Collect. Czech. Chem. Commun.
1992, 57, 1915-1927
https://doi.org/10.1135/cccc19921915
Coupling Kinetics of Benzenediazonium Ions with 2,6-Dioxo-3-(p-substituted phenylhydrazono)-1,2,3,6-tetrahydropyridine-4-carboxylic Acid
Jaroslava Horáčkováa and Vojeslav Štěrbab
a Department of Organic Technology, University of Chemical Technology, 532 10 Pardubice
b Department of Organic Chemistry, University of Chemical Technology, 532 10 Pardubice
Abstract
The kinetics have been measured of the reactions of 4-nitro-, 4-chloro-, and 4-methoxybenzenediazonium ions with substituted phenylazo derivatives of citrazinic acid in buffer solutions, and the pKa values of the corresponding monoazo and bisazo compounds have been estimated. The reactions of 4-nitrobenzenediazonium ion with 4-chloro- and 4-methoxyphenylazo derivatives and of 4-chlorobenzenediazonium ion with 4-methoxyphenylazo derivative were accompanied by a partial replacement of the substituted phenylazo group by the 4-nitro- and 4-chlorophenylazo groups, respectively. The reactions of 4-chloro- and 4-methoxybenzenediazonium ions are subject to general base catalysis, the rate-limiting step consisting in the splitting off of the proton from the tetrahedral intermediate; with 4-nitrobenzenediazonium ion the reaction rate is limited by the formation of the tetrahedral intermediate.
