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Environmental fate & pathways

Phototransformation in air

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The phototransformation of 3,7-Dimethylocta-2,6-dienal (citral) in air by reaction with OH radicals and ozone, respectively,  was calculated using EPIWIN v3.12, AOPWIN v1.91. Based on the reaction rate constant k(OH)=136.0296 x 10E-12 cm³/molecule x sec (at 25°C) and a tropospheric OH radical concentration of 5 x 10E5 radicals/cm³ (24 -h day) a half-life t1/2=2.83 h was calculated. Based on the reaction rate constant k(O3)=44.183 x 10E-17 cm³/molecule x sec (at 25°C) and a ozone concentration of 7 x 10E11 molecules/cm³ a half-life t1/2=37.35 min was calculated. Therefore, a very quick photodegradation of citral present in the gas phase of the atmosphere is to be expected.

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