2-methylpentane-1,5-diamine

Dissociation constant

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

dissociation constant

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

2012

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Principles of method if other than guideline:

Calculation by online available SPARC tool.

Dissociating properties:

yes

No.:

#1

pKa:

10.66

Temp.:

25 °C

No.:

#2

pKa:

9.59

Temp.:

25 °C

Conclusions:

According to the calculation by the online available SPARC tool, the pKa value for the first protonation of MPMD is 10.66 and the pKa value for the second protonation of MPMD is 9.59.

Executive summary:

According to the calculation by the online available SPARC tool, the pKa value for the first protonation of MPMD is 10.66 and the pKa value for the second protonation of MPMD is 9.59.

Reference 2

Endpoint:

dissociation constant

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 June 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study (OECD TG 112) with acceptable restrictions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 112 (Dissociation Constants in Water)

GLP compliance:

no

Dissociating properties:

yes

No.:

#1

pKa:

10.6

Remarks on result:

other: Temperature not given.

Calculation of pKa

Water blank subtraction = BQL (< 0.01 mL at 1.04 mol/L HNO₃)

First derivative local maximum between 11.5820 mL and 11.5900 mL.

Average these points for an equivalence volume of 11.586 mL titrant

Divide 11.586 by two = 5.793 mL at half equivalence point.

pH = pKa at half equivalence point

pH at 5.793 estimated at 10.64 from titration table.

Rounded to 10.6

pKa estimated at 10.6

Notes regarding the titration

The volume of titrant required to titrate our water blank was negligible at the selected HNO3 concentration. A corrected volume titration curve may also compensate for the addition of strong base in the blank titration if calculating moles of analyte titrated. This calculation was not necessary for this pKa determination.

From literature, it was expected that the test substance would display two equivalence points. Our titration curve had insufficient resolution to distinguish between the two similar pKa values. Titration at lower concentrations of analyte and titrant, titration with a base instead of an acid, or titration in a different sample matrix may allow increased resolution for this determination.

Conclusions:

The pKa of the test substance is 10.6.

Executive summary:

The dissociation constant of the test substance was determined according to OECD TG 112 by titration. The average pKa for the two ionisable groups of the test substance is 10.6.

Description of key information

The average pKa for the two ionisable groups of the test substance is 10.6.

Key value for chemical safety assessment

pKa at 20°C:

10.6

Additional information

The dissociation constant of the test substance was determined according to OECD TG 112 by titration. The average pKa for the two ionisable groups of the test substance is 10.6.

According to the calculation by the online available SPARC tool, the pKa value for the first protonation of MPMD is 10.66 and the pKa value for the second protonation of MPMD is 9.59.