Energetic effects of ether and ketone functional groups in 9,10-dihydroanthracene compound

The energetic effects caused by replacing one of the methylene groups in the 9,10-dihydroanthracene by ether or ketone functional groups yielding xanthene and anthrone species, respectively, were determined from direct comparison of the standard (p° = 0.1 MPa) molar enthalpies of formation in the gaseous phase, at T = 298.15 K, of these compounds. The experimental static-bomb combustion calorimetry and Calvet microcalorimetry and the computational G3(MP2)//B3LYP method were used to get the standard molar gas-phase enthalpies of formation of xanthene, (41.8 ± 3.5) kJ · mol−1, and anthrone, (31.4 ± 3.2) kJ · mol−1. The enthalpic increments for the substitution of methylene by ether and ketone in the parent polycyclic compound (9,10-dihydroanthracene) are −(117.9 ± 5.5) kJ · mol−1 and −(128.3 ± 5.4) kJ · mol−1, respectively.