
fatty acid were converted by f8-oxidation to products with an even number of 
carbons (580, 588, 864, 1467, 1468, 1469). A second mechanism involved 
cleavage of the ether linkage (50, 131, 225, 915, 916, 918). 
Evidence has been obtained that 2,4-D is dissimilated by a variety 
of microorganisms (16, 1205) through 2,4-dichlorophenol and 4-chlorocatechol 
(48). A product from the degradation of 2,4-D by bacteria of the genus 
Pseudomonas has been identified as f-chloromuconic acid. A second species 
of Pseudomonas gave rise to o-chloromuconic acid (449). In other studies, 
6-hydroxy-2,4-D was reported (894). Pure cultures of a Nocardia species 
and an Achromobacter strain of bacteria rapidly degraded 2,4-D and the 
presence of 2,4-dichlorophenol, chlorohydroquinone, a monochlorophenol, 
an unchlorinated phenol and three other unidentified compounds have been. 
demonstrated (46, 101, 102, 438, 1083, 1350, 1351, 1392). The main product 
of 2,4-D metabolism by the mold Aspergillus niger van Tiegh was 2,4-dichloro- 
‘ 5-hydroxyphenoxyacetic acid. By means of infrared and mixed melting points, 
a second metabolite was identified as the 2,5-dichloro-4-hydroxyphenoxy- 
‘ acetic acid--the first time such a rearrangement was reported. Another 
unidentified acid, not the 3- or 6- hydroxyacid, was also found (439, 440). 
Arthrobacter sp. degraded 2,4-D via 2,4-dichlorophenol and 2,4-dichloroanisole 
(895, 896). In excess of 804 of the chloride was released in a 3 hour 
incubation period with crude extracts or the soluble fraction (894). A 
Corynebacterium species also degraded 2,4-D with quantitative release of 
chloride (1235). In natural surface waters, 2,4-D isopropyl and butyl 
P esters were hydrolyzed to 2,4-D and their respective alcohols (18). When 
triethanolamine salts of c14_carboxy labeled 2,4-D were applied in water to 
forest litter, liberation of C!"0, was rapid (1086). 
In the presence of water and ultraviolet light, 2,4-D decomposed rapidly 
with formation of 2,4~dichlorophenol. This underwent further decomposition 
to 4-chlorocatechol, polymeric humic acids and chloride. Some 2-hydroxy- 
4-chlorophenoxyacetic acid and a very small amount of 2-chloro-4-hydroxy 
phenoxyacetic acid were present (317, 611, 1434, 1435). In the presence of 
riboflavin, compounds containing more than one aromatic nucleus were probably 
also formed in addition to 2,4-dichlorophenol. Products differed according 
to the original pH and concentration of the treated solution (100, 611). 
113 
