Arrhenius parameters for the OH-initiated degradation of methyl crotonate, methyl-3,3-dimethyl acrylate, (E)-ethyl tiglate and methyl-3-butenoate over the temperature range of 288-314 K

ALICIA B. PEÑÉÑORY; JUAN P. COLOMER; MARÍA B. BLANCO; MARIANO A. TERUEL; IAN BARNES; PETER WISEN

RSC ADvances

RSC

Año: 2016 vol. 6 p. 53723 - 53729

The relative-rate technique has been employed to obtain rates coefficients for the reactions between the OH radical and four unsaturated esters (methyl crotonate (k1), methyl-3,3-dimethyl acrylate (k2), (E)-ethyl tiglate (k3) and methyl-3-butenoate (k4)) between 288-314 K in 760 Torr of synthetic air. The experiments were performed in a multiple-pass environmental chamber with in situ FTIR detection of the esters and reference compounds. The rate coefficients for the reactions displayed a negative dependence with temperature and low pre-exponential factors. The following Arrhenius expressions (in units of cm3 molecule-1 s-1) were obtained: k1 = (3.39 ± 0.78) × 10-12 exp[(750 ± 159) ⁄ T], k2 = (2.95 ± 0.63) × 10-12 exp[(838 ± 182) ⁄ T] , k3 = (1.49 ± 0.56) × 10-12 exp[(522 ± 114) ⁄ T] and k4 = (1.90 ± 1.25) × 10-12 exp[(834 ± 185) ⁄ T]. The kinetic results are in agreement with a mechanism involving mainly OH radical addition to the double with the reversible formation of an OH-adduct. Atmospheric implications are discussed with particular reference to the rate coefficients obtained as a function of the temperature.