this study open up a possibility of using functional nanoparticles for the separation of different analytes by CE. 相似文献
980.
A chemically bonded cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase (CSP) was prepared by a radical polymerization reaction. The prepared CSP was packed into fused-silica capillaries with inner diameter of 75 microm to perform enantiomer separations in CEC. The electrochromatographic behavior of the CSP was investigated. On the prepared CSP, high EOF could be generated under acidic mobile phases, which represented an advantage for the separation of acidic enantiomers. Several neutral, acidic, and basic enantiomers were resolved on the prepared CSP under aqueous mobile phases. The column efficiencies were between 20,000 and 100,000 plates/m, which were much higher than those of HPLC. In addition, it was observed that the separation of some enantiomers benefited from the adoption of THF as mobile phase modifier. 相似文献