Ureas 
Ureas were inactivated by the action of ultraviolet light (743, 744, 
1482, 1483) and by reaction with FMN in plants (1379). After exposure of 
N'-(4-chlorophenoxy)-phenyl-N,N-dimethylurea to ultraviolet radiations, 
thin-layer chromatography revealed small amounts of the mono- and demethyl- 
ated derivatives (532). 
Degradation by soil microorganisms apparently appeared to be the pri- 
mary cause for disappearance of the urea herbicides (656, 1205). Some 
studies showed that ureas were demethylated step-wise and degraded to the 
aniline derivative (143, 333, 532, 1170). 
A microsomal mixed function oxidase, which successively demethylates 
N,N-dimethylphenylurea herbicides, was isolated from etiolated cotton 
seedling hypocotyl and leaves of cotton, plantain, buckwheat, wild buck- 
wheat and broadbeans. The enzyme requires NADPH or NADH and oxygen. 
Optimum pH is 7.4 to 7.8. The N-demethylated substrate and formaldehyde 
were identified by TLC and mass spectra. Diuron, fluometuron, monuron 
and monomethylmonuron were studied (1758). 
Diuron [3-(3,4-dichloropheny1)-1,1-dimethylurea] 
In rats and dogs fed diuron, excretion of metabolites occurred in both 
feces and urine. N-(3,4-dichlorophenyl)urea was predominant in urine but N- 
(3,4-dichlorophenyl)-N'-methylurea, 3,4-dichloroaniline and 3,4-dichloro- 
phenol were also detected (674). 
After feeding diuron to albino rats, N-(3,4-dichlorophenyl)urea, 
N-(3,4-dichlorophenyl)-N'-methylurea and 3,4-dichloroaniline were found in 
the free state. 2-Acetamido-4,5-dichlorophenol, 6-acetamido-2 ,3-dichloro- 
phenyl, and N-(2-hydroxy-3,4-dichlorophenyl)-N'-methylurea were found only 
in the bound form. 2-Amino-4,5-dichlorophenol, N-(2-hydroxy-4,5-dichloro- 
phenyl)urea, N-(2-hydroxy-4,5-dichlorophenyl)-N'-methylurea, and N-(2-hydroxy- 
Spares Ti) were found free and bound as glucuronides or sulfates 
eee), 
337 
