摘要:

AbstractThe ionic radii of iron group elements do not decrease monotonically from Ca towards Zn but show maxima at configurations d4, d5and–possibly–d9, d10. An explanation is offered. It is based upon a heteropolar model where the influence of the other ions on the electronic distribution of 3d electrons is considered as a purely electrostatic influence of their net charges. The maxima are explained by the influence of a preponderantly cubic crystalline field, both for negliglible and strong interelectronic interact

ISSN:0165-0513    

DOI:10.1002/recl.19520710502

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractHeating of benzhydryl‐dimethyl‐2‐hydroxyethyl‐ammoniumchloride gives rise to a rearrangement in which the benzhydrylgroup migrates from the nitrogen atom to the oxygen, with the formation of benzhydryl‐dimethyl‐aminoethyl‐ether

ISSN:0165-0513    

DOI:10.1002/recl.19520710503

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractThe extrapolation of the ηsp/cversusccurves for polyelectrolytes in dilute salt solutions is difficult because these curves show a sharp maximum at a polymer concentration,c, where the equivalent concentration of the polyelectrolyte is of the same order of magnitude as that of the extraneous salt. A more reliable figure for the intrinsic viscosity can be obtained if the effective ionic strength is kept constant or nearly constant, in which case ηsp/cversuscbecomes a straight line. The slope of this line is discussed in § 8.The intrinsic viscosities discussed are those of a pectinate and three samples of sodium carboxy methyl cellulose (Na—CMC) in aqueous solutions of sodium chloride. The experimental results can be described satisfactorily by the theory ofHermansandOverbeek.The only unknown parameter is the average square of the distance between the ends of the uncharged molecule, and its value compares well with that known for other cellulose derivatives.At the limit of zero ionic strength the molecules are practically fully stretched. The application ofSimha's formula for ellipsoidal particles leads to reasonable values for the molecular length.In connection with the high precision aimed at, a study was made of the effect of surface tension in viscometry. This is described in § 4, and leads to the conclusion that for our purpose an Ubbelohde viscometer has preference above an Ostwald viscometer. It was found, further, that the intrinsic viscosity of the polyelectrolytes investigated is a function of the shear‐rate. This phenomenon will be more fully discussed el

ISSN:0165-0513    

DOI:10.1002/recl.19520710504

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractThe osmotic pressure of solutions of sodium pectinate and three samples of sodium carboxy methyl cellulose in aqueous solutions of sodium chloride were measured in a Fuoss and Mead osmometer. The primary aim was to obtain the molecular weights of the samples. As a by‐product the change of osmotic pressure with polymer concentration and salt content was studied.The reduced osmotic pressure proves to be a linear functon of the polymer concentration. The slopes of the linesp/cversuscvary with the concentration of the sodium chloride in a manner which is in reasonable agreement with the predictions of the Donnan equilibrium. An accurate check is impossible because the activity coefficients are not know

ISSN:0165-0513    

DOI:10.1002/recl.19520710505

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractSome properties of “double bond reagents” are discussed, and the mechanism of the reaction between ozone and aromatic compounds as proposed byWibautand his co‐workers, is criticised. It is suggested that the initial stage in the reaction is the formation of a π‐bond between the carbon‐carbon bond having the highest double bond character and the ozon

ISSN:0165-0513    

DOI:10.1002/recl.19520710506

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractA summary is given of experiments which lead to the conclusion that the addition of ozone is an electrophilic reaction. The points of difference and agreement in mechanism between the addition of ozone and electrophilic substitution are discussed. The suggested mechanism isnotin opposition to the interpretation ofKooyman and Ketelaar.

ISSN:0165-0513    

DOI:10.1002/recl.19520710507

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractThe activity of the solute in the adsorbed layer is calculated, and from this is obtained the activity in bulk by means of interfacial tension data at very low concentrations, using the method previously devised by the authors. This allows the investigation of the equilibrium between single and associated fatty acid molecules in hexane. It is shown that there is a simple equilibrium between monomers and dimers with lauric and palmitic acids, and the standard free energy of dimerisation is calculated, but the equilibrium with stearic acid is more complicated. The standard free energy of adsorption is calculated and it found to be independent of the chain‐length of the aci

ISSN:0165-0513    

DOI:10.1002/recl.19520710508

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractGlass electrodes of the “mixed electrode” type can be used with advantage to measure activities of metal ions in systems of known pH, containing only one kind of metal ions. The use of a valve electrometer adapted to very high input resistances made it possible to use robust bulb electrodes of a high chemical and electrical resistance. These electrodes appeared to be very suitable for this purpose and produced remarkably reproducible figures.The relationship between the potentials measured and the ion concentrations was examined theoretically and found to be in agreement with the assumption, that glass behaves as a weak acid and that the potentials are essentially membrane potentials in a Donnan sys

ISSN:0165-0513    

DOI:10.1002/recl.19520710509

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractA revised method is given for the determination of 2,4 D acid (2,4‐dichlorophenoxy acetic acid) and M.C.P.A. (2‐methyl‐4‐chlorophenoxy acetic acid) in herbicidal formulations (total phenoxy acetic acids). The preliminary removal of free phenols and cresols is not necessary if methyl red and phenol red respectively are chosen as indicators.The dissociation constants were determined of some chlorophenols and ‐cresols of the corresponding phenoxy acetic acids

ISSN:0165-0513    

DOI:10.1002/recl.19520710510

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY

摘要:

AbstractA cryoscopic study of mixtures of HNO3and BF3reveals the existence of a compound HNO3. 2BF3(melting point 53° C). Mixtures of composition HNO3. 1/2BF3, HNO3. BF3, HNO3. 2BF3and HNO3. 1/2SO3were studied spectroscopically. In liquid HNO3. 1/2BF3and HNO3. BF3the reaction HNO3+ BF3→ NO+2+ BF3OH‐ takes place to a more or less considerable extent. In HNO3. 2BF3no clear indication for the presence of NO2+ ions is found. HNO3. 2BF3probably is an addition compound comparable with those described byBaumgartenc.s. for BF3with a number of sulphates or pyrophosphates.In liquid HNO3. 1/2SO3a considerable amount of NO2+ and HSO4 ions are p

ISSN:0165-0513    

DOI:10.1002/recl.19520710511

出版商:WILEY‐VCH Verlag    

年代:1952

数据来源: WILEY