Base Catalysis of Azo Coupling of Diazotized Orthanilic and Sulfanilic Acids and Their Diethylamides with N-Acetyl I Acid in Citrate-Phosphate Buffer Solutions

摘要

Base catalysis with pyridine of azo coupling of diazotized orthanilic and sulfanilic acids and of their diethylamides with 6-acetylamino-1-hydroxynaphthalene-3-sulfonic acid(N-acetyl I acid) was studied. The limiting stages are different depending on the position of incorporation of the arylazo group. The ortho arrangement of the diazo and diethylsulfamide groups in the diazo compound molecule increases steric hindrance to deprotonation of the #sigma# complex at 4-substitution. Electrostatic repulsion of the sulfo groups in N-acetyl I acid and diazotized orthanilic acid impedes formation of the #sugna#complex at 2-substitution and deprotonation of the #sigma# complex at 4-substitution