Triethoxypropylsilane

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

2011

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The result was obtained by an appropriate predictive method.

Principles of method if other than guideline:

The result was obtained using an appropriate QSAR method (see attached QMRF and QPRF for details).

pH:

7

Temp.:

20 °C

DT50:

21.8 h

Conclusions:

A hydrolysis half life of 21.8 hours was obtained for the substance using an appropriate calculation method. The result is considered to be reliable.

Reference 2

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP; Guideline study with deviations that have been assessed with respect to study validity criteria and considered to have no influence on the results of the study.

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

test at 20ºC had temp difference of ±1.0ºC; test at 35ºC showed a minimum of 30.8ºC within first 28h; identification of degradation products not included in study plan

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products:
pH 4 at 0, 10, 15, 20, 30 minutes, 1, 1.5, 3, 6 and 16 hours, 1 and 2 days
pH 7 at 0 and 30 minutes, 1.5, 3, 6 and 16 hours, 1, 2, 3, 5, 7 and 11 days
pH 9 at 0, 15 and 30 minutes, 1, 1.5, 3, 6 and 16 hours, 1, 2, 5 and 6 days

- Sampling method:
5.0ml n-Hexane added to each selected vial and mixed.

- Sample storage conditions before analysis:
All samples analysed on day of sampling
Exception being samples taken from pH 7 at 20 deg C stored deep frozen for less than 7 days before analysis

Buffers:

- pH: 4.0
- Type and final molarity of buffer: potassium biphthalate buffer
- Composition of buffer: 0.1M biphthalate solution was prepared using potassium biphthalate and adjusted to pH 4.0 using 0.1N sodium hydroxide

- pH: 7.0
- Type and final molarity of buffer: potassium phosphate buffer
- Composition of buffer: 0.1M phosphate solution was prepared using potassiumphosphate and adjusted to pH 7.0 using 0.1N sodium hydroxide

- pH: 9.0
- Type and final molarity of buffer: boric acid buffer
- Composition of buffer: 0.1M boric acid solution was prepared using boric acid and adjusted to pH 9.0 using 0.1N sodium hydroxide

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used:
25ml plastic polyvials with screwcaps

- Lighting:
All incubation conditions in the dark

TEST MEDIUM
- Volume used/treatment:
15ml

- Kind and purity of water:
Purified water

- Identity and concentration of co-solvent:
Acetonitrile 5ml/L

Number of replicates:

22 vials prepared for each pH and temperature to cover duplicate samples at each of 11 sampling points
Exception of pH 7 at 20 deg C where 18 vials were prepared to cover duplicate samples at each of 9 sampling points

Statistical methods:

The hydrolysis rate constant of each pH-temperature combination was calculated using single first order kinetics. The hydrolysis rate constant for any specific temperature (i.e. for 20°C and 25°C) was calculated using the Arrenius equation.

Test performance:

During the test at 20°C, the temperature difference was between 19.0 and 21.0°C, which is ± 1.0ºC. The test at 35°C showed a minimum of 30.8°C within the first 28 hours. Most probably the probe was exposed to air for a short period of time due to movement of the shaker bath. Based on the results, it is the opinion of the study director that these temperature deviations had no significant impact on the results of the study.

Transformation products:

not specified

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

Analysis of extracts by GC-MS did not identify any transformation products. The structure of the possible metabolite peaks were not related to the parent.

% Recovery:

ca. 2.6

pH:

4

Temp.:

20 °C

Duration:

0.5 h

% Recovery:

ca. 3.4

pH:

4

Temp.:

35 °C

Duration:

0.5 h

% Recovery:

ca. 5.3

pH:

4

Temp.:

50 °C

Duration:

0.5 h

% Recovery:

ca. 25

pH:

7

Temp.:

20 °C

Duration:

72 h

% Recovery:

ca. 20.7

pH:

7

Temp.:

35 °C

Duration:

48 h

% Recovery:

ca. 7.9

pH:

7

Temp.:

50 °C

Duration:

48 h

% Recovery:

ca. 5.4

pH:

9

Temp.:

20 °C

Duration:

48 h

% Recovery:

ca. 2.1

pH:

9

Temp.:

35 °C

Duration:

24 h

% Recovery:

ca. 0.5

pH:

9

Temp.:

50 °C

Duration:

24 h

pH:

4

Temp.:

20 °C

Hydrolysis rate constant:

9.7 h-1

DT50:

4.3 min

Type:

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

Remarks on result:

other: Arrenius equation

pH:

4

Temp.:

35 °C

DT50:

3.6 min

Type:

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

Remarks on result:

other: Arrenius equation

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

10.3 h-1

Type:

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

Remarks on result:

other:

Remarks:

Arrhenius equation

pH:

7

Temp.:

20 °C

Hydrolysis rate constant:

0.018 h-1

DT50:

1.4 d

Type:

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

Remarks on result:

other: Arrenius equation

pH:

7

Temp.:

35 °C

DT50:

0.7 d

Type:

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

Remarks on result:

other: Arrenius equation

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

0.026 h-1

Type:

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

Remarks on result:

other:

Remarks:

Arrhenius equation

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

0.08 h-1

DT50:

9.4 h

Type:

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

Remarks on result:

other: Arrenius equation

pH:

9

Temp.:

35 °C

DT50:

1.6 h

Type:

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

Remarks on result:

other: Arrenius equation

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0.14 h-1

Type:

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

Remarks on result:

other:

Remarks:

Arrhenius equation

Details on results:

pH 4 DT50 estimated as 4.3, 3.6 and 3.6 minutes for temperatures 20, 35 and 50°C respectively
pH 4 DT90 estimated as 14.3, 12.0 and 12.0 minutes for temperatures 20, 35 and 50°C respectively

pH 7 DT50 estimated as 1.41, 0.67 and 0.15 days for temperatures 20, 35 and 50°C respectively
pH 7 DT90 estimated as 4.7, 2.23 and 0.51 days for temperatures 20, 35 and 50°C respectively

pH 9 DT50 estimated as 9.4, 1.6 and 0.5 hours for temperatures 20, 35 and 50°C respectively
pH 9 DT90 estimated as 31.1, 5.4 and 1.6 hours for temperatures 20, 35 and 50°C respectively

Validity criteria fulfilled:

yes

Conclusions:

At pH 7 the hydrolysis half life of the test substance was measured to be 1.4 days at 20°C and 0.7 days at 25°C

Description of key information

DT50 = 1.4 days at pH 7 and 20 °C (OECD 111)

Key value for chemical safety assessment

Half-life for hydrolysis:

1.4 d

at the temperature of:

20 °C

Additional information

The hydrolysis half-life of the test substance was measured to be 4.3, 3.6 and 3.6 minutes, at pH 4 for 20°C, 35°C and 50°C, respectively. For pH 7 it was calculated to be 1.4, 0.7 and 0.2 days and for pH 9 it was 9.4, 1.6 and 0.5 hours, for 20°C, 35°C and 50°C, respectively.

The hydrolysis rate constant at pH 4 was calculated to be 9.7 for 20°C and 10.3 for 25°C. For pH 7 for 20°C and 25°C the rate constant was calculated to be 0.02 and 0.03 and for pH 9 it was 0.08 and 0.14, respectively. The study was conducted according to OECD Guideline 111 (Hydrolysis as a Function of pH) and is selected as key.

This study is supported by a half-life of approximately 21.8 hours which was obtained for the substance using an appropriate calculation method.

The initial hydrolysis products are expected to be propylsilanetriol and ethanol.