Dodecenylsuccinic acid, compound with 2,2',2''-nitrilotriethanol (1:1)

Dissociation constant

Administrative data

Endpoint:

dissociation constant

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Guideline study performed 2017 at GLP accredited laboratory
however, due to the nature of the substance, distinct pKa values could not be determined

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 112 (Dissociation Constants in Water)

Principles of method if other than guideline:

Titration with KOH

GLP compliance:

no

Remarks:

GLP facilities, but conducted as non-GLP

Test material

Test material information

Constituent 1

Reference substance name:

Dodecenylsuccinic acid, compound with 2,2',2''-nitrilotriethanol (1:1)

EC Number:

264-867-9

EC Name:

Dodecenylsuccinic acid, compound with 2,2',2''-nitrilotriethanol (1:1)

Cas Number:

64396-12-9

Molecular formula:

C16H28O4.C6H15NO3

IUPAC Name:

Succinic acid, dodecenyl-, triethanolamine salt (1:1)

Test material form:

liquid

Details on test material:

Commercial grade containing approximately 45% actives

Specific details on test material used for the study:

Batch PAH 330/132/1A
Commercial grade material in water

Results and discussion

Dissociating properties:

yes

Dissociation constant

Dissociation constant 1

No.:

#1

pKa:

ca. 6.2

Temp.:

23 °C

Dissociation constant 2

No.:

#2

pKa:

ca. 8

Temp.:

23 °C

Any other information on results incl. tables

The normal pH of the material is 6.2

The reported pKa for triethanolamine is 6.2

Applicant's summary and conclusion

Conclusions:

The substance is a salt of tertiary amine and a weak organic acid and will be dissociated under normal biological and environmental conditions.
The pKa measured is comparible to that of the amine and is at the measure pH of 6.2.
The dissociation of the salt means that for environmental and toxicological assessment, the substance will have comparible propteries to the triethanolamine and dodecenylsuccinic acid starting materials.
1 At pH 1 (stomach pH), we would suggest that the acid would exist as the free acid and the triethanolamine as the protonated amine cation.
2 At pH 6 – 8 (environmental pH), we would suggest that the acid would exist in its fully ionised form and the triethanolamine as the protonated amine cation, however the extent of ionisation would be pH dependent.
3 At pH > 8, we would suggest that the acid would exist in its fully ionised form, as a salt, the nature of which would be determined by the environmental condition and the triethanolamine as the free amine however the extent of ionisation would be pH dependent.

Executive summary:

From literature references, we would suggest that the pKa value of 7.97 probably relates to the triethanolamine undergoing conversion from the pronated NH (Structure 1) to the free amine N (Structure 2).

 

The pKa value of 6.17 therefore probably relates to thedoubly deprotonated dodecenyl succinic carboxy anion (Structure 3), undergoing conversion to the mono protonated dodencenyl succininc carboxy anion with the expectation that a mono protonated dodecenyl succinic carboxy anion (Structure 4) would be formed from the free acid (Structure 5) with a lower pKa. Structures of the species detailed are given below: