bromoxynil
{{chembox
| Watchedfields = changed
| verifiedrevid = 443428550
| ImageFile = Bromoxynil.png
| ImageSize = 160
| ImageAlt = Skeletal formula of bromoxynil
| ImageFile1 = Bromoxynil-3D-spacefill.png
| ImageSize1 = 170
| ImageAlt1 = Space-filling model of the bromoxynil molecule
| PIN = 3,5-Dibromo-4-hydroxybenzonitrile
| OtherNames = Brominal, Bromotril, Bronate, Buctril, Certrol B, Litarol, M&B 10064, Merit, Pardner, Sabre, Torch
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 14775
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C04178
| InChI = 1/C7H3Br2NO/c8-5-1-4(3-10)2-6(9)7(5)11/h1-2,11H
| InChIKey = UPMXNNIRAGDFEH-UHFFFAOYAP
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C7H3Br2NO/c8-5-1-4(3-10)2-6(9)7(5)11/h1-2,11H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = UPMXNNIRAGDFEH-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 1689-84-5
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = J46EK95K0P
| PubChem = 15531
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 453905
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 17192
| SMILES = Brc1cc(C#N)cc(Br)c1O
}}
|Section2={{Chembox Properties
| C=7 | H=3 | Br=2 | N=1 | O=1
| Appearance= colorless or white solid
| Density=2.243 g/mL
| MeltingPt=194–195 °C
| BoilingPt=
| Solubility= organic solvents
}}
|Section3={{Chembox Hazards
| MainHazards=
| FlashPt=
| AutoignitionPt =
}}
}}
Bromoxynil is an organic compound with the formula HOBr2C6H2CN. It is classified as a nitrile herbicide, and as such sold under many trade names. It is a white solid. It works by inhibiting photosynthesis. It is moderately toxic to mammals.
It is used in Australia,{{cite web |title=4Farmers Bromoxynil 200 |url=https://4farmers.com.au/products/herbicides/bromoxynil-200/ |website=4farmers.com.au |publisher=4Farmers Australia}} New Zealand,{{cite web |title=APP203468-Final-Decision-Signed.pdf |url=https://www.epa.govt.nz/assets/FileAPI/hsno-ar/APP203468/ae23a99d07/APP203468-Final-Decision-Signed.pdf |website=www.epa.govt.nz}} and the USA, which used 614,000 lbs of it in 1974.{{cite web |last1=US EPA |first1=OCSPP |title=EPA Implements Protections for Endangered Fish Species from Four Pesticides |url=https://www.epa.gov/pesticides/epa-implements-protections-endangered-fish-species-four-pesticides |website=www.epa.gov |language=en |date=1 February 2023}}{{cite web |title=Pesticide Usage Survey of Agricultural, Governmental, and Industrial Sectors in the United States, 1974 |url=https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=91012P4O.txt |website=epa.gov |publisher=EPA |date=1977}}
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 {{doi|10.1002/14356007.o28_o01}}
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 by the microorganism Desulfitobacterium chlororespirans.{{cite journal | vauthors=Cupples AM, Sanford RA, Sims GK | year = 2005 | title = Dehalogenation of Bromoxynil (3,5-Dibromo-4-Hydroxybenzonitrile) and Ioxynil (3,5-Diiodino-4-Hydroxybenzonitrile) by Desulfitobacterium chlororespirans | journal = Applied and Environmental Microbiology | volume = 71 | issue = 7 | pages = 3741–3746 | doi = 10.1128/AEM.71.7.3741-3746.2005 | pmid = 16000784 | pmc = 1169022}} Bromoxynil also breaks down photochemically, by releasing the halogen bromines.{{cite journal |last1=Malouki |first1=Moulay A. |last2=Zertal |first2=Abdennour |last3=Lavédrine |first3=Bernadette |last4=Sehili |first4=Tahar |last5=Boule |first5=Pierre |title=Phototransformation of 3,5-dihalogeno-4-hydroxybenzonitriles (ioxynil and chloroxynil) in aqueous solution |journal=Journal of Photochemistry and Photobiology A: Chemistry |date=1 November 2004 |volume=168 |issue=1 |pages=15–22 |doi=10.1016/j.jphotochem.2004.05.007}} In aerobic conditions, it can persist for a month or more.{{cite journal |last1=Nolte |first1=J. |last2=Heimlich |first2=F. |last3=Grass |first3=B. |last4=Zullei-Seibert |first4=N. |last5=Preuss |first5=G. |title=Studies on the behaviour of dihalogenated hydroxybenzonitriles in water |journal=Fresenius' Journal of Analytical Chemistry |date=1995 |volume=351 |issue=1 |pages=88–91 |doi=10.1007/BF00324296}}
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.{{cite journal|title=Pesticides in Surface Drinking-Water Supplies of the Northern Great Plains|vauthors=Donald DB, Cessna AJ, Sverko E, Glozier NE |journal=Environ. Health Perspect. |year=2007 |volume=115 |issue=8 |pages=1183–1191 |pmid=17687445 |doi=10.1289/ehp.9435 |pmc=1940079}}
Safety
Lethal doses in mammals range between 60 and 600 milligrams ingested per kilogram, and teratogenic 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.{{cite web |url=http://ace.orst.edu/info//extoxnet/pips/bromoxyn.htm |title=Extension Toxicology Network: Pesticide information profiles |url-status=dead |archiveurl=https://web.archive.org/web/20070401230247/http://ace.orst.edu/info/ |archivedate=2007-04-01 }}
In the United States it is distributed as a restricted use pesticide in toxicity class II (moderately toxic) and not available for homeowner use.
Bromoxynil's taste is "slight, not characteristic".{{cite journal |title=Technical Bulletin Ioxynil and Bromoxynil Selective Herbicides |journal=International Journal of Pest Management: Part C |date=September 1968 |volume=14 |issue=3 |pages=301–322 |doi=10.1080/05331856809438464 |url=https://www.tandfonline.com/doi/epdf/10.1080/05331856809438464?needAccess=true}}
Tradenames
Bromoxynil has been sold as: Brominal, Nu-Lawn Weeder, (Union Carbide), Buctril, and Chipco Buctril, (Rhone-Poulenc).{{cite book |last1=Elmore |first1=C. L. |last2=McHenry |first2=W. B. |last3=Smith |first3=N. L. |last4=Shaefer |first4=K. M. |title=COMMON AND PROPRIETARY TRADE NAMES OF HERBICIDES: A Cross Indexed Guide |date=April 1980 |publisher=Division of Agricultural Sciences University of California}} This list is incomplete.
References
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