FTIR Product Study of the Reactions of Z-3-Heptenol and E-3-Hexenol Initiated by OH Radicals at NOx-free Conditions

RODRIGO GASTÓN GIBILISCO, IUSTINIAN BEJAN, IAN BARNES, PETER WIESEN, MARÍA BELÉN BLANCO AND MARIANO TERUEL

Simposio; Atmospheric Chemical Mechanisms; 2014

After wounding of plants, during drying and pathogen attack, high fluxes of (Z)-3-hepten-1-ol and (E)-3-hexen-1-ol have been observed. Therefore, these compounds represent an important fraction of the total OVOCs emitted by vegetation. On the other hand, it is known that they have a potential use as biopesticides for the control of plagues. The OH radical initiated photodegradation of (Z)-3-hepten-1-ol and (E)-3-hexen-1-ol was studied, to determine the possible contribution of these unsaturated alcohols in the formation of secondary pollutants such as ozone and oxygenates. Furthermore, when possible, the reaction products were identified and quantified. This work represents the first study of the OH radical-initiated degradation of these unsaturated alcohols under NOx free conditions. The reactions where carry out in a 1080 L quartz-glass environmental chamber at 298  2 K and atmospheric pressure of synthetic air using in situ FTIR spectroscopy to monitor the reactants and products. Products observed from the OH-initiated oxidation of these species in 1 atm of synthetic air at 298 K were Butanal (32.7±2.4)% for (Z)-3-hepten-1-ol; and propanal (35.3±5.1)%, from (E)-3-hexen-1-ol. In both cases it was detected carbon monoxide and formic acid as products of secondary reactions. The reaction products found confirm that the reaction proceeds mainly via an addition mechanism of the OH radical to the double bond. The 2,3-hydroxyalcoxy radical formed in the OH addition steo can then decomposed leading to the corresponding aldehydes. Although a significant fraction can also react by isomerization by a1,5-H shift through a six membered transition state, and react with O2.