Hexasodium 2,2'-[vinylenebis[(3-sulphonato-4,1-phenylene)imino[6-[bis(2-hydroxyethyl)amino]-1,3,5-triazine-4,2-diyl]imino]]bis(benzene-1,4-disulphonate)

Hydrolysis

Description of key information

Stable at pH 4, 7 and 9 at 50 °C: it has a half-life period longer than one year at 25 °C at pH 4, 7 and 9.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

Hydrolysis is a common degradation route in the environment, namely reaction of a substance with water with a net exchange of the X group with an OH at the reaction centre such that RX + H2O → ROH + HX. Hydrolysis is often dependent upon pH as the reaction is commonly driven by hydrogen or hydroxide ions. Hydrolysis kinetics are usually determined experimentally and should be used to consider the test type and whether parent or degradation product should be tested.

In the case of the substance, it can be estimated that hydrolysis does not occur because there are not hydrolysable groups in any of the structures; this is also confirmed by calculation with HYDROWIN 2.0.

Hydrolyzable organic groups are in fact those groups that can react with water like Esters, Anhydrides, Amides, Carbammates, Nitriles, Cyanates, Epoxides, Halomethanes, Alkylhalides, Urea and none of these groups are present within the substance or their impurities.

A test was conducted according to internationally accepted testing guidelines and according to GLP on an analogous substance of the Stilbene Fluorescent Whitening Agents category, group 3, OB 3a-MSA, for which a reliable Hydrolysis study has been reported. The two substances (OB 3a-MSA and OB 3a-DSA) are very similar and with the difference that OB 3a-MSA is tetrasulphonated instead than hexasulphonated, sodium salt. The difference in sulphonation can have an influence on water solubility, but not on the hydrolysation potential, since both substances have no hydrolysable groups in the chemical structure. Quantity and chemical identity of the impurities have no influence on the possibility of Read Across for this end point. For further details refer to the Category Justification Report attached to the section 13 of this dossier.

Hydrolysis was determined at 50 °C at pH 4, 7 and 9 for the preliminary test in the analogous substance. The determination of residual test substance was performed by high performance liquid chromatography (HPLC) using an external standard. The test substance is stable at pH 4, 7 and 9 at 50 °C: it has a half-life period longer than one year at 25 °C at pH 4, 7 and 9 (Ciba-Geigy Ltd., 1992).