Atmospheric degradation of CH2C(CH3)C(O)OCH3 initiated by OH radicals: Mechanistic study and quantification of CH3C(O)C(O)OCH3 in NOx free air
| Autor: | Rodrigo G. Gibilisco, Ana N. Santiago, Mariano A. Teruel, Jorge G. Uranga |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Radical
Analytical chemistry Reaction intermediate Photochemistry Decomposition Transition state Product distribution Ciencias de la Tierra y relacionadas con el Medio Ambiente chemistry.chemical_compound chemistry PEROXY RADICAL Yield (chemistry) METHYL METHACRYLATE DENSITY FUNCTIONAL THEORY Physical and Theoretical Chemistry Methyl methacrylate SPME GAS-PHASE REACTION Meteorología y Ciencias Atmosféricas NOx CIENCIAS NATURALES Y EXACTAS |
| DOI: | 10.1021/acs.jpca.5b04273 |
| Popis: | The product distribution of the gas-phase reaction of OH radicals with methyl methacrylate (CH2═C(CH3)C(O)OCH3, MMA) in the absence of NOx was studied at 298 K and atmospheric pressure of air. The experiments were performed in a Teflon chamber using solid-phase microextraction (SPME) with GC–MS and GC–FID for product identification and quantification, respectively. In the absence of NOx, methyl pyruvate (CH3C(O)C(O)OCH3) was identified with a yield of 76 ± 13% in accordance with the decomposition of the 1,2-hydroxyalkoxy radicals formed. In addition, a detailed quantum chemical study of the degradation of MMA was performed by density functional theory (DFT) methods using the MPWB1K functional. This calculation suggests that formation of methyl pyruvate, from C1–C2 scission of 1,2-hydroxyalkoxy radical, is kinetically and thermodynamically the most favorable reaction path taking into account the electronic properties of reaction intermediates and transition states. The difference observed on the degradation mechanism of MMA in the presence and absence of NOx was explained in terms of the associated thermochemistry. Furthermore, this study propose that reaction between peroxy radical (RO2•) and hydroxyl radical (OH) became relevant at NOx-free environments. This statement is in agreement with recent studies concerning small peroxy radicals such as CH3OO•. Fil: Gibilisco, Rodrigo Gastón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Uranga, Jorge Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Santiago, Ana Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Teruel, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|