Sodium 4-[(C16-18-(even numbered)-alkylamino)carbonyl]benzoate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Specific details on test material used for the study:

- Appearance/physical state: White solid
- Batch: A026/99 and A026/50-01
- Purity: 100% (UVCB)
- Expiry date: 01 July 2019
- Storage conditions: Room temperature, in the dark

Remarks on result:

not determinable

Details on results:

No determination of water solubility was feasible for the test item. This was due to the test item, representative of the chemical class of anionic surfactants, showed significant surface-active properties in an aqueous environment. When attempting to generate saturated solutions, a colloidal suspension (i.e. containing micelles < 0.2 µm) was formed. As this dispersed, excess, undissolved material could not be satisfactorily removed by either centrifugation of filtration techniques, it was not possible to isolate a genuine saturated aqueous solution of test item suitable for analysis and quantification.

The observations recorded after each stage of the sample treatment are shown in the following table.

Sample number	Actual loading concentration (g/L)	Observations on completion of re-equilibriation at 20°C	Observations of isolated supernatants after centrifugation	Observations of isolated filtrates after filtration
1	10.2	A cloudy solution with excess, undissolved test item visible.	A clear, colourless solution with excess, undissolved test item visible.	A clear, colourless solution free from excess, undissolved test item; however presenting a positive Tyndall beam on evaluation.
2	1.0	A hazy solution with excess, undissolved test item visible.	A clear, colourless solution with excess, undissolved test item visible.	A clear, colourless solution free from excess, undissolved test item; however presenting a positive Tyndall beam on evaluation.
3	0.10	A clear, colourless solution with excess, undissolved test item visible.	A clear, colourless solution with excess, undissolved test item visible.	A clear, colourless solution free from excess, undissolved test item; however presenting a positive Tyndall beam on evaluation.

The Tyndall beam observed in all three sample filtrates, indicating light scattering originating from a dispersion of emulsified, undissolved material remaining in each solution, increased in intensity across the three samples, relative to the initial saturation concentration used during their preparation. The presence of this Tyndall beam, after filtration of each supernatant through a 0.2 μm filter, indicated a colloidal (< 0.2 μm) nature to the dispersions. The sample solution pH values were 10.3, 9.7 and 9.1 for sample number 1, sample number 2 and sample number 3 respectively.

The behaviour of the test item in an aqueous environment was as expected, based on it being representative of the chemical class of anionic surfactants. The significant surface-active properties presented by the test item resulted in the formation of a colloidal (< 0.2 μm) dispersion of excess, undissolved test item throughout the saturated solutions. As this dispersed, excess, undissolved material could not be satisfactorily removed by either centrifugation or filtration techniques, it was not possible to isolate a genuine saturated aqueous solution of test item suitable for analysis and quantification.

Conclusions:

The water solubility of sodium 4-[(C16-18-(even numbered)-alkylamino)carbonyl]benzoate could not be determined.

Executive summary:

An attempt was made to determine the water solubility of sodium 4-[(C16-18-(even numbered)-alkylamino)carbonyl]benzoate, in a GLP-compliant study following OECD guideline 105 (Envigo 2018). The study is considered relevant and reliable for use for this endpoint.

No determination of water solubility was feasible for the test item. This was due to the test item, representative of the chemical class of anionic surfactants, showed significant surface-active properties in an aqueous environment. When attempting to generate saturated solutions, a colloidal suspension (i.e. containing micelles < 0.2 µm) was formed. As this dispersed, excess, undissolved material could not be satisfactorily removed by either centrifugation of filtration techniques, it was not possible to isolate a genuine saturated aqueous solution of test item suitable for analysis and quantification.  

Description of key information

No determination of water solubility was feasible for Sodium 4-[(C16-18-(even numbered)-alkylamino)carbonyl]benzoate.

Additional information

An attempt was made to determine the water solubility of Sodium 4-[(C16-18-(even numbered)-alkylamino)carbonyl]benzoate, in a GLP-compliant study following OECD guideline 105 (Envigo 2018). The study is considered relevant and reliable for use for this endpoint. No determination of water solubility was feasible for the test item. This was due to the test item, representative of the chemical class of anionic surfactants, showed significant surface-active properties in an aqueous environment. When attempting to generate saturated solutions, a colloidal suspension (i.e. containing micelles < 0.2 µm) was formed. As this dispersed, excess, undissolved material could not be satisfactorily removed by either centrifugation of filtration techniques, it was not possible to isolate a genuine saturated aqueous solution of test item suitable for analysis and quantification.

Under standard test conditions, it was not feasible to derive a water solubility value. The QSAR model WATERNT v 1.01 and WSKOWWIN v 1.42 were used and the studies were assigned a reliability score of 2 (Reliable with restrictions) as they are accepted calculated methods. The water solubility prediction of the sodium 4-[(hexadecylamino)carbonyl]benzoate was 0.00038897 mg/L using WATERNT and 0.1349 mg/L using WSKOWWIN. The water solubility prediction of the sodium 4-[(octadecylamino)carbonyl]benzoate was 3.5104E-5 mg/L mg/L using WATERNT and 0.01307 mg/L using WSKOWWIN.