Registration Dossier

Physical & Chemical properties

Dissociation constant

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Study initiation date: 24 June 2009 Study completion date: 12 October 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Version / remarks:
adopted on 12 May 1981
Deviations:
no
GLP compliance:
yes
Dissociating properties:
yes
No.:
#1
pKa:
10.8
Temp.:
23.5 °C
Remarks on result:
other: pKa for alkaline functional group
Remarks:
based on 2 replicate experiments

Details on measurements:

First run:

pH: 11.4

pKa: 10.77

Second run:

pH: 11.4

pKa: 10.76

Mean value of pKa: 10.8 (for alkaline functional group)

Conclusions:
Dissociation constant (at 23.5 °C; OECD 112): pKb = 10.8 (i.e. pKa for alkaline functional group)
Executive summary:

The dissociation constant of the test item was determined compliant with GLP according to OECD guideline no. 112 [adopted on 12 May 1981] with the titration method. Dissociation constant from duplicate determinations (at 23.5 °C): pKb = 10.8 (i.e. pKa for alkaline functional group).

Description of key information

pka (OECD 112): 10.8 at 23.5°C (for alkaline functional group)

Key value for chemical safety assessment

pKa at 20°C:
10.8

Additional information

The dissociation constant of the test item was determined compliant with GLP according to OECD guideline no. 112 [adopted on 12 May 1981] with the titration method. Dissociation constant from duplicate determinations (at 23.5 °C) for n-butylamine: pKb = 10.8 (i.e. pKa for alkaline functional group).

This result is corroborated from reliable (RL 2) supporting data (Koelzer and Büchi, 1971):

In this work, the pKa for n-butylamine was determined experimentally from 10 replicate experiments:

pKa (20 °C): 10.65; n= 10; standard deviation (SD) = 0.0091)