Ethoxytrimethylsilane

Phototransformation in air

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

phototransformation in air

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 analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

DT50:

4.1 d

Remarks on result:

other: Sommerlade, 1993

Conclusions:

Three different results are available investigating the degradation of the substance in contact with OH-radicals. The studies resulted in a DT50 value of 4.1 d (rate constant 3.95E-12 cm³ molecule-1 second-1 at 24 °C).

Reference 2

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.

Principles of method if other than guideline:

Direct photolysis: Irradiation of three different concentrations of both test substances with wavelengths above 290 nm (xenon lamp, wavelengths representative of troposphere) in N, O2 and air, at start concentrations of 1, 5 and 10 ppm. Quantification of products via GC-MS.
Indirect photolysis: Conducted as above. Source of OH radicals was HONO.

GLP compliance:

no

Light source:

Xenon lamp

Reference substance:

yes

No direct photolysis observed under these conditions.

These test substances do react with OH-radicals. Rate constant for reaction with hydroxyl radicals 3.13E-12 cm3/mol/sec.

Conclusions:

A rate constant for reaction with hydroxyl radicals of 3.13E-12 cm3/mol/sec was determined in a reliable study conducted according to generally accepted scientific principles.

Reference 3

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP. .

Principles of method if other than guideline:

Smog chamber mass spectrometer system

GLP compliance:

not specified

% Degr.:

50

Sampling time:

4.1 d

Test condition:

indirect photolysis

Photoinduced oxidative degradation in the gaseous phase by reaction with hydroxyl-radicals.

Rate Constant K = 3.95E-12 cm3/molecule.s. 

Conclusions:

An experimental relative rates study found a reaction with the OH radical rate constant of 3.95E-12 cm3 molecule-1 second-1 at 24 °C (half-life 4.1 days).

Reference 4

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.

GLP compliance:

no

% Degr.:

50

Sampling time:

22 d

Conclusions:

An experimental rate study found a reaction with the OH radical rate constant of 7.2 E-13 cm3 molecule-1 second-1 (half-life 22 days).

Key value for chemical safety assessment

Half-life in air:

4.1 d

Degradation rate constant with OH radicals:

0 cm³ molecule-1 s-1

Additional information

There are no data available on the phototransformation in air for ethoxytrimethylsilane (CAS 1825-62-3). In accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 “Grouping of substances and read-across” and in accordance with the read across assessment framework (RAAF, ECHA 2017) a read-across from the silanol hydrolysis product trimethylsilanol (CAS 1066-40-6) has been applied to support the environmental hazard assessment of ethoxytrimethylsilane. Details on the read across justification can be found in the overall justification for grouping of substances attached in IUCLID Section 13.

In the key study a rate constant of 3.95E-12 cm3 molecule-1 second-1 at 24 °C for the reaction with OH-radicals resulted (half-life 4.1 days). The DT50 of 4.1 d for trimethylsilanol is used in the exposure assessment as a worst case.