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Physical & Chemical properties

Partition coefficient

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Description of key information

The QSAR estimated values of 2.14 and 2.33, provides an averaged estimated log Kow for 2-methylpropane-2-thiol of 2.235. This is supported by a log Kow of 2.28 at 25˚C, which has been read across within the category from butane-1-thiol.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.14
at the temperature of:
25 °C

Additional information

The use of a QSAR to predict the partition coefficient is an appropriate technique and is suitable as a key study. The model used a training set to fit standard linear regressions of the partition coefficient of 2447 compounds to their molecular weights. No applicability domain has been set for the model, but the substance falls within the molecular weight of the training set. The result from this QSAR has been averaged with the result from the SPARC online calculator.

There are limitations in design and reporting of the SPARC online calculator. No details are available regarding the method of calculation or the training set used. The QSAR is considered appropriate as a supporting study.

This is supported by the log Kow of butane-1 -thiol, which has been read across within the category in a precautionary approach within molecular weight. The presence of branching indicates that the log Kow of 2 -methylpropane-2 -thiol is expected to be lower than that of the linear butane-1 -thiol, as it is more soluble in water. The read across results are taken from the WHO IPCS International Chemical Safety Card (ICSC 0018, 2000). No information on the primary source of these data or the methods used is available. However, this information is taken from an internationally peer-reviewed chemical safety card and can be considered reliable and suitable for use as the key study for this endpoint.