摘要:

AbstractThe interaction between ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA or H4Z) and Th(IV) and Zr(IV) ions has been investigated potentiometrically by using a mercury indicator electrode. The formation constants of the chelates ThZ and ZrZ have been evaluated at a constant ionic strength of 0.10 (KNO3) and at 0, 10, 20, 30 and 40°. Enthalpy and entropy changes characterizing the formation of the chelates have been calculated by the least‐squares method at 25°. The results are collected as foll

ISSN:0009-4536    

DOI:10.1002/jccs.198100022

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractSpectrophotometric studies of Fe(II)‐thiovioluric acid system indicates the presence of a 1:2 complex in thepH range 4.0–6.5. The apparent equilibrium constant (K′1) has been determined by general absorbance‐extinction concentration scheme. The first and second dissociation constants of the acid have been studied at an ionic strength of 0.1Mwhile the third dissociation constant has been determined atI= 1M. The effects of suddenpH change and buffer compositions on the dissociations have also been investigated. The stability constant of the complex has been calculated from the apparent equilibrium constant at ionic strength of 0.1M. The stability constant works out to be 15.67 a

ISSN:0009-4536    

DOI:10.1002/jccs.198100023

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe effect of solvent structure on the rates of redox reactions in alcohol+water mixture was discussed by some authors. The rate of photoreduction of 9,10‐anthraquinone‐2‐sulfonate was decreased by addition of H2SO4but was unchanged by increase of ionic strengh with (NH4)2SO4. The magnitude of the decrease in presence of acid was greater with ethanol or isopropanol than with N‐ethylacetamide as substrate. The formation of semiquinone and carbonate radical anions was observed(4)during the direct photoreaction. The electron transfer from the carbonate anion to sulfoanthraquinone in the first excited triplet state was the controlling step of this process. Therefore, anthraquinone β‐sodium sulfonate is efficient sensitizers of the photooxidation of organic substrates in aqu

ISSN:0009-4536    

DOI:10.1002/jccs.198100024

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe stability constants (for the formation) of LaBr2+and LaBr2+ions were obtained potentiometrically at various ionic strengths at 20°, 25°, 30°, and 35°. The molal free energy was given by ΔG°=‐2,444.04+2.67TlogT+1.39T. The thermodynamic quantities for the formation of LaBr2+were evaluated as ΔHf° = −207.9, ΔGf° = −199.1kcal mole−1andS° = −29.5ca

ISSN:0009-4536    

DOI:10.1002/jccs.198100025

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractAn internal‐standard method1–4)has been applied for the determination of La, Sb, Au, Cr and Ag in silicon single‐crystal by neutron activation analysis using cobalt as an internal‐standard element. No chemical separation is required in this case and the precision obtained with the present method is satis

ISSN:0009-4536    

DOI:10.1002/jccs.198100026

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractThe chromic acid oxidation of cyclohexanone catalyzed by picolinic acid in water undergoes a change from first‐to zero‐order dependence in both cyclohexanone and acidity. The mechanism proposed indicates the formation of an intermediateC1by picolinic acid and chromic acid. ThenC1would react with enol form of cyclohexanone to give another intermediateC2.C2finally cleaves into produ

ISSN:0009-4536    

DOI:10.1002/jccs.198100027

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractExperiments are performed to investigate the effects of oxidation upon coal liquefaction in a combined pre‐oxidation‐liquefaction process. It is found that the air‐oxidation of coal preceding liquefaction is generally detrimental to liquefaction yields for both cases with or without presence of hydrogen gas in the dissolution step, and could be highly harmful to the processes which rely solely upon hydrogen donor solvents such as 1,2,3,4‐tetrahydronaphthalene. The analyses of oxidized and unoxidized coals show a significant decrease in hydrogen but increase in oxygen contents of the coal with oxidation. These factors together with the possible formation of oxygen‐coal bonds and the increase in —OH and/or —COOH groups in the oxidized coal are thought to account for the decreasing conversion of oxidized coal when it is subjected to

ISSN:0009-4536    

DOI:10.1002/jccs.198100028

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractAs the first synthesis of sydnone derivatives having a carbon‐oxygen bond at the 4‐position of sydnone ring, 4‐sydnonyl tosylate were successfully prepared by anodic substitution rea

ISSN:0009-4536    

DOI:10.1002/jccs.198100029

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

摘要:

AbstractSynthesis of a new reagent diacetylmonoquinolylhydrazone (DAmQH) and its application in the selective spectrophotometric determination of copper is presented. DAmQH reacts with copper instantaneously to form a green complex in thepH range 7.5–11.6 with molar absorptivity 1.45 × 104l mole−1cm−1. Beer's law is obeyed upto 2.20ppmof copper. Copper has also been analysed in several

ISSN:0009-4536    

DOI:10.1002/jccs.198100030

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY

ISSN:0009-4536    

DOI:10.1002/jccs.198100031

出版商:WILEY‐VCH Verlag    

年代:1981

数据来源: WILEY