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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Physical & Chemical properties

Partition coefficient

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Administrative data

Link to relevant study record(s)

Description of key information

The Log Kow for tert-amyl hydroperoxide has been read-across from 1,1,3,3-Tetramethylbutyl hydroperoxide and was determined to be 2.9. This is supported by a QSAR estimated log octanol/water partition coefficient (KOWWIN and VCClab models) for tert-amyl hydroperoxide:  Log Kow = 1.43 +/- 0.48. 
The test substance should have low potential for bioaccumulation.

Key value for chemical safety assessment

Log Kow (Log Pow):

Additional information

The log Kow of tert-amyl hydroperoxide has been read across from 1,1,3,3-Tetramethylbutyl hydroperoxide, for which the value of 2.9 was determined according to the OECD 107 guideline. It should be noted that as tert-amyl hydroperoxide is more soluble in water than 1,1,3,3-Tetramethylbutyl hydroperoxide, the real log Kow is expected to be lower.


This is supported by KOWWIN and VCClab models:


The QSAR model KOWWIN v1.68 is based on Atom/Fragment Contribution (AFC) method.The calculated result is log Kow = 1.43, with a standard deviation provided by the model of 0.48. Temperature and pH values are not considered in this model.

(the value is not an experimental result, however the QSAR model is recommended by the ECHA guidance document on information requirements, is well documented with regard to validation parameters according to OECD principles. Moreover, the substance is fully characterised towards the applicability domain).


VCClab gives access on its website to a friendly-user java interface that easily calculates the log Pow of a substance using nine different QSARs including KOWWIN. It automatically calculates the average log Pow with the standard error. Results ranged from 1.10 to 1.55, with an average log Kow = 1.32, and a standard deviation of +/- 0.18 unit.

(the values are not experimental results, and no documentation is available in the on-line calculator with regard to validation parameters according to OECD principles. The result of the recommended QSAR model KOWWIN v1.68 is thus preferred).