Oxidative Decarboxylation. On the Mechanism of the Potassium Persulfate Promoted Decarboxylation Reaction

Article abstract of DOI:10.1021/jo00230a007

The competitive rates for the potassium persulfate promoted decarboxylation of a series of aliphatic and aromatic carboxylic acid salts were determined.The rates for the ring-substituted phenylacetic acids showed a linear free energy correlation, ρ = -0.44, with ?⁺ substituent constants.The aliphatic carboxylates, likewise, showed a structure-reactivity relationship; The carboxylates that produce the most stable radicals upon loss of carbon dioxide are decarboxylated at the fastest rate.No clear demarcation between the rates of decarboxylation of the aromatic and aliphatic carboxylates was found.The benzyl-substituted phenylacetic acids , both phenyl and methyl substituted, show only small increases in the rates of electron transfer from their anions, while ring substitution was more effective in increasing the rates.Electron transfer from the HOMO of the aromatic carboxylate is marginally easier than transfer from the aliphatic carboxylate anions that undergo concerted-electron-transfer fragmentation.