Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Tripotassium propylsilanetriolate is a mono-constituent substance containing propylsilanetriolate and potassium hydroxide in aqueous solution. The substance is only stable in aqueous solution at high pH (>14). As the pH is lowered, polymerisation may occur if the triolate concentration is high enough.

 

The effects of potassium hydroxide on the aquatic environment are limited to pH effects in unbuffered media and are not relevant for PNEC derivation.

 

The substance as registered is stable only as an alkaline aqueous solution at pH >14. Tripotassium propylsilanetriolate is the potassium salt of propylsilanetriol. In solution tripotassium propylsilanetriolate will be completely dissociated to propylsilanetriolate and three free potassium ions. Under comparable conditions of concentration and pH, propylsilanetriolate is equivalent to the parent acid propylsilanetriol; the first pKa of propylsilanetriol is approximately 10. 

Under some conditions, condensation may occur producing dimer, trimer and oligomers of propylsilanetriol(ate) in dynamic equilibrium. At concentrations relevant for the environment, the monomer is expected to predominate. Therefore, read-across from methylsilanetriol or propylsilanetriol, or substances that rapidly hydrolyse to propylsilanetriol or methylsilanetriol, is appropriate.

 

Only the monomer will be considered for the environment fate assessment, which is the applicable approach at high dilution.

Additional information