Atmospheric chemistry of Z- and E-CF₃CHCHCF₃

Abstract

The atmospheric fates of Z- and E-CFCH[double bond, length as m-dash]CHCF have been studied, investigating the kinetics and the products of the reactions of the two compounds with Cl atoms, OH radicals, OD radicals, and O. FTIR smog chamber experiments measured: k(Cl + Z-CFCH[double bond, length as m-dash]CHCF) = (2.59 ± 0.47) × 10, k(Cl + E-CFCH[double bond, length as m-dash]CHCF) = (1.36 ± 0.27) × 10, k(OH + Z-CFCH[double bond, length as m-dash]CHCF) = (4.21 ± 0.62) × 10, k(OH + E-CFCH[double bond, length as m-dash]CHCF) = (1.72 ± 0.42) × 10, k(OD + Z-CFCH[double bond, length as m-dash]CHCF) = (6.94 ± 1.25) × 10, k(OD + E-CFCH[double bond, length as m-dash]CHCF) = (5.61 ± 0.98) × 10, k(O + Z-CFCH[double bond, length as m-dash]CHCF) = (6.25 ± 0.70) × 10, and k(O + E-CFCH[double bond, length as m-dash]CHCF) = (4.14 ± 0.42) × 10 cm molecule s in 700 Torr of air/N/O diluents at 296 ± 2 K. E-CFCH[double bond, length as m-dash]CHCF reacts with Cl atoms to give CFCHClC(O)CF in a yield indistinguishable from 100%. Z-CFCH[double bond, length as m-dash]CHCF reacts with Cl atoms to give (95 ± 10)% CFCHClC(O)CF and (7 ± 1)% E-CFCH[double bond, length as m-dash]CHCF. CFCHClC(O)CF reacts with Cl atoms to give the secondary product CFC(O)Cl in a yield indistinguishable from 100%, with the observed co-products C(O)F and CFOCF. The main atmospheric fate for Z- and E-CFCH[double bond, length as m-dash]CHCF is reaction with OH radicals. The atmospheric lifetimes of Z- and E-CFCH[double bond, length as m-dash]CHCF are estimated as 27 and 67 days, respectively. IR absorption cross sections are reported and the global warming potentials (GWPs) of Z- and E-CFCH[double bond, length as m-dash]CHCF for the 100 year time horizon are calculated to be GWP = 2 and 7, respectively. This study provides a comprehensive description of the atmospheric fate and impact of Z- and E-CFCH[double bond, length as m-dash]CHCF.

Atmospheric chemistry of (Z)- and (E)-1,2-dichloroethene: kinetics and mechanisms of the reactions with Cl atoms, OH radicals, and O3

“…Reactive isomerization has been observed in several other similar systems, including the reaction of ( Z )-CF 3 CHCHCF 3 with Cl atoms, which shows Cl-mediated isomerization to the ( E )-isomer, whereas no evidence of isomerization was observed in the Cl atom initiated degradation of ( E )-CF 3 CHCHCF 3 . 25…”

“…Reactive isomerization has been observed in several other similar systems, including the reaction of (Z)-CF 3 CHQCHCF 3 with Cl atoms, which shows Cl-mediated isomerization to the (E)-isomer, whereas no evidence of isomerization was observed in the Cl atom initiated degradation of (E)-CF 3 CHQCHCF 3 . 25 The thermochemistry for the addition of Cl to the two isomers of CHClQCHCl was investigated computationally. Schematic potential energy surfaces are shown in the upper half of Fig.…”

Trends of Studies on Controlled Halogenated Gases under International Conventions during 1999–2018 Using Bibliometric Analysis: A Global Perspective

“…Some scholars have also used physical and chemical experiments to study the technologies for the removal of CHGs. In the study of reaction rate and atmospheric life, chemical experimental methods such as the relative rate method and absolute rate method are often used to determine the reaction rate of CHGs with OH radicals or chlorine atoms [45][46][47][48][49][50][51][52][53]. The reaction rate determines the atmospheric lifetime of a substance.…”

DFT Study of Photochemical Properties and Radiative Forcing Efficiency Features of the Stereoisomers cis- and trans-CHCl═CH–CF3

“…The stereoisomers cis - and trans -1-chloro-3,3,3-trifluoropropene ( cis - and trans -CHClCH-CF 3 ), − noted cis - and trans -CTFP throughout this work, are the halogenated hydrofluoro-olefines (HFOs) known as short-lived compounds. They are being used as potential replacements of hydrofluoroethers (HFEs), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs) in a number of industrial processes. − The latter compounds are used as cleaning solvents, heat transfer agents in refrigeration, carrier of fluids, anesthetic agents in the pharmaceutical industry, etc.. − Despite the large applicability of fully halogenated hydrocarbons in various industries, the production and use of bromo­(chloro) fluorocarbons have been phased out because they have consequent effects on the Earth’s stratospheric ozone layer. − In fact, such compounds released into the lower troposphere are driven to the upper troposphere and stratosphere where they act as greenhouse gases and/or dissociate under UV radiation to yield Cl atoms, which in turn initiate catalytic ozone destruction. − <...…”

“…Several studies have been carried out to determine the impact of the above-mentioned greenhouse gases on the climate by the measurement of infrared spectra, atmospheric lifetimes (τ), radiative forcing efficiencies (RFEs), and global warming potentials (GWPs). − The molecules under this investigation have been severely studied by different authors. − , Wuebbles et al have experimentally determined the lifetime and RFE of trans -CTFP using two different methods. The 3D model gave 30.5 day lifetime and 0.11 W m –2 ppbv –1 RFE, while the simple model approach yielded 26 day lifetime and 0.214 W m –2 ppbv –1 RFE.…”