1,3-diethyl-2,4-diisocyanato-5-methylbenzene

Water solubility

Administrative data

Endpoint:

water solubility

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
According to REACH Annex XI, 2. TESTING IS TECHNICALLY NOT POSSIBLE, Testing for a specific endpoint may be omitted, if it is technically not possible to conduct the study as a consequence of the properties of the substance: e.g. very volatile, highly reactive or unstable substances cannot be used, mixing of the substance with water may cause danger of fire or explosion or the radio-labelling of the substance required in certain studies may not be possible. The guidance given in the test methods referred to in Article 13(3), more specifically on the technical limitations of a specific method, shall always be respected.
As depicted in more detail in the attached Expert Statement on the reactions of Isocyanates and Di-isocyanates (e.g. DETDI) with water, Isocyanates have the possibility to react under different pH-conditions in water.
Under neutral and acidic conditions first formation of unstable carbamic acid takes place. This decomposes immediately to the corresponding amine (neutral conditions) or ammonium salt (acidic conditions). Acidic conditions (catalysis) accelerate the formation of unstable carbamic acid.
Under basic conditions formation of carbamic acid anion should occur which does not decompose to the amine and carbon dioxide because no proton is available. The carbamic acid anion should be stable under basic conditions.
Isocyanates are capable to react with water via carbamic acid to the corresponding amine and carbon dioxide, the resulting amines are capable to react with isocyanates to form urea-derivatives. As isocyanates bear two isocyanate-groups, these molecules have the possibility to react further with water to form polyurea.
Further, experiments were performed by an external laboratory (attached) to evaluate also practically the feasibility of ecotoxicity testing. As proposed above using common literature data, the pre-test for Ecotoxicity testing show that DETDI is rapidly transformed into another substance. However, the design of the pre-test does not allow determination of neither the half-life time nor the degradation products for DETDI due to the anticipated rapid polymerization of the hydrolysis products. Thus, the author concluded that testing DETDI in aquatic studies would not result in reliable conclusions concerning possible effects during testing.
Last but not least, interim results for the feasibility of hydrolysis testing showed that in pure water and different buffer solutions DETDI degraded immediately after preparation of the standard and analysis. By comparing the spectra of the peaks in Acetonitrile and in buffer solution, DETDI could not be observed in the aqueous samples, and a few unknown products were found.
So in summary, water solubility testing of DETDI is technically not possible, as it reacts immediately with water to unknown products, and so, the Waiving criteria according to Annex XI of REACH are met and testing can be omitted.