Chemistry Reference
In-Depth Information
taBLe 12.1
Properties of Some Pyrethroid Insecticides
water Solubility
μg/mL @ 20 or 25°c
Vapor Pressure
#Pa @ 20 or 25°c
compound
log
K
ow
Permethrin
(racemate)
0.2
6.5
1.3 × 10
−6
Cypermethrin
(racemate)
0.009
6.3
1.9 × 10
−7
alpha Cypermethrin
(2 cis isomers)
0.005-0.01
5.16
1.7 ×10
−7
Deltamethrin
<0.002
5.43
2 × 10
−6
Fenvalerate
0.002
6.2
3.7 × 10
−5
Note:
#1 Pascal (Pa) = 0.0075 torr (i.e., mms of Hg).
Source:
Data from Environmental Health Criteria 82, Environmental Health Criteria 94,
Environmental Health Criteria 95, Environmental Health Criteria 97, and Environmental
Health Criteria 142.
CH
3
CH
3
C
O
CH
2
O
Cl
Cl
trans
-Permethrin
CCH
O
2
O
2
H
2
O
OH
CH
3
CH
3
CH
3
CH
2
OH
C
O
CH
2
C
O
CH
2
O
O
2
1
Cl
Cl
Cl
Cl
O
O
H
2
O
CCH
CCH
H
2
O
CH
3
CH
2
OH
CH
3
CH
3
C
OH
C
OH
Cl
Cl
Cl
Cl
O
O
HO
CH
2
O
CCH
3
5
CCH
4
O
2
OH
O
2
HO
CH
2
O
6
HO
C
O
7
O
fIgure 12.2
The metabolism of
trans
-permethrin.
different forms of cytochrome P450 and yields metabolites with hydroxyl groups sub-
stituted in both the acidic and basic moieties. The principal metabolites formed by
primary oxidation are compounds 1 and 2 in the figure. Hydroxylation occurs on a
methyl group of the acid moiety and on a free para ring position in the basic moiety.
Esteratic hydrolysis of permethrin yields metabolites 4 and 5. Metabolite 4 is a base,
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