Bromoxynil is an organic compound with the formula HOBr₂C₆H₂CN. It is classified as a

nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix ''cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including met ...

herbicide Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page fo ...

, and as such sold under many trade names. It is a white solid. It works by inhibiting photosynthesis. It is moderately toxic to mammals.

Production and use

It is produced by bromination of 4-hydroxybenzonitrile. It is a post-emergence to control annual broadleaved weeds.Franz Müller and Arnold P. Applebyki "Weed Control, 2. Individual Herbicides" in Ullmann's Encyclopedia of Industrial Chemistry 2010

Degradation

Bromoxynil decomposes with a half life of approximately two weeks in soil. Persistence increases in soils with elevated clay or organic matter content, suggesting the compound has somewhat limited bioavailability to microorganisms in these environments. Under aerobic conditions in soils or pure cultures, products of bromoxynil degradation often retain the original bromine groups. The herbicide, and one of its common degradation products (3,5-dibromo-4-hydroxybenzoic acid) have been shown to undergo metabolic reductive

dehalogenation In organic chemistry, dehalogenation is a set of chemical reactions that involve the cleavage of carbon- halogen bonds; as such, it is the inverse reaction of halogenation. Dehalogenations come in many varieties, including defluorination (remov ...

by the microorganism

Desulfitobacterium chlororespirans ''Desulfitobacterium chlororespirans'' is a Gram-positive, anaerobic, spore-forming species of bacteria. Its type strain is Co23 (= ATCC 700175 = DSM 11544). It grows by coupling the oxidation of lactate to the reductive dechlorination In o ...

. In the Great Plains region of Canada, where it is widely used on cereal grains, average levels detected in drinking water were 1 nanogram per liter. In one case as high as 384 nanograms per liter were detected. Levels of bromoxynil were consistently lower than of several other pesticides tested, and it was observed to undergo greater reduction in water treatment than the others.

Safety

Lethal doses in mammals range between 60 and 600 milligrams ingested per kilogram, and

teratogenic Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology. The related t ...

effects have been observed in rats and rabbits above 30 milligrams per kilogram. Chronic exposure for more than one year in humans caused symptoms of weight loss, fever, vomiting, headache, and urinary problems in one documented case. In the United States it is distributed as a

restricted use pesticide Restricted use pesticides (RUP) are pesticides not available to the general public in the United States. Fulfilling its pesticide regulation responsibilities, the United States Environmental Protection Agency (EPA) registers all pesticides and ins ...

in toxicity class II (moderately toxic) and not available for homeowner use.

References

External links

* {{Herbicides Herbicides Bromoarenes Nitriles Phenols