Bis[(2-ethyl-1-oxohexyl)oxy]dioctylstannane

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 September 2016 to 07 November 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

2004

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

no

Remarks:

(not required as study is not a toxicological/ ecotoxicological study)

Test material

Test material information

Constituent 1

Reference substance name:

Bis[(2-ethyl-1-oxohexyl)oxy]dioctylstannane

EC Number:

246-325-3

EC Name:

Bis[(2-ethyl-1-oxohexyl)oxy]dioctylstannane

Cas Number:

24577-34-2

Molecular formula:

C32H64O4Sn

IUPAC Name:

[(2-ethylhexanoyl)oxy]dioctylstannyl 2-ethylhexanoate

Details on test material:

- Storage conditions: In original container, at 15°C to 25°C

Radiolabelling:

not specified

Results and discussion

Any other information on results incl. tables

HYDROLYSIS AT PH 4,7 AND 9

- At pH 4 and 7 the 119Sn-NMR spectra were analogous to the unhydrolised substance.

- The pH 9 spectrum of the extracted hydrolysate shows a significant decrease of the product peak  at -156 ppm and two sharp peaks (of equal intensity) at -224 and -222 ppm.

- Acyl-substituted teraorganodistannoxanes are reported in literature to be formed as hydrolysis products of dialkyltincarboxylates, following an initial formation of a hydroxide. The reported chemical shifts correlate well with the shifts found in the extract of the hydrolysate.

- So the formation of a dimeric teraoctyl distannoxane is most likely breakdown product of the test material at pH 9.

HYDROLYSIS AT PH 1.2

- The 119Sn-NMR spectrum of the organic extract the substance signal broadens significantly and decrease to 39.5 Mol% in intensity.

- An additional broad peak appears at -34 ppm (52 Mol%).

- This behaviour is similar to the simulated gastric breakdown under the same conditions of DBTL and DOTL.

- The broad signal can be attributed to the formation of dioctyltin chloro 2-ethylhexanoate a monochloroester of the test material.

- The broadening of the signals may point to a intermolecular conjugation of the test material itself or with DOTO. However this is speculative.

- In contrast to the mentioned dioctyltin di laurates here no signals are found which indicate the formation of a dimeric tetraoctyl dichloro distannoxane.

- No DOTC was formed under the conditions of the study

MASS BALANCE RECOVERY RATES

pH 4: 95 %

pH 7: 91 %

pH 9: 77 %

pH 1.2 97 %

ATOMIC ABSORPTION SPECTOMETRY

- The aqueous phase of the low pH hydrolysis has been analysed after extraction with hexane by AAS and contained < 5mg/L Sn. So the formation of an organotin substance better soluble in water than in hexane can be excluded.

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study, the test material can be considered hydrolytically stable at pH 4 and 7.
After 5 days of hydrolysis at 50 °C at pH 4 and 7 no reaction could be identified based on the 119Sn NMR spectra of the extracted hydrolysates.
At pH 9 under the same conditions the formation of a dimeric teraoctyl distannoxane is the most likely breakdown product.
Under simulated gastric conditions the test material breaks down to its monochloroester. The Formation of DOTC and a dimeric teraoctyl dichloro distannoxane can be excluded. The tin content in the aqueous phase of the hydrolysis remained under the detection limit of < 5 mg/L in AAS. Thus the formation of a water soluble organotin species can be excluded.

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.

Under the conditions of this study, the test material can be considered hydrolytically stable at pH 4 and 7.

After 5 days of hydrolysis at 50 °C at pH 4 and 7 no reaction could be identified based on the 119Sn NMR spectra of the extracted hydrolysates.

At pH 9 under the same conditions the formation of a dimeric teraoctyl distannoxane is the most likely breakdown product

Under simulated gastric conditions the test material breaks down to its monochloroester. The Formation of DOTC and a dimeric teraoctyl dichloro distannoxane can be excluded. The tin content in the aqueous phase of the hydrolysis remained under the detection limit of < 5 mg/L in AAS. Thus the formation of a water soluble organotin species can be excluded.