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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

A study was performed in order to determine the dissociation constant of N-(2-nitrophenyl)phosphoric triamide (2-NPT).

The determination was performed in triplicate. 

A three-point-calibration was performed using three standard-buffer-solutions (pH 4.01, 7.00 and 9.21).

Titration was performed using HCl concentration 0.001 mol/L; turning-point was detected electrometrically.

 The pKa was determined as 5.670 ± 0.124 and the pKb was determined as 8.330 ± 0.124 these values are the mean of three independent determinations ± their standard deviation.

Key value for chemical safety assessment

pKa at 20°C:

Additional information