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Environmental fate & pathways

Hydrolysis

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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 the Direct Orange 118, it can be estimated that hydrolysis can be considered as negligible degradation pathway due to the chemical structure and functional groups presents.

Additionally, by the nature of their destination of use, dyes are not intended to be readily trasformabile in water as this would assist in the rapid destruction of the dyestuff, rendering it unfit for purpose. As such, it is accepted that such substances are not readily hydrolyzed.