2-hydroxypropyl [(1R,2S,5R)-2-isopropyl-5-methyl-cyclohexyl] carbonate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-03-14 to 1994-06-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(1992)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 1994-03-16

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the Preliminary test/Test 1: 0 h (test start), 48 h, 70 h, and 120 h
- Sampling intervals for the Test 3: 0 h (test start), 48 h, 70 h, and 120 h for pH 9; 0 h (test start), 24 h, and 50 h for pH 7
- Sampling method: test material was monitored by GC-FID
- Sample storage conditions before analysis:
Preliminary test/Test 1: at 50 °C in pH 4 and pH 7 buffer solutions;
Test 3: at 25 °C in pH 9 buffer, at 70 °C and 60 °C in pH 7 buffer

Buffers:

- pH 4 and 7 in Preliminary test/Test 1 and pH 9 and pH 7 in Test 3
- Temperature: 50 °C in Preliminary test/Test 1 and 25 °C for pH 9, and 60 and 70 °C for pH 7 in Test 3
- Composition of buffer:
Buffer solution pH 4: 0.05 mol/dm³ citric acid, 0.10 mol/dm³ sodium hydroxide, 0.05 mol/dm³ hydrochloric acid.
Buffer solution pH 7: 0.04 mol/dm³ disodium hydrogen orthophosphate, 0.03 mol/dm³ potassium dihydrogen orthophosphate.
Buffer solution pH 9: 0.05 mol/dm³ disodium tetraborate, 0.02 mol/dm³ hydrochloric acid.

Estimation method (if used):

A logarithmic graph of the concentration against time was plotted for each test and an estimate of the rate constant and the half-life was directly determined at 25 °C for pH 9. The Arrhenius relationship of the rate constant at higher temperatures was used for pH 7.

Details on test conditions:

TEST MEDIUM
- Standards: Standard solutions were prepared in hexane at a nominal concentration of 250 mg/L.

Duration:

120 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

38.3 mg/L

Duration:

120 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

33.1 mg/L

Duration:

120 h

pH:

9

Temp.:

25 °C

Initial conc. measured:

46.8 mg/L

Duration:

50 h

pH:

7

Temp.:

60 °C

Initial conc. measured:

36.2 mg/L

Remarks:

A

Duration:

50 h

pH:

7

Temp.:

60 °C

Initial conc. measured:

32.4 mg/L

Remarks:

B

Duration:

50 h

pH:

7

Temp.:

70 °C

Initial conc. measured:

25 mg/L

Number of replicates:

eplicates except for Test 3 in pH 7 buffersolution at 60 °C which was performed in duplicates.

Positive controls:

not specified

Negative controls:

not specified

Statistical methods:

no data

Preliminary study:

- In the preliminary test/test 1, the test item was found to ungergo less than 10 % hydrolysis after 5 days at 50 °C in pH 4 buffer solution. At 50 °C in pH 7 buffer solution, the test item was found to undergo greater than 10 % hydrolysis after 5 days.

- Estimated rate constant and half-life was estimated for pH 7 buffer solution at 50 °C to be 0.00388 per hour and 179 hours, respectively.

Test performance:

No unusual observations during test performance.

Preliminary testing at 50 °C was deemed unnecessary for the pH 9 buffer solution based on the results obtained from an abiotic degradation study performed on a related test material.

Transformation products:

not measured

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

not applicable

% Recovery:

102

pH:

4

Temp.:

50 °C

Duration:

120 h

% Recovery:

63.1

pH:

7

Temp.:

50 °C

Duration:

120 h

% Recovery:

18.8

pH:

9

Temp.:

25 °C

Duration:

120 h

% Recovery:

55.5

pH:

7

Temp.:

60 °C

Duration:

50 h

Remarks on result:

other: test A

% Recovery:

54

pH:

7

Temp.:

60 °C

Duration:

50 h

Remarks on result:

other: test B

% Recovery:

22

pH:

7

Temp.:

70 °C

Duration:

50 h

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

3 300 h

Key result

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0.014 h-1

DT50:

49.6 h

Type:

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

Other kinetic parameters:

no data

Details on results:

RESULTS
- At pH 7 and pH 9: t1/2 (25 °C) for pH 7 = 3.3*10^3 hours, t1/2 (25 °C) for pH 9 = 49.6 hours
- At pH 4: stable at pH 4 (less than 10 % hydrolysis after 5 days at 50 °C)

Validity criteria fulfilled:

yes

Conclusions:

In the preliminary test (50 °C), the test item was found to be stable at pH 4, but at pH 7 a decrease of the test concentration greater than 10 % was observed after 5 days. In further tests, the half-life of the reactions at 25 °C have been estimated to be 3330 h and 49.6 h for pH 7 and pH 9, respectively.

Executive summary:

The hydrolysis of the test item was investigated as a function of pH at 50 °C, 25 °C and pH 4, 7, and 9 according to Directive 92/69/EEC, Method C.7 (1992). The test item was hydrolytically stable at pH 4 (<10 % decrease in 5 days). At pH 7 the rate constant and half-life of the reactions at 25 °C have been estimated to be 0.000210 h^-1and 3300 h, respectively. At pH 9 the rate constant and half-life of the reactions at 25 °C have been estimated to be 0.0140 h^-1and 49.6 h, respectively.

Description of key information

pH 4: stable

pH 7: half-life of the reactions at 25 °C: 3330 h

pH 9: half-life of the reactions at 25 °C: 49.6 h

Key value for chemical safety assessment

Half-life for hydrolysis:

3 330 h

at the temperature of:

25 °C

Additional information

The hydrolysis of the test item was investigated as a function of pH at 50 °C, 25 °C and pH 4, 7, and 9 according to Directive 92/69/EEC, Method C.7 (1992). The test item was hydrolytically stable at pH 4 (<10 % decrease in 5 days). At pH 7 the rate constant and half-life of the reactions at 25 °C have been estimated to be 0.000210 h^-1and 3300 h, respectively. At pH 9 the rate constant and half-life of the reactions at 25 °C have been estimated to be 0.0140 h^-1and 49.6 h, respectively.