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Hydrolysis

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Description of key information

The hydrolysis as a function of pH of 3-isocyanatomethyl-3,5,5-trimethylcyclo-hexylisocyanate homopolymer (uretdione type) is expected to be similar to that of the isocyanurate type homopolymer, which was determined at room temperature (22.1 – 23.0 °C) and using the isophorone diisocyanate trimer as a representative of the whole test item:
Test series pH co-solvent concentration Kobs [h–1] t½ [h]
1 4 30 % acetonitrile in water 0.7129 0.97
2 7 30 % acetonitrile in water 0.1870 3.71
3 9 30 % acetonitrile in water 1.4721 0.47
4 7 15 % acetonitrile in water 0.0920 7.54
5 7 7.5 % acetonitrile in water 0.1958 3.54
The hydrolysis half-life was always clearly below 12 hours. Both acidic and basic media appear to accelerate the hydrolysis. No simple relationship between the rate of hydrolysis and the concentration of the organic co-solvent acetonitrile could be observed.

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Additional information

The hydrolytizable functions are identical in both substances and have a similar structural neighborhood.

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