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81.
介绍了聚氯乙烯膜碘离子选择电极(PVC-I-ISE)的制备方法,电极对碘离子的能斯特响应斜率为59 mV/pI,响应的线性范围为4.0×10-5~1.0×10-2mol.L-1,检出限为1.6×10-5mol.L-1,低于用银ISE的检出限,电极的使用寿命为一个月以上。将制备的碘离子选择电极作为指示电极用于对溴、碘混合离子体系进行连续分别电位滴定,并与以银电极为指示电极的电位滴定方法进行了比较。结果表明用PVC-I--ISE作指示电极,可在I--Br-共存的混合溶液中进行两离子的连续电位滴定,而用银-ISE时则不能。 相似文献
82.
Earlier work by Lindenbaum and Boyd has demonstrated the important role of hydrophobic interactions involving the water solvent in determining the osmotic coefficients and properties of aqueous solutions of the tetraalkylammonium halides. Osmotic coefficients of solutions of tetramethyl-, tetraethyl-, tetrapropyl-, and tetrabutylammonium bromides in the more highly structured solvent D2O have now been determined by the gravimetric isopiestic method, using reference solutions of NaCl in D2O. The data were fitted to the Rush-Johnson and Pitzer equations. Satisfactory agreement with the results for aqueous solutions at comparable concentrations indicates that the solution chemistry of these quaternary ammonium bromides is not highly dependent on the degree of structure of the pure solvents. Supplementary data for mixtures of Me4NBr with Et4NBr, Pr4NBr, or Bu4NBr in both H2O and D2O are consistent with this conclusion.On leave 1980–82 from Banaras Hindu University, India 相似文献
83.
SyntheticinterestsinhighlyfunctionalizedacyclicandcyclicamineshavecontributedtothewealthofexPerimentalmethodologydeveloPedfortheadditionofcarbanionstothecarbon-nitrogendoublebondofimines.Generally,organometallicreagentsorilltermedi-atesareusedascarbanionsandadditionofallylicorganometallicspeciestothenieconshtutesavaluablemethodforthesynthesisofhomoallylamines.'Amongthese,allyLlithium,'-magnesium,'-zinc,'-boraneandboronate,'-silaneand-stannane'havebeenusedforallylationofdriines.Ontheotherhand,… 相似文献
84.
Copper-catalyzed N-arylation of diazoles can be accomplished using air-stable CuI as a copper source and 1,10-phenanthroline in the presence of KF/Al2O3 as a base. This is a simple and efficient method for the coupling of aryl bromide with diazoles. Different functionalized aryl bromides were coupled with diazoles using this system. 相似文献
85.
铬天青S共振光散射法测定脱氧核糖核酸 总被引:3,自引:0,他引:3
介绍在阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)存在下阴离子染料铬天青S(CAS)共振光散射(RLS)法测定脱氧核糖核酸(DNA)的方法。在pH=5.27的六次甲基四铵一盐酸缓冲溶液中,研究了CAS—CT-MAB—yDNA体系的RLS光谱特征、影响因素和最佳反应条件。在最佳条件下,体系的RLS强度增加值△I与yDNA的浓度在50~800μg/L和1000~2000μg/L呈线性关系,其线性回归方程分别为△I=0.48c 2.56和△I=0.14c 17.86,相关系数分别为0.9997和0.9991,检出限为4.3ng/mL。该方法简便、快速,应用于合成样品中yDNA的测定,测定结果的相对标准偏差为2.93%~4.71%,回收率为97.8%~105.2%。 相似文献
86.
The mean aggregation number (n) and the critical micelle concentrations (CMC) of reverse micelles formed by hexadecyltrimethylammonium bromide have been determined by means of an optical absorption probe (acridine orange). The procedure to obtain these quantities from absorption spectrophotometric measurements is described. The CMC and mean aggregation number are in satisfactory agreement with published results obtained from more sophisticated methods. 相似文献
87.
Micelle size and shape of dodecyldimethylammonium bromide have been determined by measurement of light scattering from its aqueous NaBr solutions. In water and in the presence of NaBr up to 0.07 M, the Debye plots give straight lines with positive slopes, and spherical micelles having molecular weight less than 30 000 are formed. At higher NaBr concentrations, the Debye plots decrease with increasing micelle concentration, indicating the aggregation of the primary spherical micelles into larger secondary micelles. The molecular weight and the radius of gyration of the secondary micelles increase with increasing NaBr concentration, and the relation between molecular weight and radius of gyration suggests that they are rodlike and flexible. Linear logarithmic relations between micelle molecular weight and ionic strength hold for spherical and rodlike micelles, respectively, and the threshold concentration of NaBr for the sphere-rod transition is located at 0.07 M. The spherical micelle of dodecyldimethylammonium ions has a size more than 20 surfactant ions larger in NaBr solutions than in NaCl solutions, and their rodlike micelle has a shorter length in NaBr solutions than in NaCl solutions, when compared at an identical aggregation number, indicating 2 more surfactant ions in its cross-section. 相似文献
88.
Bismuth(III) salts are efficient catalysts for the selective allylic oxidation using tert-butyl hydroperoxide. BiCl3 is especially effective and can be easily recovered and reused as BiOCl. Using BiCl3/K-10 as catalyst, an increase in the reaction rate was observed. 相似文献
89.
González-Pérez A. Galán J. J. Rodríguez J. R. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):741-749
The specific conductivities of dodecyldimethylbenzylammonium bromide (C12BBr) have been determined in aqueous butanol and
aqueous benzyl alcohol solutions in the temperature range of 5-40°C. From these data the temperature dependent critical micelle
concentration (cmc) was determined. The molar fraction of alcohol in the micelle was estimated using the theory suggested by Motomura et al. for surfactant binary mixtures. The thermal properties such as standard Gibbs free energy, enthalpy and entropy of solubilization
of alcohols in the micelles were estimated for the phase separation model. The change in heat capacity upon solubilization
of alcohol in the micelle has been estimated form the above properties.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
90.
The interaction of Amido black 10B (AB) with DNA in basic medium was studied in the presence of cetyltrimethylammonium bromide (CTMAB) based on the measurements of resonance light scattering (RLS), UV–vis, CD spectra, and RLS imaging. The interaction has been proved to give a ternary complex of CTMAB–DNA–AB in Britton–Robinson buffer of pH 11.55, which exhibits strong negative Cotton effect at 233.3 nm and 642.8 nm, and strong RLS signals characterized at 469 nm. Experiments showed that the enhanced RLS intensities (ΔIRLS) against the mixture of AB and CTMAB are proportional to the concentration of fish sperm DNA (fsDNA) and calf thymus DNA (ctDNA), respectively over the range of 0.03–1.0 and 0.05–1.5 μg ml−1, with the limits of determination (3σ) of 7.3 ng ml−1 for fsDNA and 7.0 ng ml−1 for ctDNA. 相似文献