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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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


Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Substance is not hydrolytically stable at pH 7, 9, and 11 at environmental or use-conditions

Key value for chemical safety assessment

Half-life for hydrolysis:
4 d
at the temperature of:
25 °C

Additional information

The structural analogue, Reactive Black 5, was tested for abiotic degradation according to OECD 111. In addition to pH 4, 7, 9 as required by the guideline, the substance was also tested at pH 11 (dyeing conditions) and pH 1.2.

At pH 1.2 and 37°C, there was no abiotic degradation within the 5 days observation period. At pH 4, 7, 9, and 11, the test substance was not stable at 50°C. The degradation at pH 4, 7, and 9 were hence investigated further.

At pH 4, the half-life at 25°C is ca. 5 years; at pH 7, the half-life at 25°C is ca. 2 days; at pH 9, the half-life at 20°C is ca. 50 minutes.

During degradation of the bis-ester, both isoforms of the mono-vinyl form appear temporarily as degradation product. One main degradation product is Reactive Black 5 bis-vinyl as the active dye-form which further hydrolyses to Reactive Black 5-OH.

For Structural Analogue 01, a study was conducted to determine hydrolysis as a function of pH according to OECD Guideline 111 and EU Method C.7, in compliance with GLP.

Based on the results of a preliminary test which demonstrated >50% hydrolysis within 2.4 h at pH 9.0 and <10% hydrolysis within 5 d at pH 4.0, additional testing was only required at pH 7. Results of the main test at pH 7 and 50°C demonstrated a pseudo first order reaction. Therefore, further testing at pH 7 and 38°C was carried out. From the results, the rate constant (Kobs) and the half-life (t1/2) of the test substance were derived or calculated for different temperatures and pH conditions.

Under the conditions of the study, the half-life of the test substance at pH 9 was <2.4 h and at pH 4 was >120 h. The half-life of the test substance at pH 7 was found to be 22.6 and 4.6 h at 38 and 50°C, respectively.

The rate constant at 25°C was calculated to be 0.004769 h-1,leading to a half-life of 146 h (6 days).

Due to the fact that Reactive Blue 203 is a combination of both structural analogues, a half-life at pH 7 and at 25°C was estimated to be 4 days.