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Allgemeine Basenkatalyse der Azokupplung von o ‐Diazophenolen. 19. Mitteilung zur Kenntnis der Azokupplungsreaktion
Author(s) -
Jermini C.,
Koller S.,
Zollinger H.
Publication year - 1970
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.19700530108
Subject(s) - chemistry , diazo , medicinal chemistry , catalysis , base (topology) , reaction mechanism , kinetics , organic chemistry , mathematical analysis , physics , mathematics , quantum mechanics
1. The kinetics and the mechanism of the diazo coupling reaction of 2‐diazophenol‐4‐sulphonic acid with 1‐naphthol‐2‐sulphonic acid have been investigated at 0° and ionic strength I =0.45. 2. The p K a ‐value of the hydroxyl group in 2‐diazophenol‐4‐sulphonic acid has been determined: p K a =‐ 0.04 ± 0.10. It is the diazonium‐phenolate anion which actually enters into the diazo coupling reaction. 3. The reaction is subject to general base catalysis. It is shown that no intermediate is enriched during the reaction at pH 11.3–11.6 which proceeds by a two‐step mechanism with a steady state intermediate.