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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Physical & Chemical properties

Dissociation constant

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
dissociation constant
Type of information:
calculation (if not (Q)SAR)
Remarks:
estimated by calculation
Adequacy of study:
key study
Study period:
October 30, 1998
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to guideline
Guideline:
other: Estimation method
GLP compliance:
no
Dissociating properties:
yes
pKa:
>= -7.4 - <= 7.2
Remarks on result:
other: Temperature not specified
Conclusions:
pKa of FAT 40571/A is >= -7.4 to 7.2
Executive summary:

Calculation of the Dissociation Constants of FAT 40'571/A revealed that t he molecule is negatively charged and is present in anionic form over the whole environmentally relevant pH range. The primary amine is protonated in the strong acidic range of pH (pka = 2.0). However, the behaviour of the test substance in aqueous solutions is dominated by the strongly acidic -S03H groups and the alkylsulfuric acid group. Additionally, the hydroxy group in the alpha-naphthol is

dissociated in the neutral and alkalic range pH

Description of key information

pKa of Reactive Brown 49 is >= -7.4 to 7.2

Key value for chemical safety assessment

pKa at 20°C:
-7.4

Additional information

Calculation of the Dissociation Constants of FAT 40'571/A revealed that t he molecule is negatively charged and is present in anionic form over the whole environmentally relevant pH range. The primary amine is protonated in the strong acidic range of pH (pka = 2.0). However, the behaviour of the test substance in aqueous solutions is dominated by the strongly acidic -S03H groups and the alkylsulfuric acid group. Additionally, the hydroxy group in the alpha-naphthol is dissociated in the neutral and alkalic range pH.

Based on the calculation pKa of FAT 40571/A 49 is >= -7.4 to 7.2