Bromoxynil

Structural formula
General
Surname	Bromoxynil
other names	3,5-dibromo-4-hydroxybenzonitrile; 3,5-dibromo-4-hydroxyphenyl cyanide;
Molecular formula	C 7 H 3 Br 2 NO
Brief description	Solid
External identifiers / databases
ECHA InfoCard	100.015.348
PubChem	15531
Wikidata	Q408345
properties
Molar mass	276.91 g mol −1
Physical state	firmly
density	1.632 g cm −3
Melting point	188.7 ° C
boiling point	318.2 ° C
Vapor pressure	1.7 · 10 −4 Pa (25 ° C)
solubility	poorly soluble in water (0.13 g l −1 at 25 ° C) and hexane; soluble in 1-octanol (5.0 g l −1 at 25 ° C) and methanol (8.5 g l −1 at 25 ° C);
safety instructions
H and P phrases	H: 301-330-317-361d-410
	P: 201-273-280-301 + 310 + 330-302 + 352-304 + 340 + 310
Toxicological data	190 mg kg −1 ( LD 50 , rat , oral ) ; 3660 mg kg −1 ( LD 50 , rabbit , transdermal ) ;
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Bromoxynil is a chemical compound from the group of benzonitriles and organic bromine compounds.

history

Bromoxynil was first registered as a herbicide in the United States in 1965 . From 1972, limit values were issued there for the presence in meat products and in 1980 in fruit and vegetables. It also comes in the form of a butyrate - Octanoat - or heptanoate - derivative used, but with the approval of the butyrate derivative was withdrawn in 1989 because of concerns about its dangers.

Extraction and presentation

Bromoxynil can be obtained by reacting 4-hydroxybenzaldehyde with bromine and then reacting with hydroxylamine .

properties

Bromoxynil is a solid that is poorly soluble in water. Bromoxynil octanoate and bromoxynil heptanoate are brown crystalline solids with a melting point of about 44 ° C.

The esters are practically insoluble in water. Bromoxynil octanoate is soluble in acetone and ethanol (10 g / 100 ml), benzene and xylene (70 g / 100 ml), chloroform and dichloromethane (80 g / 100 ml) and cyclohexanone (55 g / 100 ml). Bromoxynil heptanoate is soluble in 1-octanol (33.8 g / 100 ml), methanol (52.4 g / 100 ml), hexane (77.5 g / 100 ml), dichloromethane (111.1 g / 100 ml ), Acetone (106.4 g / 100 ml) and ethyl acetate (102.7 g / 100 ml). The octanoic acid and heptanoic acid esters easily hydrolyze to bromoxynil under alkaline conditions.

use

Estimated US application rate in 2011

Bromoxynil is used as an active ingredient in crop protection products. It is a selective herbicide applied to foliage to control various grasses and dicotyledonous leaf weeds (especially in post-emergence cereals and corn ). The substance inhibits the photosynthetic electron transport ( Hill reaction ) and also influences the oxidative phosphorylation in the mitochondria. This affects the plants' energy production and breathing. Some plants are resistant to the herbicide through the enzyme bromoxynil nitrilase .

In many EU countries, including Germany and Austria, as well as Switzerland, bromoxynil (sometimes in combination with other active ingredients such as terbuthylazine , prosulfuron , isoproturon , ioxynil and fluroxypyr ) is contained in various herbicides.

safety instructions

Similar to the related ioxynil, bromoxynil is only moderately toxic in mammals, but highly toxic to fish.

literature

Barbara Schaller: Studies on the metabolism of bromoxynil in selected plant systems ; University of Halle, dissertation 1990.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Entry on bromoxynil in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
↑ European Commission: Bromoxynil (PDF; 532 kB).
↑ ^a ^b ^c ^d ^e United States Environmental Protection Agency : Reregistration Eligibility Decision of Bromoxynil (PDF; 989 kB), accessed on June 8, 2011.
↑ Entry on 3,5-dibromo-4-hydroxybenzonitrile in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Thomas A. Unger: Pesticide synthesis handbook , ISBN 978-0-81551401-5 , p. 816 ( limited preview in the Google book search).
^ Directorate-General for Health and Food Safety of the European Commission: Entry on bromoxynil in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 13, 2016.
↑ Gyorgy Matolcsy Miklós Nádasy, Viktor Andriska, Sándor Terényi: Pesticide Chemistry , Volume 32, ISBN 978-0-44498903-1 , S. 589th

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Entry on bromoxynil in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .

[2] European Commission: Bromoxynil (PDF; 532 kB).

[EPA-3] United States Environmental Protection Agency : Reregistration Eligibility Decision of Bromoxynil (PDF; 989 kB), accessed on June 8, 2011.

[CLP_100.015.348-4] Entry on 3,5-dibromo-4-hydroxybenzonitrile in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[5] Thomas A. Unger: Pesticide synthesis handbook , ISBN 978-0-81551401-5 , p. 816 ( limited preview in the Google book search).

[PSM-6] Directorate-General for Health and Food Safety of the European Commission: Entry on bromoxynil in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 13, 2016.

[7] Gyorgy Matolcsy Miklós Nádasy, Viktor Andriska, Sándor Terényi: Pesticide Chemistry , Volume 32, ISBN 978-0-44498903-1 , S. 589th