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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Estimated value with EPIWIN using the formula of the zinc free substance '5,5'-(E)-diazene-1,2-diylbis(4,6-dihydroxypyrimidin-2(5H)-one)'
(CAS No. 25157-64-6). The model KOWWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of -3.15. The predicted value can be considered reliable yielding a useful result for further assessment.

Key value for chemical safety assessment

Log Kow (Log Pow):
-3.15

Additional information

In accordance with REACH annex VII column 2, the study does not need to be conducted as the substance does not dissolve in water (experimentally determined water solubility: 0.52 mg/L). As required a calculated value with details in the calculation method was provided. However, it is not possible to calculate log Kow for the zinc complex with accepted software such as EPIWIN as the trainig set does not include organometallic complexes. Therefore, the zinc free molecule was used giving a log Kow of -3.15. This value is assumed to be adequate as zinc as well has a very low log Kow.