摘要:

AbstractThe state‐of‐the‐art and trends of development with the inductively coupled plasma (ICP) and microwave induced plasmas (MIP) as radiation sources for optical emission spectrometry arc presented. Especially techniques for sample introduction are discussed. Here special reference is given to the use of spark ablation as well as 10 direct sample insertion and slurry atomization for the direct analysis of powder samples. The development in MIP optical emission Spectrometry is shown to center on the improvement of the plasma sources, their characterization and their tailoring to various sampling techniques. Results of the use of pneumatic nebulization of liquids and electrothermal evaporation of dry solution residues will be pres

ISSN:0009-4536    

DOI:10.1002/jccs.199000001

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe trend in the modern analytical laboratory is toward lower and lower analytical concentration measurements. The analyst has a variety of analytical instruments and techniques in which to meet the ever growing need for lower concentration measurements with improved precision and accuracy. Techniques available to the analyst include flame and electrothermal atomization‐atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, inductively coupled plasma/mass spectrometry, laser enhanced ionization spectrometry, neutron activation analysis, spectrophotometry, isotope dilution mass spectrometry, X‐ray fluorescence spectometry, electroanalytical, and chromatography. However, there is no analytical technique that is a panacea for all analytes in the modern analytical laboratory. Steps the analyst must consider to obtain the highest degree of precision and accuracy include the obtaining of a representative sample, the selection of the “best” analytical method, the preparation of the sample, the calibration of the instrumentation, the deciding on the level of effort for the chemical measurement and the evaluation of the data are di

ISSN:0009-4536    

DOI:10.1002/jccs.199000002

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractA number of diazadioximes have been prepared by reactions of the corresponding diamines with 2,3‐butanedione monoxime in the presence of p‐toluenesulfonic acid or in etha

ISSN:0009-4536    

DOI:10.1002/jccs.199000003

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractA series at mixed oxides of titanium and phosphorus were prepared by co‐precipitation method accompanying refluxing treatment. The effect of the pH values of the solutions on the structures, compositions, and surface acidities of the resultants compounds was determined. The samples were characterized by BET surface area measurement, X‐ray powder diffraction (XRD) for structural analysis and amine‐titration for surface acidities. After calcinating the oxides at 773 K, the surface acidities were attributed mainly to Ti(OH)PO4structure. Elemental analysis revealed that the P/Ti ratios in the samples decreased with increasing the pH value of the preparative solution. When the mixed oxides were used as catalysts for 2‐propanol decomposition reaction, the highest activities were obtained over the samples prepared in the solutions with the pH values being 2 or 3. That result was in agreement with the variation in surface area and acid amount of the ca

ISSN:0009-4536    

DOI:10.1002/jccs.199000004

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractDiffusion coefficients of atomic halogen with noble gases were calculated from the potential curves reported in the literature from the crossed molecular‐beam scattering experiments. The deviations of the diffusion constants between the atomic halogen‐noble gas systems and the neighboring noble gas‐noble gas systems were obtained over the temperature range of 200 K to 1100 K. The parameters of Lennard‐Jones 6–12 potentials were also obtained for the chlorine and iodine atoms. The internal consistency of the diffusion constants calculated from the 6–12 potential parameters among the halogen atom‐noble gas systems is very good. However, the agreement was found to be only fair for the inert molecular systems with the chlorine atoms. The extent of the similarity of the diffusion constants between the atomic halogen‐noble gas and the noble gas‐noble gas sys

ISSN:0009-4536    

DOI:10.1002/jccs.199000005

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractLaser‐induced addition reactions of iodine with acetylene at 5145 and 4880 Å excitation wavelengths are studied, while trans‐1,2‐diiodoethylene is identified as the exclusive reaction product. A sequential addition reaction mechanism initiated by iodine atoms from the direct photodissociation process or collisional induced dissociation can be in

ISSN:0009-4536    

DOI:10.1002/jccs.199000006

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe dissolution of aluminium in sodium hydroxide and hydrochloric acid in the presence of butyltin trichloride as corrosion inhibitor has been studied by hydrogen evolution and thermometric methods.Experimental findings indicate that the inhibition effect of butyltin trichloride takes place through an adsorption mechanism following the Frumkin's isotherm.Butyltin trichloride acts as a weakly adsorbed inhibitor in NaOH and as a strongly adsorbed inhibitor in hydrochloric acid medium.

ISSN:0009-4536    

DOI:10.1002/jccs.199000007

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe chemical thermodynamic properties Cp°, ΔHf° S°, ΔGr° and Kpof gaseous perfluoro n‐alkanes, P(CF2)n F(2≤n≤10), have been calculated from 298.15 to 1000 K using the Benson method with Cp° = a″;b/T + c/T2, Cp°=a+bT+c+/T2and Cp°=a″ + bT +cT2. Better results are obtained for Cp°=a+b/T+c/T2. The calculated chemical thermodynamic properties of C2F6(g) are in excellent agreement with the literature data of Stull, Westrum, and Sinke under IBM/PC microcomputer with STEP data bas

ISSN:0009-4536    

DOI:10.1002/jccs.199000008

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractSingle crystal x‐ray structures of the diastereomeric 2‐dimethylamino‐4‐phenyl‐2H‐1,3,2‐oxazaphosphorinane‐2‐oxides, 5c and 6c, have been determined. The pair has been prepared in a straightforward manner by reaction of 3‐amino‐3‐phenylpropanol with Mo2P(O)Cl2, and separated into pure forms by column chromatography. Crystal data of 5c: space group P21/n, a = 11.087(3), b = 6.087(6), c = 18.465(6)Å, β = 98.40(3)°, R = 0.035 for 1845 reflections. Crystal data of 6c: space group P21/n, a = 11.176(2), b = 6.893(2), c = 16.673(3)Å, β = 95.29(1)°, R = 0.037 for 1253 reflections. The fast‐migrating 5c is cis (Ph and P = O group cis) with the configuration of 2RS, 4SR. The slow migrating 6c is trans with the configuration of 2RS, 4RS. In both structures the 1,3,2‐oxazaphosphorinane rings are chair like with the P‐end essentially flattened, The skeleton made up with 4‐phenyl‐1,3,2‐oxazaphosphorinane is essentially the same. With a conformationally demanding 4‐phenyl substituent, 5c has an axial Mc2N whereas 6c has an equatorial Me2N. For 6c, the exocyclic P‐N bond has a partial double bond character the geometry about exocyclic N is planar. On the other hand, for 5c, the geometry about exocyclic N deviates considerably from planarity, the sum of the angles around N being 348.1°. In the crystalline state, the screw‐related 5c molecules are hydrogen bonded whereas in the crystalline state, the centro‐symmetrically related 6c molecules are paired‐up by h

ISSN:0009-4536    

DOI:10.1002/jccs.199000009

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

Abstract3‐Arylsydnone‐4‐carbohydroximic acid chlorides react with compounds containing activated methylene groups in the presence of bases to give 3‐aryl‐4‐(4′,5′‐disubstituted‐iso‐xazol‐3′‐yl)sydnones which have not been reported in the literature. All the products were obtained in good yields, and their structures were confirmed by spectral anal

ISSN:0009-4536    

DOI:10.1002/jccs.199000010

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY