Rate Coefficient and Mechanism of the OH-Initiated Degradation of 1-Chlorobutane: Atmospheric Implications

R. A. JARA-TORO; J. BARRERA; J. P. ARANGUREN; R. A. TACCONE; G. A. PINO *

JOURNAL OF PHYSICAL CHEMISTRY A

AMER CHEMICAL SOC

Lugar: Washington; Año: 2020 vol. 124 p. 229 - 239

1089-5639

In this work, we investigate the degradation process of 1-chlorobutane, initiated by OH radicals, under atmospheric conditions (airpressure of 750 Torr and 296 K) from both experimental and theoreticalapproaches. In the first one, a relative kinetic method was used to obtainthe rate coefficient for this reaction, while the products were identified forthe first time (1-chloro-2-butanone, 1-chloro-2-butanol, 4-chloro-2-butanone, 3-hydroxy-butanaldehyde, and 3-chloro-2-butanol) using massspectrometry, allowing suggesting a reaction mechanism. The theoreticalcalculations, for the reactive process, were computed using theBHandHLYP/6-311++G(d,p) level of theory, and the energies for all ofthe stationary points were refined at the CCSD(T) level. Five conformersfor 1-chlorobutane and 33 reactive channels with OH radicals were found,which were considered to calculate the thermal rate coefficient (as the sumof the site-specific rate coefficients using canonical transition state theory). The theoretical rate coefficient (1.8 × 10−12 cm3molecule−1 s−1) is in good agreement with the experimental value (2.22 ± 0.50) × 10−12 cm3 molecule−1 s−1 determined in thiswork. Finally, environmental impact indexes were calculated and a discussion on the atmospheric implications due to theemissions of this compound into the troposphere was given.