摘要:

AbstractPotentiometric titrations of solutions of various aromatic hydrocarbons in 1,2‐dimethoxyethane and tetrahydrofuran with a solution of biphenylsodium have shown chemical reduction to proceed in two stages:The reduction potentials of the aromatic hydrocarbons, calculated from the potentiometric curve, are in good agreement with the half‐wave potentials obtained from polarographic reductions in 96% dioxan‐water. The standard potentials of the first reduction step expressed in Volts against the standard potential of biphenyl fit the following equation:\documentclass{article}\pagestyle{empty}\begin{document}$$ \varepsilon _1 = a\gamma + 1.95\,{\rm Volts}, $$\end{document}with γ = ‐ 2.19 ± 0.059 e.V. (2 × stand. dev. from mean) in whichastands for the root of the m.o. secular equation (overlap S = 0.25 included) corresponding to the lowest non‐occupied π‐orbital of the hydrocarbon and γ is the resonance‐parameter.The electrochemical series of aromatic hydrocarbons including a rough estimate of the standard potential of sodium in 1,2‐dimethoxyethane and the mechanism of chemical reduction in inert and proton‐active

ISSN:0165-0513    

DOI:10.1002/recl.19560750502

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

摘要:

AbstractExhaustive chlorination of methyl 4‐amino‐2‐hydroxy‐benzoate (XIII) (P.A.S. methyl ester) in a mixture of glacial acetic acid and hydrochloric acid (s.g. 1.19) yielded methyl 1,3,3,5,5,6‐hexachloro‐cyclohexanedione‐2,4‐carboxylate‐1 (XIV). Methyl 4‐amino‐3,5‐dichloro‐2‐hydroxy‐benzoate (XV), methyl 2‐amino‐4‐hydroxy‐benzoate (XVI), methyl 2,4‐dihydroxy‐benzoate (XVII), and methyl 3,5‐dichloro‐2,4‐dihydroxy‐benzoate (XVIII) could also be used as starting material for XIV. Reduction of XIV with stannous chloride yielded XVIII. With hypochlorous acid, XIV reacted with ring fission to form 1,1,2,3,5,5,5‐heptachloro‐3‐carbomethoxy‐pentanone‐4‐carboxylic acid‐1 (XIX). Both compounds XIV and XIX decomposed in alkaline medium and yielded monomethyl trichloro‐glutaconate (XX). In the first case the latter compound was accompanied with dichloro‐acetic acid, in the second case trichloro‐acetic acid was the other decomposition product. Glutaconic acid (XXI) was formed when XIX was reduced with sodium amalgam, while the structure of a 5‐carbomethoxy‐6‐trichloromethyl‐pyron

ISSN:0165-0513    

DOI:10.1002/recl.19560750503

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

摘要:

AbstractIn the homologous series of n‐alkanes two alternating effects are known, viz. the familiar alternation of melting points for the short‐chain members and the recently reported alternation of transition points for members with chains of more than 20 carbon atoms.A further study of the phase behaviour of these hydrocarbons now reveals that both effects are due to some peculiarity in one of two structures in which n‐alkanes may crystallize, viz. the Sβ‐modification. As a consequence, the thermodynamic properties of this solid modification show an alternation; this effect, in its turn, is responsible for the specific behaviour of the melting and transition point temperatures.It is to be expected that the other crystal structure, viz. Sα, and the liquid do not show similar pecu

ISSN:0165-0513    

DOI:10.1002/recl.19560750504

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

摘要:

AbstractThe properties of the crystalline Sβ‐modifications of n‐alkanes show alternation: this alternation effect is the basis of all alternation effects occurring in the general behaviour of n‐alkanes, also when other states of matter (liquid state or Sα‐modification) are involved. The properties of the latter states do not show alternation themselves.Quantitative experimental evidence by means of thermodynamic data has now been obtained. In terms of enthalpy the magnitude of the alternation effect is about 600 cal/mole, in terms of entropy and free enthalpy the magnitudes are about 1.5 cal/mole °C and 80 cal/mole, respectively. Generally the Sβ‐phases of n‐alkanes with an even number of carbon atoms show relatively lower values for the absolute thermodynamic quantities as compared with the n‐alkanes with an odd numbe

ISSN:0165-0513    

DOI:10.1002/recl.19560750505

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

摘要:

AbstractThe electrophoretic velocity of a uniformly charged porous sphere in a salt solution is considered to be composed of three contributions. These are:1a motion caused by that part of the charge which is exactly compensated by counter‐ions within the porous sphere.2a motion caused by the net charge of the porous sphere.3a motion caused by the counter‐ions outside the sphere.The influence of relaxation is left out of consideration. The presence of the counter‐ions is shown to lead to a relatively high degree of draining. In solutions of high ionic strength, where the porous sphere model fails, polyelectrolyte coils are shown to be freely drained and the application of Henry's theory of electrophoresis of a cylindrical rod is disc

ISSN:0165-0513    

DOI:10.1002/recl.19560750506

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19560750507

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19560750508

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

摘要:

AbstractA survey is given of different types of ionic and covalent complexes.

ISSN:0165-0513    

DOI:10.1002/recl.19560750509

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

摘要:

AbstractThree fields of complex chemistry which have attracted great interest during recent years are(I)The stabilisation of oxidation states by complex formation.(II)The correlation of magnetic and other physical properties with the structures of complexes as determined by X‐ray crystallography.(III)The factors which influence the reactivity of complexes, and the nature of substitution processes.An attempt is made to review some of the major recent advances in each of these subjects, to indicate some of the difficulties involved, and to suggest in which direction further work is most likely to be profitable. Among the subjects to which reference is made are: recent work on complex fluorides; the stereochemistry of nickel and copper; the correlation of analytical uses with structure for metal derivatives of dioximes; and recent work on the mechanism of substitution in octahedral complexe

ISSN:0165-0513    

DOI:10.1002/recl.19560750510

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY

摘要:

AbstractEs wird über die Darstellung einiger bislang noch unbekannter Alkali‐und Bariumfluorometallate berichtet. Ausserdem wurden mehrere bereits bekannte Verbindungen dieser Reihe erneut dargestellt und untersucht.In vielen Fällen, nämlich bei der Darstellung der komplexen Alkalisalze, hat sich die vonKlemmundHussgefundene Methode der Fluorierung von Gemischen geeigneter binärer Salze (z.B. KCl + AgNO3) weiterhin bewährt; zur Erhaltung sehr homogener Präparate (insbesondere für magnetische Untersuchungen) ist es jedoch oft zweckmässiger, Komplexsalze entsprechender Zusammensetzung zu fluorieren.Die Darstellung der Bariumfluorometallate gelingt im allgemeinen nur auf dem zweiten Wege. Dieses auffällige Verhalten hängt damit zusammen, dass bei Alkalisalzen primär die sehr aktiven Alkalifluoride MeFx(1<×<3) gebildet werden, während beim Barium nur das hochschmelzende, reaktionsträge BaF2entsteht.Die Verbindungen wurden magnetochemisch, röntgenographisch und analy

ISSN:0165-0513    

DOI:10.1002/recl.19560750511

出版商:WILEY‐VCH Verlag    

年代:1956

数据来源: WILEY