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EC number: 218-747-8
CAS number: 2224-33-1
Hydrolysis: Weigh of evidence: Based on read-across approach from
experimental results on analogue substances VAC3, MAC3 and
propyltriacetoxysilane, the test item is determined to be hydrolytically
unstable (half-life < 12hours).
Biodegradation in water: Screening test: Key study: Based on read-across
approach from experimental results on analogue butan-2-one
O,O',O''-(methylsilanetriyl)oxime, the test item was determined not to
be readily biodegradable. This result was supported by EPI-Suite, EPA
(USA) / BIOWIN v4.10 calculation method.
Biodegradation in water and sediment: Simulation tests: Data waiving
(other justification): In accordance with column 2 of REACH Annex IX,
the study does not to be conducted since direct and indirect exposure of
sediment is unlikely.
Biodegradation in soil: Data waiving (other justification): In
accordance with column 2 of REACH Annex IX, the study does not to be
conducted since direct and indirect exposure of sediment is unlikely.
Bioaccumulation: aquatic/sediment: Based on the read-across approach
from analogue butanone oxime, the substance butan-2-one
O,O',O''-(vinylsilanetriyl)oxime was determined to have a low
Adsorption: Key study: Soil adsorption for butan-2-one
O,O',O''-(vinylsilanetriyl)oxime was estimated by KOCWIN v2.00, MCI
method and was determined to be: Koc = 5.933E+005 L/kg and Log Koc =
silicon chemicals are known as silanes. A silane that contains at least
one silicon carbon bond, (e.g -Si-CH3) is an organosilane. They normally
contain two different types of reactive groups: the hydrolysable groups
such as methoxy, ethoxy or acetoxy groups and the organo-functional
group, such as epoxy, amino, methacryloxy, or sulfido. It is well known
that the Si-OR bonds hydrolyse readily with water, even if only with
moisture absorbed on the surface, to form silanol Si-OH groups. These
silanol groups can then condense with each other to form polymeric
structures with very stable siloxane Si-O-Si bonds.
to confirm that hydrolysis of silanes is fast, several hydrolysis tests
have been conducted in analogue silanes. In
the hydrolysis test performed on propyltriacetoxysilane, the process was
very fast. The half-life at different pH of test item was determined to
be < 37.5 seconds since it completely hydrolysed at 150 seconds after
the initial contact with water.
Moreover, the hydrolysis
test performed on two acetone oxime silanes, more than 50% of the
components hydrolysed in less than 0.75hafter
starting the dissolution of the test substance at
25 ºC and independently of the pH.
it is stated in different publications, silanols hydrolyse well in water
and the carbon- bounded substituents can have profound effects on the
rate of hydrolysis. (Arkles B., Chemtech 1977; Pluddemann E. P., Plenum
Press NY, 1982; Kay, B. D. and Assink R. A, J. Non-Cryst. Solids, 1988).
rates of hydrolysis of the alkoxy groups are generally related to their
steric bulk: CH3O>C2H5O> t-C4H9O
and a methoxysilane hydrolyzes at 6-10 times rate of an ethoxysilane.
Smith (Smith K. J. Org. Chem 1986) proved that increased organic
substitution enhances the hydrolysis rate Me3SiOMe> Me2Si(OMe)2>
the hydrolysis test performed with propyltriacetoxysilane, the
condensation and polimerysation of the molecules formed in hydrolysis
were observed too. It was observed as the phase separation.
Unfortunately, this phase separation caused the technical difficulties
of the determination of the molecular weight of larger condensation
products. It was possible to determined MW of smaller condensates which
still are in solutions. Their
average MW were between 604-695.
phase separation as a result of condensation was described by Arkles.
The hydrolysis of propyltrimetoxysilane showed that oligomers are formed
and branched structures presages phase separation (Arkles B. et al,
Silanes and Coupling Agents, 1992).
in account both, the hydrolysis and condensation, it is expected that
the observed in the hydrolysis test phase changed product contains large
chain polymers with MW>1000.
showed that molecules of MW>1000 cannot be biologically available (Van
Gestel et a, Reg. Toxicol. and Pharmacol., 1985, 5, 422-31 and Zitko V,
Handbook of Environmental Chemistry, v. 2 221-29).
The results for environmental fate and pathways are as follows:
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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