stirred for 1 h, the mixture was filtered and the filtrate cooled to 0 °C and acidified with 35 mL of concentrated HC1. Evaporation of the water in vacuo, followed by thorough drying of the residue at 100 °C in vacuo, yielded 40.3 g (73%) of HOPC1, mp 160-164 °C, NMR (D20) 4.83 (s, 3 ), 8.50 (m, 2 H), 8.92 (m, 2 H), which gave a satisfactory equivalent weight on titration with AgN03.Solution Preparation. The mixed solvents were prepared from weighed amounts of distilled water and ethanol or dimethyl sulfoxide. Dissolved carbon dioxide was removed from all solvents by passing C02-free nitrogen gas through a sintered glass bubbler immersed in the solvent. HOAI and HOPC1 solutions were prepared by weight, followed by dilution when necessary. NaOH solutions were standardized by titration with HC1.Heats of Reaction. The heats of reaction were measured at 25.0 °C with an LKB 8700-2 titration calorimeter. Solutions of HOPC1 or HOAI, 1-10 mL, at concentrations ranging from 0.005 to 0.05 M were added to 90 mL of NaOH solution having the same concentration as the phenol. In some cases, the procedure was reversed and the NaOH solution was titrated into an excess of phenol solution. Both procedures gave the same results. Heat of dilution corrections were found to be insignificant. In the aqueous cases, allowance was also made for the partial ionization of the phenol by using the ionization equilibrium constant of the phenol and the heat of dissociation of H20. This correction was found to be less than 1 % in all cases.Heats of Solution. Heats of solution were measured with an LKB 8700-1 reaction and solution calorimeter.

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