Dimethoxymethylvinylsilane

Biodegradation in water: screening tests

Description of key information

Biodegradation in water, screening tests: 0% (-6.78%) degradation in 28 days (OECD Guideline 301A) read-across from an analogous substance

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

There are no reliable ready biodegradation data available for dimethoxy(methyl)vinylsilane (CAS 16753-62-1), therefore good quality data for the analogous substance, dichloro(methyl)(vinyl)silane (CAS 124-70-9), have been read across. Both substances hydrolyse very rapidly and share the same silanol hydrolysis product, methylvinylsilanediol. In view of the very rapid hydrolysis, it is the silanol hydrolysis product that is relevant for environmental risk assessment. The other hydrolysis products are methanol and hydrogen chloride, respectively.

Methanol is readily biodegradable (OECD 2004).

 

Hydrogen chloride is inorganic and biodegradation is not relevant.

Dimethoxy(methyl)vinylsilane (CAS 16753-62-1) and dichloro(methyl)(vinyl)silane (CAS 124-70-9) are within an analogue group of substances within which, in general, there is no evidence of any significant biodegradation once hydrolysis and subsequent biodegradation of alkoxy/acetoxy groups has been taken into account.

 

This analogue group for the ready biodegradability endpoint consists of a number of sub-classes of substances (based on structure/functionality) with different main codes (used to represent the different sub-classes). However, read-across is carried out between substances with the same main code in most cases.

 

The table below presents ready biodegradation data for substances within the sub-class I-2 of Alkoxysilanes, silanols, acetoxysilanes and chlorosilanes, etc. where the Si part of low-biological reactivity, once any hydrolysis is accounted for.

 

Dimethoxy(methyl)vinylsilane (CAS 16753-62-1) and dichloro(methyl)(vinyl)silane (CAS 124-70-9) are members of this sub-class. It is therefore considered valid to read-across the results for dichloro(methyl)(vinyl)silane (CAS 124-70-9) to fill the data gap for the registered substance. Additional information is given in a supporting report (PFA, 2013f) attached in Section 13 of the IUCLID 5 dossier.

A report considering read across for all endpoints is attached in Section 13.

Table: Ready biodegradation data available for substances within the relevant sub-class I-2 of chemicals

CAS	Name	Main code	Readily biodegradable? Yes/no	Result: Biodegradation after 28 days (%)	Guideline	Test type	PFA Klimisch code	Result: Biodeg (%)	Corrected % biodegradation once alkoxy/acetoxy biodegradation is accounted for[1]
013154-25-1	Chlorotri(3-methyl-propyl)silane	I-2-M-C	No	0%	OECD 301B	CO2	1a	0	0
139147-73-2	Silane, dichlorodicyclopentyl-	I-2-D-C	No	0.80%	OECD 301D	BOD	2b	0.8	1
000098-12-4	Cyclohexyltrichlorosilane	I-2-D-C	No	0%	OECD 301C	BOD	1a	0	0
000124-70-9	Dichloro(methyl)(vinyl)silane	I-2-D-C	No	-6.78% (0%)	OECD 301 A	DOC	1a	0	0
017865-32-6	Cyclohexyldimethoxymethylsilane	I-2-D-Me-H	No	15-17%	OECD 301D	BOD	1a	17	-5
126990-35-0	Dicyclopentyldimethoxysilane	I-2-D-Me-M	No	12%	OECD 301C	BOD	1	12	-5
None46	t-butoxycyclopentyldimethoxysilane	I-2-D-Me-M	No	15% BOD; 25% TOC; 100% GC	OECD 301C	BOD/DOC	1a	25	7
017689-77-9	Triacetoxyethylsilane	I-2-T-A	Yes	74% in 21 days	EC C4-A	DOC	1a	74	-1
154518-41-9	Alkoxy exchange product of vinyltriacetoxysilane and glycidoxypropyltrimethoxysilane	I-2	No	50% in 28 days	OECD 301B	CO2	1a	50
017980-47-1	Triethoxyisobutylsilane	I-2-T-Et-M	Yes	75%	OECD 301D	BOD	1a	75	15
002943-75-1	Triethoxyoctylsilane	I-2-T-Et-M	No	31.50%	OECD 301D	BOD	1a	31.5	-11
035435-21-3	Triethoxy(2,4,4-trimethylpentyl)silane	I-2-T-Et-M	No	13%	OECD310	CO2	1a	13	-30
016415-13-7	Triethoxyhexadecylsilane	I-2-T-Et-S	No	43% by BOD; 74% by HPLC	MITI	BOD	1c	43	16
001067-25-0	Trimethoxypropylsilane	I-2-T-Me-H	No	54%	Annex V C4-A	DOC	1a	54	4
087135-01-1	1,6-Bis(trimethoxysilyl)hexane	I-2-T-Me-H	yes but not meeting 10-day window	74%	OECD 301B	CO2	1a	74	24
None45	Mixture of 1,1- and 1,2-bis(trimethoxysilyl)ethane	I-2-T-Me-H	Yes	93% BOD; 78% TOC; 100% GC (ethanol?)	"Biodegradation study of chemical substances by microorganisms and the like"[2]	BOD/DOC	1a	93	18
018395-30-7	Trimethoxy(2-methylpropyl)silane	I-2-T-Me-H	No	36 - 47%	OECD 301B	CO2	1a	47	4
002768-02-7	Trimethoxyvinylsilane	I-2-T-Me-H	No	51%	OECD 301F	BOD	1a	51	-9
142877-45-0	Silane, trimethoxy(1,1,2-trimethylpropyl)-	I-2-T-Me-S	No	31%	OECD 301D	BOD	1a	31	-2

 

[1]The negative values in this column are where the biodegradation rate observed in the test is less than that expected assuming only alkoxy/acetoxy parts biodegrade. This could be due to low solubility of parent substance or low rates of hydrolysis. These values should in effect be considered as zero.

 

[2]Stipulated in "Testing Method for New Chemical Substances etc." (Kanhogyo No.5, Yakuhatsu 615, 49Kikyoku No.392, July 13, 1974 )

In the study with dichloro(methyl)(vinyl)silane (CAS 124-70-9), 0% (-6.78%) biodegradation was observed in 28 days. The study was conducted according to OECD TG 301 A and is considered reliable. This is selected as the key study.

The study is considered to be reliability 1 (reliable without restrictions); the read across of the result is considered to be reliability 2 (reliable with restrictions).

References:

OECD (2004): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1.

PFA, 2013f, Peter Fisk Associates, Biodegradation Main Analogue Group report, PFA.300.005.007