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Environmental fate & pathways

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Hexachlorodisilane hydrolyses very rapidly to hexahydroxydisilane and HCl. 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 SiO2 equivalents), 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 SiO2 equivalents).

These hydrolysis products are inorganic substances which enter natural biogeochemical cycles

. It is not appropriate to calculate Predicted Environmental Concentrations (PECs) for monosilicic acid. Refer to Section 9.0 of the CSR.