SOLVENT EFFECTS ON HOMOLYTIC BOND-DISSOCIATION ENERGIES OF HYDROXYLICACIDS

The homolytic bond dissociation energies (BDEs) of the O-H bonds in DM SO solution for (a) phenol and a number of its derivatives, (b) three oximes, (c) three alcohols, (d) three hydroxylamines, and (e) two hydr oxamic acids have been estimated by eq 1: BDE(HA) = 1.37pK(HA) + 23.1E (ox)(A(-)) + 73.3 kcal/mol. For most of these hydroxylic acids, the BD Es of the O-H bonds estimated by eq 1 are within +/-2 kcal/mol of the literature values in nonpolar solvents or in the gas phase. There is n o reason to believe, therefore, that these BDEs are ''seriously in err or because of failure to correct for solvent effects'' as has been cla imed on the basis that BDEs in highly polar solvents estimated for the O-H bond in phenol by photoacoustic calorimetry must be so corrected.