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Environmental fate & pathways

Phototransformation in air

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Description of key information

QSAR estimations are available for the 3 main constituents of DAPD.
1) Supporting study (QSAR): EpiWeb estimation for R-59_12h (CAS 74-31-7) (0 methyl groups)
2) Supporting study (QSAR): EpiWeb estimation for R-1679_12h (CAS 27173-16-6) (1 methyl group)
3) Supporting study (QSAR): EpiWeb estimation for R-898_12h (CAS 15017-02-4) (2 methyl groups)

Key value for chemical safety assessment

Half-life in air:
0.64 h

Additional information

The phototransformation rate in air was estimated with the aid of a QSAR model (EpiWeb) since no actual data are available for the substance of concern. This model was run for the 3 main constituents of DAPD.

The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals.The rate constants estimated by the program are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals.

The default settings for 12 -hour daylight hydroxyl radical concentration of 1.5 *106 radicals/cm3 was used.

The DT50 (at 25°C) was similar for all 3 constituents, namely 0.64 hrs, the overall degradation rate constant (OH) was 200.2720 * 10-12 cm3/molecule-sec.