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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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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Endpoint:
dissociation constant
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
ARChem SPARC. version 4.6

2. MODEL
pKa

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables".

5. APPLICABILITY DOMAIN
See information provided in "Any other information of materials and methods incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: SPARC v4.6
- Model(s) used: pKa
SPARC breaks the molecule into two type of functional units: the reaction center (with known chemical properties) and the perturber. pKa of the reaction center is adjusted for the molecule in question using the mechanistic perturbation models. For the complete method's description see field 'Any other information on materials and methods incl. tables'.
The datasets used for the model development and for the external validation are described in the field 'Any other information on materials and methods incl. tables'.
- Model description: see field 'Any other information on materials and methods incl. tables'.
- Justification of QSAR prediction: see field 'Justification for type of information' and 'overall remarks'.
GLP compliance:
no
Dissociating properties:
yes
pKa:
>= 1.06 - <= 1.07
Temp.:
25 °C
Remarks on result:
other: range for C14 EO=5 -> EO=0

For detailed description on the model and its applicability, see "Any other information on materials and methods incl. tables".

On the basis of a number of calculations performed with selected representative constituents of substances from the Alkyl Ether Sulfate category, it can be concluded that for the linear alkyl chains from the range C8 - C18 (including C18 1 -fold unsaturated), the result is independent from the alkyl chain length and the analogical range 1.06 -1.07 can be obtained also for C12.

Endpoint:
dissociation constant
Type of information:
other: experimental data for the cation
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
Method not specified
GLP compliance:
no
Dissociating properties:
yes
No.:
#1
pKa:
9.94
Temp.:
10 °C
No.:
#2
pKa:
9.62
Temp.:
20 °C
No.:
#3
pKa:
9.32
Temp.:
30 °C

Description of key information

pKa of MIPA (monoisopropanolamine): 9.62 at 20 °C
pKa of AES anion: 1.06-1.07 at 25 °C

Key value for chemical safety assessment

Additional information

Due to the dissociation constants of the corresponding alkyl ether sulfate (pKa < 2) and monoisopropanolamine (pKa = 9.62) at room temperatures of 20-25 °C, it can be assumed that the substance is existent as a salt and thus completely dissociated in the range of pH 5 -9. Additionally, pKa values for MIPA are available at 10 °C (9.84) and at 30 °C (9.32).