Thermochemistry of bridged-ring substances. Enthalpies of formation of diamantan-1-, -3-, and -4-ol and of diamantanone

Abstract

The enthalpies of combustion and of sublimation of four mono-oxygenated diamantanes have been determined. The derived solid and gas-phase enthalpies of formation in kcal mol^–1 at 298.15 K follow: diamantanone, –81.16 ±0.38, –56.53 ± 0.41; diamantan-1-ol, –102.49 ± 0.24, –74.30 ± 0.28; diamantan-3-ol, –98.89 ± 0.35, –71.14 ± 1.10; diamantan-4-ol, –103.96 ± 0.39, –75.80 ± 0.39. Oxo and hydroxy group increments within the diamantane, adamantane, and cyclohexane series are discussed. Enthalpy differences between the isomeric diamantanols are compared with existing data from equilibration studies in solution. Comparisons are made between the experimental gas-phase enthalpies of formation and those obtained by molecular mechanics (empirical force field) calculations based on the Allinger MM1 force field model.