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Environmental fate & pathways

Phototransformation in air

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Description of key information

1,2-Cyclohexanedicarboxylic acid, 4-methyl- (4-MHHPAc)

Half-life for reaction with photochemically-produced hydroxyl radicals: 30.1 hours.

Overall degradation rate constant with OH radicals= 1.28E-11 cm3/(molecule-sec).

Hexahydro-4-methylphthalic anhydride (4-MHHPA)

Half-life for reaction with photochemically-produced hydroxyl radicals: 45.3 hours.

Overall degradation rate constant with OH radicals= 8.51E-12 cm3/(molecule-sec).

Key value for chemical safety assessment

Half-life in air:
30.1 h
Degradation rate constant with OH radicals:
0 cm³ molecule-1 s-1

Additional information

The stability of the substances in the atmosphere was calculated using the software AOPWIN (v1.92). It is predicted that both the anhydride and its acid degradation product will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals, with a half-life between 10.0 and 45.3 hours, and overall degradation rate constants with OH radicals between 1.10E-06 and 7.35E-07 cm3/(molecule-day), at different test conditions.

The most conservative values were selected.