Registration Dossier

Diss Factsheets

Environmental fate & pathways

Hydrolysis

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 March 1989 to 12 November 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes
Radiolabelling:
yes
Analytical monitoring:
yes
Details on sampling:
Test conducted using individual samples contained in sealed brown glass tubes (10 mL). Sampling intervals determined in a pre-test and dependent on pH.
Buffers:
pH 5 buffer - 0.01M acetic acid + 0.01M sodium acetate
pH 7 buffer - 0.01M disodium hydrogen phosphate + 0.007M potassium dihydrogen phosphate
pH 9 buffer - 0.011M disodium tetraborate + 0.004M potassium dihydrogen phosphate
Experiment also conducted at pH 1 and pH13 using 0.1M HCl and 0.1M sodium hydroxide, respectively.
Estimation method (if used):
Data analysed assuming first-order kinetics. Half-life calculated using t1/2 = ln2/k.
Duration:
24 h
pH:
1
Temp.:
70.5 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
208 h
pH:
1
Temp.:
51 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
26 d
pH:
1
Temp.:
1.5 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
9 d
pH:
5
Temp.:
70.5 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
427 h
pH:
5
Temp.:
51 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
30 d
pH:
5
Temp.:
25.2 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
70 h
pH:
7
Temp.:
70.5 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
96 h
pH:
7
Temp.:
51 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
26 d
pH:
7
Temp.:
19.5
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
150 min
pH:
9
Temp.:
70 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
1 035 min
pH:
9
Temp.:
51 °C
Initial conc. measured:
ca. 0.4 other: ppm
Duration:
196 h
pH:
9
Temp.:
25.2 °C
Initial conc. measured:
ca. 0.4 other: ppm
Transformation products:
yes
No.:
#1
Details on hydrolysis and appearance of transformation product(s):
identity of transformation product: [(5-chloroquinolin-8-yl)oxy]acetic acid; CAS#: 88349-88-6; company code CGA153433
% Recovery:
> 93.9 - < 117
pH:
1
Temp.:
50 °C
Duration:
> 0.1 - < 96 h
% Recovery:
> 94.3 - < 100.6
pH:
7
Temp.:
70 °C
Duration:
> 0.1 - < 24 h
pH:
1
Temp.:
20 °C
DT50:
29.8 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: r = > 0.98
pH:
5
Temp.:
20 °C
DT50:
4.4 yr
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: r = > 0.99
pH:
7
Temp.:
20 °C
DT50:
133.7 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: r = 1.00
pH:
9
Temp.:
20 °C
DT50:
6.6 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: r = > 0.98
pH:
13
Temp.:
25 °C
DT50:
< 5 min
Remarks on result:
other: r = 0.997
Validity criteria fulfilled:
yes
Conclusions:
The substance hydrolyses relatively slowly at pH 7 and 20 °C, with an estimated half-life of about 133.7 days. Hydrolysis is faster under basic conditions and slower under acidic conditions.
Executive summary:

The hydrolysis of the substance was studied under GLP to OECD TG 111. Radiolabelled test material was used in the study at an inital concentration of about 0.4 ppm. Studies were conducted at various pH values of 1, 5, 7, 9 and 13, and test vessels were kept at intended environmental temperatures of 25, 50 and 70 °C. In strongly alkaline solution de-esterification was very rapid, slower at slightly alkaline pH and very slow in the range of pH 5 to 7. The following half-lives at 20 °C were derived from the experimental data: pH 1 = 29.8  days, pH 5 = 4.4  years, pH 7 = 133.7 days, pH 9 = 6.6 days and pH 13 = < 5 minutes (25°C). The free acid ([(5-chloroquinolin-8-yl)oxy]acetic acid; CAS#: 88349-88-6) was the sole hydrolysis product found in these experiments, therefore the transformation product can be considered as hydrolytically stable.

Description of key information

Hydrolysis of cloquintocet-mexyl was determined according to OECD test guidelines. The substance behaves as expected for an ester. In strongly alkaline solution de-esterification is very rapid, slower at slightly alkaline pH and very slow in the range of pH 5 to 7. The free acid (i.e. Acetic acid, 2-[(5-chloro-8-quinolinyl)oxy]-; CAS#: 88349-88-6) was the sole hydrolysis product found in the experiment and is therefore considered to be hydrolytically stable.

Key value for chemical safety assessment

Half-life for hydrolysis:
133.7 d
at the temperature of:
20 °C

Additional information

Categories Display