2,4-Dichlorophenoxyacetic Acid


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2,4-dichlorophenoxyacetic acid

[¦tü ¦fȯr dī¦klȯr·ō·fə¦näk·sē·ə′sēd·ik ′as·əd]
(organic chemistry)
Cl2C6H3OCH2COOH Yellow crystals, melting at 142°C; used as a herbicide and pesticide. Abbreviated 2,4-D.

2,4-Dichlorophenoxyacetic Acid

 

(also called 2,4-D), C12C6H3OCH2COOH, a herbicide for combating dicotyledonous weeds in sowings of grain crops and in meadows. In pure form it exists as white odorless crystals; melting point, 140.5° C. Its solubility in water is 560 mg per liter at 20° C. The industrial preparation has an unpleasant phenolic odor caused by an admixture of 2,4-dichlorophenol. In industry, 2,4-D is made by the reaction of salts of monochloroacetic acid with sodium 2,4-dichlorophenate and by chlorination of phenoxyacetic acid. It is the most extensively produced and utilized herbicide. It is used in the form of water-soluble salts with acyclic amines (dimethylamine, diethylamine, ethanolamines, and so on) and in the form of a sodium salt, esters with various alcohols (isopropanol, butanol, octanol, and others), and amides (for example, the o-chloroanilide).

At the consumption levels of 0.5-2.0 kg per hectare (kg/ha), almost all dicotyledonous weeds can be killed (creeping thistle, hogweed, and centaurea). Grain crops are treated in the tillering stage.

Plants that are sensitive to the action of 2,4-D include cotton and sunflower plants, fruit trees (apple, pear, plum, cherry, apricot, and peach), and berries (currant, strawberry, gooseberry, and raspberry), as well as deciduous trees and shrubs. The action of the herbicide is weaker on poor soils and in periods of drought; plants raised on rich and moist soils die more quickly. 2,4-D is moderately toxic to animals and humans.

The mechanism of action of 2,4-D has not been conclusively studied. It is known to be rapidly absorbed by plant leaves and to cause expansion of meristematic cells, which leads to the destruction of tissues and to curling and death of the plant. It is comparatively rapidly destroyed by microorganisms in the soil and does not accumulate.

REFERENCES

Mel’nikov, N. N., and lu. A. Baskakov. Khimiia gerbitsidov i reguliatorov rosta rastenii. Moscow, 1962.
Crafts, A., and W. Robbins. Khimicheskaia bor’ba s sorniakami Moscow, 1964. (Translated from English.)
Mel’nikov, N. N. Khimiia pestitsidov. Moscow, 1968.

N. N. MEL’NIKOV

References in periodicals archive ?
Case Control Study of Non-Hodgkin's Lymphoma and the Herbicide 2,4-Dichlorophenoxyacetic Acid (2, 4-D) in Eastern Nebraska", Epidemiology, 15).
Metabolic fate of 2,4-dichlorophenoxyacetic acid in the stem tissue of Phaseolus vulgaris.
Here in Canada, ornamental pesticides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP) have been partially banned in Halifax, NS, and completely banned in Shediac, NB, and Perth, ON.
Plant regeneration from barley callus: effects of 2,4-dichlorophenoxyacetic acid and phenylacetic acid.
Effetc of 2,4-dichlorophenoxyacetic acid and gibberellic acid in delaying preharvest drop and rind senescence on 'Ellendale' mandarin fruit.
Genetical analysis of immature embryo response to 2,4-dichlorophenoxyacetic acid.
2,4-D: The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is the most commonly used herbicide in western Canada.
4] Mercury, 2007-2008 NRC benchmark NA concentration assessment, NRC 2000 Thallium, 2007-2008 HBM-I, German HBC NA 2011 Current-use pesticides, 2001-2002 2,4-Dichlorophenoxyacetic acid RfD, U.
Assessment of the changes of 2,4-dichlorophenoxyacetic acid concentrations in plant tissue culture media in presence of activated charcoal.
BACKGROUND: Several extensive studies of exposure to 2,4-dichlorophenoxyacetic acid (2,4-D) using urinary concentrations in samples from the general population, farm applicators, and farm family members are now available.