摘要:

AbstractThermodynamic considerations indicate that in areference method for water determinationit is imperative to choose the water vapour pressure (p), prevailing during the analysis, very low (order: 1 mm Hg), to prevent a retention of water, which surpasses the precision of the method (order: 0.1% abs.).To reach the desiccation equilibrium in a reasonable time (≤ 8h) an elevated temperature is necessary; the upper limit of temperature is determined by the thermostability of the least stable component of the actual substrate.Out of the existing methods,entrainment distillation with isooctane(bpt 99° C) was chosen, since in a comparison, incorporating thermodynamic, kinetic, chemical and experimental aspects, it showed the highest overall suitability.For this technique p was found to be directly proportional to the solubility of water in the entrainer at the temperature of the receiver. For isooctane as an entrainer, p was calculated from solubility data and found to be of the order of 1 or a few mm Hg, involving a totalretentionof water equalling 10‐30 mg for an intake of 10‐20 grams. The retention of water by the boiling entrainer was calculated and turned out to be negligible; the amount of waterdissolvedby the entrainer in the receiver was calculated and found not to surpass 10 mg.Kinetic considerations revealed that under “ideal” conditions dehydration of the normal intake in entrainment distillation can be completed in about ½ hour.The additional time of operation (∼ 5 h), noticed in practice, must be attributed to slow sedimentation and collection of small water droplets and to internal transport phenomena in

ISSN:0165-0513    

DOI:10.1002/recl.19510700112

出版商:WILEY‐VCH Verlag    

年代:1951

数据来源: WILEY

摘要:

AbstractKawaïn, one of the pyronones occurring in the kawa kawa‐plant (Piper methysticum), has been synthesised. The melting point of the synthetic substance is not identical with the melting point of kawaïn given byBorsche.Probably this is due to the fact, thatBorschedid not obtain kawaïn in a pure s

ISSN:0165-0513    

DOI:10.1002/recl.19510700113

出版商:WILEY‐VCH Verlag    

年代:1951

数据来源: WILEY

摘要:

AbstractA general proof is given for the equality of the streaming‐potential E/P and the electro‐osmotic transport of liquid V/I, independent of the structure of the diaphragm. The presence of surface conductance and even inhomogeneity of the material from which the diaphragm is constructed, does not impair this relation. Three other relations involving also the streaming current and the electro‐osmotic counter pressure, can easily be derived on the same base.The proof is given by two independent methods, one method using a model of a diaphragm, which consists of a network of simple capillaries, the other treatment being based upon die thermodynamics of irreversible proc

ISSN:0165-0513    

DOI:10.1002/recl.19510700114

出版商:WILEY‐VCH Verlag    

年代:1951

数据来源: WILEY

摘要:

AbstractLes sulfones qui sont susceptibles de subir une hydrolyse se scindent généralement en acidesulfiniqueet composé hydroxylé (ou oléfinique). Soumises à l'action décomposante d'amines, ces sulfones peuvent engendrer également un acide sulfinique, le second produit étant une amine substituée.Par contre, les dérivés substitutées du tris‐méthylsulfonyl‐méthane ZC(SO2CH3)3donnent, par hydrolyse, l'acide méthane‐sulfoniqueet des disulfones substituées.L'aminolyse de ces trisulfones a lieu dans la plupart des cas selon le même principe; d'acide méthanesulfonique se présente à l'état d'amide substitué.Cependant les thioaryl‐tris‐méthylsulfonyl‐méthanes font exception; tandis que l'hydrolyse alcaline suit le schéma des autres trisulfones, les amines attaquent le groupe thioaryle, au lieu d'un groupe méthylsulfonyle.Le mécanisme électron

ISSN:0165-0513    

DOI:10.1002/recl.19510700115

出版商:WILEY‐VCH Verlag    

年代:1951

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19510700101

出版商:WILEY‐VCH Verlag    

年代:1951

数据来源: WILEY