Chemical |
Lenacil |
CAS-number : |
2164-08-1 |
|
Synonyms : |
1H-Cyclopentapyrimidine-2,4(3H,5H)-dione, 3-cyclohexyl-6,7- dihydro- |
3-cyclohexyl-1,5,6,7-tetrahydrocyclopentapyrimidine-2,4-(3H)- dione |
3-cyclohexyl-5,6-trimethyleneuracil |
3-cyclohexyl-6,7-dihydro-1H-cyclopentapyrimidine-2,4(3H,5H)-dione |
Lenasiini |
Venzar *. |
|
Sumformula of the chemical : |
C13H18N2O2
|
EINECS-number : |
2184990 |
|
Uses : |
Active ingredient in herbicides.
|
|
State and appearance : |
White, crystalline solid.
Wettable powder (Venzar *)
(PESREG)
|
|
Odor : |
Odorless (PESREG)
|
|
Molecular weight : |
243.3 |
|
Water solubility, mg/l : |
6 |
at 25°C, PESREG |
|
Melting point, °C : |
315.5 |
315.5 - 316.8 °C |
316.8 |
PESREG |
|
Log octanol/water coefficient, log Pow : |
2.3 |
2.30 - 2.31 |
2.31 |
PESREG |
|
Mobility : |
The leaching behaviour of (C-14) lenacil was studied in the
soil columns.
% of the applied radioactivity percolated through the columns
in 50 cm of water:
________________________________________________________________
sandy loam soil silty loam soil
________________________________________________________________
freshly treated soil 86 0.52
aged (30 days) soil 9.3 1.0
________________________________________________________________
(PESREG)
Rf-values of lenacil on soil plates were 0.46 (sandy loam),
0.41 (sand) and 0.21 - 0.37 (silt loam) (PESREG).
|
|
Other physicochemical properties : |
Solubility in organic solvents (g/100 g) at 25 °C:
dimethylformamide: 0.8
buthylacetate: 0.4
cyclohexanone: 0.4
xylene: 0.2
(PESREG)
|
|
Photochemical degradation in water : |
Aqueous solutions of (C-14) lenacil were irradiated with
simulated sunlight in a photo-reactor.
About 85-90% was still
present after an irradiation period of 30 days (PESREG).
|
|
Hydrolysis in acid : |
The half-life of lenacil (6 ppm) was >169 hours at pH 2
(PESREG).
|
|
Hydrolysis in base : |
The half-life of lenacil (6 ppm) was >169 hours at pH 12
(PESREG).
|
|
Aerobic degradation in soil : |
Approximately 50% of 2-(C-14)-lenacil (2.3 ppm and 11.5 ppm)
degraded to 14CO2 within 12 months under aerobic (silt loam
soil) conditions.
The half-life of intact (C-14) lenacil was to
be approximately 3 months, and degradation was shown to be
induced by microorganisms, since minimal 14CO2 production was
observed in the sterile soil systems.
Three metabolites
3-cyclohexyl-6,7-dihydro-7hydroxy-1H-cyclopentapyrimidine-2,4
(3H,5H)-dione,
3-cyclohexyl-5,6-dihydro-7H-cyclopentapyrimidine-2,4,7(1H,3H)-
trione and
6,7-dihydro-3-(4-hydrocyclohexyl)-5H-cyclopenta(D)pyrimidine-2,4
(1H,3H)-dione (PESREG).
|
|
Degradation and transformation products : |
3-cyclohexyl-6,7-dihydro-7hydroxy-1H-cyclopentapyrimidine-2,4
(3H,5H)-dione;
3-cyclohexyl-5,6-dihydro-7H-cyclopentapyrimidine-2,4,7(1H,3H)-
trione;
6,7-dihydro-3-(4-hydrocyclohexyl)-5H-cyclopenta(D)pyrimidine-2,4
(1H,3H)-dione (PESREG).
|
|
LD50 values to mammals in oral exposure, mg/kg : |
4000 |
>4000, orl-gpg male, PESREG |
|
LD50 values to mammals in non-oral exposure , mg/kg : |
5000 |
>5000, idr-rat albino, PESREG |
|
LC50 values to mammals in inhalation exposure, mg/m3 : |
5200 |
>5.2 mg/m3, 1hr, ihl-rat male, PESREG |
|
Subacute LC50 values to birds in feeding ex posure, mg/kg : |
5620 |
>5620, 5d+3d, Peking duck |
2300 |
5d+3d, Coturnix virginianus |
|
PESREG |
|
Effects on invertebrates : |
Filter paper test: LC50, 0.427 mg/cm2, 48hr, Eisenia foetida
Artificial soil test: LC50, >10000 mg/kg, 14d, Eisenia foetida
OECD No 207, PESREG
|
|
Effects on microorganisms : |
Venzar (10-50 ppm, incubation 72hr) had no effect to the growth
of Azotobacter chroococcum (Pietr 1981).
|
|
EC50 values to algae, mg/l : |
0.012 |
72hr, EbC50, grw ihb |
0.014 |
120hr, EbC50, grw ihb |
0.015 |
24 - 48 hr, ErC50, grw ihb |
|
Selenastrum capricornutum |
|
EPA, OECD No 201, PESREG |
|
NOEC values to algae, mg/l : |
0.01 |
120hr, Selenastrum capricornutum |
|
EPA, OECD No 201, PESREG |
|
EC50 values to crustaceans, mg/l : |
8.4 |
>8.4 mg/l, 48hr, imb, Dapnia magna |
|
GLP, OECD No 202, PESREG |
|
-- |
1.2 |
21d, imb, Daphnia magna |
1.1 |
21d, rpd, Daphnia magna |
|
GLP, OECD No 202, PESREG |
|
-- |
33 |
48hr, imb, Daphnia magna |
|
EPA, OECD No 202, PESREG |
|
LOEC values to crustaceans, mg/l : |
0.97 |
21d, Daphnia magna |
|
GLP, OECD No 202, PESREG |
|
NOEC values to crustaceans, mg/l : |
0.48 |
21d, Daphnia magna |
|
GLP, OECD No 202, PESREG |
|
-- |
5.6 |
48hr, imb, Daphnia magna, PESREG |
|
LC50 values to fishes, mg/l : |
10 |
96hr, Cyprinus carpio |
|
Pesticide Manual 1983 |
|
-- |
257 |
48hr, Salmo gairdneri |
135 |
96hr, Salmo gairdneri |
100 |
100 |
1000 |
Lepomis macrochirus |
|
PESREG |
References |
70 | Anon. 1983c.
Pesticide Manual.
Worthing, C.R.
(toim.)
A world compedium.
The British Crop Biotection Council.
London. 7 th edition. |
2779 | PESREG.
Application for registration of pesticides accepted by
the Pesticide Commission, National Board of Waters and the
Environment, Chemical Control Unit.
|
2783 | Pietr, S.
J. 1981.
Herbicidal effect on some metabolic
processes of Azotobacter chroococcum.
Acta Microbiologica
Polonica, Vol 30(2): 173 - 182. |