Kinetik und Mechanismus einer Dis-Azokupplung. 22. Mitteilung zur kenntnis der azokupplungsreaktion

✍ Scribed by B. Gloor; H. Zollinger

• Publisher: John Wiley and Sons
• Year: 1971
• Tongue: German
• Weight: 593 KB
• Volume: 54
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19710540215

✦ Synopsis

Abstract

The kinetics of the second step in the formation of a dis‐azocompound from 4,4′‐bis‐diazobiphenyl (bisdiazotized benzidine) with 2‐naphthol‐3,6‐disulfonic acid have been investigated at 25°C, ionic strength I = 0.01 in aqueous buffers (pH 6.78 to 7.71). As expected the reaction is first order with respect to the naphtholdisulfonate (triple) anion, but astonishingly it has only an apparent order n = 0.65 with respect to the electrophilic reagent. This order is due to an aggregation equilibrium in which dimeric and oligomeric aggregates are formed whose electrophilicity is at least 50 times lower than that of the monomeric diazonium ion.