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EC number: 221-641-4 | CAS number: 3173-72-6
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
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Hydrolysis
Administrative data
Link to relevant study record(s)
Description of key information
Hydrolysis of 1,5-naphthylene diisocyanate results in formation of the main hydrolysis products 1,5-naphthylene diamine and carbon dioxide. Half-life of the parent compound 1,5-naphthylene diisocyanate is less than 1 hour at pH values between 4 and 9 under ambient conditions (Bayer Industry Services, 2006b).
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 1 h
- at the temperature of:
- 25 °C
Additional information
The study on hydrolysis of 1,5-naphthylene diisocyanate which was performed in accordance with OECD 111 reported of rapid hydrolysis (T1/2 < 1 hour) with mainly the formation of 1,5-naphthylene diamine and carbon dioxide. The test item had been stirred in the study which allowed dispersion of particles in the water phase and by this increased the surface which may be subject to hydrolysis compared to conditions without stirring. The formation of amines is commonly known for isocyanates under such laboratory test conditions and in particular when the test item is treated by ultra turrax which results in extremely fine dispersed test item with huge reaction surface and small particle volume. Under such test conditions the formation of amines is assumed to be dominant.
However, it is also commonly known that amines being formed from hydrolysis reactions of isocyanates are not the final reaction product. In fact amines use to react with isocyanates spontaneously in a secondary exothermal reaction (already at room temperature) resulting in the formation of poly-urea. This process was e.g. described by Meier-Westhues (Polyurethane – Lacke, Kleb- und Dichtstoffe, Vincentz Network, 2007, ISBN 3-86630-896-5).
Taking into account the laboratory test conditions with artificial stirring and particle dispersion which does not reflect environmentally relevant conditions the above mentioned allows to interpret the study results of 1,5-naphthylene diisocyanate in a specific light. This test item was treated by stirring which preferably leads to the formation of small particles with huge surfaces. Hydrolysis takes only place at the particle surface and 1,5-naphthylene diamine as well as carbon dioxide are formed. The smaller the particles due to the stirring process the less likely that the amine may spontaneously react with 1,5-naphthylene diisocyanate as less of the latter one is available inside the particle.
Under environmentally more relevant conditions, however, clearly lower or even no “stirring” effect is to be expected and isocyanate particles remain in original size. The same hydrolytical reaction as described above would be expected at the particle surface resulting in the formation of 1,5-naphthylene diamine. However, in a second step the amine will spontaneously and exothermically react with 1,5-naphthylene diisocyanate isocyanate groups forming poly-urea. Poly-urea is a chemically inert substance which is not classified (no H or P phrases according to Regulation (EC) No 1272/2008).
Heimbach, Jäger and Sporenberg (Ecotoxicol Environ Saf. 1996 Mar; 33(2):143-53) investigated on fate and biological effects of polymeric 4,4’-diphenylmethanediamine (MDI) - another isocyanate - in small artificial ponds (mesocosm). They reported of the formation of carbon dioxide (released as bubbles) which fits to the theoretical chemical reaction expected and described above. Furthermore, they reported of the formation of poly-urea from the isocyanate. Thus, this study supports the more theoretical assumption on commonly known chemical reactions of isocyanates.
Another supporting aspect is that the reaction of amines with isocyanates under formation of poly-urea is rapid enough to cause problems for the use of isocyanates in varnish applications as e.g. reported by Müller and Poth (Lackformulierung und Lackrezeptur, Vincentz Network, 2005, ISBN 3-87870-170-5).
Concluding, based on theory of isocyanate chemical reaction, mesocosm studies as well as practical experience with vanisher applications the formation of amines (i.e. 1,5-naphthylene diamine) is likely but should be understood as an intermediate reaction. The final reaction product, in particular under environmentally relevant conditions, is the chemically inert poly-urea. Any evaluation of isocyanates, i.e. of 1,5-naphthylene diisocyanate, as well as classification and regulatory decisions in general should be based on those findings.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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