Diquat dibromide

Structural formula
General
Surname	Diquat dibromide
other names	6,7-dihydrodipyrido [1,2- a : 2 ′, 1′- c ] pyrazinium dibromide ( IUPAC ) ; 1,1'-Ethylene-2,2'-bipyridyldiylium dibromide; Ortho-Quat; Reglone;
Molecular formula	C 12 H 12 Br 2 N 2
Brief description	colorless to yellowish, flammable solid
External identifiers / databases
EC number	201-579-4
ECHA InfoCard	100.001.436
PubChem	6794
Wikidata	Q910903
properties
Molar mass	344.05 g · mol -1
Physical state	firmly
density	1.22-1.27 g · cm −3
Melting point	325 ° C (decomposition)
solubility	good in water (718 g l −1 at 20 ° C); insoluble in non-polar solvents such as chloroform and diethyl ether , soluble in ethanol ;
safety instructions
H and P phrases	H: 330-372-302-319-335-315-317-410
	P: ?
MAK	Switzerland: 0.5 mg m −3
Toxicological data	230–440 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Diquatdibromide is a salt and at the same time a heterocyclic , organic compound from the class of bipyridines , which is used as a fast-acting contact herbicide . It is a colorless to yellowish powder.

Extraction and presentation

By oxidative coupling of pyridine over a Raney nickel catalyst, this is converted into 2,2'-bipyridine . The ethylene bridge in diquatdibromide is then formed by 1,2-dibromoethane :

use

Diquatdibromide is a contact herbicide introduced by ICI (now Syngenta ) in 1957, is used against weeds and works by inhibiting photosynthesis . However, it is particularly suitable for killing potato tops before harvesting ( desiccant ). However, the use of the compound is restricted to a few cases in Germany (potatoes, hops). Use in nature reserves and national parks is prohibited (the substance is considered particularly dangerous for bees and aquatic organisms).

Admission

In a number of EU countries, including Germany and Austria, plant protection products with this active ingredient were approved. In 2019, the EU approval for Diquat as an active ingredient in plant protection products was not renewed. For some products, there is still a sell-off period until November 4, 2019 and a use-by period until February 4, 2020. In Switzerland, the use-by period for most products continues until July 1, 2022.

safety instructions

Diquatdibromide is toxic. Like paraquat , it is a very potent redox cyclist and leads to the formation of superoxide anions. The hydroxyl radicals formed destroy the lipid chains of the cell membranes and thus lead to cell death . The potentially lethal dose is given as 6–8 mg, with one documented case of poisoning in which the patient survived a dose of 60 mg / kg. Diquat initially leads to a local toxic reaction with ulcerations and swelling of the mucous membranes in the gastrointestinal tract , which is associated with vomiting, diarrhea and abdominal pain. As the disease progresses, paralytic ileus with fluid sequestration and hypovolemic shock can occur. Acute kidney failure usually occurs within one to four days. Liver cell necrosis often occurs with impaired liver function, which, however, is usually mild, transient and spontaneously improves.

Web links

Manufacturer information ( Memento of October 25, 2007 in the Internet Archive )
Limit values according to the Maximum Residue Quantity Ordinance ( BGBl. 2003 I p. 11 ) (PDF file; 117 kB)
Report on Diquat in drinking water from the WHO (PDF file; 122 kB)
Health and Safety Guide (HSG) for Diquat

Individual evidence

↑ ^a ^b ^c ^d ^e Entry on diquatdibromide in the GESTIS substance database of the IFA , accessed on February 22, 2017(JavaScript required) .
↑ Data sheet at Extension Toxicology Network (English) .
↑ Entry on Diquat dibromide 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 .
↑ Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 85-00-7 ), accessed on November 2, 2015.
↑ site to dipyridinium herbicides .
↑ Environmental Health Criteria (EHC) for Paraquat and Diquat , accessed October 5, 2011.
↑ Entry on diquat-dibromide. In: Römpp Online . Georg Thieme Verlag, accessed December 12, 2012.
↑ Study on the use of chemicals in aquaculture (PDF; 2.5 MB).
↑ Directive 2001/21 / EC of the Commission of March 5, 2001 amending Annex I of Directive 91/414 / EEC of the Council on the placing of plant protection products on the market and the inclusion of the active substances amitrole, diquat, pyridate and thiabendazole , accessed on 13. June 2019.
↑ ^a ^b Directorate-General for Health and Food Safety of the European Commission: Entry on Diquat (dibromide) in the EU pesticide database ; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on December 8, 2019.

↑ Are there alternatives to using Reglone in potato cultivation? In: proplanta.de. August 12, 2019, accessed August 12, 2019 .

↑ Toxicity description (PDF; 109 kB).

↑ External identifiers or database links for diquat dichloride : CAS number: 4032-26-2, EC number: 223-714-6, ECHA InfoCard: 100.021.559 , GESTIS substance database : 496416 , PubChem : 19943 , ChemSpider : 18784 , Wikidata : Q23057985 .

↑ External identifiers or database links for diquat dihydroxide : CAS number: 94021-76-8, EC number: 301-467-6, ECHA InfoCard: 100.092.201 , GESTIS substance database : 183347 , ChemSpider : 21166480 , Wikidata : Q83123007 .

[GESTIS-1] Entry on diquatdibromide in the GESTIS substance database of the IFA , accessed on February 22, 2017(JavaScript required) .

[2] Data sheet at Extension Toxicology Network (English) .

[CLP_100.001.436-3] Entry on Diquat dibromide 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 .

[4] Swiss Accident Insurance Fund (Suva): Limit values - current MAK and BAT values (search for 85-00-7 ), accessed on November 2, 2015.

[5] site to dipyridinium herbicides .

[6] Environmental Health Criteria (EHC) for Paraquat and Diquat , accessed October 5, 2011.

[roempp-7] Entry on diquat-dibromide. In: Römpp Online . Georg Thieme Verlag, accessed December 12, 2012.

[8] Study on the use of chemicals in aquaculture (PDF; 2.5 MB).

[9] Directive 2001/21 / EC of the Commission of March 5, 2001 amending Annex I of Directive 91/414 / EEC of the Council on the placing of plant protection products on the market and the inclusion of the active substances amitrole, diquat, pyridate and thiabendazole , accessed on 13. June 2019.

[PSM-10] Directorate-General for Health and Food Safety of the European Commission: Entry on Diquat (dibromide) in the EU pesticide database ; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on December 8, 2019.

[11] Are there alternatives to using Reglone in potato cultivation? In: proplanta.de. August 12, 2019, accessed August 12, 2019 .

[12] Toxicity description (PDF; 109 kB).

[13] External identifiers or database links for diquat dichloride : CAS number: 4032-26-2, EC number: 223-714-6, ECHA InfoCard: 100.021.559 , GESTIS substance database : 496416 , PubChem : 19943 , ChemSpider : 18784 , Wikidata : Q23057985 .

[14] External identifiers or database links for diquat dihydroxide : CAS number: 94021-76-8, EC number: 301-467-6, ECHA InfoCard: 100.092.201 , GESTIS substance database : 183347 , ChemSpider : 21166480 , Wikidata : Q83123007 .