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Environmental fate & pathways

Hydrolysis

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Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted under GLP conformance according to the procedures outlined in :OECD Guideline No. 111 [1]EEC's Annex V. Part C.7. [2] EPA's Chemical Fate Guidleline, [3] EPA's Pesticide Assessment Guidelines.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Isobutyric anhydride
EC Number:
202-603-6
EC Name:
Isobutyric anhydride
Cas Number:
97-72-3
Molecular formula:
C8H14O3
IUPAC Name:
isobutyric anhydride
Details on test material:
The Hydrolysis testing was performed in eight different matrices, each containing approximately two percent acetonitrile: distilled deionized water (DDW); aquatic culture water (ACW); distilled water buffered at pH 4, 7 and 9; aquatic culture water buffered at pH 4, 7 and 9. Each matrix contained 1 percent by volume of acetonitrile prior to the introduction of the test substance.
A test substance stock solution was prepared by weiging approximately 1.0 gram of the test substance into 10-ml volumetric flasks and diluting with acetonitrile. The working test sytems were prepared at aproximately 1000 mg/L. Each test system was prepared in triplicate.











































































Study design

Analytical monitoring:
yes
Details on sampling:
The working test systems were prepared at approximately 1000 mg/L by trasnferring 0.5 mls of the test substance stock solution into a labeled 50 ml volumetric flask containing approximately 45 ml of a the matrix of study, adjusted to the desired pH. Each flask wasthen diluted to volume with the appropriate solvent. Aliquots of the test solutions were distributed between several GC vials and each was analyzed as is using GC/FID.
Buffers:
ph4 Buffer- (.01 M Sodium Acetate in water with 1% Acetonitrile)
pH7 Buffer- (0.1 M Potassium Phosphate dibasic anhydrous in water with 1% acetonitrile)
pH 9 Buffer- (0.025 M Sodium Borate in water, with 1% acetonitrile
Details on test conditions:
Test temperature was maintained at 22 C throughout the analysis. Time was measure using a hand timer.
Number of replicates:
3 replicates per matrix run.

Results and discussion

Transformation products:
yes
Identity of transformation products
No.:
#1
Reference
Reference substance name:
Unnamed
IUPAC name:
2-methylpropanoic acid
Inventory number:
InventoryMultipleMappingImpl [inventoryEntryValue=EC 201-195-7]
CAS number:
79-31-2
Identity:
Propanoic acid, 2-methyl-
Molecular formula:
C4H8O2
Molecular weight:
88.105
SMILES notation:
CC(C)C(=O)O
InChl:
InChI=1/C4H8O2/c1-3(2)4(5)6/h3H,1-2H3,(H,5,6)
Details on hydrolysis and appearance of transformation product(s):
In every analysis, the isobutyric anhydride hydrolyzed completely to isobutyric acid.
Dissipation DT50 of parent compoundopen allclose all
pH:
7
Temp.:
22 °C
Hydrolysis rate constant:
0.086 - 0.097 min-1
DT50:
7.18 - 8.05 min
Type:
not specified
Remarks on result:
other: Distilled Deionized Water
pH:
7
Temp.:
22 °C
Hydrolysis rate constant:
0.037 - 0.04 min-1
DT50:
17.3 - 18.9 min
Type:
not specified
Remarks on result:
other: Aquatic Culture Water
pH:
4
Temp.:
22 °C
Hydrolysis rate constant:
0.034 - 0.067 min-1
DT50:
10.4 - 20.4 min
Type:
not specified
Remarks on result:
other: distilled Deionized Water
pH:
7
Temp.:
22 °C
Hydrolysis rate constant:
0.078 - 0.132 min-1
DT50:
5.27 - 8.9 min
Type:
not specified
Remarks on result:
other: Distilled deionized water
pH:
9
Temp.:
22 °C
Hydrolysis rate constant:
0.361 - 0.372 min-1
DT50:
1.86 - 1.92 min
Type:
not specified
Remarks on result:
other: Distilled Deionized Water
pH:
4
Temp.:
22 °C
Hydrolysis rate constant:
0.034 - 0.041 min-1
DT50:
14.5 - 20.6 min
Type:
not specified
Remarks on result:
other: Aquatic Culture Water
pH:
7
Temp.:
22 °C
Hydrolysis rate constant:
0.077 - 0.104 min-1
DT50:
6.64 - 9.04 min
Type:
not specified
Remarks on result:
other: Aquatic culture Water
pH:
9
Temp.:
22 °C
Hydrolysis rate constant:
0.3 - 0.377 min-1
DT50:
1.84 - 2.31 min
Type:
not specified
Remarks on result:
other: Aquatic Culture Water

Applicant's summary and conclusion

Executive summary:

A abiotic hydrolysis study was conducted to determine the stability of the test article in water. Isobutyric anhydride was added to vials containing double distilled water, aquatic culture water, or buffered double distilled water. Half-lives in the various media ranged from 1.8 to 20.6 minutes. In buffered solutions of pure water at neutral pH, the half life was 5.2 -8.9 minutes.

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