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Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data from peer-reviewed handbook or collection of data.
Qualifier:
no guideline followed
Principles of method if other than guideline:
The dissociation constant was measured in an unsymmetrical cell with diffusion potentials. The pH was measured in buffer solutions using hydrogen electrodes.
GLP compliance:
no
Dissociating properties:
not determined
No.:
#1
pKa:
4.69
Temp.:
25 °C
Remarks on result:
other: Estimated uncertainty:
No.:
#2
pKa:
4.8
Temp.:
20 °C
Remarks on result:
other: Estimated uncertainty:
Conclusions:
The dissociation constant of the substance is 4.80 at 20°C and 4.69 at 25°C.
Executive summary:

The experimentally determined dissociation constant of m-toluidine was 4.80 at 20°C and 4.69 at 25°C, Perrin, 1965. Both values indicate that under environmental relevant pH (5 -9) the substance is present mainly in its neutral form.

Description of key information

The experimentally determined dissociation constant of m-toluidine was 4.80 at 20°C and 4.69 at 25°C.

Key value for chemical safety assessment

pKa at 20°C:
4.8

Additional information

The experimentally determined dissociation constant of m-toluidine is supported by a calculated pKa value of 4.7. The substance undergoes association (e.g. protonation) in water. Under environmental relevant pH (5 -9) the substance is present mainly in its neutral form.

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