Kinetic study of the Cl and NO3-initiated photo-oxidation of unsaturated (allyl and vinyl) ethers under simulated atmospheric conditions

ARANGUREN ABRATE, JUAN PABLO; COLMENAR, INMACULADA; SALGADO, SAGRARIO; MARTÍNEZ, ERNESTO; CABAÑAS, BEATRIZ; MARÍN, PILAR

Ghent

Conferencia; The 9th International Conference on Chemical Kinetics; 2015

Oxygenated volatile organic compounds (OVOCs) are strongly involved in key atmospheric processes and play a central role in the chemical reactions that determine the oxidizing capacity of the atmosphere. Vinyl, Allyl ethers and allyl derivatives of carbohydrates are used in the synthesis of copolymers, in coatings, inks and in the preparation of air-drying prepolymers or oligomers.1In the troposphere, the main gas-phase removal process of OVOCs is the reactions with OH radicals, being the oxidation with Cl atoms, O3 molecules and NO3 radicals other important degradation pathways.In this work, we present the first experimental determination of the relative rate constants for the reactions of allyl ethyl ether (AEE), allyl ether (AE) and 2-chloro ethyl vinyl ether (2ClEVE) with Cl and NO3 at 298 K and atmospheric pressure. Rate coefficients for all the reactions were determined using a relative rate method. The following equation has been used to evaluate the kinetic data: ln{ [Ether]t0 / [Ether]t } = k1/k2 ln{ [reference]t0 / [reference]t }where [Ether]t0 and [reference]t0 are the concentrations of the ether and reference compound, respectively, at time t0; [Ether]t and [reference]t are the corresponding concentrations at time t; k1 and k2 are the rate coefficients for the reaction of Ether and reference with the oxidant (Cl or NO3), respectively. Plots of ln{ [Ether]t0 / [Ether]t } vs ln{ [reference]t0 / [reference]t } should give straight lines with slopes of k1/k2. The rate constant k1 can be derived from the known rate coefficient k2. The experiment was performed using a 50 L Pyrex glass reaction chamber in conjunction with Fourier Transform Infrared spectroscopy (FTIR) as a detection technique. The chamber was equipped with a White-type multiple-reflection mirror system with a total pass optical path length of 200 meters2. The obtained rate constants were: k(Cl + AEE)= (3.38 ± 0.34)x10-10, k(Cl + AE)= (4.67 ± 0.48)x10-10 , k(Cl + 2ClEVE)= (6.65 ± 0.65)x10-10 , k(NO3 + AEE)= (9.21 ± 2.62)x10-15 , k(NO3 + AE)= (1.19 ± 0.36)x10-14 , k(NO3 + 2ClEVE)= (4.85 ± 0.58)x10-13. The reference compounds were: 1-butene and 2-metyl-propene for reactions with Cl atoms and 1-butene, propene, 2-metyl-propene and t-2-butene for reactions with NO3 radicals. The results are presented and discussed in terms of trend of reactivity with analogous compounds.