Aromatic Arylation with Aryl Radicals. I. A Novel Method for Generating Aryl Free Radical

Abstract
Benzenediazonium tetrafluoroborate in DMSO decomposed instantaneously with evolution of nitrogen upon addition of a DMSO solution of sodium nitrite. Orientations and partial rate factors for phenylation of substituted benzenes indicated that not phenyl cation but phenyl radical was produced as an intermediate. Hammett’s plots of partial rate factors of meta and para positions yielded good straight lines with ρm=0.46 and ρp=1.67. Plausible mechanisms were discussed. From m-dinitrobenzene 2,6- and 2,4-dinitrobiphenyl were produced in 47 and 23% yields, respectively, and the synthetic value of this method was pointed out.
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