A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Atmospheric degradation of chloroacetoacetates by Cl atoms: Reactivity, products and mechanism in coastal and industrialized areas
https://orcid.org/0000-0003-2656-1597
https://orcid.org/0000-0003-4597-8793
Abstract Kinetic studies of the reaction of Cl atoms with ethyl 2-chloroacetoacetate, CH3C(O)CHClC(O)OCH2CH3, (k 1) and methyl 2-chloroacetoacetate, CH3C(O)CHClC(O)OCH3, (k 2) have been developed for the first time using SPME/GC-FID and in situ FTIR spectroscopy at (298 ± 2) K and 1000 mbar in glass atmospheric chambers. Relative rate coefficients obtained by Fourier Transform Infrared Spectroscopy (FTIR) using different reference compounds, were the following (in cm3.molecule−1.s−1): kE2CAA-FTIR= (2.41 ± 0.57) × 10−10 and k M2CAA-FTIR= (2.16 ± 0.85) × 10−10. Similar and reproducible values were obtained using Gas Chromatography equipped with Flame Ionization Detection coupled with Solid Phase Micro Extraction (SPME), k E2CAA-GC-FID = (2.54 ± 0.81) × 10−10 and k M2CAA-GC-FID = (2.34 ± 0.87) × 10−10 all values in units of cm3.molecule−1.s−1. In addition, product studies were performed in similar conditions to the kinetic experiments to identify the reaction products and postulate their tropospheric degradation mechanisms. The reaction of Cl atoms with saturated esters initiates via H-atom abstraction from the alkyl groups of the molecule. Formyl chloride, chloroacetone, and acetyl chloride were positively identified as reaction products by FTIR. On the other hand, acetyl chloride, 1,1,1-trichloropropan-2-one, 1,1-dichloropropan-2-one, 1-chloropropan-2-one, ethyl chloroformate, and methyl chloroformate were identified by the GC-MS technique. Structure–Activity Relationship (SAR), calculations were also performed to estimate the more favorable reactions pathways in agreement with the products observed. The atmospheric implications of these reactions were assessed by the estimation of the residence times of the chloroesters studied as following: τCl-E2CAA = 1.47 days, and τCl-M2CAA = 1.57 days. Additionally, the possible impact of the emission of chloro acetoacetates in rain acidification was evaluated from the moderate Acidification Potentials (AP), 0.19, and 0.21 obtained for E2CAA and M2CAA, respectively.
Graphical abstract Display Omitted
Highlights First kinetics and products study for the Cl-initiated oxidation of chloroacetates. SARs estimations indicates the reactivity trend: CHCl–, –OCH3 and –OCH2 –. Several small chlorinated carbonyls and small esters identified as reaction products. Residence times towards Cl atoms of few hours with a local impact. Acidification potentials of 0.2 for chloroacetoacetates and 0.3 for chloroformates produced.
Atmospheric degradation of chloroacetoacetates by Cl atoms: Reactivity, products and mechanism in coastal and industrialized areas
https://orcid.org/0000-0003-2656-1597
https://orcid.org/0000-0003-4597-8793
Abstract Kinetic studies of the reaction of Cl atoms with ethyl 2-chloroacetoacetate, CH3C(O)CHClC(O)OCH2CH3, (k 1) and methyl 2-chloroacetoacetate, CH3C(O)CHClC(O)OCH3, (k 2) have been developed for the first time using SPME/GC-FID and in situ FTIR spectroscopy at (298 ± 2) K and 1000 mbar in glass atmospheric chambers. Relative rate coefficients obtained by Fourier Transform Infrared Spectroscopy (FTIR) using different reference compounds, were the following (in cm3.molecule−1.s−1): kE2CAA-FTIR= (2.41 ± 0.57) × 10−10 and k M2CAA-FTIR= (2.16 ± 0.85) × 10−10. Similar and reproducible values were obtained using Gas Chromatography equipped with Flame Ionization Detection coupled with Solid Phase Micro Extraction (SPME), k E2CAA-GC-FID = (2.54 ± 0.81) × 10−10 and k M2CAA-GC-FID = (2.34 ± 0.87) × 10−10 all values in units of cm3.molecule−1.s−1. In addition, product studies were performed in similar conditions to the kinetic experiments to identify the reaction products and postulate their tropospheric degradation mechanisms. The reaction of Cl atoms with saturated esters initiates via H-atom abstraction from the alkyl groups of the molecule. Formyl chloride, chloroacetone, and acetyl chloride were positively identified as reaction products by FTIR. On the other hand, acetyl chloride, 1,1,1-trichloropropan-2-one, 1,1-dichloropropan-2-one, 1-chloropropan-2-one, ethyl chloroformate, and methyl chloroformate were identified by the GC-MS technique. Structure–Activity Relationship (SAR), calculations were also performed to estimate the more favorable reactions pathways in agreement with the products observed. The atmospheric implications of these reactions were assessed by the estimation of the residence times of the chloroesters studied as following: τCl-E2CAA = 1.47 days, and τCl-M2CAA = 1.57 days. Additionally, the possible impact of the emission of chloro acetoacetates in rain acidification was evaluated from the moderate Acidification Potentials (AP), 0.19, and 0.21 obtained for E2CAA and M2CAA, respectively.
Graphical abstract Display Omitted
Highlights First kinetics and products study for the Cl-initiated oxidation of chloroacetates. SARs estimations indicates the reactivity trend: CHCl–, –OCH3 and –OCH2 –. Several small chlorinated carbonyls and small esters identified as reaction products. Residence times towards Cl atoms of few hours with a local impact. Acidification potentials of 0.2 for chloroacetoacetates and 0.3 for chloroformates produced.
Atmospheric degradation of chloroacetoacetates by Cl atoms: Reactivity, products and mechanism in coastal and industrialized areas
https://orcid.org/0000-0003-2656-1597
https://orcid.org/0000-0003-4597-8793
Abstract Kinetic studies of the reaction of Cl atoms with ethyl 2-chloroacetoacetate, CH3C(O)CHClC(O)OCH2CH3, (k 1) and methyl 2-chloroacetoacetate, CH3C(O)CHClC(O)OCH3, (k 2) have been developed for the first time using SPME/GC-FID and in situ FTIR spectroscopy at (298 ± 2) K and 1000 mbar in glass atmospheric chambers. Relative rate coefficients obtained by Fourier Transform Infrared Spectroscopy (FTIR) using different reference compounds, were the following (in cm3.molecule−1.s−1): kE2CAA-FTIR= (2.41 ± 0.57) × 10−10 and k M2CAA-FTIR= (2.16 ± 0.85) × 10−10. Similar and reproducible values were obtained using Gas Chromatography equipped with Flame Ionization Detection coupled with Solid Phase Micro Extraction (SPME), k E2CAA-GC-FID = (2.54 ± 0.81) × 10−10 and k M2CAA-GC-FID = (2.34 ± 0.87) × 10−10 all values in units of cm3.molecule−1.s−1. In addition, product studies were performed in similar conditions to the kinetic experiments to identify the reaction products and postulate their tropospheric degradation mechanisms. The reaction of Cl atoms with saturated esters initiates via H-atom abstraction from the alkyl groups of the molecule. Formyl chloride, chloroacetone, and acetyl chloride were positively identified as reaction products by FTIR. On the other hand, acetyl chloride, 1,1,1-trichloropropan-2-one, 1,1-dichloropropan-2-one, 1-chloropropan-2-one, ethyl chloroformate, and methyl chloroformate were identified by the GC-MS technique. Structure–Activity Relationship (SAR), calculations were also performed to estimate the more favorable reactions pathways in agreement with the products observed. The atmospheric implications of these reactions were assessed by the estimation of the residence times of the chloroesters studied as following: τCl-E2CAA = 1.47 days, and τCl-M2CAA = 1.57 days. Additionally, the possible impact of the emission of chloro acetoacetates in rain acidification was evaluated from the moderate Acidification Potentials (AP), 0.19, and 0.21 obtained for E2CAA and M2CAA, respectively.
Graphical abstract Display Omitted
Highlights First kinetics and products study for the Cl-initiated oxidation of chloroacetates. SARs estimations indicates the reactivity trend: CHCl–, –OCH3 and –OCH2 –. Several small chlorinated carbonyls and small esters identified as reaction products. Residence times towards Cl atoms of few hours with a local impact. Acidification potentials of 0.2 for chloroacetoacetates and 0.3 for chloroformates produced.
Atmospheric degradation of chloroacetoacetates by Cl atoms: Reactivity, products and mechanism in coastal and industrialized areas
Straccia C, V.G. (author) / Lugo, P.L. (author) / Rivela, C.B. (author) / Blanco, M.B. (author) / Teruel, M. (author)
Atmospheric Environment ; 309
2023-06-24
Article (Journal)
Electronic Resource
English
Aerodynamic drag coefficient over equatorial coastal industrialized and urban areas
| Online Contents | 2012
Economic consequences of an excavation in industrialized urban areas
| British Library Conference Proceedings | 1987