Copper, [29H,31H-phthalocyaninato(2-)-N29,N30,N31,N32]-, sulfo [[4-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]amino]sulfonyl derivs.

Hydrolysis

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:

2 d

at the temperature of:

25 °C

Additional information

Reactive Blue 21 is a complex UVCB with a main constituent in a concentration of approx. 10%. Standard tests for this endpoint are intended for less complex substances and are not appropriate for this complex substance. However, this endpoint is characterized using a read-across approach to substances of analogues functional groups and structural elements.

Reactive Black 5, the most important reactive dye based on parabase ester, 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.

Overall results:

pH	T [°C]	k=<	t1/2
4	25	0.0004 1/d	258.5 weeks
7	25	0.0152 1/d	1.9 days
9	20	0.0146 1/min	48 minutes