Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Phototransformation in air

In the presence of moisture, 1,2,3,6-tetrahydro-3-methylphthalic anhydride is rapidly hydrolysed to the correspondent 3-methylcyclohex-4-ene-1,2-dicarboxylic acid, that is most relevant to various environmental compartments than the submission substance.

The stability of the substances in the atmosphere was calculated using the software AOPWIN (v1.92). It is predicted that both anhydride and acid forms will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals, with a half-life of 5.9 hours, and overall degradation rate constants with OH radicals of 5.66E-6 cm3/(molecule-day).


Hydrolysis of a structural analogue of the substance, tetrahydromethylphthalic anhydride (MTHPA), has been investigated. The substance was found to hydrolyse rapidly, resulting in formation of the respective di-acid. The calculated half-lives at 20 deg C are, for all three pH values ( 4, 7 and 9) below 3.5 minutes (about 0.06 hours).