Registration Dossier

Diss Factsheets

Physical & Chemical properties

Dissociation constant

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

SPARC estimates

Key value for chemical safety assessment

pKa at 20°C:

Additional information

Material consists of approximately equal amounts of cocoalkyl amine (C6 -C18), beta-alanine, N-cocoalkyl (C6 -C18) and beta-alanine, N-cocoalkyl (C6 -C18), 2 -carboxyethyl. SPARC does not discriminate according to chain length for C6 -C18 alkylamines; as such all alkyl isomers of the three components are estimated to have the same pKa.

In isolation, the mono- and di-beta-alanine components have pKa values (one for the mono, and two for the di-beta-alanine component) around 3.5, for the carboxylic acid group. The primary and secondary amino groups (cocoalkyl amine and the mono-beta-alanine component) have pKa values around 10.5; the tertiary amino group (the di-beta-alanine component) has a pKa value around 7.5.

Ideally, all pKas would be observable in a titration-type experiment with the commercial material, although it is questionable whether the three pKas around 3.5 and the two pKas around 10.5 would be resolved. In practice, what would most likely be observed is a shallow/compound inflection point around 3.5 (for three species), a steep inflection point around 7.5 (one species) and a shallow/compound inflection point around 10.5 (two species). However, it cannot be excluded that the amines and acids present in the material would combine into amides under influence of acid/base titration pH-changes - in that case only amine pKas may be observable, depending on the extent of amide-formation.