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Environmental fate & pathways

Hydrolysis

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Description of key information

The test substance is estimated to be stable at pH 4, 7 and 9 at 50 °C: its analogue 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 the 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 CAS 13863-31-5, 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 reliable test on the Hydrolysis was conducted on an analogous substance of the Stilbene Fluorescent Whitening Agents category, group 3, CAS 16470-24-9, according to internationally accepted testing guidelines and performed according to GLP. The two substances (CAS 16470-24-9 and CAS 13863-31-5) are very similar and are constituted by similar functional groups. The sulphonation degree is different: CAS 16470-24-9 is tetrasulphonated instead than CAS 13863-31-5 that is disulphonated, 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 to section 13 of the 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.