Registration Dossier

Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Testing was conducted between 27 March 2007 and 11 June 2007.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Sponsor's identification: C-Y9
Description : yellow powder
Lot number : MB-1
Date received : 6 March 2007
Storage conditions: room temperature in the dark, over silica gel

Results and discussion

Dissociating properties:
yes
Dissociation constant
pKa:
4.64
Remarks on result:
other: The dissociation constant of the addition of a proton, to a triazine group in the test material, has been determined to be 4.64.

Any other information on results incl. tables

Results

The sample solution pH and the calculated dissociation constant after each addition of titrant are shown in the following tables:

Determination 1

Reading

Titrant
(ml)

pH

Stoichiometric Concentration

[H+]

X

log X

pKa

[HA]

[A-]

1

0.0

7.540

0

1.05 x 10-2

2.88 x 10-8

0.000

-

-

2

0.5

5.913

1.00 x 10-3

9.41 x 10-3

1.22 x 10-6

0.106

-0.974

4.94

3

1.0

5.381

2.00 x 10-3

8.30 x 10-3

4.16 x 10-6

0.240

-0.619

4.76

4

1.5

5.051

3.00 x 10-3

7.20 x 10-3

8.89 x 10-6

0.415

-0.382

4.67

5

2.0

4.798

4.00 x 10-3

6.10 x 10-3

1.59 x 10-5

0.652

-0.186

4.61

6

2.5

4.607

5.00 x 10-3

4.99 x 10-3

2.47 x 10-5

0.991

-3.78 x 10-3

4.60

7

3.0

4.402

6.00 x 10-3

3.90 x 10-3

3.96 x 10-5

1.52

0.180

4.58

8

3.5

4.176

7.00 x 10-3

2.80 x 10-3

6.67 x 10-5

2.42

0.384

4.56

9

4.0

3.905

8.00 x 10-3

1.70 x 10-3

1.25 x 10-4

4.31

0.634

4.54

10

4.5

3.547

9.00 x 10-3

6.10 x 10-4

2.84 x 10-4

9.76

0.989

4.54

11

5.0

3.148

1.00 x 10-2

0

7.11 x 10-4

13.1

1.12

4.26

Mean of readings 4 to 10:      4.59

Determination 2

Reading

Titrant
(ml)

pH

Stoichiometric Concentration

[H+]

X

log X

pKa

[HA]

[A-]

1

0.0

7.401

0

1.05 x 10-2

3.97 x 10-8

0.000

-

-

2

0.5

5.900

1.00 x 10-3

9.41 x 10-3

1.26 x 10-6

0.106

-0.974

4.93

3

1.0

5.451

2.00 x 10-3

8.30 x 10-3

3.54 x 10-6

0.240

-0.619

4.83

4

1.5

5.144

3.00 x 10-3

7.20 x 10-3

7.18 x 10-6

0.415

-0.382

4.76

5

2.0

4.895

4.00 x 10-3

6.10 x 10-3

1.27 x 10-5

0.653

-0.185

4.71

6

2.5

4.674

5.00 x 10-3

4.99 x 10-3

2.12 x 10-5

0.993

-3.16 x 10-3

4.67

7

3.0

4.464

6.00 x 10-3

3.90 x 10-3

3.44 x 10-5

1.52

0.181

4.65

8

3.5

4.246

7.00 x 10-3

2.80 x 10-3

5.68 x 10-5

2.43

0.386

4.63

9

4.0

3.986

8.00 x 10-3

1.70 x 10-3

1.03 x 10-4

4.37

0.641

4.63

10

4.5

3.632

9.00 x 10-3

6.10 x 10-4

2.33 x 10-4

10.4

1.02

4.65

11

5.0

3.218

1.00 x 10-2

0

6.05 x 10-4

15.5

1.19

4.41

Mean of readings 4 to 10:      4.67

Determination 3

Reading

Titrant
(ml)

pH

Stoichiometric Concentration

[H+]

X

log X

pKa

[HA]

[A-]

1

0.0

7.496

0

1.05 x 10-2

3.19 x 10-8

0.000

-

-

2

0.5

5.904

1.00 x 10-3

9.41 x 10-3

1.25 x 10-6

0.106

-0.974

4.93

3

1.0

5.446

2.00 x 10-3

8.30 x 10-3

3.58 x 10-6

0.240

-0.619

4.83

4

1.5

5.135

3.00 x 10-3

7.20 x 10-3

7.33 x 10-6

0.415

-0.382

4.75

5

2.0

4.885

4.00 x 10-3

6.10 x 10-3

1.30 x 10-5

0.653

-0.185

4.70

6

2.5

4.665

5.00 x 10-3

4.99 x 10-3

2.16 x 10-5

0.993

-3.24 x 10-3

4.66

7

3.0

4.457

6.00 x 10-3

3.90 x 10-3

3.49 x 10-5

1.52

0.181

4.64

8

3.5

4.239

7.00 x 10-3

2.80 x 10-3

5.77 x 10-5

2.43

0.386

4.63

9

4.0

3.983

8.00 x 10-3

1.70 x 10-3

1.04 x 10-4

4.37

0.640

4.62

10

4.5

3.636

9.00 x 10-3

6.10 x 10-4

2.31 x 10-4

10.4

1.02

4.65

11

5.0

3.227

1.00 x 10-2

0

5.93 x 10-4

15.9

1.20

4.43

Mean of readings 4 to 10:      4.67
Overall mean:                          4.64

Discussion

The dissociation constant indicates the addition of a proton, to a nitrogen atom of a triazine group, in the test material.

The dissociation constants of the sulphonic acid sodium salt groups were not attempted as they were outside the practical limits of the test. The pKa of a typical sulphonic acid group is ‑1.8 (McMurry, Organic Chemistry 3rded. 1992).

Applicant's summary and conclusion

Conclusions:
The dissociation constant of the addition of a proton, to a triazine group in the test material, has been determined to be 4.64.
Executive summary:

Dissociation Constants in Water. 

The dissociation constant of the addition of a proton to a triazine group in the test material has been determined to be 4.64, using Method 112 of the OECD Guidelines for Testing of Chemicals, 12 May 1981.