RESUMEN
Hydrogen chloride (HCl) contributes substantially to the atmospheric Cl; both species could affect the composition of Earth's atmosphere and the fate of pollutants. Here, we present the kinetics study for syn-CH3CHOO reaction with HCl using experimental measurement and theoretical calculations. The experiment was conducted in a flow tube reactor at a pressure of 10 Torr and temperatures ranging from 283 to 318 K by using the OH laser-induced fluorescence (LIF) method. Transition-state theory and quantum chemistry calculations with QCISD(T) were used to calculate the rate coefficients. Weak negative temperature dependence was observed with a measured activation energy of -(2.98 ± 0.12) kcal mol-1 and a calculated zero-point-corrected barrier energy of -3.29 kcal mol-1. At 298 K, the rate coefficient was measured to be (4.77 ± 0.95) × 10-11 cm3 s-1, which was in reasonable agreement with 2.2 × 10-11 cm3 s-1 from the theoretical calculation.
RESUMEN
Hydroxytyrosol (HT) is a natural phenolic compound with potent antioxidant activity extracted from olive trees. It is generally a slightly hydrated viscous liquid at ambient conditions, and it is highly susceptible to oxygen due to the presence of catechol moiety. Although encapsulation technique provides HT in powder form, it does not improve its chemical stability. Herein, we propose an efficient solution to the high hygroscopicity and poor stability of HT. Four cocrystals were first reported, and their intermolecular interactions were analyzed in detail. After cocrystallization, the melting point is increased and the hygroscopicity is significantly decreased. HT cocrystals are thus solid at room temperature. Moreover, hydroxytyrosol cocrystals with betaine (HT-BET) and nicotinamide (HT-NIC) demonstrate superior chemical stability than pure HT, olive extract, and HT encapsulation material. Therefore, cocrystallization can be considered as a promising approach to overcome the application obstacles of HT.