Tropospheric chemical degradation of methyl acrylate and butyl methacrylate initiated by chlorine atoms

M. B. BLANCO, I. BEJAN, I. BARNES, P. WIESEN AND M. TERUEL

Viena, Austria

Congreso; European Geosciences Union 2004; 2008

EGU

Unsaturated esters are widely used in the industry of polymers, paper coating, paint formulations, etc, the source of their emissions are numerous such as manufactures of plastics, aircraft and electronic components1. While the OH radical is considered to be the major daytime oxidant, in the marine environment and coastal areas, the reactions with Cl atoms have been postulated to be an additional and significant removal process of these compounds2 and it may significantly contribute to the formation of ozone and other components of the photochemical smog in these areas. The aim of this study was to extend the existing scant data base of the rate constants for the reactions of chlorine atoms with unsaturated esters. In the present study we reported a kinetic study of the reaction between Cl and methyl acrylate (k1) and butyl methacrylate (k2), using a relative method: Cl + CH2=CHC(O)OCH3                                                               Products,  (k1)                                Cl + CH2=C(CH3)C(O)O(CH2)3CH3                                             Products   (k2)    Relative rate constants were measured by comparing the Cl atom reaction rate with the acrylates to that isobutene and 1,3-butadiene used as the reference compounds. All the experiments were performed at room temperature and atmospheric pressure in a 1080 l quartz-glass photoreactor using in situ FTIR analysis to monitor the decay of the organics and the reference compounds3. The following values of k1= (2.14±0.54) × 10-10 and k2= (3.77±0.82) × 10-10 in units of cm3 molecule-1 s-1 were obtained. To the best of our knowledge this is the first experimental determination of the rate constants for these reactions. Kinetic data are used to estimate the tropospheric lifetimes and to discuss reactivity trends for these unsaturated esters.