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Description of key information

The calculated HLC for the hydrolysis product methanol is 0.3 Pa.m3.mol-1 at 12°C

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
0.3
at the temperature of:
12 °C

Additional information

Tetramethyl orthosilicate hydrolyses rapidly (t1/2 = < 1 h at pH 7and 25°C) to (poly)silicic acid and methanol. (Poly)silicic acid is an inorganic substance with a negligible vapour pressure, which enters natural biogeochemical cycles for silicon. Therefore, volatilisation from water is not a relevant process. Methanol is expected to biodegrade fast. The HLC for ethanol can be estimated from the ratio of the vapour pressure (VP) to the water solubility (WS). HLC = (VP x MW)/WS where MW is molecular weight. The calculated HLC value for methanol at environmental temperature (12°C) is 0.3 Pa.m3.mol-1 (taken from EUSES 2.1.2). This indicates some potential to evaporate from water.