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bromoxynil
Herbicide
HRAC C3, also M WSSA 6; hydroxybenzonitrile
NOMENCLATURE
bromoxynil
Common name bromoxynil (BSI, E-ISO, (m) F-ISO, ANSI, WSSA)
IUPAC name 3,5-dibromo-4-hydroxybenzonitrile; 3,5-dibromo-4-hydroxyphenyl cyanide
Chemical Abstracts name 3,5-dibromo-4-hydroxybenzonitrile
CAS RN [1689-84-5] EEC no. 216-882-7 Development codes M&B 10 064 (May & Baker) Official codes ENT 20852
bromoxynil heptanoate
CAS RN [56634-95-8]
bromoxynil octanoate
Common name bromoxynil octanoate
IUPAC name 2,6-dibromo-4-cyanophenyl octanoate
Chemical Abstracts name 2,6-dibromo-4-cyanophenyl octanoate
CAS RN [1689-99-2] EEC no. 216-885-3 Development codes M&B 10 731 (May & Baker); 16 272 RP (Rhône-Poulenc)
bromoxynil-potassium
Common name bromoxynil-potassium
CAS RN [2961-68-4]
PHYSICAL CHEMISTRY
bromoxynil
Composition Tech. grade is c. 95% pure. Mol. wt. 276.9 M.f. C7H3Br2NO Form Colourless solid. M.p. 194-195 ºC (sublimes at 135 ºC/0.15 mmHg); (tech., 183-192 ºC) V.p. 1.7 ´ 10-4 mPa (20 ºC) KOW logP = 2.8 (unionised) Henry 5.3 ´ 10-4 Pa m3 mol-1 (calc.) Solubility In water 89 mg/l (25 ºC). In dimethylformamide 610, tetrahydrofuran 410, acetone, cyclohexanone 170, methanol 90, ethanol 70, mineral oils <20, benzene 10 (all in g/l, 25 ºC). Stability Very stable to dilute alkalis and acids. Stable to u.v. light. Thermally stable below the melting point. pKa 3.86
bromoxynil heptanoate
Mol. wt. 389.1 M.f. C14H15Br2NO2
bromoxynil octanoate
Mol. wt. 403.0 M.f. C15H17Br2NO2 Form Cream, waxy solid. M.p. 45-46 ºC V.p. 1.9 ´ 10-1 mPa (25 ºC) KOW logP = 5.4 Henry <2 ´ 10-3 Pa m3 mol-1 (calc.) Solubility In water 0.03 mg/l (pH 7, 25 ºC). In chloroform 800, xylene, dimethylformamide 700, ethyl acetate 620, cyclohexanone 550, carbon tetrachloride 500, n-propanol 120, acetone, ethanol 100 (all in g/l, 20-25 ºC). Stability Rapidly degraded to the phenol by aqueous photolysis; DT50 4-5 h. Moderately stable to hydrolysis; DT50 11 d (pH 7); 1.7 d (pH 9).
bromoxynil-potassium
Mol. wt. 315.0 M.f. C7H2Br2KNO M.p. c. 360 ºC Solubility In water 61 g/l (20-25 ºC). In acetone 70, 20% aqueous acetone 240, tetrahydrofurfuryl alcohol 260 (all in g/l, 20-25 ºC). Sodium salt: In water 42 g/l (20-25 ºC). In tetrahydrofurfuryl alcohol 430, methyl cellosolve 310, 20% aqueous acetone 150, acetone 80 (all in g/l, 20-25 ºC).
COMMERCIALISATION
History Herbicidal properties of bromoxynil described independently by R. L. Wain (Nature (London), 1963, 200, 28), by K. Carpenter & B. J. Heywood (ibid., p. 28), and by Amchem Products Inc. Development reviewed by B. J. Heywood (Chem. Ind. (London), 1966, p. 1946). Introduced by May & Baker Ltd and by Amchem Products Inc. (both now Bayer CropScience). Patents GB 1067033 to May & Baker; US 3397054; US 4332613 both to Amchem Manufacturers Bayer CropScience Nufarm Ltd; Hesenta; Makhteshim-Agan; Punjab; Sundat; Zhejiang
APPLICATIONS
Biochemistry Photosynthetic electron transport inhibitor at the photosystem II receptor site; also uncouples oxidative phosphorylation. Mode of action Selective contact herbicide with some systemic activity. Absorbed by the foliage, with limited translocation. Uses Post-emergence control of annual broad-leaved weeds, especially young seedlings of the Polygonaceae, Compositae, and certain Boraginaceae, in cereals, ryegrass-seed crops, turf, and non-crop land, at rates up to 450 g octanoate/ha; in maize and sorghum, applied at up to 600 g/ha. Often used in combination with other herbicides, to extend the spectrum of control. Formulation types EC; SC; WP.
bromoxynil
Selected products: 'Bromotril' (name used for all forms of bromoxynil) (Makhteshim-Agan); 'Mutiny' (Barclay)
bromoxynil octanoate
Selected products: 'Brominal' (Bayer CropScience); 'Bromox' (Dow AgroSciences); 'Bromoxan' (Dow AgroSciences); 'Buctril' (Bayer CropScience); 'Emblem' (Nufarm SA, Nufarm UK); 'Pardner' (Bayer CropScience); mixtures: 'Bronate' (+ MCPA-2-ethylhexyl) (Bayer CropScience); 'Trionyl' (+ ioxynil octanoate) (Agriphar)
OTHER PRODUCTS
bromoxynil
'Alpha Bromotril P' (Makhteshim-Agan); 'Bravado' (DAPT); 'Herbo Stef' (Bayer CropScience, Nufarm SA); 'Litarol M' (Nufarm SA, Sedagri); 'Optimaïs' (Nufarm SA); 'Tassle' (GreenCrop); 'Toplan' (Nufarm SA, DuPont) mixtures: 'Alpha Briotril' (+ ioxynil) (name used for all forms of bromoxynil and ioxynil) (Makhteshim-Agan); 'Alpha Bromotril PT' (+ terbuthylazine) (name used for all forms of bromoxynil) (Makhteshim-Agan); 'Arpix Ter' (+ terbuthylazine) (Aragro); 'Asset' (+ ioxynil+ benazolin) (as salts) (Bayer CropScience); 'Biotite 380' (+ ioxynil) (DAPT); 'Briotril MS' (+ ioxynil+ mecoprop) (Makhteshim-Agan); 'Briotril' (+ ioxynil) (name used for all forms of bromoxynil and ioxynil) (Makhteshim-Agan); 'Capture' (+ diflufenican+ ioxynil) (Bayer CropScience); 'Certrol' (+ mecoprop) (Nufarm SA); 'Chamois' (+ diflufenican+ ioxynil) (Philagro); 'Dièze' (+ diflufenican+ mecoprop-P) (Bayer CropScience); 'Eclat' (+ prosulfuron) (Syngenta); 'Extoll' (+ bentazone) (diolamine salts) (BASF); 'First' (+ diflufenican+ ioxynil) (Bayer CropScience); 'Image' (+ mecoprop-P) (Nufarm SA); 'Jester' (+ prosulfuron) (Syngenta); 'Karal' (+ atrazine) (Nufarm SA); 'Koril' (+ dicamba+ mecoprop) (Nufarm SA); 'Leyclene' (+ ethofumesate+ ioxynil) (as salts) (Bayer CropScience); 'Maestro' (+ dicamba+ MCPA) (Nufarm SA); 'Quattro' (+ MCPA) (Nufarm SA); 'RPA 04481H' (+ terbuthylazine) (Bayer CropScience); 'Sabrine' (+ atrazine) (Nufarm SA); 'Swipe' (+ ioxynil+ mecoprop-P) (Syngenta); 'Teal' (+ ioxynil+ triasulfuron) (Syngenta); 'Traviata' (+ diflufenican+ mecoprop-P) (Bayer CropScience); 'Treble' (+ fluroxypyr+ ioxynil) (Barclay); 'Trilin' (+ fluroxypyr-meptyl+ ioxynil) (Makhteshim-Agan) Discontinued products: 'Brominil' * (Amchem); 'Merit' * (CFPI); 'Sabre' * (CFPI Nufarm, La Quinoléine) mixtures: 'Advance' * (+ fluroxypyr+ ioxynil) (Dow, Zeneca); 'Crusader S' * (+ clopyralid+ fluroxypyr+ ioxynil) (Dow); 'Deloxil' * (+ ioxynil) (AgrEvo); 'Korilene' * (+ dicamba+ mecoprop) (Ciba); 'Sickle' * (+ fluroxypyr) (Dow); 'Templar' * (+ terbuthylazine) (Makhteshim-Agan); 'Vindex' * (+ clopyralid) (Dow AgroSciences)
bromoxynil heptanoate
Mixtures: 'B-4' (+ bromoxynil octanoate+ 2,4-D-2-ethylhexyl) (Agsco); 'Bronate Gel' (+ bromoxynil octanoate+ MCPA-2-ethylhexyl) (Bayer CropScience); 'Buctril 4' (+ bromoxynil octanoate) (Bayer CropScience); 'Buctril Gel' (+ bromoxynil octanoate) (Bayer CropScience); 'Buctril M' (+ bromoxynil octanoate+ MCPA-2-ethylhexyl) (Bayer CropScience)
bromoxynil octanoate
'Alpha Bromolin' (Makhteshim-Agan); 'Batril' (Bayer CropScience); 'Brox' (Albaugh); 'Flagon 400' (Makhteshim-Agan); 'Moxy 2E' (Agriliance) mixtures: 'B-4' (+ 2,4-D-2-ethylhexyl+ bromoxynil heptanoate) (Agsco); 'Bison' (+ MCPA-2-ethylhexyl) (Agriliance); 'Blespring Combi' (+ dicamba+ MCPA+ mecoprop) (Siapa); 'Brioxil Super' (+ ioxynil octanoate+ MCPA) (Aragro); 'Bronate Gel' (+ MCPA-2-ethylhexyl+ bromoxynil heptanoate) (Bayer CropScience); 'Brox-AT' (+ atrazine) (Albaugh); 'Brox-M' (+ MCPA-2-ethylhexyl) (Albaugh); 'Buctril 4' (+ bromoxynil heptanoate) (Bayer CropScience); 'Buctril Gel' (+ bromoxynil heptanoate) (Bayer CropScience); 'Buctril M' (+ MCPA-2-ethylhexyl+ bromoxynil heptanoate) (Bayer CropScience); 'Clark' (+ atrazine) (Nufarm SA, Syngenta); 'Compas' (+ clethodim) (Bayer CropScience); 'Gardobuc' (+ terbuthylazine) (Syngenta, Bayer CropScience); 'Mextrol Biox' (+ ioxynil octanoate) (Nufarm UK); 'Oxytril' (+ ioxynil octanoate) (Bayer CropScience)
ANALYSIS
bromoxynil
Product analysis by glc of a derivative (CIPAC Handbook, 1985, 1C, 1989; ibid., 2257), by glc (ibid., 1994, F, 292), or by determination of bromine. Residues determined by glc of a derivative (H. S. Segal & M. L. Sutherland, Anal. Methods Pestic., Plant Growth Regul. Food Addit., 1967, 5, 347; Anal. Methods Pestic. Plant Growth Regul., 1972, 6, 605) or by i.r. spectrometry.
bromoxynil heptanoate
Product analysis by glc (CIPAC Handbook, 1998, H, 57).
bromoxynil octanoate
Product analysis by glc (CIPAC Handbook, 1985, 1C, 1998; ibid., 2004; AOAC Methods, 17th Ed., 980.05).
MAMMALIAN TOXICOLOGY
bromoxynil
Oral Acute oral LD50 for rats 81-177, mice 110, rabbits 260, dogs c. 100 mg/kg. Skin and eye Acute percutaneous LD50 for rats >2000, rabbits 3660 mg/kg. Mild eye irritant; non-irritating to skin (rabbits). Is a skin sensitiser (guinea pigs). Inhalation LC50 (4 h) for rats 0.15-0.38 mg/ml. NOEL (2 y) for rats 20 ppm. ADI 0.003 Toxicity class WHO (a.i.) II; EPA (formulation) II EC classification R63| T; R25
bromoxynil octanoate
Oral Acute oral LD50 for rats 240-400, mice 306 mg (formulated)/kg, rabbits 325 mg/kg. Skin and eye Acute percutaneous LD50 for rats >2000, rabbits 1675 mg/kg. A skin sensitiser. Inhalation LC50 0.72 mg/l. NOEL (90 d) for rats 15.6, dogs 5 mg/kg daily. ADI 0.003 (as phenol) EC classification R63| Xn; R21/22| N; R50, R53
bromoxynil-potassium
Oral Acute oral LD50 for rats 130, mice 100 mg (formulated)/kg. NOEL (90 d) for rats 16.6 mg/kg daily.
ECOTOXICOLOGY
bromoxynil
Birds Acute oral LD50 for bobwhite quail 217 mg/kg. Sub-acute oral dietary LC50 (5 d) for bobwhite quail 2080, mallard duck 1380 ppm. Fish LC50 (96 h) for bluegill sunfish 29.2 mg/l. Daphnia LC50 (48 h) 12.5 mg/l. Algae EC50 (96 h) for Scenedesmus subspicatus 44, Selenastrum capricornutum 0.65 mg/l; EC50 (72 h) for Navicula pelliculosa 0.12 mg/l. Other aquatic spp. LC50 (14 d) for Lemna gibba 0.033 mg/l. Bees LD50 for honeybees (48 h, contact) 150 mg/bee; (48 h, oral) 5 mg/bee. Worms EC50 (14 d) 45 mg/kg.
bromoxynil octanoate
Birds Acute oral LD50 for bobwhite quail 170, mallard duck 2350 mg/kg b.w. Sub-acute oral dietary LC50 (5 d) for bobwhite quail 1315, mallard duck 2150 ppm. Fish LC50 (96 h) for bluegill sunfish 0.06, rainbow trout 0.041 mg/l. Daphnia LC50 (48 h) 0.046 mg/l. Algae EC50 (96 h) for Scenedesmus subspicatus 1 mg/l; EC50 (120 h) for Navicula pelliculosa 0.043, Selenastrum capricornutum 0.22 mg/l. Other aquatic spp. LC50 (14 d) for Lemna gibba >0.073 mg/l. Bees LD50 for honeybees (48 h, contact) >100 mg/bee; (96 h, oral) >119.8 mg/bee. Worms EC50 (14 d) 294 mg/kg.
bromoxynil-potassium
Generally as for bromoxynil.
ENVIRONMENTAL FATE
Animals See plants. Plants Metabolism in plants and animals is by hydrolysis of the ester and nitrile groups, with some debromination occurring (J. H. Buckland, Pestic. Sci.,1973, 4, 149, 689). Soil/Environment In lab. soil, DT50 <1 d. Degraded by hydrolysis and debromination to less toxic substances such as hydroxybenzoic acid. For persistence in soil, see Pestic. Sci., 1980, 11, 341.
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