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Category name:

Justifications and discussions

Category definition:
Category description:
This category covers the following substances: monochloroacetic acid and its sodium salt
Category rationale:
Free monochloroacetic acid is a strong organic acid, which forms water-soluble salts with bases. In any medium at or near neutral pH the predominant form present is the chloroacetate anion. The salts are therefore expected to be toxicologically equivalent to the free acid, except for the acute corrosive properties, which are at least partly determined by the very low pH of strong solutions of the acid.

The category hypothesis is that the members have the same functional group (monochloroacetate). Sodium is not significant in respect of all the properties under consideration. In dilute aqueous conditions of defined pH a salt will behave no differently to the parent acid, at identical concentration of the particular speciated form present and will be fully dissociated. Hence some properties (measured or expressed in aqueous media, e.g. ecotoxicity) for a salt can be directly read-across (with suitable mass correction) to the parent acid and vice versa.