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Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental starting date: 31 July 2016 Experimental completion date: 12 October 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report date:
2017

Materials and methods

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

Test material

Constituent 1
Chemical structure
Reference substance name:
2-ethoxy-4-(hydroxymethyl)phenol
EC Number:
674-192-5
Cas Number:
4912-58-7
Molecular formula:
C9H12O3
IUPAC Name:
2-ethoxy-4-(hydroxymethyl)phenol
Test material form:
solid: particulate/powder
Specific details on test material used for the study:
Information as provided by the Sponsor. The Certificate of Analysis provided by the Sponsor is presented as.

Identification: EVA
Common name: ETHYLVANILLYL ALCOHOL, White Vanilla
CAS Number: 4912-58-7
CAS Name: Benzenemethanol, 3-ethoxy-4-hydroxy-
Chemical Name: 2- Ethoxy-4-(hydroxymethyl)phenol
Appearance/Physical state: Pale yellow powder
Batch: 4K0001
Purity: 100%
Expiry date: 31 December 2017
Storage conditions: Room temperature in the dark

Results and discussion

Dissociating properties:
yes
Dissociation constant
pKa:
10.1
Temp.:
25 °C

Any other information on results incl. tables

Blank solution and sample solution pH values during the titration are summarized in Table "Basic Functional Group Evaluation Blanks, Summary of pH Data"

and Table " Basic Functional Group Evaluation Samples, Summary of pH Data" respectively, test temperature: 25.0 ± 0.5 °C. Titration curves for the sample

solution and blank solution pH during the addition of 10 aliquots (0.50 mL each) of 0.1 M sodium hydroxide solution are shown in Appendix 4 ("Attached background material").

Basic Functional Group Evaluation Blanks, Summary of pH Data

Titrant (mL)

Solution pH

Blank 1

Blank 2

0.0

5.868

8.061

0.5

9.931

11.011

1.0

9.581

11.389

1.5

9.728

11.580

2.0

11.159

11.706

2.5

11.720

11.803

3.0

11.809

11.881

3.5

11.880

11.948

4.0

11.961

12.001

4.5

12.026

12.052

5.0

12.085

12.096

Basic Functional Group Evaluation Samples, Summary of pH Data

Titrant (mL)

Solution pH

Sample 1

Sample 2

Sample 3

0.0

7.073

7.481

7.081

0.5

8.984

9.115

9.160

1.0

9.424

9.486

9.548

1.5

9.710

9.720

9.795

2.0

9.901

9.937

9.984

2.5

10.073

10.112

10.153

3.0

10.227

10.283

10.313

3.5

10.385

10.461

10.477

4.0

10.631

10.653

10.654

4.5

10.842

10.871

10.855

5.0

11.065

11.102

11.069

Sample solution pH values and stepwise calculation of the dissociation constant (pKa) are shown in the tables below:

Functional Group Evaluation Sample 1, Titration Results and Dissociation Constant Calculation

Titrant (mL)

pH

[OH-]

[HA]/[A]

Log of Previous Column

pKa

0.0

7.073

-

-

-

-

0.5

8.984

1.04 x 10-9

9.02

0.955

9.94

1.0

9.424

3.77 x 10-10

4.01

0.603

10.0

1.5

9.710

1.95 x 10-10

2.34

0.369

10.1

2.0

9.901

1.26 x 10-10

1.51

0.178

10.1

2.5

10.073

8.45 x 10-11

1.00

2.11 x 10-3

10.1

3.0

10.227

5.93 x 10-11

0.671

- 0.173

10.1

3.5

10.385

4.12 x 10-11

0.432

- 0.364

10.0

4.0

10.631

2.34 x 10-11

0.253

- 0.600

10.0

4.5

10.842

1.44 x 10-11

0.114

- 0.944

9.90

5.0

11.065

-

-

-

-

Mean dissociation constant (pKa): 10.1 (using central 7 values).

Functional Group Evaluation Sample 2, Titration Results and Dissociation Constant Calculation

Titrant (mL)

pH

[OH-]

[HA]/[A]

Log of Previous Column

pKa

0.0

7.481

-

-

-

-

0.5

9.115

7.67 x 10-10

9.04

0.956

10.1

1.0

9.486

3.27 x 10-10

4.02

0.604

10.1

1.5

9.720

1.91 x 10-10

2.35

0.370

10.1

2.0

9.937

1.16 x 10-10

1.51

0.179

10.1

2.5

10.112

7.73 x 10-11

1.01

3.14 x 10-3

10.1

3.0

10.283

5.21 x 10-11

0.673

- 0.172

10.1

3.5

10.461

3.46 x 10-11

0.434

- 0.363

10.1

4.0

10.653

2.22 x 10-11

0.255

- 0.594

10.1

4.5

10.871

2.35 x 10-11

0.115

- 0.939

9.93

5.0

11.102

-

-

-

-

Mean dissociation constant (pKa): 10.1 (using central 7 values).

Functional Group Evaluation Sample 3, Titration Results and Dissociation Constant Calculation

Titrant (mL)

pH

[OH-]

[HA]/[A]

Log of Previous Column

pKa

0.0

7.081

-

-

-

-

0.5

9.160

6.92 x 10-10

9.04

0.956

10.1

1.0

9.548

2.83 x 10-10

4.02

0.604

10.2

1.5

9.795

1.60 x 10-10

2.35

0.370

10.2

2.0

9.984

1.04 x 10-10

1.51

0.179

10.2

2.5

10.153

7.03 x 10-11

1.01

3.14 x 10-3

10.2

3.0

10.313

4.86 x 10-11

0.673

- 0.172

10.1

3.5

10.477

3.33 x 10-11

0.434

- 0.363

10.1

4.0

10.654

2.22 x 10-11

0.255

- 0.594

10.1

4.5

10.855

1.40 x 10-11

0.115

- 0.939

9.92

5.0

11.069

-

-

-

-

Mean dissociation constant (pKa): 10.1 (using central 7 values).

Overall mean dissociation constant (pKa): 10.1

Test temperature: 25.0 ± 1.0 °C

Applicant's summary and conclusion

Conclusions:
The dissociation constant in water of the test item has been determined to be 10.1 at 25.0 ± 1.0 °C.
Executive summary:

An evaluation of the dissociation constants in water for the test item was carried out by a titration method, using procedures based on OECD Guidelines for Testing of Chemicals, Section 1, No. 112: “Dissociation Constants in Water” adopted 12 May 1981.

Conclusion

The dissociation constant in water of the test item has been determined to be 10.1 at 25.0 ± 1.0 °C.

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