Rate Constants for the Reaction of Diphenyl Carbonyl Oxide with Phenols

The kinetics of the reaction of diphenyl carbonyl oxide Ph₂COO with o- and p-substituted phenols is studied by pulse photolysis and high-speed spectrophotometry. The rate constant strongly depends on the phenol structure and ranges from 1.3 × 10³ for ionol to 2.1 × 10⁸ l mol^–1 s^–1 for o-aminolphenol. A U-shaped curve illustrating how the logarithm of the rate constant changes with a change in the Hammett constants (⁰) of the substituents in the aromatic ring is found for the studied compounds. Possible pathways for the reaction of Ph₂COO with phenols are discussed.