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Diss Factsheets

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2005
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report date:
2006

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
not specified
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Dimethyl 2,5-dioxocyclohexane-1,4-dicarboxylate
EC Number:
228-528-9
EC Name:
Dimethyl 2,5-dioxocyclohexane-1,4-dicarboxylate
Cas Number:
6289-46-9
Molecular formula:
C10H12O6
IUPAC Name:
1,4-dimethyl 2,5-dioxocyclohexane-1,4-dicarboxylate

Study design

Analytical monitoring:
not specified

Results and discussion

Transformation products:
not specified
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
0.04 d-1
DT50:
472 h
Type:
(pseudo-)first order (= half-life)
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
0.13 h-1
DT50:
5.3 h
Type:
(pseudo-)first order (= half-life)
pH:
9
Temp.:
50 °C
Remarks on result:
other: complete hydrolyses
pH:
4
Temp.:
25 °C
Hydrolysis rate constant:
0.79 a-1
DT50:
7 568 h
Type:
(pseudo-)first order (= half-life)
pH:
7
Temp.:
25 °C
Hydrolysis rate constant:
0.01 h-1
DT50:
68 h
Type:
(pseudo-)first order (= half-life)
pH:
9
Temp.:
25 °C
Remarks on result:
other: complete hydrolyses

Any other information on results incl. tables

The abiotic degradation of the test item 3,6-Dihydro-2,5-dihydroxyterephthalic acid dimethyl ester was

determined according to EC-guideline 92169lEC, C.7.

The rate of degradation was estimated in preliminary tests at three different pH-values (4, 7, and 9). At

pH9 the test item was completely instable. The starting concentration could not be determined because

the test item had hydrolysed completely during the short time between preparation of solution and

analysis. Therefore no further testing at this pH-value had to be performed. At pH7, respectively, pH9

further tests according to the corresponding guideline had to be performed, because the test item had

hydrolyzed less than 50% after 2.4 hours but more than 10 % after five days at 50°C.

The main test for pH4 was performed at three temperatures (50°C, 65°C and 75°C). In each case a

linear dependence of the time of degradation on the natural logarithm of the test item concentration was

obtained, which means, that the hydrolysis reaction was pseudo-first order.

The main test for pH7 was performed at two temperatures (50°C and 35°C). In each case a linear

dependence of the time of degradation on the natural logarithm of the test item concentration was

obtained, which means, that the hydrolysis reaction was pseudo-first order.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Executive summary:

The hydrolysis of the substance is base catalyzed.

The half-life time at pH 7 at 25°Cdetermined from the regression line received from measurements at 35°C, 65°C and 75°C is 68,6 hours