The enthalpies of formation of two dibenzocyclooctadienones

• Published in: Thermochimica acta 2003-04, Vol.400 (1), p.109-120
• Main Authors: Perisanu, St, Contineanu, Iulia, Banciu, M.D., Liebman, Joel F., Farivar, Behzad S., Mullan, Melissa A., Chickos, James S., Rath, Nigam, Hillesheim, Dorothea M.
• Format: Article
• Language: English
• Subjects: Ab initio calculations; Chemical thermodynamics; Chemistry; Dibenzocyclooctadienones; DSC; Elements, mineral and organic compounds; Enthalpies of combustion; Exact sciences and technology; Formation; Fusion; General and physical chemistry; Thermodynamic properties; Vaporization
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/S0040-6031(02)00485-9

The standard molar enthalpies of formation ( Δ f H m 0( s)/ kJ mol −1) for 2,3:6,7-dibenzocycloocta-2,6-dien-1-one and 2,3:7,8-dibenzocycloocta-2,7-dien-1-one [6 H-11,12-dihydro-dibenzo[ a, e]cycloocten-5-one (ketone 1) and 10 H-11,12-dihydrodibenzo[ a, d]-cycloocten-5-one (ketone 2), respectively] were derived from enthalpies of combustion, measured by means of a microbomb calorimeter. The fusion and vaporization enthalpies of these compounds were obtained from DSC and correlation gas chromatography measurements. The standard molar enthalpies of formation in the gas phase were calculated by combining the condensed phase standard molar enthalpies of formation with the fusion and vaporization enthalpies adjusted to 298.15 K. Values for Δ f H m 0(g) of (−39.9±5.5) and (−14.8±5.3) kJ mol −1 were obtained for 2,3:6,7-dibenzocycloocta-2,6-dien-1-one and 2,3:7,8-dibenzocycloocta-2,7-dien-1-one, respectively. Quantum chemical calculations are reported for the compounds investigated experimentally and an additional four isomers. Isomerization enthalpies are derived from computed energies. The enthalpies of formation are also calculated by group additivity, compared with the experimental values and then correlated with the structure of the molecules investigated. The X-ray analysis of ketone 1 is also reported.