1,4-D 2,4-dichlorophenoxyacetic

Herbicide Glasses and Databases. Herbicides can be classified as selective and nonselective. Selective herbicides, like 2,4-D (2,4-dichlorophenoxyacetic acid), metolachlor [51218-45-2] and EPTC [759-94 ] are more effective against some types of plants than others, eg, broadleaved plants vs grasses. Glyphosate [1071 -83-6] is representative of the nonselective herbicides used for total vegetable control. 

Phenoxyacids (PA) have been widely used as herbicides in agriculture, forestry, and, to a lesser extent, garden activities. The principal products are represented by 2,4-D (2,4-dichlorophenoxyacetic acid) 2,4,5-T (2,4,5-trichlo-rophenoxyacetic acid) and MCPA (4-chloro, 2-methylphenoxyacetic acid) (Stevens and Sumner, 1991). 2,4,5-T has been banned in many countries for a long time because of contamination of the commercial formulations of 2,4,5-T by 2,3,7,8-tetrachlorodibenzodioxin. At present, dioxin contamination of these formulations has been reduced to very low concentrations. 

ATPase, adenosine triphosphatase GABA, -y-aminobutyric add 2,4-D, 2,4-dichlorophenoxyacetic acid 2,4,5-T, 2,4,5-trichlorophenoxyacetic acid. 

US Environmental Protection Agency (2005) 2, 4-D (2,4-Dichlorophenoxyacetic Acid) Reregistration Eligibility Decision (RED) Document, document number EPA 738-R-05-002, US Environmental Protection Agency Office of Prevention, Pesticides and Toxic Substances, Washington, DC. 

Dicblorophenol, hexagonal ndls (from benz), mp 43°, bp 2o6-08°at 753 mm press, vol with steam forms some unstable salts most important use is in the manuf of 2,4 D (2,4-dichlorophenoxyacetic acid), a powerful plant-growth regulator (Refs 2 6)... 

T (2,4,5-trichlorophenoxyacetic acid) ester formulation to a complex mixture of successively less-chlorinated phenoxyacetic esters, and Que Hee, et al. (16) reported a similar dechlorination of 2,4-D (2,4-dichlorophenoxyacetic acid). The toxic 2,4,5-T impurity, TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), was dechlo-rinated in a herbicide ester deposit on a sunlit leaf surface within a few hours (Figure 5) (17). 

Fig. 19.7 TOC decay with total charge passed during the mineralization of 125 cm3 of an 02-saturated 220 mg dm 3 2,4-D (2,4-dichlorophenoxyacetic acid) solution with ImM Fe3+ in H2SO4 of pH 2 at room temperature in the cathodic compartment of a divided Pt/carbon felt cell at Ecm = —0.5V vs. SCE giving a current of 60 mA [adapted from Oturan (2000)]...

We can apply these ideas to the synthesis of the herbicide 2,4-D (2,4-dichlorophenoxyacetic add). The most reasonable disconnection of an ether is the C-0 bond because we know that ethers can be made from alkyl halides by substitution with an alkoxide anion. We don t at this stage need to decide exactly which alkyl halide or alkoxide to use, so we just write the synthons. 

D (2,4-dichlorophenoxyacetic acid) is a systemic herbicide used to control broad-leaf weeds. It undergoes both chemical and biological degradation in the environment and usually does not accumulate. According to the EPA, 2,4,-D has been detected in surface and groundwaters. It has been classified in the EPA s Group D (not classifiable). 

Abbreviations 2,4,-D 2,4-dichlorophenoxyacetic acid 2,4,5-T tiichlorophenoxyacetic acid BTEX benzene, toluene, ethylbenzene, xylenes PAH polycyclic aromatic hydrocarbons. 

Dichlorophenol, hexagonal ndls (from benz), mp 43° bp 2o6-08°at 753 mm press, vol with steam forms some unstable salts most important use is in the manuf of 2,4" D (2,4-dichlorophenoxyacetic acid), a powecful plant-growth regulator (Refs 2 6) 2,5-Dichlorophenol, crysts (from benz), mp 59° bp 209 11° volatile with steam of no coml importance (Refs 3 6) 2,6 Dichlorophenol, crysts (from petr eth), mp 66-68°, bp 220°, volatile with steam no Coml application (Refs 4 8c 6) 3,4 f it hloropkenol, ndls (from petr eth) mp 64-66°, bp 145-46° volatile with steam no coml utility (Refs 5 6)... 

In addition to its use in making resins and adhesives, phenol is also the starting material for the synthesis of chlorinated phenols and the food preservatives BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole). Fenta-chlorophenol, a widely used wood preservative, is prepared by reaction of phenol with excess CI2. T he herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) is prepared from 2,4-dichlorophenol, and the hospital antiseptic agent hexa-chlorophene is prepared from 2,4,5-trichlorophenol. 

D (2,4-dichlorophenoxyacetic acid) patented as a plant growth regulator and later as a general herbicide dithiocarbamate fungicide marketed... 

---