Home > 2,4-D

Uses today include:

• weed control in lawns and other turf
• no-till burndown
• control of weeds and brush along fences and highway and railroad rights of way
• conifer release, that is, control of broadleaf trees in conifer plantings
• grass hayfields and pastures
• cereal grains
• Occasionally, in corn and sorghum.

2,4-D is sold in various formulations under a wide variety of brand names. It continues to be used because of its low cost despite the availability of more selective, more effective, safer products.

1 Physical Properties

Note: properties given are for the acid. Commercial formulations used today use the trimethylamine salt or one of several esters, for which properties differ.

• Relative molecular mass 221.04
• Appearance: Colourless, white to yellow powder when pure
• Melting point 140.5 C
• Water Solubility: 900 mg/L @ 25 C
• Relative vapour density 7.6
• Vapour pressure: 0.02 mPa @ 25 C, 52.3 Pa @ 160 C
• CAS Number: 94-75-7

2 Toxicity

The LD₅₀ in rats has been reported as 375 and 666 mg/kg in two different studies. Single oral doses of 5 and 30 mg/kg body weight did not cause any acute toxic effects in human volunteers.

The amine salt formulations can cause irreversible eye damage.

3 Manufacture

2,4-D is a member of the phenoxy family of herbicides, which include:

• 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)
• 2-methyl-4-chlorophenoxyacetic acid (MCPA)
• 2-(2-methyl-4-chlorophenoxy)propionic acids (mecoprop, MCPP)
• 2-(2,4-dichlorophenoxy)propionic acid (dichloroprop, 2,4-DP)
• (2,4-dichlorophenoxy)butyric acid (2,4-DB)

2,4-D is manufactured from 2,4 dichlorophenol, which is itself produced by chlorination of phenol. The production process creates several contaminants including isomers, monochlorophenol , and other polychorophenol s and their acids.

The product Agent Orange, used extensively throughout the Vietnam War, contained 2,4-D. However, the controversies associated with the use of Agent Orange were associated with a contaminant ( dioxin) in the 2,4,5-T component.

4 External links

For some widely divergent views on 2,4-D, compare the industry's web site

• http://www.24d.org

to the "fact sheet" from an anti-pesticide group:

• http://www.beyondpesticides.org/pesticides/factsheets/2,4-D.pdf

2,4-D has been evaluated by the European Union and included on its list of approved pesticides. The evaluation report contains a large quantity of data on the properties (phys-chem, toxicity, environmental fate) of 2,4-D and is available at:

• http://europa.eu.int/comm/food/plant/protection/evaluation/exist_subs_rep_en.htm