Registration Dossier

Physical & Chemical properties

Dissociation constant

Currently viewing:

Administrative data

Link to relevant study record(s)

Referenceopen allclose all

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
7 October 2008 to 27 February 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed according to GLP and internationally accepted test guidelines.
Qualifier:
according to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
yes (incl. certificate)
No.:
#1
pKa:
10.1
Temp.:
20 °C
No.:
#2
pKa:
10.3
Temp.:
20 °C
No.:
#3
pKa:
10.2
Temp.:
20 °C

Included in the tabulated data are the end point volumes for each titration and the pH at half of the end point volume (equivalent to the pKa value). The pKa values for samples A, B and C were determined to be 10.3, 10.1 and 10.2, respectively. The mean pKa value was determined to be 10.2.

Conclusions:
The pKa of 1,3-Bis(aminomethyl)cyclohexane was found to be 10.2.
Executive summary:

A package of physico-chemical testing including a determination of the dissociation constant was conducted on the test material 1,3 -Bis(aminomethyl)cyclohexane (1,3 -BAC). The dissociation constant determination was conducted according to OECD test guidelines, and in compliance with GLP.

The dissociation constant of a 1 mg/mL solution (approximately 50 mg of 1,3 -BAC dissolved in 50 mL water) was determined in triplicate by a potentiometric titration against 0.1M aqueous hydrochloric acid. Solutions were equilibrated to 20°C prior to the determination.

The mean pKa of the test solutions was found to be 10.2.

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12 November 1999 - 10 January 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study realised according to OECD guideline
Qualifier:
according to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Dissociating properties:
yes
No.:
#1
pKa:
9.05
Temp.:
20 °C
No.:
#2
pKa:
11.09
Temp.:
20 °C
Conclusions:
The pKa of 1,3-BAC have been determined to be 9.05±0.02 and 11.09±0.02 at 20±0.5°C.
Executive summary:

A package of physico-chemical testing including a dissociation coefficient determination was conducted on the test material 1,3 -Bis(aminomethyl)cyclohexane (1,3 -BAC). The tests were conducted in compliance with GLP, and the dissociation coefficiant determination was performed according to OECD test guidelines.

Solutions of the test material were prepared in triplicate and the pKas of each solution were determined by potentiometric titration with 0.02M Hydrochloric acid. The test was conducted at 20±0.5°C.

The pKas of 1,3 -BAC were determined to be 9.05±0.02 and 11.09±0.02.

Description of key information

The pKas of 1,3-Bis(aminomethyl)cyclohexane were found to be 9.05 and 11.09.

Key value for chemical safety assessment

Additional information

A package of physico-chemical testing including a dissociation coefficient determination was conducted on the test material 1,3 -Bis(aminomethyl)cyclohexane (1,3 -BAC). The tests were conducted in compliance with GLP, and the dissociation coefficient determination was performed according to OECD test guidelines. This package of work was undertaken and reported in 2000.

Solutions of the test material were prepared in triplicate and the pKas of each solution were determined by potentiometric titration with 0.02M Hydrochloric acid. The test was conducted at 20±0.5°C.

The pKas of 1,3 -BAC were determined to be 9.05±0.02 and 11.09±0.02.

A package of physico-chemical testing including a determination of the dissociation constant was conducted on the test material 1,3 -Bis(aminomethyl)cyclohexane (1,3 -BAC). The dissociation constant determination was conducted according to OECD test guidelines, and in compliance with GLP. This package of work was undertaken and reported in 2009.

The dissociation constant of a 1 mg/mL solution (approximately 50 mg of 1,3 -BAC dissolved in 50 mL water) was determined in triplicate by a potentiometric titration against 0.1M aqueous hydrochloric acid. Solutions were equilibrated to 20°C prior to the determination.

The mean pKa of the test solutions was found to be 10.2.

It was noted that the two studies noted above provided conflicting results; specifically that the first study determined two pKa values, and that the second study determined only one. Both studies were considered reliable (assigned a Klimisch score 1), and so an internet-based calculation model (SPARC, available at: http://sparc.chem.uga.edu/sparc/) was used to assess the two results. The online calculation determined that the dissociation constant of the second ionisation would be different to that of the first, hence two pKa values were determined. On this basis, the earlier study (2000, reporting 2 pKa values) was used as the key study for this endpoint, and the values from this study reported.