2 :4-Dichlorophenoxyacetates

Dichlorophenoxyacetates. Amino acids react with 2 chlorophenoxyacetyl chloride to give crystalline derivatives ... 

Commercial 2 4-dichlorophenoxyacetic acid may be recrystallised from benzene m.p. 139-140°. Reflux 10 g. of the acid with 15 ml. of thionyl chloride on a steam bath for 1 hour, distil off the excess of thionyl chloride at atmospheric pressure and the residue under reduced pressure 2 4-dichlorophenoxyacetyl chloride (8 g.) passes over at 155-157°/22-23 mm. It occasionally crystallises (m.p. 44-5-45-5°), but usually tends to remain as a supercooled liquid. 

Certain natural products have been used as experimental templates upon which to constmct marketable products eg, 2,4-dichlorophenoxyacetic acid which was conceived from the indole ring. 

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. 

WHO, Environmental Health Criteria 84 2,4-Dichlorophenoxyacetic Hcid (2,4-D)-EnvironmentalHspects, Wodd Healtli Organization, Geneva, 1989. 

Dichlorophenols. Among all the dichlorophenols, C H Cl O, it is 2,4-dichlorophenol that is produced in greatest quantity. 2,4-Dichlorophenol is used in manufacturing 2,4-dichlorophenoxyacetic acid [94-75-7] (2,4-D) and 2-(2,4-dichlorophenoxy)propionic acid [720-36-5] (2,4-DP). Industrially, 2,4-dichlorophenol can be obtained by chlorinating phenol, -chlorophenol, o-chlorophenol, or a mixture of these compounds in cast-iron reactors. The chlorinating agent may be chlorine or sulfuryl chloride in combination with a Lewis acid. For example ... 

Dichlorophenoxyacetic acid (2,4-D) is a selective effect herbicide of widely applied for annihilation of bichromatic weeds in sowings of gramineous cultures. 

Chemical Designations - Synonyms Butoxyethyl 2,4-Dichlorophenoxyacetate Butyl 2,4-Dichlorophenoxyacetate 2,4-Dichlorophenoxyacetic Acid, Butoxyethyl Ester 2,4-Dichlorophenoxyacetic Acid, Isopropyl Ester Isopropyl 2,4-Dichlorophenoxy Acetate Chemical Formula 2,4-Cl2C H30CH2C00R, where R=C4H9, CjH, or CH2CH2OC4H9. 

Of agricultural importance is the plant-growth regulating activity of 6,8-dichloro-2-methyl-3-carboxymethyl-4(3H) quinazolinone which was as potent as 2,4-dichlorophenoxyacetic acid in the Lepidium test. 4-Hydroxy-5,6,7,8-tetrahydroquinazoline has been patented with reference to fungicidal activity. 

Figure 13.11 Column-switcliing RPLC trace of a surface water sample spiked with eight chlorophenoxyacid herbicides at the 0.5 p-g 1 level 1, 2,4-dichlorophenoxyacetic acid 2, 4-chloro-2-methylphenoxyacetic acid 3, 2-(2,4-diclilorophenoxy) propanoic acid 4, 2-(4-cliloro-2-methylphenoxy) propanoic acid 5, 2,4,5-trichlorophenoxyacetic acid 6, 4-(2,4-dichlorophenoxy) butanoic acid 7, 4-(4-chloro-2-methylphenoxy) butanoic acid 8, 2-(2,4,5-tiichlorophenoxy) propionic acid. Reprinted from Analytica Chimica Acta, 283, J. V. Sancho-Llopis et al., Rapid method for the determination of eight chlorophenoxy acid residues in environmental water samples using off-line solid-phase extraction and on-line selective precolumn switcliing , pp. 287-296, copyright 1993, with permission from Elsevier Science.

TJesticides derived from chlorinated phenols (Table I) are among the most prominent of those currently in worldwide use. Several major herbicides have been applied in large quantities in subtropical locations. Cahfornia used more than 1,200,000 pounds of 2,4-dichlorophenoxyacetic acid (2,4-D) and its derivatives in 1970 (I) Hawaii consumed some 465,000 pounds of pentachlorophenol (PCP) in 1968 (2), and the amount of combined butyl esters of 2,4-D and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) released in one area of Cambodia during two months of 1969 was estimated to exceed 77,000 pounds (3). 

A medium of Linsmayer Skoog (8) supplemented with 0.2 mg/L 2.4-dichlorophenoxyacetic acid as a growth regulator was used for the growth of cell suspension The cultivation was carried out in Erlenmayer flasks with 1/5 net volume on a shaker (11.6 rad/s) in the dark, at 26 - 28°C. In compliance with the nature of the experiment, flasks of different size were used 100 - 1000 cm, and the duration of the cultivation was 5 days for growing the inoculum and 12 days for studying the time course of growth. 

FIGURE 1.13 Transformation products from (a) chlorobenzene, (b) 2,4-dichlorophenoxyacetate, (c) pentachlorophenol. 

Sun Y, JJ Pignatello (1993) Organic intermediates in the degradation of 2,4-dichlorophenoxyacetic acid by Fe YHjOj and Fe YHjOj/UV. J Agric Food Chem 41 1139-1142. 

James MO, JR Bend (1976) Taurine conjugation of 2,4-dichlorophenoxyacetic acid and phenylacetic acid in two marine species. Xenobiotica 6 393-398. 

Don RH, AJ Wightman, HH Knackmuss, KN Timmis (1985) Transposon mutagenesis and cloning analysis of the pathways of degradation of 2,4-dichlorophenoxyacetic acid and 3-chlorobenzoate in Alcaligenes eutrophus JMP134 (pJP4). J Bacterial 161 85-90. 

Fukumori F, RP Hausinger (1993b) Purification and characterization of 2,4-dichlorophenoxyacetate/a-keto-glutarate dioxygenase. J Biol Chem 268 24311-24317. 

Matheson VG, LJ, Forney, Y Suwa, CH Nakatsu, AJ Sextone, AJ, WE Holben (1996) Evidence for acquisition in nature of a chromosomal 2,4-dichlorophenoxyacetic acid/a-ketoglutarate dioxygenase gene by different Burckholderia spp. Appl Environ Microbiol 62 2457-2463. 

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