N-[3-(trimethoxysilyl)propyl]butylamine

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

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:

1. SOFTWARE
ChemProp(TM) Main Module 7.0, Public OSIRIS Edition

2. MODEL (incl. version number)
Franco, Fu & Trapp (Partitioning, soil sorption coefficient, Koc), ionizable substances, acids and bases

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.

Qualifier:

according to guideline

Version / remarks:

REACH Guidance on QSARs R.6

Principles of method if other than guideline:

- Software tool(s) used including version: ChemProp v7.0
- Model(s) used: Franco, Fu & Trapp
Full reference and details of the used formulas can be found in:
1. Franco A, Fu W, Trapp S 2009. Influence of soil pH on the sorption of ionizable chemicals: Modeling advances. Environ. Toxicol. Chem. 28: 458-464.
2. Franco A, Trapp S 2008. Estimation of the soil-water partition coefficient normalized to organic carbon for ionizable organic chemicals. Environ. Toxicol. Chem. 27: 1995-2004.
- Model description: see field 'attached justification' and 'any other information on material and methods'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'

GLP compliance:

no

Type of method:

other: calculation

Media:

soil

Details on test conditions:

BASIS FOR CALCULATION OF Koc:
- Estimation software: ChemProp 7.0, Franco and Trapp 2008 model for bases
- Log Kow: -0.91
- pKa/pKb: 11.04 (calculated with SPARC)
- pH: 4.5

Type:

log Koc

Value:

1.19 dimensionless

pH:

4.5

% Org. carbon:

5

Remarks on result:

other: calculated with a model for bases

For detailed information on the results please refer to the attached report.

Validity criteria fulfilled:

not applicable

Description of key information

log Koc (silanol hydrolysis product) = 1.19 (QSAR, Franco, Fu & Trapp, ChemProp v7.0)

Koc (silanol hydrolysis product) = 15.49 (QSAR, Franco, Fu & Trapp, ChemProp v7.0)

Key value for chemical safety assessment

Koc at 20 °C:

15.49

Additional information

N-[3-(trimethoxysilyl) propyl]butylamine (CAS No. 31024-56-3) decomposes fast in the environment, due to rapid hydrolysis in contact with water forming the corresponding hydrolysis products 3-(N-butylamino)propylsilanetriol and methanol. Organic bases like N-[3-(trimethoxysilyl) propyl]butylamine and its silanol hydrolysis product are anticipated to have the potential for significant electronic interactions with negatively charged surfaces in the environment, due to their charged state (PFA, 2016), which improves their adsorption potential.

 

Since the registered substance is hydrolytically unstable in soil/sediment information on the adsorption behavior of the hydrolysis product was collected by an appropriate calculation method.

For the environmental exposure assessment, the adsorption potential of the silanol hydrolysis product of the registered compound was calculated with the Franco, Fu, and Trapp model (estimating the soil-water partition coefficient normalized to organic carbon, 2009), a model specifically developed for ionizable organic substances.

 

The silanol hydrolysis product was within the applicability domain with regard to the descriptors pKa and log Kow (OECD principle 3) and met the remaining OECD principles as described in the robust study summary.

Based on this calculation the log Koc of the hydrolysis product is 1.19 at pH 4.5, corresponding to a Koc of 15.49.

References:

Franco A. & Trapp S., 2008: Estimation of the soil-water partition coefficient normalized to organic carbon for ionizable organic chemicals. Environmental Toxicology and Chemistry, Vol. 27, No. 10, pp. 1995–2004.

Franco A, Fu W, Trapp S 2009: Influence of soil pH on the sorption of ionizable chemicals: Modeling advances.Environ. Toxicol. Chem. 28: 458-464.