Table 2.1
Physico-chemical properties of the model pesticides
Pendimethalin (40487-42-1)
Ioxynil (1689-83-4)
Bentazone (25057-89-0)
Structure
NH
N+
O
-O
N+
O
O-
OH
I
N
I
N
S
H
N
O
O
O
Molecular weight [g/mole]
281.3
371.8
240.3
Vapour pressure [mPa]
4.0 (25°C)
0.68 (25°C)
0.17 (20°C)
Aqueous solubility [mg/L]
0.3 (Tomlin, 1994)
50 (25°C) (Tomlin, 1994)
570 (20°C, pH 7) (Tomlin,
1994)
Kow [L (water)/L (oct.)]
158489
2691* (Syracuse research
corporation, 2000)
219*
(Syracuse research
corporation, 2000)
Koc [L (water)/ kg (oc)]
13400 (United States department of
agriculture, 2001) (pH 6.4)
182-276 (pH 7.3-6.7)
35 (United States department
of agriculture, 2001), 42-155
(pH 7.7-6.6)
pKa
3.96 (Tomlin, 1994)
2.92 (Syracuse research
corporation, 2000), 3.3
(Tomlin, 1994)
KH [atm m3/mole]
8.56 10-7
7.11 10-10
KH' [L(water)/L(air)]
3.56 10-5
Fenpropimorph (67306-03-0)
Glyphosate (1071-83-6)
Structure
Molecular weight [g/mole]
303.5
169.1
Vapour pressure [mPa]
2.3 (20°C)
0.04
Aqueous solubility [mg/L]
4.3 (pH 7)
12000 (25°C)
Kow [L (water)/L (oct.)]
24475 (pH9) 11441 (pH 7)
395 (pH 5)
0.00000381 (pH 4.3)
Kod [L (water)/kg (soil)] (%OC)
22.6-73.7 (0.51-2.66)
(pH 7.0-7.3)
22-205
pKa
6.98
2.74, 5.63, 10.18
*
Is considered to be for the neutral form although not specified in the source. Unless where specified, data are from Danish EPA (2002).
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