Product distribution and mechanism of the OH- initiated tropospheric degradation of three CFC replacement candidates: CH3CF=CH2, (CF3)2C] CH2 and (E/Z)-CF3CF] CHF

摘要

The OH radical initiated photodegradation of 2-fluoropropene (CH3CF] CH2), 3,3,3-trifluoro-2-(trifluoromethyl) propene ((CF3) 2C] CH2) and (E/Z)-1,2,3,3,3-pentafluoropropene ((E/Z)-CF3CF] 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 in situ FTIR spectroscopy to monitor reactants and products. The major products observed in the OH reaction were CH3C(O) F (98+/-5)% together with HC(O) H (89+/-7)% as a co-product, CF3C(O) F (103+/-8)% together with HC(O) F (96+/-7)% as a coproduct and CF3C(O) CF3 (91+/-8)% together with HC(O) H (98+/-12)% as a co-product from the C1-C2 bond cleavage channel of the intermediate hydroxyalkoxy radical, formed by addition of OH to the terminal carbon of the double bond which is designated C1 of 2-fluoropropene, (E/Z)-1,2,3,3,3pentafluoropropene 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 (E) and (Z) of 1,2,3,3,3pentafluoropropene. In addition, atmospheric implications of the reactions studied are discussed.