2,4-dichlorophenoxyacetic acid

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Structural formula
Structural formula of 2,4-dichlorophenoxyacetic acid
General
Surname 2,4-dichlorophenoxyacetic acid
other names
  • 2,4-D
  • (2,4-dichlorophenoxy) acetic acid ( IUPAC )
Molecular formula C 8 H 6 Cl 2 O 3
Brief description

white odorless solid

External identifiers / databases
CAS number 94-75-7
EC number 202-361-1
ECHA InfoCard 100.002.147
PubChem 1486
ChemSpider 1441
Wikidata Q209222
properties
Molar mass 221.04 g · mol -1
Physical state

firmly

density

1.42 g cm −3

Melting point

140.5 ° C

boiling point

160 ° C (0.53 hPa)

Vapor pressure

8.25 · 10 −5 mmHg (20 ° C)

solubility
  • Very sparingly soluble in water (0.3 g l −1 at 25 ° C)
  • soluble in ethanol (130 g l −1 )
  • soluble in many organic solvents
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
05 - Corrosive 07 - Warning

danger

H and P phrases H: 302-317-318-335-412
P: 261-264-273-280-304 + 340 + 312-305 + 351 + 338 + 310
MAK
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

2,4-Dichlorophenoxyacetic acid ( 2,4-D for short ) is a herbicide derived from phenoxyacetic acid from the group of synthetic auxins . It was developed in 1945 by the American Chemical Paint Co. and is structurally related to dichloropropane .

Manufacturing

2,4-dichlorophenoxyacetic acid can be synthesized by reacting 2,4-dichlorophenol , sodium hydroxide and monochloroacetic acid.

properties

2,4-dichlorophenoxyacetic acid is a slightly volatile, white, odorless solid that is very sparingly soluble in water. When handled, it is mainly absorbed through the skin and excreted in the urine without metabolism within days. The Endocrine Society classifies 2,4-dichlorophenoxyacetic acid, due to its hormone-like effects, as an endocrine disruptor and recommends avoiding contact with this substance as far as possible in view of the many negative health effects.

Contact with high doses can damage the nervous system. In long-term studies on farmers, the excretion (and therefore also the previous uptake) of 2,4-D with the urine could be determined. This was accompanied by an increase in the concentration of a marker for oxidative DNA damage.

The time of first menstruation in girls was also found to be influenced.

use

Estimated application rate in the USA

Plant protection

2,4-D is used as a herbicide against dicotyledons in cereals , in orchards, on grassland and lawns . It is particularly effective against knotweed , chamomile and thistles . Many of the 2,4-D preparations approved today are intended for use against weeds on ornamental lawns. In addition to other herbicidal active ingredients, often dicamba , they also contain lawn fertilizers.

In June 2011, the Brazilian environmental agency IBAMA uncovered a case in which 2,4-D-containing herbicides were sprayed from an airplane to defoliate the jungle in the state of Amazonas .

About 14,000 tons were applied in the USA in 2011. It is the third most frequently used herbicide there after glyphosate and atrazine .

military

During the Vietnam War , esters of 2,4-dichlorophenoxyacetic acid were part of the defoliants Agent Purple and Agent White . The n- butyl esters of 2,4-D and the structurally related 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were contained in the defoliant Agent Orange in a ratio of 1: 1 . 2,4-D contains traces of dioxins , but the comparatively less toxic congeners 2,7-dichlorodibenzodioxin and 2,8-dichlorodibenzodioxin predominate . The dioxin contamination by Agent Orange was mainly based on 2,4,5-T, which contained traces of the highly toxic congener 2,3,7,8-tetrachlorodibenzodioxin .

regulation

The International Agency for Research on Cancer (IARC) classified 2,4-D as “possibly carcinogenic ” (Group 2B) in 2015 .

EU

Despite the suspected health risks, the approval was extended on January 1, 2016 and will now run until December 31, 2030. At national level, 2,4-D is approved in 26 EU countries. The permitted daily dose is 0.05 and the acceptable user exposure 0.15 milligrams per kilogram of body weight and day.

The Endocrine Society - the oldest and largest endocrinological specialist society - warns against specifying supposedly harmless permitted daily doses due to the poorly understood dose-effect relationship of endocrine disruptors and the incomplete study situation.

Derivatives

2,4-D is also used in the form of its salts and esters, which have similar properties and a similar metabolism. Examples for this are:

  • 2,4-D-dimethylammonium (2,4-D DMA)
  • 2,4-D-ethylhexyl (2,4-D EHE)
  • 2,4-D-diethanolamine (2,4-D DEA)
  • 2,4-D-butoxyethyl (2,4-D BEE)
  • 2,4-D-isopropylamine (2,4-D IPA)
  • 2,4-D-triisopropanolamine (2,4-D TIPA)
  • 2,4-D-isopropyl (2,4-D IPE)
  • 2,4-D-methyl
  • Ethanol ammonium salt

Web links

Commons : 2,4-Dichlorophenoxyacetic acid  - Collection of pictures, videos, and audio files

Individual evidence

  1. a b c d e f g h i j Entry on 2,4-dichlorophenoxyacetic acid in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
  2. Entry on 2,4-dichlorophenoxyacetic acid in the ChemIDplus database of the United States National Library of Medicine (NLM), accessed on June 5, 2017.
  3. ^ A b Rainer Koch: Environmental chemicals . 3rd edition, VCH, Weinheim, 1995, ISBN 3-527-30061-9 .
  4. Entry on 2,4-D 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. Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 94-75-7 or 2,4-dichlorophenoxyacetic acid (including salts and esters) ), accessed on October 16, 2019.
  6. Entry on 2,4-D. In: Römpp Online . Georg Thieme Verlag, accessed on November 12, 2014.
  7. Thomas A. Unger: Pesticide synthesis handbook . 1996, ISBN 0-8155-1401-8 , pp. 761 ( limited preview in Google Book search).
  8. Endocrine Disrupting Chemicals (EDCs) | Hormone Health Network. Accessed November 4, 2018 .
  9. Heinz Nau, Pablo Steinberg, Manfred Kietzmann: Food toxicology . Georg Thieme Verlag, 2003, ISBN 3-8263-3330-6 , p. 88 ( limited preview in Google Book search).
  10. Catherine C. Lerro, Laura E. Beane Freeman, Lützen Portengen, Daehee Kang, Kyoungho Lee: A longitudinal study of atrazine and 2,4-D exposure and oxidative stress markers among Iowa corn farmers . In: Environmental and molecular mutagenesis . tape 58 , no. 1 , January 2017, p. 30-38 , doi : 10.1002 / em.22069 , PMID 28116766 , PMC 5763550 (free full text).
  11. ^ A b A. C. Gore, VA Chappell, SE Fenton, JA Flaws, A. Nadal: EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals . In: Endocrine Reviews . tape 36 , no. 6 , December 2015, p. E1 – E150 , doi : 10.1210 / er.2015-1010 , PMID 26544531 , PMC 4702494 (free full text).
  12. Werner Perkow: Active substances in pesticides and pesticides , 2nd edition, 1st supplement. Current issue May 1985, Paul Parey publishing house.
  13. a b Directorate-General for Health and Food Safety of the European Commission: Entry on 2,4-D in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 13, 2016.
  14. EcoDebate: Ibama impede uso, para desmatamento em Novo Aripuanã / AM, de quatro toneladas herbicidas altamente tóxicos , June 28, 2011.
  15. Karlheinz Ballschmiter, Reiner Bacher: Dioxins . Verlag Chemie (VCH), Weinheim 1996, ISBN 3-527-28768-X .
  16. IARC Monographs evaluate DDT, lindane, and 2,4-D , June 23, 2015.
  17. EDCs Myth vs. Fact | Hormone Health Network. Accessed November 4, 2018 .
  18. ^ Entry on esters of 2,4-dichlorophenoxyacetic acid in the GESTIS substance database of the IFA , accessed on December 6, 2016(JavaScript required) .
  19. FAO: Evaluation of 2,4-D
  20. pesticideinfo.org: 2,4-D - toxicity, ecological toxicity and regulatory information , accessed on December 6, 2016
  21. External identifiers or database links to dimethylammonium-2,4-dichlorophenoxyacetate : CAS number: 2008-39-1, EC number: 217-915-8, ECHA InfoCard: 100.016.288 , GESTIS substance database : 11040 , PubChem : 16180 , ChemSpider : 15356 , Wikidata : Q2813782 .
  22. Entry on dimethylammonium-2,4-dichlorophenoxyacetate in the GESTIS substance database of the IFA , accessed on December 6, 2016(JavaScript required) .
  23. External identifiers or database links for ethylhexyl 2,4-dichlorophenoxyacetate : CAS number: 1928-43-4, EC number: 217-673-3, ECHA InfoCard: 100.016.068 , PubChem : 61286 , ChemSpider : 55225 , Wikidata : Q22329336 .
  24. External identifiers or database links for 2,4-D-diethanolamine : CAS number: 5742-19-8, EC number: 227-256-8, ECHA InfoCard: 100.024.779 , PubChem : 16825 , ChemSpider : 15944 , Wikidata : Q27251594 .
  25. External identifiers or database links for 2,4-D-butoxyethyl : CAS number: 1929-73-3, EC number: 217-680-1, ECHA InfoCard: 100.016.074 , GESTIS substance database : 12480 , PubChem : 16002 , ChemSpider : 15203 , Wikidata : Q22329266 .
  26. External identifiers or database links for 2,4-D-isopropylamine : CAS number: 5742-17-6, PubChem : 57358267 , ChemSpider : 20641 , Wikidata : Q27269908 .
  27. External identifiers or database links for 2,4-D-triisopropanolamine : CAS number: 18584-79-7, EC number: 639-766-1, ECHA InfoCard: 100.167.411 , PubChem : 62724 , ChemSpider : 56468 , Wikidata : Q27236552 .
  28. External identifiers of or database links to 2,4-D-isopropyl : CAS number: 94-11-1, EC number: 202-305-6, ECHA InfoCard: 100.002.096 , PubChem : 7173 , ChemSpider : 6905 , Wikidata : Q27288441 .
  29. External identifiers or database links for 2,4-D-methyl : CAS number: 1928-38-7, EC number: 217-670-7, ECHA InfoCard: 100.016.065 , PubChem : 1488 , ChemSpider : 1443 , Wikidata : Q22329230 .
  30. External identifiers or database links for (2-hydroxyethyl) ammonium (o, p-dichlorophenoxy) acetate : CAS number: 3599-58-4, EC number: 222-752-0, ECHA InfoCard: 100.020 .684 , Wikidata : Q81976821 .