Atmospheric oxidation of furanones by OH and Cl radicals: In situ FTIR rate coefficient determinations, SAR and theoretical studies.

Gas-phase kinetics of the overall reactions of OH and Cl radicals with dihydrofuran-3(2H)-one (oxolan-3-one) and dihydro-2-methyl-3(2H)-furanone (2MTHF-3-one) were studied at 298 K and atmospheric pressure. The rate coefficients were determined using the relative method in a 480 L multipass glass reactor coupled to an FT-IR detection system. The rate coefficients found for oxolan 3-one and 2MTHF-one with OH radicals (k and k) and with Cl atoms (k and k) at 298 K and atmospheric pressure (in cm molecule s) were: k = (1.

Product study of the reactions of γ-caprolactone and γ-heptalactone initiated by OH radicals at 298 K and atmospheric pressure: Formation of acyl peroxynitrates (APN).

A product study was performed for the reaction of γ-caprolactone (GCL) and γ-heptalactone (GHL) initiated by OH radicals at (298 ± 2) K and atmospheric pressure, in presence of NO. The identification and quantification of the products were performed in a glass reactor coupled with in situ FT-IR spectroscopy. The following products were identified and quantified with the corresponding formation yields (in %) for the OH + GCL reaction: peroxy propionyl nitrate (PPN) (52 ± 3), peroxy acetyl nitrate (PAN) (25 ± 1), and succinic anhydride (48 ± 2).

Experimental and Theoretical Kinetic Studies of the Ozonolysis of Selected Allyl Sulfides (HC═CHCHSR, R = CH, CHCH): The Effect of Nascent OH Radicals.

Rate coefficients of the O-initiated oxidation of allyl methyl sulfide (HC═CHCHSCH, AMS) and allyl ethyl sulfide (HC═CHCHSCHCH, AES) were determined at atmospheric conditions by "in situ" FTIR. The relative kinetic experiments were performed using methylcyclohexane (McH) and carbon monoxide (CO) as nascent OH radical scavengers and in the absence of any scavenger, to determine the impact that the formation of OH radicals has on the rate coefficients. In the absence of scavengers, values of = (5.

FTIR product study of the Cl-initiated oxidation products of CFC replacements: (/)-1,2,3,3,3-pentafluoropropene and hexafluoroisobutylene.

A product study of the reactions of (/)-1,2,3,3,3-pentafluoropropene ((/)-CFCF[double bond, length as m-dash]CHF) and hexafluoroisobutylene ((CF)C[double bond, length as m-dash]CH) initiated by Cl atoms were developed at 298 ± 2 K and atmospheric pressure. The experiments were carried out in a 1080 L quartz-glass environmental chamber coupled FTIR spectroscopy to monitor the reactants and products. The main products observed and their yields were as follows: CFC(O)F (106 ± 9)% with HC(O)F (100 ± 8)% as a co-product for (/)-CFCF[double bond, length as m-dash]CHF, and CFC(O)CF (94 ± 5)% with HC(O)Cl (90 ± 7)% as a co-product for (CF)C[double bond, length as m-dash]CH.

Kinetics, product distribution and atmospheric implications of the gas-phase oxidation of allyl sulfides by OH radicals.

Relative rate coefficients of the OH radical -initiated oxidation of allyl methyl sulfide (AMS, HCCHCHSCH) and allyl ethyl sulfide (AES, HCCHCHSCHCH) have been measured at atmospheric pressure of synthetic air and 298 K: k= (4.98 ± 1.42) and k= (6.

Gas-phase degradation of 2-butanethiol initiated by OH radicals and Cl atoms: kinetics, product yields and mechanism at 298 K and atmospheric pressure.

Relative rate coefficients and product distribution of the reaction of 2-butanethiol (2butSH) with OH radicals and Cl atoms were obtained at atmospheric pressure and 298 K. The experiments were performed in a 480 L borosilicate glass photoreactor in synthetic air coupled to a long path "" FTIR spectrometer. The rate coefficients obtained by averaging the values from different experiments were: = (2.

Product distribution and mechanism of the OH initiated tropospheric degradation of three CFC replacement candidates: CHCF[double bond, length as m-dash]CH, (CF)C[double bond, length as m-dash]CH and (/)-CFCF[double bond, length as m-dash]CHF.

The OH radical initiated photodegradation of 2-fluoropropene (CHCF[double bond, length as m-dash]CH), 3,3,3-trifluoro-2-(tri-fluoromethyl)propene ((CF)C[double bond, length as m-dash]CH) and (/)-1,2,3,3,3-pentafluoropropene ((/)-CFCF[double bond, length as m-dash]CHF) has been investigated for the first time using a 1080 L quartz-glass environmental chamber at 298 ± 2 K and atmospheric pressure of synthetic air coupled with FTIR spectroscopy to monitor reactants and products. The major products observed in the OH reaction were CHC(O)F (98 ± 5)% together with HC(O)H (89 ± 7)% as a co-product, CFC(O)F (103 ± 8)% together with HC(O)F (96 ± 7)% as a co-product and CFC(O)CF (91 ± 8)% together with HC(O)H (98 ± 12)% as a co-product from the C-C bond cleavage channel of the intermediate hydroxyalkoxy radical, formed by addition of OH to the terminal carbon of the double bond which is designated C of 2-fluoropropene, (/)-1,2,3,3,3-pentafluoropropene and 3,3,3-trifluoro-2-(tri-fluoromethyl)propene, respectively. The present results are compared with previous studies for the reaction of OH with the separate isomers () and () of 1,2,3,3,3-pentafluoropropene.

Atmospheric Degradation of CH2═C(CH3)C(O)OCH3 Initiated by OH Radicals: Mechanistic Study and Quantification of CH3C(O)C(O)OCH3 in NOx Free Air.

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.

Atmospheric Sink of (E)-3-Hexen-1-ol, (Z)-3-Hepten-1-ol, and (Z)-3-Octen-1-ol: Rate Coefficients and Mechanisms of the OH-Radical Initiated Degradation.

A kinetic study of the gas-phase reactions of OH radicals with three unsaturated biogenic alcohols, (E)-3-hexen-1-ol, (Z)-3-hepten-1-ol, and (Z)-3-octen-1-ol, has been performed. The rate coefficients obtained are (in units of 10(-10) cm(3) molecule(-1) s(-1)) k1 (OH + (E)-CH2(OH)CH2CH═CHCH2CH3) = (1.14 ± 0.