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Assoziation bei Azoverbindungen I: Einfluss von Substituenten auf die Basizität von 4‐Dimethylamino‐azobenzol‐Derivaten
Author(s) -
Zenhäusern A.,
Zollinger Hch.
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.19620450620
Subject(s) - chemistry , protonation , medicinal chemistry , benzene , azobenzene , organic chemistry , molecule , ion
Abstract(1) The relative acidity constants K ′ of derivatives of 3‐methyl‐4‐dimethyl‐amino‐azobenzene substituted in the 3′‐or 4′‐position follow the Hammett relationship for substituted benzene derivatives (ϱ = + 0.46) (2) The relative acidity constants of substituted mono‐protonated 4‐dimethyl‐amino‐azobenzenes (DAB) follow the Hammett relationship with most substituents (ϱ = + 0.77). Significant deviations are observed with ‐M‐substituents in 4′‐position (NO 2 , COCH 3 , CN): the acidifying effect of these substituents is smaller than expected (3) Molar extinction coefficients and acidity constants are dependent on the concentration of these DAB derivatives. It can be demonstrated that these compounds are highly aggregated, even in very dilute solutions.