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Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Estimation of the dissociation constants was made by relevant computer-based estimation software.
Reason / purpose:
reference to same study
Qualifier:
no guideline available
Principles of method if other than guideline:
Estimation of the dissociation constants was made by relevant computer-based estimation software.
Dissociating properties:
no
Remarks:
At neutral pH >90% of the test substance is in a non-ionised form.
No.:
#1
pKa:
16.3
Remarks on result:
other: Acidic group: RRCHOH
No.:
#2
pKa:
16.9
Remarks on result:
other: Acidic group: RRCHOH
No.:
#3
pKa:
-0.12
Remarks on result:
other: Basic group: RCONHR
No.:
#4
pKa:
0.48
Remarks on result:
other: Basic group: RCONHR

Calculation of the dissociation constant (pKa)

From the structural formula of EA-3098, the following pKa values for acidic and basic groups in EA-3098 were calculated using the Perrin's calculation method.

 

Acidic groups:

RRCHOH: 16.3

RRCHOH: 16.9

 

Basic groups:

RCONHR: -0.12

RCONHR: 0.48

Based on these calculations, the aqueous phase used during the HPLC method (see partition coefficient study) was not buffered. At neutral pH >90% of the test substance is in a non-ionised form.

Conclusions:
From the structural formula of EA-3098, the pKa values for the basic groups were calculated to be 0.48 and -0.12 and the pKa values for the acidic groups were calculated to be 16.3 and 16.9.

At neutral pH, > 90% of the test substance is in a non-ionised form.
Executive summary:

Calculation of the dissociation constant (pKa)

From the structural formula of EA-3098, the following pKa values for acidic and basic groups in EA-3098 were calculated using the Perrin's calculation method (using computer estimation software: Software pKa: Pkalc version 5 (module in PALLAS version 3.0), an expert system for the calculation of pKa values).

 

Acidic groups:

RRCHOH: 16.3

RRCHOH: 16.9

 

Basic groups:

RCONHR: -0.12

RCONHR: 0.48

At neutral pH >90% of the test substance is in a non-ionised form.

Description of key information

From the structural formula of EA-3098, the pKa values for the basic groups were calculated to be 0.48 and -0.12 and the pKa values for the acidic groups were calculated to be 16.3 and 16.9.

At neutral pH, > 90% of the test substance is in a non-ionised form.

Key value for chemical safety assessment

Additional information

From the structural formula of EA-3098, the following pKa values for acidic and basic groups in EA-3098 were calculated using the Perrin's calculation method (using computer estimation software:Software pKa: Pkalc version 5 (module in PALLAS version 3.0), an expert system for the calculation of pKa values).

 

Acidic groups:

RRCHOH: 16.3

RRCHOH: 16.9

 

Basic groups:

RCONHR: -0.12

RCONHR: 0.48

At neutral pH >90% of the test substance is in a non-ionised form.