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Environmental fate & pathways

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Hydrolysis

 The half-lives of 1,5-naphthylene diisocyanate in all tests are less than 1 hour (cfTable 3). No dependence of the hydrolysis process on the pH-value is observed.The recovery rates for the hydrolysis products during the experiment are between 85 % and 93 %. Since a recovery rate of nearly 100 % is expected, the lower recovery rates are explained by forming not detectable degradation products. Possible hydrolysis products may be higher oligomeric urea-derivates, formed by reaction of several molecules of 1,5-naphthylene diisocyanate with 1.5 -naphthylene diamine.The oligomeric urea-derivates are regarded to be insoluble.

As 1,5-naphthylene diisocyanate (parent compound) hydrolyses by 50 % within less than one hour forming as main components1,5 -naphthylene diamine and carbon dioxide, the parent compound is factually non-existent under environmental or laboratory conditions in aquatic media and sediments. Even with the fast hydrolysis no further testing for the hydrolysis is required.

 

Phototransformation in Air

There are no experimental data available on the stability of 1,5-naphthalene diisocyanate and its hydrolysis product1,5 -naphthylene diaminein the atmosphere. As the calculated half-life of 1,5-naphthylene diisocyanate is less than 26 h and of 1,5 -naphthylene diamine

is less than 2 h, both compounds are regarded to be not stable under atmospheric conditions (Currenta, 2010).

 

Phototransformation in Water

Since 1,5-naphthylene diisocyanate hydrolyses by 50 % within less than one hour forming as main component1,5 -naphthylene diamine, the potential for phototransformation was assessed for the main hydrolysis product. In the experiment, phototransformation half-lives of 1.34 min for1,5 -naphthylene diamineat concentrations of 4.83 mg/L and 5.05 mg/L in pure water at 25°C under artificial light at > 295 nm were obtained. The concentration of1,5 -naphthylene diaminein the samples was determined by means of reversed-phase HPLC. Degradation products have been detected in the HPLC chromatograms at a wavelength of 230 nm as well as 320 nm, but could not be identified with this technique (Bayer AG, 1994).