Mechanism and Models for Copper Mediated Nucleophilic Aromatic Substitution. 2. A Single Catalytic Species from Three Different Oxidation States of Copper in an Ullmann Synthesis of Triarylamines

Article abstract of DOI:10.1021/ja00239a032

Ullmann condensations of diarylamines with iodobenzenes has been investigated under homogeneous and a heterogeneous catalytic conditions with cupruos and cupric salts, as well as powered copper metal.Copper catalyzed condensation of diarylamines with iodoaromatics is relatively insensitive to substituent (for substituted iodobenzenes p=-0.25; for substituted diphenylamines p=1.09) but quite sensitive to halogen (k₁/k_Br.200).The first direct evidence for solution catalysis after filtration of a metal catalyzed reactions was obtained.Quantitative analysis of reaction rates, product yields, and catalyst characteristics leads to a comprehensive picture of the formation of soluble cuprous ions as the single active catalytic species under all conditions investigated.This hypothesis rationalizes many of the perplexing results which typify the literature associated with copper catalyzed nucleophilic aromatic substitution.