Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 939-597-6 | CAS number: 68610-66-2
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 3 Feb 2012
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- GLP compliance:
- no
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 1.35
- Temp.:
- 20 °C
- Remarks on result:
- other: Mean of two determinations A and B
Reference
Sample measurements, solutions A and B:
Dilution factor |
Solution A, concentration, g/L |
Solution A, conductivity, µS/cm |
Solution B, concentration, g/L |
Solution B, conductivity, µS/cm |
0 |
5.061 |
834 |
4.000 |
677 |
2 |
2.5305 |
427 |
2.000 |
349 |
4 |
1.26525 |
216.9 |
1.000 |
180.1 |
8 |
0.632625 |
115.3 |
0.5000 |
92.3 |
16 |
0.3163125 |
60.5 |
0.2500 |
48.3 |
32 |
0.1581563 |
32.1 |
0.1250 |
25.4 |
64 |
0.0790781 |
17.4 |
0.0625 |
13.39 |
Solution A:
Concentration solution A, g/L |
Concentration solution A, mol/L |
Specific conductivity k, mS/cm |
Equivalent conductivity L, S cm2/mol |
Reciprocal equivalent conductivity 1/L, mol/S cm2 |
5.061 |
0.0134601 |
0.834 |
61.9609 |
0.01613922 |
2.5305 |
0.0067301 |
0.427 |
63.4467 |
0.01576125 |
1.26525 |
0.0033650 |
0.2159 |
64.1600 |
0.01558604 |
0.632625 |
0.0016825 |
0.1153 |
68.5284 |
0.01459248 |
0.3163125 |
0.0008413 |
0.0605 |
71.9162 |
0.01390507 |
0.1581563 |
0.0004206 |
0.0321 |
76.3144 |
0.01310369 |
0.0790781 |
0.0002103 |
0.0174 |
82.7334 |
0.01208702 |
1/L = a*k + b, slope a = 0.0039842, intercept b = 0.0134847
Ostwald dilution law: Ka = 1/(a*(1/b)2) = 0.04563936; pKa = - log Ka = 1.34
Solution B:
Concentration solution B, g/L |
Concentration solution B, mol/L |
Specific conductivity k, mS/cm |
Equivalent conductivity L, S cm2/mol |
Reciprocal equivalent conductivity 1/L, mol/S cm2 |
4.000 |
0.0106383 |
0.677 |
63.6380 |
0.01571388 |
2.000 |
0.0053191 |
0.349 |
65.6120 |
0.01524111 |
1.000 |
0.0026596 |
0.1801 |
67.7176 |
0.01476721 |
0.5000 |
0.0013298 |
0.0923 |
69.4096 |
0.01440723 |
0.2500 |
0.0006649 |
0.0483 |
72.6462 |
0.01376591 |
0.1250 |
0.0003324 |
0.0254 |
76.4032 |
0.01308846 |
0.0625 |
0.0001662 |
0.01339 |
80.5542 |
0.012414 |
1/L = a*k + b, slope a = 0.0041051, intercept b = 0.0133872
Ostwald dilution law: Ka= 1/(a*(1/b)2) = 0.04365714; pKa= - log Ka= 1.36
Average pKa= 1.35.
Description of key information
pKa = 1.35 at 20 °C
Key value for chemical safety assessment
- pKa at 20°C:
- 1.35
Additional information
The dissociation constant of the substance was determined according to OECD Guideline 112 (conductometric method).
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
