N-[3-(trimethoxysilyl)propyl]butylamine

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

See attached QMRF/QPRF

Principles of method if other than guideline:

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

The model is an adaptation of the existing SRC model KOWWIN v1.67, which is a component of the EPIWIN Suite. The model is based on fragment values. That is, the chemical structure is broken down into its constituent functional groups, and the contribution of each group toward the overall partition coefficient is calculated. The constants used within KOWWIN have been derived by SRC from a wide range of organic chemicals. Whilst this method is good in principle, the model was developed using a wide range of organic chemicals and only a few organosilicon compounds. Therefore, a validation procedure was undertaken to assess the applicability of the model to alkoxysilane compounds. It was noted that the model under-predicted log Kow for alkoxysilanes; therefore, a correction factor is applied when this structural feature is present. The adapted model applies to di- and tri-alkoxysilanes.

GLP compliance:

no

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

2.18

Temp.:

20 °C

Remarks on result:

other: for the non-ionised form

Type:

log Pow

Partition coefficient:

-6.47

Temp.:

20 °C

pH:

2

Remarks on result:

other: corrected for ionisation

Type:

log Pow

Partition coefficient:

-4.47

Temp.:

20 °C

pH:

4

Remarks on result:

other: corrected for ionisation

Type:

log Pow

Partition coefficient:

-2.79

Temp.:

20 °C

pH:

5.5

Remarks on result:

other: corrected for ionisation

Type:

log Pow

Partition coefficient:

-1.47

Temp.:

20 °C

pH:

7

Remarks on result:

other: corrected for ionisation

Type:

log Pow

Partition coefficient:

0.52

Temp.:

20 °C

pH:

9

Remarks on result:

other: corrected for ionisation

Details on results:

The amine group in the substance will be protonated in solution; therefore, the estimated log Kow for the non-ionised form was corrected for ionisation using the equation CORR = 1/1 +10A(pH-pKa) [where A = 1 for acids, -1 for bases; pH = pH-value of the environment; pKa = acid/base dissociation constant].

Conclusions:

Octanol-water partition coefficient values of -6.47, -4.47, -2.79, -1.47 and 0.52 at pH 2, pH 4, pH 5.5, pH 7 and pH 9 respectively were obtained for N-[3-(trimethoxysilyl)propyl]butylamine using an appropriate calculation method.

Description of key information

Log D (pH 7) = -1.47 (QSAR)

 

Key value for chemical safety assessment

Log Kow (Log Pow):

-1.47

at the temperature of:

20 °C

Additional information

A predicted log K_ow value of 2.18 was determined for N-[3-(trimethoxysilyl)propyl]butylamine using a QSAR estimation method. This prediction refers to the non-ionised form of the substance. The amine group in the substance will be protonated in solution; therefore, the estimated log K_ow for the unionised form was corrected for ionisation using the equation CORR = 1/1 +10^A(pH-pKa) [where A = 1 for acids, -1 for bases; pH = pH-value of the environment; pKa = acid/base dissociation constant.

 

Log D values of -6.47 at pH 2, -4.47 at pH 4, -2.79 at pH 5.5, -1.47 at pH 7 and 0.52 at pH 9 were obtained for the substance. The relevant/corrected log K_ow values are used for assessment purposes.