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EC number: 236-704-1
CAS number: 13465-77-5
In accordance with Column 2 of REACH Annex VII, the water solubility
study does not need to be conducted as the substance has a hydrolytic
half-life less than 12 hours at pH 4, 7 and 9. Water solubility of the
initial and ultimate hydrolysis products, hexahydroxydisilane and
monosilicic acid, is limited to approximately 100-150 mg SiO2/l,
with condensation occurring at higher concentrations.
In accordance with Column 2 of
REACH Annex VII, the water solubility study does not need to be
conducted as the substance has a hydrolytic half-life less than 12 hours
at pH 4, 7 and 9.
Hexachlorodisilane reacts very rapidly with water, generating
hexahydroxydisilane and hydrochloric acid. Further hydrolysis of the
Si-Si bonds in hexahydroxydisilane is expected to happen rapidly and
produces monosilicic acid. At concentrations above about 100-150 mg/l
(measured as SiO2equivalents), condensation products of monosilicic acid
can also form. At concentrations >100-150 mg/l of SiO2, monomeric
monosilicic acid condenses into colloidal particles of polysilicic acid
(silica sol) or a highly cross-linked network (silica gel).
Hexahydroxydisilane is also likely to form condensation products
(polyhydroxy-polysilanes) at similar concentrations (in terms of
SiO2equivalents). Distinguishing Si-Si containing hydrolysis products
(polyhydroxy-polysilanes) from (poly)silicic acid would be very
difficult analytically. The condensation rate is
dependent on temperature, concentration, and acidity/alkalinity (as in
the pH) of the system. A dynamic equilibrium is established between
monomeric monosilicic acid, oligomers and insoluble amorphous
water solubility of 1.0 E+06 mg/l was obtained for hexahydroxydisilane
and monosilicic acid using an appropriate calculation method. The method
has not been validated for inorganic substances and does not take into
account the condensation reaction.
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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