Thermochemistry and Gas-Phase Ion Energetics of 2-Hydroxy-4-methoxy-benzophenone (Oxybenzone)

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2008-04, Vol.112 (14), p.3201-3208
• Main Authors: Lago, A. F, Jimenez, P, Herrero, R, Dávalos, J. Z, Abboud, J.-L. M
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp7111999

We have investigated the thermochemistry and ion energetics of the oxybenzone (2-hydroxy-4-methoxy-benzophenone, C14H12O3, 1H) molecule. The following parameters have been determined for this species:  gas-phase enthalpy for the of neutral molecule at 298.15K, (Δf(g) = −303.5 ± 5.1 kJ·mol-1), the intrinsic (gas-phase) acidity (GA(1H) = 1402.1 ± 8.4 kJ·mol-1), enthalpy of formation for the oxybenzone anion (Δf(1 -,g) = −402.3 ± 9.8 kJ·mol-1). We also have obtained the enthalpy of formation of, 4-hydroxy-4‘-methoxybenzophenone (Δf(g) = −275.4 ± 10 kJ·mol-1) and 3-methoxyphenol anion (Δf(C7H7O2 -,g) = −317.7 ± 8.7 kJ·mol-1). A reliable experimental estimation of enthalpy related to intramolecular hydrogen bonding in oxybenzone has also been obtained (30.1 ± 6.3 kJ·mol-1) and compared with our theoretical calculations at the B3LYP/6-311++G** level of theory, by means of an isodesmic reaction scheme. In addition, heat capacities, temperature, and enthalpy of fusion have been determined for this molecule by differential scanning calorimetry.