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Dissociation constant

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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:
5.67

Additional information