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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: well performed and documented publication
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Principles of method if other than guideline:
Potentiometric titration
GLP compliance:
no
Specific details on test material used for the study:
Reagent grade, used without further purification
Dissociating properties:
no
No.:
#1
pKa:
15.1
Temp.:
25 °C
Remarks on result:
other: +/- 0.3

Data on pKa derived according to approach 1 (see above - value determined for 1,3-butanediol: 15.5 +/- 0.5) and approach 2 (see above - value determined for 1,3-butanediol: 14.8 +/- 0.2) were used to derive a so-called "best value" for acid ionisation constant pKa.

"Best value" for pKa derived for 1,3-butanediol:

pKa 15.1 (+/- 0.3)

Conclusions:
Acid ionisation constant pKa (potentiometric method, published result): 15.1 (+/- 0.3)
Executive summary:

The acid ionisation constant pKa was determined in a reliable well-documented published study using potentiometric titration. Two different approaches led to pKa values very close to each other.

Approach 1: pKa 15.5 +/- 0.5

Approach 2: pKa 14.8 +/- 0.2

These results were used to derive a so-called "best value" for acid ionisation constant pKa.

"Best value" for pKa derived for 1,3-butanediol: pKa 15.1 (+/- 0.3)

Concluding, 1,3-butanediol is of very low acidity. The pKa value is in the range of pure water. It must therefore be considered to be non-dissociated under relevant environmental conditions.

Description of key information

Dissociation constant pKa (acidic; potentiometric method): 15.1

Key value for chemical safety assessment

pKa at 20°C:
15.1

Additional information

The acid ionisation constant pKa was determined in a reliable well-documented published study using potentiometric titration. Two different approaches led to pKa values very close to each other.

Approach 1: pKa 15.5 +/- 0.5

Approach 2: pKa 14.8 +/- 0.2

These results were used to derive a so-called "best value" for acid ionisation constant pKa.

"Best value" for pKa derived for 1,3-butanediol: pKa 15.1 (+/- 0.3)

Concluding, 1,3-butanediol is of very low acidity. The pKa value is in the range of pure water. It must therefore be considered to be non-dissociated under relevant environmental conditions.