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Physical & Chemical properties

Partition coefficient

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Description of key information

log Kow [(trimethoxysilylpropyl)methylmethylphosphonate]: 0.3 at 20°C (QSAR)

log Kow [bis(trimethoxysilylpropyl)methylphosphonate]: -0.2 at 20°C (QSAR)

log Kow [(trihydroxysilylpropyl)methylmethylphosphonate]: -2.8 at 20°C (QSAR)

log Kow [bis(trihydroxysilylpropyl)methylphosphonate]: -4.0 at 20°C (QSAR)

log Kow [methanol] = -0.82 to -0.64

Key value for chemical safety assessment

Additional information

The requirement to conduct an n-octanol-water partition coefficient test for the submission substance is waived because in contact with water, the constituents of the substance hydrolyse rapidly to form the corresponding silanol hydrolysis product and methanol.

The submission substance is a multi-constituent substance containing two constituents, the log Kow of the constituents and the silanol hydrolysis products are relevant for the chemical safety assessment.

The predicted log Kow using a validated QSAR estimation method for the constituents are 0.3 at 20°C and -0.2 at 20°C for Constituent 1 and Constituent 2 respectively.

In contact with water, the constituents hydrolyse rapidly to form (trihydroxysilylpropyl)methylmethylphosphonate (HP 1) and bis(trihydroxysilylpropyl)methylphosphonate (HP 2) as the silanol hydrolysis products for Constituent 1 and Constituent 2 respectively. The predicted log Kow for the silanol hydrolysis products are -2.8 at 20°C and -4.0 at 20°C for HP 1 and HP2 respectively.

The other non-silanol hydrolysis product is methanol for both constituents. Methanol has a reported log Kow of -0.82 to -0.64 (OECD 2004).

 

Reference:

OECD (2004): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1.