} 
2,4-D and Related Compounds 
2,4-D 2,4,5-T 4—-(3-CPB) 
2,4-DB 2,4,5-TP 4-(4-CPB) 
4-(2,4-DB) 2-CPA 3-(2,4,5-TB) 
MCPA 4-CPA 4-(2,4,5-TB) 
MCPB 4—(2-CPB) Phenoxyacetic Acid 
2,4,6-T 
2,4-D[2,4-Dichlorophenoxyacetic acid] 
In feeding studies of 2,4-D with dairy cows and steers, (65, 67, 582, 
583, 887) 2,4-D was found unchanged in the urine only. No evidence of beta- 
oxidation was found. Similar findings were obtained with sheep. Ninety-six 
percent of an orally administered dose of 2,4-D-c!4 to a sheep was excreted 
unchanged in the urine in 72 hours and slightly less than 1.4% in the feces. 
Very little residual radioactivity was found in edible tissue (281). 
In rats receiving 1 to 10 mg of 2,4-D, there was almost complete 
excretion of the herbicide in the urine and feces in 48 hours. At higher 
dosage levels, some accumulation in tissues occurred. Analyses also in- 
dicated that traces of an unidentified metabolite appeared in the urine 
(785). 
After exposure of bean plants (Phaseolus), sun flowers (Helianthus 
annus), maize (Zea mays) or barley (Hordeum) to 2,4-D, 2,4-dichlorophenol 
was observed (1559). 
Hydrolysis of esters (311, 1040) and decarboxylation (93, 396, 1181) 
of 2,4-D by plants has also been shown. The free acid has been demonstrated 
on bean plants, corn plants and forage after treatment with 2,4-D 
butoxyethanol, propylene glycol butyl, butyl and 2-ethylhexyl esters (423, 
431, 600, 634, 802). Treatment of lemons with C!* labeled 2,4-D isopropyl- 
ester indicated that the ester was hydrolyzed and that part of the 2,4-D 
then reacted with some plant constituent to form an ester-like complex. 
Ester-like residues were also found after treatment with the sodiun, 
diethanolamine, or triethanolamine salts (413, 414). Samples of fresh 
citrus peel were prepared by compositing peel samples obtained from oranges 
from trees sprayed with 2,4-D isopropyl ester. In addition to free acid 
and ester, a conjugate was also found. The latter became available for 
extraction only after heat treatment. Preliminary investigations indicated 
that 2,4-D was conjugated with pectin (966). 
109 
