摘要:

AbstractRates of the reaction between Gibb's reagent and sodium thiosulphate have been measured in water‐glycerol mixtures over the temperature range 25–40°C. Log(k) varies linearly with the reciprocal of the dielectric constant. The energy of activation and the thermodynamic parameters of activation are calculated and discussed in terms of solvent proper

ISSN:0264-3413    

DOI:10.1002/jctb.504330602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe polarographic behaviour of a series of 5‐arylidene‐4‐thiohydantoin derivatives is reported and discussed. The reduction proceeds via a CECE mechanism in acid media with the formation of a 5‐benzyl‐4‐thiohydantoin and other products. The mechanism is confirmed throughpKadeterminations and Hammett's σ

ISSN:0264-3413    

DOI:10.1002/jctb.504330603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractSome 1‐phenyl‐3‐methyl‐4‐(thia‐and/or selenadiazolylphenylhydrazo)‐Δ2‐pyrazolin‐5‐one derivatives have been prepared and screenedin vitrofor their antibacterial and a

ISSN:0264-3413    

DOI:10.1002/jctb.504330604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe physical properties of plaster slurries and cast gypsum made from calcium sulphate hemihydrate containing small quantities of orthophosphoric acid, calcium oxide, added singly and together with varying CaO/P2O5weight ratios from 0 to 5, were studied. Small quantities of 0.1–0.4% P2O5severely retarded the setting times of plaster slurries, while CaO accelerated them slightly. However, when the CaO and P2O5were added together, the physical properties exhibited some unusual behaviour due to the formation of secondary calcium orthophosphate, CaHPO4.2H2O,in situ. At the CaO/P2O5weight ratio range of about 1–2, the initial setting times became excessively long, the compressive strengths and combined water contents decreased, and due to incomplete hydration the casts contained large amounts of unhydrated hemihydrate which increased with increasing concentrations of P2O5. Above the CaO/P2O5weight ratio of about 2, the setting time decreased, the compressive strength increased, the hydration was completed and the physical properties returned to the usual values reported for commercial casting plaster. The practical implications of these findings on the industrial use of phosphogypsum are discus

ISSN:0264-3413    

DOI:10.1002/jctb.504330605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA study was conducted of the influence of pH, initial reactant concentration and reaction time upon the rate of removal of lead ions from solutions of lead nitrate. Three different reactants were used:β‐dicalcium silicate (β‐C2S)*, α‐monocalcium silicate (α‐CS), in the form of finely ground clinkers, and commercial calcium hydroxide. The initial concentration of lead in solution was varied between 5 and 1000 mg cm‐3Pb2+for different additions of reactant. For each concentration of lead ion the effect of time of shaking on the removal of lead was followed by the determination of residual lead concentration in the filtrate. Lead was reduced to low levels by all the precipitants. The precipitated reaction products were identified by X‐ray diffraction techniques, electron diffraction analysis and infrared spectroscopy. The analysis characterised the products of the precipitation reactions as basic lead carbonate, basic lead nitrates and

ISSN:0264-3413    

DOI:10.1002/jctb.504330606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractAn empirical mathematical model has been derived to elucidate the factors influencing the eluate concentrations observed in a previously reported ion‐exchange study.1The efficiency of the experimental procedure used in that study is evaluated in relation to the model, and an empirical 'efficiency' parameter used in the model is discussed with respect to its physical significance. The more general applicability of an expression derived for limiting maximum eluate concentration is also considere

ISSN:0264-3413    

DOI:10.1002/jctb.504330607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe reported procedure for obtaining cresols from copper salts of toluic acids has been examined and certain improvements in yields have been obtained. It has been found that oxygen is preferable to the use of air in this reaction. The variables, oxygen flow rate, reaction temperature, reaction time and copper oxide concentration have been examined, and the effect on the percentage yields of cresols has been found. In the case ofp‐toluic acid, the molar yield ofm‐cresol could be raised to 70 % while the molar conversion was 21–22%. Form‐toluic acid the molar yield was considerabl

ISSN:0264-3413    

DOI:10.1002/jctb.504330608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

ISSN:0264-3413    

DOI:10.1002/jctb.504330601

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY