Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Tetraethyl orthosilicate (CAS 78-10-4; EC No. 201-083-8) hydrolyses rapidly (t1/2 = 4.4 h at pH 7 and 25°C) in contact with water to form monosilicic acid (CAS 10193-36-6; EC No. 233-477-0) and ethanol (CAS 64-17-5; EC No. 200-578-6).

Ethanol is readily biodegradable and has a low log Kow value.

Monosilicic acid is a naturally occurring substance which is not harmful to aquatic organisms and will be incorporated into solid inorganic matrices such as silica.

In addition, monosilicic acid is known to be the major bioavailable form of silica for aquatic organisms and plays an important role in the biogeochemical cycle of silicon. Most living organisms contain at least trace quantities of silicon. For some species silicon is an essential element taken up actively. For example, diatoms, radiolarians, flagellates, sponges and gastropods all have silicate skeletal structures. The potential releases of inorganic silicon resulting from use of tetraethyl orthosilicate are negligible compared to the natural flux of silica in the environment.

Silicic acid is therefore not considered in the environmental exposure assessment (Section 9).