Di-tert-butyl 1,1,4,4-tetramethylbut-2-yn-1,4-ylene diperoxide

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

from 2015-09-16 to 2015-09-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

13 April 20

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Version / remarks:

31 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The analysis of the test item was carried out with a HPLC method using UV detection. The samples were measured after preparation (diluted with acetonitrile two-fold).

Buffers:

- pH: 4, 7, and 9
- Composition of buffer: Buffer solution
pH = 4: 154 mL 0.1 M citric acid and 96 mL 0.2 M di-Potassium hydrogen phosphate solutions were combined
pH = 7: 37 mL 0.2 M Sodium hydroxide and 63 mL 0.2 M Potassium dihydrogen phosphate solutions were diluted to 250 mL with ultra-pure water.
pH = 9: 27 mL 0.2 M Sodium hydroxide and 63 mL 0.2 M Boric acid and Potassium chloride solutions were diluted to 250 mL with ultra-pure water.

Details on test conditions:

TEST SYSTEM AND CONDITIONS:
The hydrolysis was examined at three different pH values (pH = 4, 7 and 9) in the dark.
Temperature: 50 °C ± 0.5 °C
Light and oxygen: The hydrolysis reaction was carried out using a dark thermostat to avoid photolytic effects. Nitrogen was bubbled into the water before the preparation of the solutions in order to exclude oxygen. All glassware, water and buffer solution were sterilised.
The sterile buffer solutions were prepared using reagent grade chemicals and sterile ultra-pure water.
The pH of each buffer solution was checked with a calibrated pH meter.
The samples were analysed directly after preparation.
Sterility confirmation tests were performed at each pH level at the end of the hydrolysis experiments.

Duration:

120 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

3.69 mg/L

Duration:

120 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

4.83 mg/L

Duration:

120 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

4.65 mg/L

Number of replicates:

Five samples and one control buffer solution were analysed at the start and end of the study at each pH value.

Positive controls:

no

Negative controls:

yes

Remarks:

control buffer samples

Statistical methods:

The test item concentrations were calculated applying the calibration equations (linear regression curves).

Preliminary study:

Based on the results of the preliminary test the hydrolysis rate of the test item was found to be 65 % at pH 4, 30 % at pH 7 and 37 % at pH 9 after 5 days at 50 °C. Therefore, the test substance is hydrolytically unstable in water.

Transformation products:

not measured

% Recovery:

35

pH:

4

Temp.:

50 °C

Duration:

120 h

% Recovery:

70

pH:

7

Temp.:

50 °C

Duration:

120 h

% Recovery:

63

pH:

9

Temp.:

50 °C

Duration:

120 h

Remarks on result:

other: hydrolytically unstable

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

Validity criteria fulfilled:

yes

Conclusions:

The hydrolysis of the test item in different aqueous buffer solutions (pH = 4, 7 and 9) at 50 °C was investigated using HPLC-UV. Measurements revealed hydrolysis of the test item at pH = 4, 7 and 9 and 50 °C. Based on the result the test item was regarded as hydrolytically unstable.

Executive summary:

The hydrolysis of the test item was assessed in accordance with the OECD guideline 111 and the EU method C.7 in a preliminary test. The hydrolysis of the test item in different aqueous buffer solutions (pH = 4, 7 and 9) at 50 °C was investigated using HPLC-UV. The content of test item in the different pH buffer samples was determined at the beginning and the end of the test periods. Five samples were analysed at the start of the study. Two samples were taken from the control vessels at the start and at the end of the storage and these were measured in the same way as the samples. Based on the measured concentration the hydrolysis of the test item was determined to be 65 % at pH=4; 30 % at pH=7 and 37 % at pH=9. Based on these result a full test will be conducted. No observation were made which cause doubt on the validity of the study results.

Reference 2

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2016-09-20 to 2017-01-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The solutions were analysed at the start of the tests and then at appropriate time intervals: in order to get at least six other data points in the range of 10 to 90 % hydrolysis. Five samples were analysed at the start of the study. Two separate tubes were analysed at each analytical occasion of hydrolysis test. One sample was taken from the control vessel.
Sample dilution: twofold, threefold or directly

Buffers:

Compositions of the buffer solutions:
Buffer Solution 4 pH: 385 mL 0.2 M Dibasic potassium phosphate and 615 mL 0.1 M citric acid will be mixed
Buffer Solution 7 pH: 148 mL 0.2 M Sodium hydroxide and 250 mL 0.2 M Potassium dihydrogen phosphate will be diluted to 1000 mL with ultra-pure water
Buffer Solution 9 pH: 107 mL 0.2 M Sodium hydroxide and 250 mL 0.2 M Boric acid and Potassium chloride will be diluted to 1000 mL with ultra-pure water
1500 mL Buffer solutions were prepared at each pH level.

Details on test conditions:

The hydrolysis was examined at three different pH values (pH = 4, 7 and 9) in the dark.
Temperature: 15 °C ± 0.5 °C, 37 °C ± 0.5 °C and 50 °C ± 0.5 °C
Light and oxygen: All glassware, water and buffer solution were sterilised. : The hydrolysis reaction was carried out using a dark thermostat to avoid photolytic effects. Nitrogen was bubbled into the water before the preparation of the solutions in order to exclude oxygen.
Test solution with test item:
The test solutions were prepared by two-hundredfold dilution of the “stock solutions for the hydrolysis test” with the corresponding buffer solutions.
~10 mg/L ≈ 0.035 mM DYBP-85-WO.
Methanol concentration in the buffer solutions were ~0.5 % (v/v).
The solutions were transferred into ~20 mL stoppered tubes.

Duration:

16 d

pH:

4

Temp.:

15 °C

Initial conc. measured:

8.96 mg/L

Remarks:

Temperature - 15, 37 and 50 °C

Duration:

16 d

pH:

7

Temp.:

15 °C

Initial conc. measured:

9.02 mg/L

Remarks:

Temperature - 15, 37 and 50 °C

Duration:

16 d

pH:

9

Temp.:

15 °C

Initial conc. measured:

9.09 mg/L

Remarks:

Temperature - 15, 37 and 50 °C

Number of replicates:

From each solution 18 samples were stored at each temperature. Additionally, control buffer samples were stored at each temperature.

Positive controls:

no

Negative controls:

yes

Remarks:

The buffer solution themselves.

Transformation products:

yes

No.:

#1

Details on hydrolysis and appearance of transformation product(s):

On the basis of retention times one potentional hydrolysis product Tert-Butanol was identified in all stored buffer solutions (pH= 4, 7, 9) using an GC-FID method. Thus the hydrolysis scheme presumed by the sponsor is confirmed.
The potential hydrolysis products (2,5-dimethylhex-3-yne-2,5-diol and tert-butylhydroperoxide) could not be detected in stored buffer solutions. It was assumed that these hydrolysis products undergoes further degradation forming substances which could not be analyzed by the techniques used.

% Recovery:

25.7

pH:

4

Temp.:

15 °C

Duration:

16 d

% Recovery:

15.7

pH:

4

Temp.:

37 °C

Duration:

16 d

% Recovery:

23.1

pH:

4

Temp.:

50 °C

Duration:

14 d

% Recovery:

27.7

pH:

7

Temp.:

15 °C

Duration:

16 d

% Recovery:

18.2

pH:

7

Temp.:

37 °C

Duration:

14 d

% Recovery:

18.2

pH:

7

Temp.:

50 °C

Duration:

13 d

% Recovery:

29.4

pH:

9

Temp.:

15 °C

Duration:

16 d

% Recovery:

25

pH:

9

Temp.:

37 °C

Duration:

14 d

% Recovery:

20.3

pH:

9

Temp.:

50 °C

Duration:

14 d

Key result

pH:

4

Temp.:

20 °C

Hydrolysis rate constant:

0.091 d-1

DT50:

7.6 d

Type:

(pseudo-)first order (= half-life)

Key result

pH:

7

Temp.:

20 °C

Hydrolysis rate constant:

0.077 d-1

DT50:

9 d

Type:

(pseudo-)first order (= half-life)

Key result

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

0.079 d-1

DT50:

8.8 d

Type:

(pseudo-)first order (= half-life)

Validity criteria fulfilled:

yes

Conclusions:

The calculated half-life of the hydrolysis reactions at 20 °C at pH 4, pH 7 and pH 9 were calculated to be:
pH 4 - 7.6 days
pH 7 - 9.0 days
pH 9 - 8.8 days

Executive summary:

The purpose of the main test was to evaluate the hydrolysis of the test item in different pH buffer solutions according to OECD guideline 111 and EU method C.7 using HPLC method. The secondary objective of the study was to identify the degradation products of the hydrolysis by using HPLC-UV and GC-FID.

The calculated half-life of the hydrolysis reactions at 20 °C at pH 4, pH 7 and pH 9 were calculated to be:

pH 4 - 7.6 days

pH 7 - 9.0 days

pH 9 - 8.8 days

The potential hydrolysis product (tert-butanol) was identified in all stored buffer solutions (pH= 4, 7, 9) using a GC-FID method. Thus, the presence of the hydrolysis product, tert-butanol, was confirmed.

Description of key information

In a preliminary test was determined that the test item is not stable in water. Therefore, the performance of a main test was required.

In a main test, the calculated half-life of the hydrolysis reactions at 20 °C at pH 4, pH 7 and pH 9 were calculated to be:

pH 4 - 7.6 days

pH 7 - 9.0 days

pH 9 - 8.8 days

Key value for chemical safety assessment

Half-life for hydrolysis:

9 d

at the temperature of:

20 °C

Additional information

The purpose of the main test was to evaluate the hydrolysis of the test item in different pH buffer solutions according to OECD guideline 111 and EU method C.7 using HPLC method. The secondary objective of the study was to identify the degradation products of the hydrolysis by using HPLC-UV and GC-FID.

The calculated half-life of the hydrolysis reactions at 20 °C at pH 4, pH 7 and pH 9 were calculated to be:

pH 4 - 7.6 days

pH 7 - 9.0 days

pH 9 - 8.8 days

The potential hydrolysis product (tert-butanol) was identified in all stored buffer solutions (pH= 4, 7, 9) using a GC-FID method. Thus, the presence of the hydrolysis product, tert-butanol, was confirmed.

The hydrolysis of the test item was assessed in accordance with the OECD guideline 111 and the EU method C.7 in a preliminary test. The hydrolysis of the test item in different aqueous buffer solutions (pH = 4, 7 and 9) at 50 °C was investigated using HPLC-UV. The content of test item in the different pH buffer samples was determined at the beginning and the end of the test periods. Five samples were analysed at the start of the study. Two samples were taken from the control vessels at the start and at the end of the storage and these were measured in the same way as the samples. Based on the measured concentration the hydrolysis of the test item was determined to be 65 % at pH=4; 30 % at pH=7 and 37 % at pH=9. Based on these result a full test will be conducted. No observation were made which case doubt on the validity of the study results.