1-o-tolylbiguanide

Dissociation constant

Administrative data

Endpoint:

dissociation constant

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18/02/2016 -2/03/2-16

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 112 (Dissociation Constants in Water)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

1-o-tolylbiguanide

EC Number:

202-268-6

EC Name:

1-o-tolylbiguanide

Cas Number:

93-69-6

Molecular formula:

C9H13N5

IUPAC Name:

1-o-tolylbiguanide

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

CAS Number: 93-69-6
LOT number: composite of PR9999 batches 340/341/342/343
Purity: >98%
Description: White Powder
Expiry: 1 Year - 15/02/17

Results and discussion

Dissociating properties:

yes

Dissociation constant

pKa:

11

Temp.:

20 °C

Any other information on results incl. tables

A test solution of the sample in water is prepared to a concentration of 0.01M. The solution is then titrated with a standard base or acid solution as appropriate, measuring the pH after each addition of titrant. About 0.1mL to 2mL of titrant is added at a time. Where possible, about 10 incremental additions should be made before the equivalence point is reached.

At the end of the titration, a titration curve is obtained by plotting the pH of the test solution after each addition of titrant vs. volume of titrant added.

The equivalence point or point of inflection of the titration is obtained by plotting the ratio of change in pH of test solution (after each addition of titrant) to change in volume (of titrant) vs. mean volume of titrant.

The mid-point of the equivalence point is where a well buffered region exists, and the concentration of the undissociated species is approximately equal to the concentration of dissociated species. The pH of the solution at this mid-point provides the pKa of the test material.

Using this estimate, the titration is repeated as before. At approximately 2mL of titrant to the mid-point of equivalence point, 0.5mL increments are added at a time. The pH of the test solution, when half of the volume of titrant required to reach the equivalence point has been added, is obtained as the pKa of the sample.