Photolysis of chlorpyrifos-methyl, chlorpyrifos-methyl oxon, and 3,5,6-trichloro-2-pyridinol

LOBATTO, VIRGINIA L.; ARGÜELLO, GUSTAVO A.; BUJÁN, ELBA I.

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY

JOHN WILEY & SONS LTD

Año: 2019 vol. 32 p. 1 - 8

0894-3230

The photodegradation of chlorpyrifos-methyl (1), and two of its photodegradation products, chlorpyrifos-methyl oxon (2), and 3,5,6-trichloro-2-pyridinol (3) was studied using low pressure Hg lamps irradiating at 254 nm either in pure acetonitrile (ACN) or in 10% ACN/H 2 O. Experiments conducted in pure ACN allowed us to identify the photoproducts in the photolysis of 1, 2, and 3 both, in air saturated samples and in the absence of oxygen as analyzed by gas chromatography?mass spectrometry (GC-MS), high resolution mass spectrometry (HRMS), and phosphorus-31 nuclear magnetic resonance ( 31 P NMR). Since 2 and 3 are products in the photodegradation of 1, their degradations in 10% ACN/H 2 O were independently measured, and it was determined that 1 and 2 degrade at comparable rates. Instead, 3 does not interfere in the measurement since it degrades much faster, and their products do not absorb in the region of 1. Our results indicate that short wave photolysis could become a plausible detoxification mechanism.