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Data bank of environmental chemicals     |     The Finnish Environment Institute (SYKE)
 


29.3.2024

Data bank of environmental properties of chemicals


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 :
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
70Anon. 1983c. Pesticide Manual. Worthing, C.R. (toim.) A world compedium. The British Crop Biotection Council. London. 7 th edition.
2779PESREG. Application for registration of pesticides accepted by the Pesticide Commission, National Board of Waters and the Environment, Chemical Control Unit.
2783Pietr, S. J. 1981. Herbicidal effect on some metabolic processes of Azotobacter chroococcum. Acta Microbiologica Polonica, Vol 30(2): 173 - 182.

 
 
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