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2814993 
Technical Report 
Action Of Sunlight On Parathion 
Mansour, M; Thaller, S; Korte, F 
1983 
NIOSH/00140690 
30 
3 
358-364 
Parathion (56382) degradation in sun light was investigated. Parathion was irradiated with a mercury low pressure lamp producing light of 290 nanometer wavelengths in water, methanol, 2-propanol, and various aqueous solvent mixtures for 2, 5, or 10 hours. Aqueous solvent mixtures included titanium-oxide, magnesium-oxide, and zinc-oxide. The identity of the compounds obtained was confirmed with gas chromatography. Nitrophenol (25154556) and paraoxon (311455) were produced. Nitrophenol was produced in all solutions at all time intervals in amounts ranging from a trace to 10 percent of the original parathion. Paraoxon was produced in water, methanol, water and methanol, and water and propanol solutions in amounts ranging from a trace to 2 percent of the original parathion. Dinitrophenol (25550587) and trinitrophenol (88891) could not be identified. The relative amounts of the photo products produced were dependent on the reaction time. The reaction proceeded more slowly in apolar solvents such as n-hexane and cyclohexane. The reaction rate with the oxides depended on the polarity of the oxide. The authors conclude that the rate of photo degradation of parathion depends on the solvent used and the increasing polarization of the molecule in the medium. Two principal reactions are involved in the photochemical decomposition of parathion: a free radical mechanism in apolar solvents and an ionic break down in aqueous solvents.