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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Link to relevant study record(s)

Description of key information

The conduct of a study is scientifically not justified. From the calculated results, it can be determined that the substance would always be ionised at 
environmentally relevant pH’s.

Key value for chemical safety assessment

Additional information

Since the test item was a mixture, overlapping dissociation constants would be present.

For this reason, estimation of the dissociation constants was made by relevant computer-based estimation software.

The calculation with the Advanced Chemistry Development I-Lab Web Service (ACD I-Lab 2.0) using the corresponding SMILES Codes yielded the following values:




dipotassium phosphate

not applicable*

phosphoric acid monoalkyl ester, potassium salt

1. :1.6 ± 0.4 ;2. :6.5 ± 0.7

phosphoric acid dialkyl ester, potassium salt

1.5 ± 0.4

diphosphoric acid dialkyl ester, potassium salt

1. :0.8 ± 0.4 ;2. :2.7 ± 0.5


15.9 ± 0.4


Commercially available software for pKaprediction, such as the Advanced Chemistry Development I-Lab Web Service (ACD I-Lab 2.0) which was used for this estimation, normally produces precise and reliable results as it employs many concepts and theories simultaneously. The uncertainty resulting from erroneous choices of the parent compound and its substituents is reduced by the size of the database included in the software.