摘要:

AbstractThe ultraviolet absorption spectra of benzophenones show well‐defined steric effects arising fromortho‐substitutions.In this paper the experimental data are given for a series of 12 methylsubstituted ketones, including benzophenone.From these data the oscillator strengthsfwere calculated for the C‐bands; mutual comparison of thesef‐values gives and idea of the magnitude of the steric effects caused byortho‐substituted meth

ISSN:0165-0513    

DOI:10.1002/recl.19540731202

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

摘要:

AbstractThe theoretical approach of separation by thermal diffusion is somewhat hampered by the lack of sufficient experimental data.In an effort to meet this want, a microthermal diffusion column was constructed, which enables the composition of the mixture to be determined all along the column. This column, which is described in the present paper, has 43 outlets, placed along its length, from which samples can be taken.With the aid of this column the separation of some binary hydrocarbon mixtures was studied after various time intervals. Results so far have confirmed current theories describing thermal diffusion as a counter current fractionation process.The degree of separation in the stationary state is expressed by the concentration gradient at the point of inflection of the concentration‐length curve. From this concentration gradient the thermal diffusion constant D′ is calculated for the various mixtures stud

ISSN:0165-0513    

DOI:10.1002/recl.19540731203

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

摘要:

AbstractA “redistribution reaction” is defined. The heat of redistribution (ΔHr) is a direct measure of the departure of bond‐energy term values from constancy. ΔHrvalues are given for examples chosen from hydrocarbon chemistry, and discussed in terms of conjugation and hyperconjugation effects. Other examples from a wider field (including some redistribution reactions of alkyl halides, cyanogen, mercury alkyls, dimethylaminochloroborines) are used to illustrate the influence of polar groups, ionicity, and back‐coordination on bond‐energy

ISSN:0165-0513    

DOI:10.1002/recl.19540731204

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

摘要:

AbstractThe condensation rate of a few tripeptide methyl esters in methanol has been studied at 65° C. The peptide esters with a glycyl residue at both ends have been found to be equally reactive, regardless of the nature of the amino acid residue in the middle. A side chain situated on one of the terminal amino acid residues decreases the reaction rate (table I)

ISSN:0165-0513    

DOI:10.1002/recl.19540731205

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

摘要:

AbstractThe conditions necessary to prevent interference of Fe with the oxidimetric titration of U have been derived on the basis of calculations regarding the relations between the redox potential and the pH. The method of calculation may be applied to other possibly interfering ions. It is shown that a successful determination of both U and Fe can be carried out in a solution with an atomic ratio Fe/U of 1000 and containing only 2 mg of U per 150 ml. By using the “dead stop end point” indication method, U and Fe may be determined separately without previous separation and without any pretreatment but reduction by a common Jones reduc

ISSN:0165-0513    

DOI:10.1002/recl.19540731206

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

摘要:

AbstractIn an attempt to prepare 4‐amino‐3,5‐dichloro‐2‐hydroxy‐benzoic acid (I) from 4‐amino‐2‐hydroxy‐benzoic acid (II) by a chlorination reaction, it was found that the isolated reaction product was identical with 2,4,4,6,6‐pentachloro‐cyclohexene‐1‐dione‐3,5 (III). Exhaustive chlorination of 2,4‐dihydroxy‐benzoic acid (IV) led to the same 1,3‐dihydroxy‐benzene derivative. (I) could be prepared by chlorination of 4‐acetylamino‐2‐hydroxy‐benzoic acid (V) to 4‐acetylamino‐3,5‐dichloro‐2‐hydroxy‐benzoic acid (VI) and subsequent saponification of the latter compound. By converting I into 3,5‐dichloro‐2‐hydroxy‐benzoic acid (VII) and into 3,5‐dichloro‐2,4‐dihydroxy‐benzoic acid (VI

ISSN:0165-0513    

DOI:10.1002/recl.19540731207

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

摘要:

AbstractDie Chloride und Perchlorate der Alkalimetalle lassen sich papierchromatografisch gut trennen, ihr Nachweis ist aber schwierig. Es wird ein Apparat beschrieben, mit dem die Ionen auf Grund des Stromdurchganges durch die Flecken gefunden werden. Der optimale Spannungsbereich sowie die Empfindlichkeit der Methode werden für die Ionen von Li, Na und K, einzeln und nebeneinander, erörter

ISSN:0165-0513    

DOI:10.1002/recl.19540731208

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

摘要:

AbstractAn improved iodometric procedure for the determination of hydroperoxides is described. Theoretical values are obtained for seven structurally different compounds. The estimation of 1‐tetralyl hydroperoxide is affected by the presence of α‐tetralone if the determination is carried out at too high a tempera

ISSN:0165-0513    

DOI:10.1002/recl.19540731209

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

摘要:

AbstractThe theory of adsorption chromatography for liquid multicomponent mixtures is critically reviewed and it is shown to what limitations the introduction of a number of assumptions leads.As regards the shape of chromatograms in development chromatography with two solutes, it is proved that both the discontinuous shape(Glueckauf)and the continuous one(OffordandWeiss)are consistent with the equilibrium theory, the shape to be found in a specific case depending on the mathematical characteristics of the adsorption isotherms that govern the process.The most important check on theory will be to verify in what cases the relation, according to which all concentrations belonging to a given set move at equal velocity through a column, is valid.

ISSN:0165-0513    

DOI:10.1002/recl.19540731210

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19540731201

出版商:WILEY‐VCH Verlag    

年代:1954

数据来源: WILEY