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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Hydrolysis

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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.
Holdren (1983) investigated the hydrolysis in air. Abele and Brochhagen (1976) and Fujiwara (1980), although having created valuable data for incident management, do not provide robust data to calculate the half-life of TDI in water.
The results of Yakabe et al (1999) allows the derivation of a linear regression algorithm for the calculation of the yield of TDA due to 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 h
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).