REACTIONS OF HALOTOLUENES WITH POTASSIUM DIPHENYLPHOSPHIDE - EVIDENCE FOR A THERMALLY INDUCED AROMATIC SRN1 REACTION

The reaction of m-or p-iodo-or-bromotoluene with potassium diphenylphosphide in refluxing ammonia or dimethyl sulfoxide at 25 °C gives the corresponding diphenyltolylphosphine in good yield. Reaction occurs in the dark, but is stimulated by irradiation with broad spectrum ultraviolet light. There is no evidence for the formation of an aryne intermediate. Electron acceptors such as m-dinitrobenzene and azobenzene inhibit the reaction and suggest a mechanism with electron transfer steps. Entrainment studies indicate a chain mechanism. All data are consistent with the SRN1 mechanism of nucleophilic substitution with both thermal and photochemical initiation steps. © 1979, American Chemical Society. All rights reserved.