FTIR kinetics study and products distribution of the reactions of CHCl2C(O)OCH3 with Cl atoms at 298 K and 760 Torr.

VIANNI STRACCIA; CYNTHIA RIVELA; MARIA BELEN BLANCO; MARIANO TERUEL

Simposio; 26th International Symposium on Gas Kinetics and Related Phenomena; 2022

Relative rate coefficients and products distribution of the gas-phase reactions of methyl dichloroacetate (CHCl2C(O)OCH3) with Cl atoms were obtained at 298 K and atmospheric pressure. All the experiments were measured in a 480 L Pyrex glass atmospheric simulation reactor coupled to“in situ”Fourier Transform Infrared Spectrometry. The rate coefficient obtained from the average of different experiments was: kCl = (3.31 ± 0.50) ×10-13 cm3.molecule-1s-1. In addition, products studies were performed in similar conditions of the kinetic experiments. The initial pathway, for the degradation of methyl dichloroacetate in the reaction with Cl atoms occur via H-atom abstraction at alkyl groups. Dichloroacetic acid, phosgene, methyl trichloroacetate and carbon monoxide, were the main products identified and quantified for both reactions. The product yield for the reaction with Cl atoms obtained were the following (22±2; 19±3; 16±1 and 38±2)% for Cl2CHCOOH, COCl2, CO, and CCl3C(O)OCH3, respectively. Phosgene is an extremely toxic gas; this gas can be gradually degraded through UV-radiation to produce ClOx which has an important impact on the depletion of ozone layer. The atmospheric implications of the reactions were assessed by the estimation of the tropospheric lifetimes, the values obtained was τCl= 10 years. In addition, other parameters were estimated to evaluate the possible impact of the emission of MDCA. The Ozone Depletion Potentials obtained, (ODP) were 0.044, This fact reflects that the relative influence of this chlorinated organic compound on the destruction of the ozone layer is less than what presents the CFCl3. Photochemical Ozone Creation Potentials, (POCP) was estimated 0.03. Compounds with Cl, F, N and S substituents may contribute to rainfall acidification, due to this the Acidification Potential, (AP) was estimated using the empirical equation given by (de Leeuw, 1993), AP is 0.45. This value indicates that methyl dichloroacetate degradation may play some role in acidifying rainwater and increase the environmental problems. In order to evaluate the contribution to greenhouse warming, the Global Warming Potential, (GWP) is calculated to be 103, 28, 8 for a time horizon of 20, 100 and 500 years respectively, its impact to the global warming is significant compared with carbon dioxide due to its long lifetime.