HDI oligomers, isocyanurate

Partition coefficient

Description of key information

In accordance with column 2 of REACH Annex VII, the test cannot be performed, as the substance decomposes in water within a few hours (half-time 7.7 hours). 
The calculated partition coefficient (KOWWIN v 1.66) on the basis of the structural formula of the ideal HDI Trimer with 3 HDI (1,3,5-Triazine -2,4,6(1H,3H,5H)-trione, 1,3,5-tris(6-isocyanatohexyl)-) units is 9.81.  By calculation the log Pow value of  9.81 for the main constituent of HDI Trimer (HDI Isocyanurate, n = 3)  was calculated according to the KOWWIN program, v. 1.68 © 2000 U.S. Environmental Protection Agency. The calculated log Pow of the corresponding triamine of the main constituent (1,3,5-Triazine -2,4,6(1H,3H,5H)-trione, 1,3,5-tris(6-aminohexyl)-) is 5.54.
In a  non-standard test it has been tried to get an estimation of the logPow after hydrolysis. The test item (500 mg) was allowed to drop into water while stirring. Most of the substance adhered to the wall of the glass vessel. About 4 % of the material after hydrolysis was found to be soluble. A water solubility of approx. 20 mg/L can be estimated from DOC- and TNb-determination. However it was not possible to measure the logPow as the concentrations were too low. This means that only a small amount of the hydrolysed product might contribute to a logPow. 

Key value for chemical safety assessment

Log Kow (Log Pow):

9.81

at the temperature of:

20 °C

Additional information

A determination of the partition coefficient cannot be performed. The TNb-results determined are only slightly above the LOQ. As the test item and the hydrolysis products are only poorly soluble in water it is expected that after shaking with n-octanol, the residue in the aqueus phase is below the limit of quantitation of 1 mg/L. A determination of the partition coefficient is therefore not possible.

The substance hydrolyses rapidly with a half life of 7.7 hours. Therefore, an experimental study with HDI trimer is scientifically unjustified. The hydrolysis product is a complex mixture of water-insoluble oligomeric and polymeric ureas and of

compounds derived from isocyanurates (n-3, 5, 7) where the isocyanate groups have been transformed to amino groups.

Although being a more theoretical apprach, an ideal structure the "corresponding triamine of the sym. HDI trimer (n=3)" was considered in order to get an estimation on the behaviour of the hydrolysed product. For both, the unreacted HDI Isocyanurate (n=3) as well as for the corresponding triamine of the sym. HDI trimer (n=3), calculated values are presented.