Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Phototransformation in air

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The half-life of 4-aminophenol and its degradation rate constant in the presence of hydroxyl radicals were predicted by the use of quantitative structural activity relationship modeling, by the use of AOPWIN v1.92a, a model within the EPI Suite v4.00, validated QSAR model, part of OECD (Q)SAR Toolbox.

Key value for chemical safety assessment

Half-life in air:
1.729 h

Additional information

The photolysis half-life and degradation rate constant of 4-aminophenol were estimated, based on QSAR modeling. The degradation constant with hydroxyl radicals was predicted to be74.2471 E-12cm3/molecule-1s-1. Assuming a hydroxyl radical concentration [-OH] of 1.5 x 106molecules/cm3and 12 hours of sunlight, the half-life was predicted as 1.729 hours (0.144 days).

The model User's Guide states that the 24-hour daylight average hydroxyl radical concentration may be more appropriate for chemicals that react more slowly (i. e.,> a few days). Since the modeling results indicate that 4-aminophenol is a fast-reacting chemical (with a half-life in the scale of hours), the estimated half-life associated with the default hydroxyl radical concentration with 12-hour daylight cycle (i. e., 1.729 hours) is considered the more appropriate of the two estimated half-life values.