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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

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Environmental fate & pathways


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Administrative data

Link to relevant study record(s)

Description of key information

The study carried out with a loading of 1000mg TDI/l (Kitano et al, 1989) under rapid stirring conditions gave a half-life of ca. 0.7h (corresponding to a rate constant of 1 h-1). This result reflects a more realistic environmental situation. The Yakabe et al (1999) work was carried out under less realistic environmental conditions, using a loading of 28mg TDI/l and with vigorous agitation, leading to a shorter half-life of less than one minute.

The results of Yakabe et al allow the derivation of a linear regression algorithm for the calculation of the yield of TDA resulting from the high speed stirring of TDI into water:

[TDA] = 0.0606 x log [TDI] + 0.1108; mmol/l.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 d
at the temperature of:
300 K

Additional information

TDI is rapidly hydrolysed in aqueous solution, with a half-life of under one minute (Yakabe et al., 1999). The product of hydrolysis of the isocyanate group is an amine, which itself reacts with another isocyanate group to yield a urea. This reaction of an amine with isocyanate is considerably faster than the reaction of water with the isocyanate (Yakabe et al, 1999). With TDI, a diisocyanate, this reaction leads to polyureas, which are inert, insoluble solids.Tests with wet soil have demonstrated that the hydrolytic self-polymerization of TDI is the predominant reason for TDI disappearance in this compartment (Blumencron, 1978).