Dibutyl hydrogen phosphate

Dissociation constant

Link to relevant study record(s)

Reference

Endpoint:

dissociation constant

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Principles of method if other than guideline:

1. - Phase distribution studies (Conductometric method)
2. - Measurements of pH changes during titrations using glass electrodes (Titration method)

GLP compliance:

not specified

Dissociating properties:

yes

No.:

#1

pKa:

1

Temp.:

25 °C

Remarks on result:

other: Conductometric method

No.:

#2

pKa:

1.72

Temp.:

25 °C

Remarks on result:

other: Titration method

Assessment of the reliability of the quoted constant si given as "uncertain", where the estimated uncertainty is greater than 10 per cent of the value of K, i.e. ∆pK > +/- 0.04

Conclusions:

The pKa of dibutyl hydrogen phosphate is 1.0 at 25°C (Conductometric method) and 1.72 at 25°C (Titration method).

Executive summary:

The pKa of dibutyl hydrogen phosphate was 1.0 at 25°C determined in a phase distribution study (Conductometric method), and 1.72 at 25°C determined via measurements of pH changes during titrations using glass electrodes (Titration method).

Description of key information

The pKa of dibutyl hydrogen phosphate is 1.0 at 25°C (Conductometric method).

Key value for chemical safety assessment

pKa at 20°C:

1

Additional information

Several data on pKa for dibutyl hydrogen phosphatein the range of 0.98 - 1.72 are available, all indicating that dibutyl hydrogen phosphate exists predominantly in its deprotonated form under environmental conditions.

The most reliable value is the pKa of 1.0 at 25°C determined in a phase distribution study (Conductometric method).

Additionally the experimental dissociation constant of dibutyl hydrogen phosphate is supported by an estimated value. A pKa of 1.53 was estimated by ACD/pKa DB included in ACD/labs 7.00 Release. The result is in good correlation to the measured values.