26th International Symposium on Gas Kinetics and Related Phenomena

PEDRO LUGO; IULIA PATROESCU-KLOTZ; MARIANO A. TERUEL; VIANNI G. STRACCIA C.; ILLMANN NIKLAS; MARIA BELEN BLANCO; CYNTHIA B. RIVELA; PETER WIESEN

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

Introduction: Diketones are characterized by the presence of two carbonyl groups (C=O) separatedby a carbon atom and present a keto-enol equilibrium. If the hydrogen bond acceptors are close, itchanges the equilibrium to its enol form1. Due to their properties, diketones have been used in thechemical industry2, for example: CF3C(O)CH2C(O)CH3 (1,1,1-Trifluoro-2,4-pentanedione) is used as achelating ligand3and for the preparation of trifluoromethyl pyrimidines by reaction with guanidines.However, to our knowledge, the effects of these compounds on the chemistry of the atmosphere havenot yet been evaluated.Objectives: To determine the rate coefficients of the following reactions at 298 ± 3 K:CF3C(O)CH2C(O)CH3 (TFP) + OH Products, k1CF3C(O)CH2C(O)CH2CH3 (TFH) + OH Products, k2CF3C(O)CH2C(O)CH(CH3)2 (TFMH) + OH Products, k3Materials and methods: Kinetic experiments were carried out in two atmospheric simulationchambers, one located at the University of Wuppertal-Germany coupled to in situ Fourier TransformInfrared Spectroscopy (FTIR) and the other chamber located at the National University of Córdoba(LUQCA) coupled with Gas Chromatography with Flame Detector (GC-FID) at (990 ± 10) mbar of airand a temperature of (298 ± 3) K.Results: The following rate coefficients (in cm3 molecule−1s−1) have been determined with FTIRanalysis: k1(TFP+OH) = (1.30 ± 0.22) ×10-11, k2(TFH+OH) = (2.25 ± 0.45) ×10-11 and k3(TFMH+OH)= (3.19 ± 0.38) ×10-11. On the other hand, the rate coefficients obtained by GC-FID (in cm3molecule−1s−1)were the following: k1(TFP+OH) = (1.27 ± 0.30) ×10-11, k2(TFH+OH) = (2.07 ± 0.48) ×10-11 andk3(TFMH+OH) = (3.47 ± 0.84) ×10-11.Conclusions: This work represents the first kinetic study for the three reactions studied underatmospheric conditions. The rate coefficients show an increase of the rate coefficients of the reactionsstudied with the number of CH3 substituents. In addition, reactivity trends were developed and thetropospheric lifetimes of these fluorinated diketones were estimated to assess their atmospheric impact.References1) Burdett J., L., Rogers M., T. J. Am. Chem. Soc.1964, 86, 2105–21092) Włodzimierz U., Katarzyna J., Katarzyna W., Andrzej G. Chemik, 2011, 65, 4, 273-282.3) Russian Chemical Reviews. 1981, 50, 180.