Carbonyl compounds are emitted into the atmosphere from a variety of natural and anthropogenic sources and play an important role in the formation of tropospheric ozone in urban and regional areas. These compounds are also produced in the atmosphere during the oxidation of hydrocarbons. Carbonyl compounds, such as 4-hexen-3-one, 5-hexen-2-one, and 3-penten-2-one, are emitted into the environment from different sources; from mechanical and biological treatment plants, as intermediate products resulting from the synthesis of perfume, insecticides and fungicides and also from biomass burning in Europe. Field and laboratories studies show that these compounds are also released into the atmosphere by the wounded leaves of variety of plants. The release of these unsaturated ketones into the atmosphere is likely to contribute to the formation of ozone and other components of photochemical smog found in urban areas through their reactions mainly with OH radicals and but also other oxidants such as NO3 radicals, O3 molecules and Cl atoms. Thus, knowledge of the rate coefficients of the OH-initiated reactions of ketones is needed to better determine their role in the formation of tropospheric photooxidants. To help in this respect, an experimental kinetic study of the reactions of OH radicals with 4-hexen-3-one, 5-hexen-2-one, and 3-penten-2-one has been carried performed.
3 radicals, O3 molecules and Cl atoms. Thus, knowledge of the rate coefficients of the OH-initiated reactions of ketones is needed to better determine their role in the formation of tropospheric photooxidants. To help in this respect, an experimental kinetic study of the reactions of OH radicals with 4-hexen-3-one, 5-hexen-2-one, and 3-penten-2-one has been carried performed.The rate coefficients were determined using the relative method and were performed at room temperature and atmospheric pressure in a 480 L photoreactor using in situ FTIR analysis to monitor the decay of the organics and the reference compounds. To the best of our knowledge this work provides the first kinetic studies for these reactions, except for CH3C(O)CH2CH2CH=CH2 were there is one previous determination reported in the literature. Our value of k2 is in very good agreement with the value reported previously for this reaction. The atmospheric lifetimes of the studied compounds with respect to reaction with OH have been estimated using the kinetic data obtained in this work and compared with those calculated for other oxidants. The reactivity trends for the compounds with different oxidants are also discussed.
To the best of our knowledge this work provides the first kinetic studies for these reactions, except for CH3C(O)CH2CH2CH=CH2 were there is one previous determination reported in the literature. Our value of k2 is in very good agreement with the value reported previously for this reaction. The atmospheric lifetimes of the studied compounds with respect to reaction with OH have been estimated using the kinetic data obtained in this work and compared with those calculated for other oxidants. The reactivity trends for the compounds with different oxidants are also discussed.
the rate coefficients of the OH-initiated reactions of
the rate coefficients of the OH-initiated reactions ofthe rate coefficients of the OH-initiated reactions of
the rate coefficients of the OH-initiated reactions of