C H R I~T I A N ECOUTURE and ANTHONY JAMES PAINE. Can. J. Chem. 63, 1 I 1 (1985). The title reactions arc an important class of copper mediated nucleophilic aromatic substitution processes, which constitute a useful tool in the molecular design and synthesis of small molecules. We report the results of extensive investigation of these processes, primarily focussing on cyanodeiodination (Arl + CuCN + Cul + ArCN). Among the interesting features of these processes are: (a) an unusual rate equation involving autocatalysis by Cul product; (b) retardation by both excess nucleophile (as KCN) and excess leaving group (as KI), which compete with ArX to complex with CuNu; (c) only cuprous nucleophiles are active (ligand exchanged products from cupric salts arise from prior redox equilibria which form CuNu); (d) the halogen effect is large (kl -40-100 kBr -300-5000 kc,) but the Hammett p value is zero; (c) ortho-alkyl groups do not hinder the reaction (and actually cause mild acceleration by relief of steric strain). Finally, the introduction of an ortho-COO group accelerates the reaction by a factor of 10"-lo5, but the general features of the accelerated reactions are also the same, again indicating a common mechanism, with entropic acceleration by ortllo-carboxylatc. Both kinetic and thermodynamic factors were considered in detail, the latter apparently for the first time. Applications to practical syntheses are considered, and novel mechanistic models for these interesting processes are discussed. i la prCsence du groupe carboxylate en ortlzo. On a considire en detail les facteurs cinktiques et therrnodynamiques; il sernble que ces derniers ont Ct C exarnints pour la premiere fois. On considere les applications de ces rkactions dans des syntheses pratiques et on discute de nouveaux modkles rnkcanistiques pour ces reactions intkressantes.[Traduit par Ic journal]

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