2,2-dimethyl-1,3-dioxolan-4-ylmethanol

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 11 December 2013 to 11 July 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed in accordance with international guideline under GLP and was considered as reliable without restrictions.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Test Condition Sampling Intervals
pH 4, 15°C Day 0, 1.0, 2.0, 3.0, 5.0, 7.0, 11 and 15
pH 4, 20°C Day 0, 1.0, 2.0, 3.0, 4.0, 5.0, 7.0 and 11
pH 4, 25°C Day 0, 0.91, 1.2, 1.9, 2.2, 2.9 and 3.2

Buffers:

- pH: 4, 7 et 9
- Composition of buffer:
pH 4: Mixed 16.4826 g of sodium acetate and 67.1830 g of acetic acid in 4-L of reagent-grade water in an amber glass bottle. The pH was adjusted to nominal using 1 M aqueous sodium hydroxide.
pH 7: Mixed 27.2375 g of potassium dihydrogen phosphate and 4.7947 g of sodium hydroxide in 4-L of reagent-grade water in an amber glass bottle. The pH was adjusted to nominal using 1 M aqueous sodium hydroxide.
pH 9: Mixed 14.9282 g of potassium chloride, 12.3667 g of boric acid and 3.6121 g of sodium hydroxide in 4-L of reagent-grade water in an amber glass bottle. The pH was adjusted to nominal using 1 M aqueous hydrochloric acid.

Duration:

5 d

pH:

4

Temp.:

50

Initial conc. measured:

ca. 102 mg/L

Duration:

5 d

pH:

7

Temp.:

50

Initial conc. measured:

ca. 101 mg/L

Duration:

5 d

pH:

9

Temp.:

50

Initial conc. measured:

ca. 101 mg/L

Number of replicates:

Triplicates measurements

Preliminary study:

The mean measured hydrolytic degradation was less than 10% under the preliminary test conditions for pH 7 and pH 9, but was greater than 10% for the pH 4 test condition. Since hydrolysis did not exceed the 10% degradation criterion for the pH 7 and pH 9 test conditions, Augeo SL191
was considered hydrolytically stable at 25°C at pH 7 and pH 9 with an estimated half-life (t1/2) greater than one year. No further testing was warranted for pH 7 and pH 9. Since hydrolytic degradation in the pH 4 preliminary test exceeded the 10% criterion cited in the protocol and the relevant guidelines, Augeo SL191 was considered hydrolytically unstable at pH 4, thereby triggering pH 4 definitive testing.

Test performance:

Augeo SL191 was found to be hydrolytically active in pH 4 aqueous buffer at 50°C. Definitive testing at pH 4 at three temperatures (15°C, 20°C and 25°C) showed a temperature dependence of Augeo SL191 hydrolysis at pH 4. The hydrolysis rate constants for Augeo SL191 at pH 4 and 15°C, 2°C and 25°C were 0.105 day-1, 0.197 day-1 and 0.723 day-1, respectively. The corresponding half-lives for 15°C, 20°C and 25°C were 6.59, 3.51, and 0.959 days, respectively.

Transformation products:

not measured

pH:

4

Temp.:

15 °C

Hydrolysis rate constant:

ca. 0.105 d-1

DT50:

ca. 6.59 d

Key result

pH:

4

Temp.:

20 °C

Hydrolysis rate constant:

ca. 0.197 d-1

DT50:

ca. 3.51 d

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

ca. 0.723 d-1

DT50:

ca. 0.959 d

Preliminary Test

The hydrolysis potential of Augeo SL191 was evaluated at pH 4 (acetate buffer),7 (phosphate buffer) and 9 (borate buffer) at 50°C over a five-day time period. The pH 4 samples were fortified at a nominal concentration of 102 mg a.i./L. The pH 7 and 9 samples were fortified at a nominal concentration of 101 mg a.i./L. Preliminary test samples were collected and analyzed on Days 0 and 5. Representative chromatograms of pH 4, 7 and 9 samples from Days 0 and 5 of the preliminary test are presented. Day 0 samples prepared in pH 4, 7 and 9 aqueous buffer solutions yielded mean measured values of 100 ± 1.2, 105 ± 0.23 and 92.1 ± 0.67 mg a.i./L, respectively (Table 4). The three Day 5 samples at pH 4 gave measured concentrations less than the LOQM. Day 5 samples prepared in pH 7 and pH 9 aqueous buffer solutions yielded mean measured values of 97.8 ± 0.50 and 92.2 ± 0.34 mg a.i./L, respectively. For pH 4, 7 and 9, these results corresponded to <10.0%, 92.8%, and 100% of the mean measured Day 0 concentrations, and this represented >90%, 7.2% and <0.1% hydrolysis of the initial Augeo SL191 concentration for pH 4, 7 and 9, respectively. Measured pH of the fortified test solutions at test initiation was 4.02, 7.03 and 9.00 for the pH 4, 7 and 9 test systems, respectively. Measured pH at test termination was 4.04, 7.04 and 9.01 for the pH 4, 7 and 9 test systems, respectively. The differences in pH of 0.02 or less between the beginning and end of the preliminary test showed that pH was maintained during the test for pH 4, 7 and 9.

The mean measured hydrolytic degradation was less than 10% under the preliminary test conditions for pH 7 and pH 9, but was greater than 10% for the pH 4 test condition. Since hydrolysis did not exceed the 10% degradation criterion for the pH 7 and pH 9 test conditions, Augeo SL191

was considered hydrolytically stable at 25°C at pH 7 and pH 9 with an estimated half-life (t1/2) greater than one year. No further testing was warranted for pH 7 and pH 9. Since hydrolytic degradation in the pH 4 preliminary test exceeded the 10% criterion cited in the protocol and the relevant guidelines, Augeo SL191 was considered hydrolytically unstable at pH 4, thereby triggering pH 4 definitive

testing.

Main Test:

The hydrolysis rate of Augeo SL191 in the definitive test was evaluated at pH 4 at three temperatures: 15°C, 20°C and 25°C. The 25°C definitive test temperature was selected as a preferred target temperature for determining the hydrolysis rate constant, as cited in the protocol and relevant

guidelines. A 35°C incubation was initially attempted as an elevated test temperature, but hydrolysis was unexpectedly rapid so that it was impractical to sample sufficient intervals across the preferred extent of hydrolytic degradation (at the first sampling interval, after one day only approximately 30% of initial concentration remained). The 15°C and 20°C definitive test temperatures were selected based on the relatively rapid hydrolysis exhibited at 25°C, as well as taking into account the practicality of collecting and analyzing samples at 6 sampling intervals with between 10 and 90% hydrolysis and sufficient separation to produce a reliable hydrolysis regression. At the 15°C, 20°C,

and 25°C test conditions, incubation durations of 15, 11, and 3.2 days, respectively allowed adequate sampling intervals to yield between approximately 10% and 90% hydrolysis of the initial Augeo SL191 concentration.

The measured pH of the Augeo SL191 fortified pH 4 buffer test solutions was 3.97 at the 25°C test initiation (Day 0) as well as the 15°C/20°C test initiation. The pH of duplicate incubated samples was measured at test termination for each incubation temperature. showed very little difference between test initiation and termination (0.04 or less) which indicated that pH 4 was maintained by the buffer during the definitive test and was not affected by hydrolysis of the test substance. Measured concentrations for Augeo SL191 from the pH 4 definitive tests at 15°C, 20°C and

25°C are summarized in Tables 5, 6 and 7, respectively. Representative chromatograms from Day 0 (definitive test initiation) for the 15°C and 20°C incubation conditions are presented in Figure 10.

At 15°C, approximately 80% of the initial concentration of Augeo SL191 was hydrolyzed after a 15 day incubation period. At 20°C, approximately 90% of the initial concentration of Augeo SL191 was hydrolyzed after an 11 day incubation period. At 25°C,

approximately 90% of the initial concentration of Augeo SL191 was hydrolyzed after a 3.2 day incubation period. The linear regression plots of the natural logarithm of the Augeo SL191

Based on these regressions, the hydrolysis rate constants for Augeo SL191 in pH 4 aqueous buffer solution were 0.105 day-1 at 15°C, 0.197 day-1 at 20°C, and 0.723 day-1 at 25°C. The corresponding half-lives were 6.59 days, 3.51 days and 0.959 days at 15°C, 20°C and 25°C, respectively.

Validity criteria fulfilled:

yes

Conclusions:

Augeo SL191 test substance was considered hydrolytically stable at pH 7 and pH 9 at 25°C with an estimated half-life (t1/2) greater than one year. Augeo SL191 was found to be hydrolytically active in pH 4 aqueous buffer at 50°C. Definitive testing at pH 4 at three temperatures (15°C, 20°C and 25°C) showed a temperature dependence of Augeo SL191 hydrolysis at pH 4. The hydrolysis rate constants for Augeo SL191 at pH 4 and 15°C, 20°C and 25°C were 0.105 day-1, 0.197 day-1 and 0.723 day-1, respectively. The corresponding half-lives for 15°C, 20°C and 25°C were 6.59, 3.51, and 0.959 days, respectively.

Executive summary:

The study was performed to determine the rate of hydrolysis of 2,2-dimethyl-1,3-dioxolan-4- ylmethanol ( Augeo SL191) according to the OECD 111 Hydrolysis as a Function of pH and OPPTS 835.2120, Hydrolysis under GLP.

The rate of hydrolysis of Augeo SL191 in aqueous pH buffer solutions (pH 4, 7 and 9) was evaluated for five days at 50°C. Hydrolytic degradation of Augeo SL191 was evident in pH 4 buffer solution after a 5-day incubation period at 50°C, but was not evident at pH 7 and pH 9. Therefore the Augeo SL191 test substance was considered hydrolytically stable at pH 7 and pH 9 at 25°C with an estimated half-life (t1/2) greater than one year. Augeo SL191 was found to be hydrolytically active in pH 4 aqueous buffer at 50°C. Definitive testing at pH 4 at three temperatures (15°C, 20°C and 25°C) showed a temperature dependence of Augeo SL191 hydrolysis at pH 4. The hydrolysis rate constants for Augeo SL191 at pH 4 and 15°C, 20°C and 25°C were 0.105 day-1, 0.197 day-1 and 0.723 day-1, respectively. The corresponding half-lives for 15°C, 20°C and 25°C were 6.59, 3.51, and 0.959 days, respectively.

The study was performed in accordance with international guideline under GLP and was considered as reliable without restrictions.

Description of key information

Augeo SL191 test substance was considered hydrolytically stable at pH 7 and pH 9 at 25C with an estimated half-life (t1/2) greater than one year. Augeo SL191 was found to be hydrolytically active in pH 4 aqueous buffer at 50°C. Definitive testing at pH 4 at three temperatures (15°C, 20°C and 25°C) showed a temperature dependence of Augeo SL191 hydrolysis at pH 4. The hydrolysis rate constants for Augeo SL191 at pH 4 and 15°C, 20°C and 25°C were 0.105 day-1, 0.197 day-1 and 0.723 day-1, respectively. The corresponding half-lives for 15°C, 20°C and 25°C were 6.59, 3.51, and 0.959 days, respectively.

Key value for chemical safety assessment

Half-life for hydrolysis:

0.959 d

at the temperature of:

25 °C

Additional information

Key study was performed to determine the rate of hydrolysis of 2,2-dimethyl-1,3-dioxolan-4- ylmethanol ( Augeo SL191) according to the OECD 111 and OPPTS 835.2120 under GLP.

The rate of hydrolysis of Augeo SL191 in aqueous pH buffer solutions (pH 4, 7 and 9) was evaluated for five days at 50°C. Hydrolytic degradation of Augeo SL191 was evident in pH 4 buffer solution after a 5-day incubation period at 50°C, but was not evident at pH 7 and pH 9. Therefore the Augeo SL191 test substance was considered hydrolytically stable at pH 7 and pH 9 at 25°C with an estimated half-life (t1/2) greater than one year. Augeo SL191 was found to be hydrolytically active in pH 4 aqueous buffer at 50°C. Definitive testing at pH 4 at three temperatures (15°C, 20°C and 25°C) showed a temperature dependence of Augeo SL191 hydrolysis at pH 4. The hydrolysis rate constants for Augeo SL191 at pH 4 and 15°C, 20°C and 25°C were 0.105 day-1, 0.197 day-1 and 0.723 day-1, respectively. The corresponding half-lives for 15°C, 20°C and 25°C were 6.59, 3.51, and 0.959 days, respectively.

The study was performed in accordance with international guideline under GLP and was considered as reliable without restrictions.