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Physikalisch‐chemische Eigenschaften und Elektronenstruktur der Azo‐Verbindungen. Teil XI: Bemerkung zur Struktur des Azonium‐Kations des p , p ′‐Bis‐dimethylamino‐azobenzols
Author(s) -
Gerson F.,
Heilbronner E.
Publication year - 1962
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19620450108
Subject(s) - chemistry , bathochromic shift , protonation , azobenzene , medicinal chemistry , polymer chemistry , stereochemistry , molecule , organic chemistry , ion , physics , quantum mechanics , fluorescence
The absorption spectrum of p , p ′‐bis‐dimethylamino‐azobenzene has been measured in solvents of different acidities. The bathochromic shift of the long‐wave transition associated with protonation of the azo link falls in line with the corresponding shifts, observed for a series of p ′‐substituted p ‐dimethylamino‐azobenzenes. The same is true – inside wider limits of error – for the p K ′ values of the equilibrium: base + H ⊕ ⇆ azonium‐cation of these compounds. These results support the view that protonation of p , p ′‐bis‐dimethylamino‐azobenzene does not differ in principle from that of the unsymmetric p ′‐substituted p ‐dimethylaminoazobenzenes.