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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Dissociation constant

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Administrative data

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Description of key information

The dissociation constant of Tri-n-Butylamine in water was measured by conductometry. The pKa at 25° is 10.89 and 11.04 at 18 °C. The pKa at 20°C was calculated using the temperature coefficient of -0.021 as given in Damsgaaard-Sorensen and Unmack (1935): 10.998 rounded to 11.0.

Due to the low water solubility of the test substance correction for dissolved carbonate were carried out. This was necessary, because at low concentrations, conductivity will be influenced significantly by dissolved carbonate and hydrogen carbonate and falsify results for pKa determination. Measurements were performed at 18°C.

In the supporting study (OXEA, 2009), a determination according to the titration method was not feasible due to the low water solubility of the submission susbstance.

Key value for chemical safety assessment

pKa at 20°C:

Additional information

The following results were determined from the key study:

pKa at 20°C: 10.998 (from temperature coefficient of -0.021 as given in Damsgaaard-Sorensen and Unmack (1935), rounded to 11.0

pKa at 18°C (Damsgaaard-Sorensen and Unmack, 1935): 11.04

pKa at 25°C (Damsgaaard-Sorensen and Unmack, 1935): 10.89