Chlorimuron ethyl

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Materials and methods

Principles of method if other than guideline:

0.5 and 5 ppm solutions (pH 5, 7, and 9) of the radiolabeled test substance, with the radiolabel located in the phenyl and pyrimidine moiety of the test substance, were incubated in water for 30 days. Aliquots were removed after 0, 1, 3, 9, 14, 21, and 30 days of incubation. The pH of each aliquot was adjusted to between 3 and 4 with dilute acetic acid. Each acidified aliquot was then extracted three times with 20-mL portions of methylene chloride. The combined methylene chloride extracts were dried over anhydrous magnesium sulfate, filtered, and concentrated to 5 mL under a stream of nitrogen. The extracted, aqueous phase was neutralized with dilute ammonium hydroxide and concentrated to 5 mL under a stream of nitrogen. The radioactivity remaining in the extracted aqueous phase, the combined methylene chloride phase, and the concentrates was measured by liquid scintillation counting (LSC).

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

EC Number:

618-690-2

Cas Number:

90982-32-4

Molecular formula:

C15H15ClN4O6S

IUPAC Name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

Test material form:

solid

Remarks:

White

Details on test material:

95 to >99% purity

Radiolabelling:

yes

Remarks:

The radiolabel was located in the phenyl and pyrimidine moiety of the test substance

Study design

Analytical monitoring:

no

Duration of test

Duration of test 1

Duration:

30 d

pH:

5

Temp.:

25 °C

Initial conc. measured:

0.5 other: ppm

Duration of test 2

Duration:

30 d

pH:

7

Temp.:

25 °C

Initial conc. measured:

0.5 other: ppm

Duration of test 3

Duration:

30 d

pH:

9

Temp.:

25 °C

Initial conc. measured:

0.5 other: ppm

Duration of test 4

Duration:

30 d

pH:

5

Temp.:

25 °C

Initial conc. measured:

5 other: ppm

Duration of test 5

Duration:

30 d

pH:

7

Temp.:

25 °C

Initial conc. measured:

5 other: ppm

Duration of test 6

Duration:

30 d

pH:

9

Temp.:

25 °C

Initial conc. measured:

5 other: ppm

Number of replicates:

1

Positive controls:

no

Negative controls:

no

Results and discussion

Transformation products:

yes

Identity of transformation products

Identity of transformation products 1

No.:

#1

Reference

Reference substance name:

Unnamed

Inventory number:

InventoryMultipleMappingImpl [inventoryEntryValue=EC 611-882-7]

CAS number:

59777-72-9

Identity of transformation products 2

No.:

#2

Reference

Reference substance name:

Unnamed

Inventory number:

InventoryMultipleMappingImpl [inventoryEntryValue=EC 611-506-1]

CAS number:

5734-64-5

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

At pH 5, the major hydrolysis products were 2-(aminosulfonyl)benzoic acid, ethyl ester (63-65% at day 30) and 4-chloro-6-methoxy-2-pyrimidinamine (71-78% at day 30). At pH 7 and pH 9, 6% or less of the original radioactivity was identified as 2-(aminosulfonyl)benzoic acid, ethyl ester, and 11% or less of the original radioactivity was identified as 4-chloro-6-methoxy-2-pyrimidinamine.

Executive summary:

0.5 and 5 ppm solutions (pH 5, 7, and 9) of the radiolabeled test substance, with the radiolabel located in the phenyl and pyrimidine moiety of the test substance, were incubated in water for 30 days. Aliquots were removed after 0, 1, 3, 9, 14, 21, and 30 days of incubation. The pH of each aliquot was adjusted to between 3 and 4 with dilute acetic acid. Each acidified aliquot was then extracted three times with 20-mL portions of methylene chloride. The combined methylene chloride extracts were dried over anhydrous magnesium sulfate, filtered, and concentrated to 5 mL under a stream of nitrogen. The extracted, aqueous phase was neutralized with dilute ammonium hydroxide and concentrated to 5 mL under a stream of nitrogen. The radioactivity remaining in the extracted aqueous phase, the combined methylene chloride phase, and the concentrates was measured by liquid scintillation counting (LSC).

At pH 5 in the dark at 25°C, the radiolabeled test substance hydrolyzed with a first half-life of about 17 and 25 days, respectively for the pyrimidine and phenyl labeled moieties; the half-life was independent of initial concentration. The major hydrolysis products were 2-(aminosulfonyl)benzoic acid, ethyl ester (63 - 65%) and 4-chloro-6-methoxy-2-pyrimidinamine (71 - 78%). Less than 10% of the original radioactivity was found as polar materials. The nature of these polar materials was not investigated.

 

The radiolabeled test substance was stable for 30 days at pH 7 and pH 9 at 25°C. 6% or less of the original radioactivity was identified as 2-(aminosulfonyl)benzoic acid, ethyl ester, and 11% or less of the original radioactivity was identified as 4-chloro-6-methoxy-2-pyrimidinamine. Polar materials constituted less than 10% of the original radioactivity during the exposure period.

 

Total radiolabel recoveries at the end of the 30-day exposure period ranged from 96 to 109% of the original, applied radioactivity, indicating no loss of volatile, radiolabeled compounds.