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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

The dissociation constant for 5-methyl-1H-benzotriazole is 8.85. It is slightly below the value for the 4-methyl-1H-benzotriazole isomer (9.15).

Key value for chemical safety assessment

pKa at 20°C:
8.85

Additional information

The dissociation constant was calculated by SPARC. The physical properties predicted by SPARC are regarded "as reliable as most of the experimental measurements for these properties". [EPA/600/R-03/033, March 2003].

By the scientific definition, the dissociation constant (pKa) is identical for the acid (Tolyltriazole) and its conjugated base (Sodium Tolyltriazolide). Therefore the value of Tolyltriazole is valid also for Sodium Tolyltriazolide.