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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

The log Pow of BHMT (Bishexamethylenetriamine) is 1.3 at 24 °C and pH=12.
The calculated log Pow of HMD (Hexamethylenediamine) is max. 0.44.

Key value for chemical safety assessment

Log Kow (Log Pow):
at the temperature of:
24 °C

Additional information

The following weight-of-evidence data is available for the particion coefficient of the main components of the submission substance:

BHMT (Bishexamethylenetriamine):

The partition coefficient (n-octanol/water) of BHMT was determined by the shake-flask method according to EU A.8 / OECD 107. The log Pow of the test item is 1.3 at pH=12 and 24 °C. This value applies to the neutral (not protonated) form of BHMT.

The partition coefficient (n-octanol/water) of BHMT was also determined by the shake-flask method according to EU A.8 / OECD 107, but without buffer as required by the guideline for ionisable test substances, therefore this study was rated as not reliable. The outcome is: log Pow = 0.63 at a pH of ca. 10.4 and 24 °C.

But actually this value is considered to be more relevant for environmental conditions, where BHMT will be partially ionised (protonated), and is therefore taken for safety assessment purposes.

The following data is available for Hexamethylenediamine (HMD):

An experimental study was provided, however it was considered as not reliable since it was conducted at pH below the pKa, where the substance is not unionised: Log Kow = 0.02 at pH ca 10.5 (HMD partially ionised form).

Study performed apparently close to recommendations of OECD 107 but not on the unionised form of the substance, considering the pH measured (< pKa). Analysis was performed by titrometry at two concentrations (1 and 2.75 g/L based on summed measured recovered concentrations). However the two assays performed provide similar results which can be considered as indicative values at the pH given.

Therefore a weight-of evidence was based on the SPARC model, able to calculate the log D (distribution coefficient) as a function of pH, and a robust publication on Log Pow calculation (QSAR):

SPARC: Log Kow = 0.44 at pH >= 13 (unionised).

The pH-dependent partition coefficient of HMD was estimated using the recommended QSAR model SPARC v4.5, based on Linear Solvation Energy Relationships. No data is available with regard to validation parameters according to OECD principles.

The calculated result log D increases from -4.04 to 0.44 with increasing pH from 0 to 14 at 25 °C, due to ionisation of the substance.

Publication on Log Pow calculation (QSAR):

This publication describes a QSAR method and validation parameter for prediction of log P based on fragments contribution. HMD is in the applicability domain of this model, and the calculated log P is 0.35.

This information is considered to be sufficient for classification and risk assessment purposes.