摘要:

AbstractDrawbacks of the well‐known potential‐step method are briefly mentioned. A new method called thecyclicpotential‐step method is introduced, the essential of which is that a square wave voltage is applied to a polarisable electrode. It is shown mathematically that the current response approaches rapidly to a constant pattern. The derivations presented are free from restrictions concerning the reversibility of the system and the magnitude of the amplitude of the square wave.It is shown that the cyclic potential‐step method offers easy means for the determination of the transfer‐coefficient (α) and the standard exchange current den

ISSN:0165-0513    

DOI:10.1002/recl.19600790102

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractA new method, designated the cyclic current‐step method, for the evaluation of kinetic parameters of electrochemical processes (especially the exchange current j0) is introduced in addition to the well‐known (single) current‐step method. Its essential basis is that a square wave current is forced through a polarisable electrode and the voltage response of the electrode is measured.It is shown mathematically that the voltage response approaches a constant pattern when “coulomb‐symmetry” is present and a gradually changing pattern is observed when a departure from coulomb‐symmetry occurs. Even when the pattern is continuously changing due to the presence of coulomb‐asymmetry the evaluation of j0may be easily achieved.By means of the cyclic current‐step method it is easily visualised whether or not the influence of the double layer capacity is negligible. Moreover, the method provides a ready means for the elimination of the ohmic part of the voltage response of the

ISSN:0165-0513    

DOI:10.1002/recl.19600790103

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractThe frequencies of and the polarization of most of the Raman lines of liquid P2O3Cl4have been determined.The molecule contains an oxygen bridge connecting twogroups.From the polarization measurements it is deduced that at least one symmetry element is still present in the molecule.

ISSN:0165-0513    

DOI:10.1002/recl.19600790104

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractThe Raman spectrum of a liquid mixture consisting of one mole of sodium chloride with a half mole of Ga2Cl6(one GaCl3), melting temperature 103.7°, gives indications for the presence of an equilibrium between the molecular species NaCl, Ga2Cl6and NaGaCl4

ISSN:0165-0513    

DOI:10.1002/recl.19600790105

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractFrom the reaction mixture, obtained by reacting ethyl diazoacetate and acetic anhydride in the manner described in previous communications1, we have isolated ethyl acetoxyacetate, ethyl (α‐acetoxy)‐acetoacetate and 1‐acetyl‐3,4,5‐tri(ethoxycarbonyl)‐2‐pyrazoline. The reaction mechanis

ISSN:0165-0513    

DOI:10.1002/recl.19600790106

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractThe reaction between catalyst components has been studied and polymerization experiments carried out on ethylene using the systems pentyl‐sodium – TiCl4(I) and diethylaluminium bromide – TiCl4(II). Results of reduction of TiCl4can be interpreted on the basis of the following equations: AmNa + TiCl4→ TiCl3+ NaCl + Am•, in the case of I, Et2AlBr + TiCl4→ TiX3+ EtAlX3+ Et•and EtAlX2+ TiCl4→ TiX3+ + AlX3+ Et•(X = Cl, Br), in the case of II. The occurrence of the second reaction in II was confirmed by analyses of the precipitates formed in the reaction and by reacting TiCl4with EtAlBr2. The reducing power of the organometallic compounds examined decreases in the range: AmNa>Et2AlBr>EtAlBr2.Polymerization results with system I showed that active catalysts are obtained only with AmNa/TiCl4mole ratios>unity. The polymer yield appeared to increase with increasing catalyst ratio. This may reasonably be explained by postulating the existence of an AmNa‐TiCl3complex as the actual catalytic species. In this range of catalyst ratios, the intrinsic viscosities of the polyethylenes remain approximately constant.In the case of system II, polymerization results could also be interpreted by assuming the existence of one complex or a mixture of a number of complexes as the catalyst. With Et2AlBr/TiCl4mole ratios>∼ 2, a complex between Et2AlBr and TiCl3(Et2AlX‐TiX3) is postulated. With catalyst ratios in the vicinity of unity and lower, ambiguous results were obtained due to the occurrence of reactions between the catalyst component

ISSN:0165-0513    

DOI:10.1002/recl.19600790107

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

Abstract2‐Carboxyphenylpyruvic acid and its derivatives with substituents in the phenyl nucleus can be prepared via a modified azlactone synthesis. These phenylpyruvic acids display a spontaneous ring closure into the corresponding isocoumarin carboxylic acid

ISSN:0165-0513    

DOI:10.1002/recl.19600790108

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractIn view of their herbicidal properties a number of similarly or differently 2,4‐substituted 6‐chloro‐1,3,5‐triazines was synthesized. Their herbicidal properties are briefly di

ISSN:0165-0513    

DOI:10.1002/recl.19600790109

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractEster interchange equilibrium products prepared from dimethyl terephthalate and ethylene glycol, in the presence of zinc acetate as a catalyst, have been investigated at 180 and 195°. For the analysis of these products quantitative volumetric methods for the determination of free methanol and of free ethylene glycol have been developed. In addition, a method for the fractional vacuum distillation and sublimation of methanol, ethylene glycol, dimethyl terephthalate, and β‐hydroxyethyl methyl terephthalate has been worked out.The analytical results are evaluated in terms of equilibrium constants for the various reversible reactions pertaining to the present system. All equilibrium constants are found to depend only slightly on temperature and composition. The small values of the equilibrium constants related to the removal of methyl ester groups are in line with the practical difficulty of achieving complete glycolysis of dimethyl terephthalate before polycondensation to polyethylene terephthalate starts.The most important result is the fact that the “molecular” equilibrium constant KIof the first step of the glycolysis of dimethyl terephthalate equals the corresponding overall equilibrium constant Kein terms of functional groups after correction for the functionality of reactants and products. Prom this fact it is concluded that the “molecular” equilibrium constants KIand KIIfor the first and second step of the glycolysi

ISSN:0165-0513    

DOI:10.1002/recl.19600790110

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY

摘要:

AbstractThe rapid decrease in extinction of deoxyribonucleic acid in the first moments of irradiation with U.V. light (2537 Å) is due to the conversion of the pyrimidines into low‐absorbing substances. Thymine in this natural polymer reacts according to the so‐called “first irreversible reaction” shown by the free bases in solution. This could be demonstrated by means of a peculiar property of the irradiation product of thymine. Cytosine is supposed to react in the same way. The importance of this finding with respect to the lethal action of U.V. light on micro‐organisms is

ISSN:0165-0513    

DOI:10.1002/recl.19600790111

出版商:WILEY‐VCH Verlag    

年代:1960

数据来源: WILEY