On the use of CO as scavenger for OH radicals in the ozonolysis of simple alkenes and isoprene

The OH radical yields generated in the ozonolysis of ethene (ET), propene (PR), cis-2-butene (CB), trans-2-butene (TB), 2,3-dimethyl-2-butene (TME), and isoprene (ISP) in the presence of 20 Vol.% O2 have been determined in a darkened glass reactor at 1 bar total pressure. The hydroxyl radicals formed were scavenged by an excess of CO added to the systems. The O2 present converted H atoms formed in this reaction into HO2. From measurements of the increase in CO2 generation by FTIR the OH formation yields were determined to be 0.08 (ET), 0.18 (PR), 0.17 (CB), 0.24 (TB), 0.36 (TME), and 0.19 (ISP), respectively, per molecule of reacted ozone. The combined error in the OH determinations is estimated to be <10%.