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Physical & Chemical properties

Partition coefficient

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Description of key information

Waived:  Measurement of octanol-water partition cannot be performed, due to reactive and UVCB nature of the substance

Key value for chemical safety assessment

Log Kow (Log Pow):
4.51
at the temperature of:
20 °C

Additional information

The test substance is covered by the category approach of methylenediphenyl diisocyanates (MDI). Hence, data of the category substances can be used to cover this endpoint. The n-octanol/water partitioning coefficient was determined with MDI mixed isomers (Yakabe et al., 2000). The test was done according to OECD 117 with the HPLC method. The fact that only one sharp peak was observed in the chromatogram indicates that the two isomers (4,4'-MDI and 2,4'-MDI) present in the test material have very similar log Pow values. As the addition of DPG and/or TPG to MDI would result in increased values of log Pow, and because the MDI/DPG/TPG substance can be expected to contain some amount of unreacted 4,4'-MDI, the log Pow is reported as "log Pow > 4.5".

However, given the reactivity of MDI and MDI/DPG/TPG prepolymer in the aquatic environment and its transient existence in water, the log Pow has little direct relevance to the calculation of its environmental fate and ecotoxicity.