Trichloro(octadecyl)silane

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 Mar 2015

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study was conducted according to an appropriate OECD test guideline but was not in compliance with GLP.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(in analogy to OECD test guideline
111)

Deviations:

no

GLP compliance:

no

Remarks:

Iso 9001:2008 certified 2015-03-11 TÜV Süd Management Service GmbH

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Samples could not be prepared because the test item (CAS 005894-60-0) hydrolyzes immediately in water with formation of insoluble products. Thus, a determination of the solubility of the test item in water and its hydrolysis kinetics is not possible.

Buffers:

- pH: 4.0; 7.0 and 9.0
- Composition of buffer:
pH 4: CertiPur, Citric acid + hydrochloric acid + sodium hydroxide, company Merck
pH 7: Baker Analyzed, Potassium dihydrogen phosphate + disodiumhydrogen phosphate, company J. T. Baker
pH 9: CertiPur, Boronic acid + potassium chloride + sodium hydroxide, company Merck

Transformation products:

not measured

pH:

4

DT50:

<= 2 min

pH:

7

DT50:

< 2 min

pH:

9

DT50:

< 2 min

Details on results:

A determination of the solubility of SILAN HEXADECYL in water and its hydrolysis kinetics was not possible since suitable samples for kinetic 1H NMR spectroscopic measurements could not be prepared because of very fast hydrolysis and precipitation of solids. The halflife times were thus assumed to be much smaller than 2 min.

Table 1: Results

Parameter	Result	Method
Degradation – Abiotic	t1/2 (pH 4) = <<2 min	EC test guideline C.7 (in analogy to OECD testing method 111)
Degradation - Hydrolysis as a Function of pH	t1/2 (pH 7) = <<2 min
	t1/2 (pH 9) = <<2 min

Reference 2

Endpoint:

hydrolysis

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Transformation products:

not measured

pH:

4

DT50:

<= 2 min

pH:

7

DT50:

< 2 min

pH:

9

DT50:

< 2 min

Details on results:

A determination of the solubility of SILAN HEXADECYL in water and its hydrolysis kinetics was not possible since suitable samples for kinetic 1H NMR spectroscopic measurements could not be prepared because of very fast hydrolysis and precipitation of solids. The halflife times were thus assumed to be much smaller than 2 min.

Description of key information

Hydrolysis half-life: < 2 min (EU method C.7)

Additional information

No data on the hydrolysis of trichloro(octadecyl)silane (CAS 112 -04 -9) are available. Therefore good quality data from the similar substance trichloro(hexadecyl)silane (CAS 5894 -60 -0) were read across. Details on the read across justification can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.

The hydrolysis study for the chlorosilane trichloro(hexadecyl)silane (CAS 5894 -60 -0) was performed according to EC test guideline C.7 (in analogy to OECD test guideline 111). A determination of the solubility of the read across substance in water and its hydrolysis kinetics was not possible since suitable samples for kinetic 1H NMR spectroscopic measurements could not be prepared due to very fast hydrolysis and precipitation of solids. The half-life was thus assumed to be much lower than 2 min. This is confirmed from other chlorosilanes, for which measured data are available (Fisk, 2013).

On this basis the hydrolysis of the substance is expected to be very fast and the hydrolysis products are trichloro(octadecyl)silane and hydrochloric acid.