Bis(dodecylthio)dimethylstannane

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

16 October 2017 to 03 November 2017

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)

Version / remarks:

2004

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:

(this is not a toxicological or ecotoxicological test - GLP conditions not required)

Radiolabelling:

not specified

Analytical monitoring:

yes

Details on sampling:

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

Buffers:

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: 250 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.
- 1 g (1.8 mMol) of the test material was added to 100 mL of the respective buffer solution in a 250 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/ 37 °C)
- The test material was used without a co-solvent or a detergent.
- 1 g (1.8 mMol) of the test material was added to 100 mL of 0.1 M aqueous solution of hydrochloric acid that was preheated to 37 °C in a 250 mL Erlenmeyer flask with ground in stopper.
- The flask was closed with a stopper and heated in a heating cabinet for 4 hours at 37 °C.
- The mixture was stirred by a magnetic stirrer using a 40 x 7 mm stir bar at approximately 100 rpm.
- 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 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.:

37 °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:

yes

Remarks:

Chloro dodecylthio dimethylstannane (DMT-SLau Cl)

% Recovery:

85

pH:

4

Temp.:

50 °C

Duration:

5 d

% Recovery:

99

pH:

7

Temp.:

50 °C

Duration:

5 d

% Recovery:

99

pH:

9

Temp.:

50 °C

Duration:

5 d

Key result

pH:

4

Temp.:

50 °C

DT50:

> 1 yr

Key result

pH:

7

Temp.:

50 °C

DT50:

> 1 yr

Key result

pH:

9

Temp.:

50 °C

DT50:

> 1 yr

Details on results:

HYDROLYSIS AT pH 4,7 AND 9
- Samples of the test material were added to the respective buffer solutions at 50 °C for 5 days (120 h). None of the 119Sn-NMR spectra of the extracted reaction products, at any of the pH levels tested, showed signs of hydrolysis.
- 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

HYDROLYSIS AT PH 1.2
- 1 g (1.8 mMol) of the test material was added to an excess 0.1 M hydrochloric acid at 37 °C for 4 hours and extracted with hexane after cooling down to room temperature. The 119Sn-NMR spectrum of the organic extract shows a decrease of the products peak and an increase of the breakdown product, the monochloride of the substance. A new peak at 158 ppm, a chemical shift area which is typical for disulphur bridged organotin compounds. However, the peak cannot be unequivocally assigned to a substance.
- The composition of the test material hydrolysate at pH 1.2 based on 119Sn-NMR analysis was:
DMT(-SLau)2 22 Mol%, DMT(-SLau)Cl 70 Mol% and 8 Mol% unknown.

MASS BALANCE RECIVERY RATES
pH 4: 83 %
pH 7: 98 %
pH 9: 99 %
pH 1.2: 79 %

ATOMIC ABSORPTION SPECTOMETRY
- The aqueous phases of the low pH hydrolysis has been analysed after extraction with hexane by AAS and contain 1720 mg/L Sn.

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of this study, the test material was is hydrolytically stable at pH 4, 7 and 9. At pH 1.2 the only identifiable breakdown product was the monochloride of the test material chlorododecylthio dimethylstannane (DMT-SLau Cl). It appears besides the unreacted test material with traces of a not further characterised substance. DMTC was not detected in the organic extract. The lower recovery of substance in the hexane extract and the content of 1720 mg/L tin remaining in the aqueous phase indicates that the dimethyltin cation remains in a soluble form in water.

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 at pH 9, 7 and 4. After 5 days of hydrolysis at 50 °C less than 10 % of the test material was hydrolysed (half life at 25 °C > 1 year).

At simulated gastric conditions (0.1 M HCl /pH 1.2 /37 °C/ 4 h) the only identifiable breakdown product was the monochloride of the test material, chlorododecylthio dimethylstannane (DMT-SLau Cl). It appears besides the unreacted test material with traces of a not further characterised substance. DMTC was not detected in the organic extract.

The lower recovery of substance in the hexane extract and the content of 1720 mg/L tin remaining in the aqueous phase indicates that the dimethyltin cation remains in a soluble form in water.

Description of key information

Under the conditions of this study, the test material was is hydrolytically stable at pH 4, 7 and 9. At pH 1.2 the only identifiable breakdown product was the monochloride of the test material, chlorododecylthio dimethylstannane (DMT-SLau Cl). It appears besides the unreacted test material with traces of a not further characterised substance. DMTC was not detected in the organic extract. The lower recovery of substance in the hexane extract and the content of 1720 mg/L tin remaining in the aqueous phase indicates that the dimethyltin cation remains in a soluble form in water.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

50 °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 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 at pH 9, 7 and 4. After 5 days of hydrolysis at 50 °C less than 10 % of the test material was hydrolysed (half life at 25 °C > 1 year).

At simulated gastric conditions (0.1 M HCl /pH 1.2 /37 °C/ 4 h) the only identifiable breakdown product was the monochloride of the test material, chlorododecylthio dimethylstannane (DMT-SLau Cl). It appears besides the unreacted test material with traces of a not further characterised substance. DMTC was not detected in the organic extract.

The lower recovery of substance in the hexane extract and the content of 1720 mg/L tin remaining in the aqueous phase indicates that the dimethyltin cation remains in a soluble form in water.