Fatty acids, C16-18 (even numbered), ammonium salts

Dissociation constant

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

dissociation constant

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
The study is technically not feasible since the substance has a low water solubility (<0.05 mg/L). Moreover, the substance is a UVCB. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance.

Reference 2

Endpoint:

dissociation constant

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Principles of method if other than guideline:

No data provided on the method.

GLP compliance:

not specified

Dissociating properties:

yes

No.:

#1

pKa:

9.25

Temp.:

25 °C

Remarks on result:

other: Data from ammonia aqueous solution. Ammonia ion is characterised by pKa.

Conclusions:

The pKa of pKa of ammonium in aqueous solution is 9.25. is 9.25.

Executive summary:

The pKa of ammonium in aqueous solution is 9.25.

Reference 3

Endpoint:

dissociation constant

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source

Justification for type of information:

1. SOFTWARE : ACD/Labs

2. MODEL (incl. version number) : Algorithm Version: v5.0.0.184

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL: C(CCCCCCCCCCC)CCCCCC(=O)O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL: based on internationally accepted and acknowledged source.

Guideline:

other: REACH Guidance on QSARs R.6

Principles of method if other than guideline:

ACD/Labs, I-Lab 2.0 , Algorithm Version: v5.0.0.184

Specific details on test material used for the study:

SMILES: C(CCCCCCCCCCC)CCCCCC(=O)O

Dissociating properties:

yes

Strongest pKa (Acid): 4.9 ± 0.4

Strongest pKa (Base): No Base pKa

Conclusions:

Strongest pKa (Acid): 4.9 ± 0.4
Strongest pKa (Base): No Base pKa

Executive summary:

Dissociation constant:

Strongest pKa (Acid): 4.9 ± 0.4

Strongest pKa (Base): No Base pKa

(ACD/Labs, I-Lab 2.0 , Algorithm Version: v5.0.0.184)

Reference 4

Endpoint:

dissociation constant

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source

Justification for type of information:

1. SOFTWARE: ACD/Labs

2. MODEL (incl. version number): Algorithm Version: v5.0.0.184

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL: C(CCCCCCCCCC)CCCCC(=O)O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL: based on internationally accepted and acknowledged source.

Guideline:

other: REACH Guidance on QSARs R.6

Principles of method if other than guideline:

ACD/Labs, I-Lab 2.0 , Algorithm Version: v5.0.0.184

GLP compliance:

no

Specific details on test material used for the study:

SMILES: C(CCCCCCCCCC)CCCCC(=O)O

Dissociating properties:

yes

Strongest pKa (Acid): 4.9 ± 0.4

Strongest pKa (Base): No Base pKa

Conclusions:

Strongest pKa (Acid): 4.9 ± 0.4
Strongest pKa (Base): No Base pKa

Executive summary:

Dissociation constant:

Strongest pKa (Acid): 4.9 ± 0.4

Strongest pKa (Base): No Base pKa

(ACD/Labs, I-Lab 2.0 , Algorithm Version: v5.0.0.184)

Description of key information

Data waiving (study technically not feasible): The study is technically not feasible since the substance has a low water solubility (<0.05 mg/L). Moreover, the substance is a UVCB. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance.

Supporting data: The dissociation constant of Fatty acids, C16 -18 (even numbered), ammonium salts would be pKa(1) = 9.25 weak base and pKa(2)= 4.9 weak acid.

Key value for chemical safety assessment

pKa at 20°C:

9.25

Additional information

Data waiving (study technically not feasible): The study is technically not feasible since the substance has a low water solubility (<0.05 mg/L). Moreover, the substance is a UVCB. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance.

Supporting data: For substances which contain multiple ionisable functionalities, pKa values should be reported for each dissociated species likely to exist in solution.

Ammonium: The pKa of ammonium in aqueous solution is 9.25 (CRC, 2009)

Stearic and palmitic acid (constituents of the substance): According to ACD/Labs, I-Lab 2.0, Algorithm Version: v5.0.0.184 estimation method the pKa values are as follows:

Strongest pKa (Acid): 4.9 ± 0.4 and

Strongest pKa (Base): No Base pKa

The dissociation constant of Fatty acids, C16 -18 (even numbered), ammonium salts would be pKa(1) = 9.25 weak base and pKa(2) = 4.9 weak acid.