2,4-Dichlorophenoxyacetic acid

• 2,4-D
• (2,4- dichlorophenoxy ) acetic acid

White odorless solid

Fixed

1.42 g · cm -3

140.5 ° C

160 ° C (0.53 hPa)

1.86 Pa ( 25 ° C)

In water 600 mg · l-1 (20 ° C) in ethanol 130 g · l-1, soluble in many organic solvents

Risk

1 mg · m-3

Template: Infobox chemical / molecular formula search available

2,4-dichlorophenoxyacetic acid ( 2,4-D short ) is a derivative of the phenoxyacetic acid herbicide from the group of synthetic auxins. It was developed in the 1940s by the American Chemical Paint Co. and is structurally related to dichlorprop.

• 4.1 EU

Production and representation

2,4-dichlorophenoxyacetic acid can be obtained by reaction of phenol with chlorine, sodium hydroxide, monochloroacetic acid and hydrogen chloride.

Properties

2,4-dichlorophenoxyacetic acid is somewhat volatile, white odorless solid that is very slightly soluble in water. It is excreted mainly taken when handling through the skin and unmetabolized within days in the urine. With larger doses lead to damage to the nervous system.

Use

Plant protection

2,4-D is used as a herbicide against Dicotyledons in cereals, orchards, grassland and grass. It works especially against buckwheat family, chamomile and thistles. Many of today's approved 2,4-D products are intended for use against weeds in lawns. They contain, among other herbicidal active compounds, often dicamba, and lawn fertilizer.

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

During the Vietnam War were esters of 2,4-dichlorophenoxyacetic acid component of the defoliant Agent Purple and Agent White. The n- butyl ester of 2,4-D and 2,4,5- trichlorophenoxyacetic acid of structurally related (2,4,5 -T) were included Orange in a 1:1 ratio in the defoliant Agent. 2,4-D contains trace amounts of dioxins, however, outweigh the relatively few toxic congeners 2.7 - and 2.8 - Dichlordibenzodioxin Dichlordibenzodioxin. The dioxin exposure to Agent Orange was chiefly driven by 2,4,5 -T, which contained traces of highly toxic congener is 2,3,7,8- tetrachlorodibenzodioxin.

Regulation

EU

The currently valid authorization will expire on 31 December 2015. At national level, 2,4-D is approved in 26 EU countries. The Permitted daily dose is 0.05 and the Acceptable Operator Exposure 0.15 milligrams per kilogram of body weight per day.