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Environmental fate & pathways

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4,4’-Methylenedicyclohexyl diisocyanate hydrolyses rapidly in the presence of water. A half-life for 4,4’‑methylenedicyclohexyl diisocyanate of approximately 2 hours was determined experimentally. Main hydrolysis product – beside a majority of oligomeric and polymeric ureas - is methylene bis(4-cyclohexylamine). Due to the rapid hydrolysis of 4,4’-methylenedicyclohexyl diisocyanate, equilibrium partitioning of the substance between environmental compartments is unlikely. Consequently, a calculation of the Henry’s Law Constant and of the distribution between the environmental compartments according to the Mackay fugacity model level 1 is not suitable.

4,4’-Methylenedicyclohexyl diisocyanate degrades relatively rapidly in the atmosphere by reaction with hydroxyl radicals (half-life, 15 hrs), and may also undergo hydrolysis. The photochemically induced half life of the hydrolysis product methylene bis(4-cyclohexyldiamine) is 3hours. Both half-lives correspond to an OH concentration of 0.5 x 106 OH radicals/cm³, which is a typical 24 hour-mean in Central Europe.