Butyltris[(2-ethyl-1-oxohexyl)oxy]stannane

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07 February 2018 to 09 May 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

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:

no

Remarks:

GLP is not required as the study is not a toxicological or ecotoxicological study

Radiolabelling:

not specified

Analytical monitoring:

yes

Details on sampling:

Sample preparation: 370 µL/ 330 µL toluene-d8 (10 mg/mL CrAcAc)

Buffers:

Buffer Solutions
pH 1.2: HCl 0.1 M
pH 4.0: HCl/NaCl/Citric acid
pH 7.0: Na2HPO4/NaH2PO4
pH 9.0: H3BO3/KCl/NaOH

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 2000 mL Erlenmeyer flask with ground in stopper

HIGH pH TESTING (pH 4.0, 7.0, 9.0)
- The test material was used without a co-solvent or a detergent.
- 20 g of the test material was added to 1000 mL of the respective buffer solution in a 2000 mL Erlenmeyer flask.
- The flask was closed with a stopper and heated in a heating cabinet for 5 days (120 hours) at 50°C.
- The mixture was stirred by a magnetic stirrer using a 40 x 7 mm stir bar at approx. 100 rpm.
- After the pre-determined reaction time, the solution was allowed to cool down to room temperature; 10 mL of each reaction mixture was taken by a syringe and placed in a headspace glass for TOC analysis. The rest of each reaction mixture was extracted with 20 mL hexane, the phases were separated using a separatory funnel. The organic phase was transferred into a pre-weighed flask and the solvent was removed in a rotary evaporator (< 40°C, 10 mbar). The weight difference was recorded for the mass balance, and the samples were analysed by 119Sn-NMR.

GASTRIC pH TESTING (pH 1.2/ 40 °C)
- The test material was used without a co-solvent or a detergent.
- 100 g of the test material was added to 5000 mL of 0.1 M aqueous solution of hydrochloric acid that was preheated to 40°C in a 1000 mL stirred and tempered reactor.
- After the pre-determined exposure time, the solution was allowed to cool down to room temperature; extracted 2 times with 25 mL hexane; the phases were separated using a separatory funnel. The organic phase was transferred into a flask, and the solvent was removed in a rotary evaporator (< 40°C, 10 mbar). The sample was analysed by 119Sn-NMR.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

100 other: %

Remarks:

The test material was used without a solvent

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

100 other: %

Remarks:

The test material was used without a solvent

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

100 other: %

Remarks:

The test material was used without a solvent

Duration:

4 h

pH:

1.2

Temp.:

40 °C

Initial conc. measured:

100 other: %

Remarks:

The test material was used without a solvent

Number of replicates:

1

Positive controls:

no

Negative controls:

no

Transformation products:

not specified

Remarks:

Monobutyltin X bis (2-ethylhexanoate) (X = Ligand out of buffer solution)

% Recovery:

> 90

pH:

4

Temp.:

50 °C

Duration:

5 d

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Type:

not specified

Details on results:

HYDROLYSIS AT PH 1.2 AND 4.0
- The samples did not show significant changes in the 119Sn-NMR Spectrum.
- The half-life time of the test material under the conditions of the study is > 1 year.
- The test material is considered as hydrolytically stable at pH 1.2 and 4.

HYDROLYSIS AT PH 7 AND 9
- The 119Sn-NMR spectrum of the organic extract shows a decrease of the products signal and an increase of the signal δ = -470 respectively δ=-485 which can be assigned to monobutyltin X bis (2-ethylhexanoate). X = Ligand out of buffer solution

Validity criteria fulfilled:

not specified

Conclusions:

The study shows that the test material is hydrolytically stable under simulated gastric conditions (0.1 M HCl /pH 1.2 /40°C/ 4 h at pH 1.2 and at pH 4. After 5 days of hydrolysis at 50°C and pH 4 less than 10% of the test material was hydrolysed (half life at 25°C > 1 year).
At pH 7 and 9 a signal at δ = -470 respectively δ=-485 appears in the NMR spectra, which can be assigned to monobutyltin X bis (2-ethylhexanoate) (X = Ligand out of buffer solution).

Executive summary:

The hydrolysis of the test material as a function of pH was investigated in accordance with the standardised guidelines OECD 111 and EU Method C.7.

The stability of the test material was investigated at pH 4, 7 and 9 and pH 1.2 using NMR spectroscopy.

The study shows that the test material is hydrolytically stable under simulated gastric conditions (0.1 M HCl /pH 1.2 /40°C/ 4 h at pH 1.2 and at pH 4. After 5 days of hydrolysis at 50°C and pH 4 less than 10% of the test material was hydrolysed (half life at 25°C > 1 year).

At pH 7 and 9 a signal at δ = -470 respectively δ=-485 appears in the NMR spectra, which can be assigned to monobutyltin X bis (2-ethylhexanoate) (X = Ligand out of buffer solution).

Description of key information

The study shows that the test material is hydrolytically stable under simulated gastric conditions (0.1 M HCl /pH 1.2 /40°C/ 4 h at pH 1.2 and at pH 4. After 5 days of hydrolysis at 50°C and pH 4 less than 10% of the test material was hydrolysed (half life at 25°C > 1 year).

At pH 7 and 9 a signal at δ = -470 respectively δ=-485 appears in the NMR spectra, which can be assigned to monobutyltin X bis (2-ethylhexanoate) (X = Ligand out of buffer solution).

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

The hydrolysis of the test material as a function of pH was investigated in accordance with the standardised guidelines OECD 111 and EU Method C.7. The study was awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).

The stability of the test material was investigated at pH 4, 7 and 9 and pH 1.2 using NMR spectroscopy.

The study shows that the test material is hydrolytically stable under simulated gastric conditions (0.1 M HCl /pH 1.2 /40°C/ 4 h at pH 1.2 and at pH 4. After 5 days of hydrolysis at 50°C and pH 4 less than 10% of the test material was hydrolysed (half life at 25°C > 1 year).

At pH 7 and 9 a signal at δ = -470 respectively δ=-485 appears in the NMR spectra, which can be assigned to monobutyltin X bis (2-ethylhexanoate) (X = Ligand out of buffer solution).