In sandy loam soil, dimethoate has half life of 2 1/2 days, where 
moderate rainfall occurs following application, to approximately 4 days 
during drought conditions (135). 
Dimethoate rapidly hydrolyzed in alkali (pH 11). Ina half hour, 
approximately 50% of the dimethoate was degraded to water-soluble materials, 
predominantly desmethyl dimethoate (49.3%) 0,0-dimethylphosphoric acid (32.8%), 
the carboxy derivative (9.5%), and some 0,0-dimethyl phosphorodithioic acid 
(<0.1%) (167). In air the hydrolysis product thioacetamide was oxidized to 
the corresponding disulfide (1266). | 
= 
CH, 0 y S-CH 5 N-CH 
Er (eae uae rae 
CH, H 
Dimethoate 
Air H0 | 
(Slowly) | 
0 
CHO. p CH 3°N NI 
-S-CH,-C-W-CH, yin OH+HS- CH, - -Y-CH, 
CHO H CH ell H 
3 
air 
[0] 
_ CH, 
H 
H 
-CH, -C-N- -CH., 
iT 
0 
When dimethoate was stored at 48 - 52°C in a pure state or in 
commercial concentrates, it lost potency because of hydrolysis, even in 
glassware. In galvanized containers the loss was apparent at 18 - 26°C. 
Hydrolysis affected the SCH. and PS bonds (1280). 
164 
