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EC number: 700-674-2 | CAS number: 147993-65-5
- 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
Hydrolysis
Administrative data
Link to relevant study record(s)
Description of key information
In a read-across approach based on a tests performed with 4,4'-MDI and polymeric MDI, the hydrolysis according to OECD 111 half time is < 5 minutes at 20°C. The reaction with water followed zero order kinetics. The hydrolysis product MDA is recovered by about 100%. In such dilute systems, isocyanate functions are generally converted to amino functions.
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 5 min
- at the temperature of:
- 20 °C
Additional information
The test substance is covered by an analogue approach. The read-across justification document is attached in IUCLID section 13.
Two types of experimental studies are presented under this endpoint explaining the hydrolysis behavior.
Firstly, exposure in heterogeneous conditions, under which the water insoluble MDI substances form droplets suspended in aqueous phase (i.e OECD 120; determination of solution/extraction behaviour in water). Note that this type of study is not a standard required but used as supporting information to give an insight about the behavour of MDI and its derivatives in e.g. acute ecotox studies.
Secondly, exposure in homogeneous conditions (i.e. OECD 111), under which the insoluble MDI substances are artificially solubilized in solution. In this regard it should be noted that such homogeneous testing conditions do not exist in the natural environment and can only be achieved under highly artificial laboratory conditions.
Testing of solution/extraction behaviour in water (OECD 120):
In the studies performed under heterogeneous testing conditions (i.e.
OECD 120), reaction of the NCO group with water occurs rapidly at the
boundary layer of the MDI substances droplet and by water diffusing onto
and into the organic phase forming inert polyurea particles. Under these
conditions only trace levels of MDA are formed. The results have been
obtained from hydrolysis studies using heterogeneous conditions (in
concentrations above the water solubility) showing that source substance
4,4'-MDI and target substance MDI MT exhibit a similar hydrolysis
behavior when in contact with water. Source and target substance contain
high levels of mMDI and have aromatic NCO groups which under
heterogeneous testing conditions are hydrolysed to polymeric ureas with
only minimal formation of MDA. The key relevant findings of hydrolysis
information obtained from the measurement of solution/extraction
behaviour (heterogeneous test conditions) in water show that
the transformation processes, which are relevant to aquatic exposure and
toxicity of MDI type aromatic diisocyanates, complete within the first
72 hours within the organic phase. concentrations.
Hydrolysis testing (OECD 111):
In contrast, in studies performed under artificial homogeneous testing
conditions (i.e. OECD 111) the 4,4’-MDI and pMDI source substances are
fully solubilized in water, and MDI is quantitatively converted to MDA.
For the analogue read-across approach, reliable hydrolysis data under
homogeneous conditions are used from 4,4’-MDI and pMDI. Read-across is
used to predict the outcome of the source substance to the target
substances on the basis that all the substances contain a high content
of monomeric MDI. The hydrolysis half-life of monomeric 4,4-MDI under
homogeneous conditions was extremely short and ranged between 11.9 and
17.6 seconds over the pH range 4 to 9 at 20°C. Acidic conditions do not
accelerate MDI hydrolysis, but there is a slight enhancement of the
hydrolysis rate under alkaline conditions. Comparable short half-lives
and trends were observed for pMDI. Moreover, the decay of monomeric MDI
present in high levels is not affected by the presence of other
constituents containing NCO groups as e.g. in pMDI. Under these
homogeneous conditions with a solvent present, 4,4’-MDA was by far is
the most common transformation product formed. The yield of the common
compound MDA was essentially 100% under the highly dilute and stirred
reaction conditions studied. In addition, trace amounts of higher aminic
compounds (three-ring MDA in pMDI) were formed. The hydrolysis of higher
constituents (e.g. 3-ring MDI) appears to be slower than that observed
for free MDI but is nevertheless still rapid i.e. less than 5 minutes.
Overall, the two source substances show rapid hydrolysis with a half-life of less than five minutes at 20°C, over the pH range of 4 to 9. The dependence of hydrolysis rate constant on temperature (10, 20, and 30°C) was evaluated and showed the expected doubling of rate constant with each 10°C increase in temperature according to the Arrhenius rate law.
Notwithstanding that only hydrolysis under heterogeneous conditions will be truly relevant for hazard and risk assessment for the aquatic environment, the assessment of this endpoint addresses hydrolysis under homogeneous conditions (OECD 111) as required by REACH. A half-life of 5 min. is considered for the chemical safety assessment.
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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