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Diss Factsheets

Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
4 November 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study conducted in accordance with OECD Guideline

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1996
Report date:
1996

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:
N1-(5-methylhexan-2-yl)benzene-1,4-diamine
Cas Number:
63302-43-2
Molecular formula:
C13H22N2
IUPAC Name:
N1-(5-methylhexan-2-yl)benzene-1,4-diamine
Details on test material:
Distilled TRAE, supplied by sponsor.
Laboratory #: AA4525
lot #: Y-775
Active component: N-(l ,4-dimethy lpenty 1) 1,4-Benzenediamine
CAS #: 63302-43-2

Results and discussion

Dissociating properties:
yes
Dissociation constantopen allclose all
No.:
#1
pKa:
2.76
Temp.:
20 °C
Remarks on result:
other: Primary amino group, COV = 1.09%
No.:
#2
pKa:
6.75
Temp.:
20 °C
Remarks on result:
other: Secondary amino group, COV = 1.75%

Any other information on results incl. tables

All measurements were carried out at 20 ± 1 °C with 0.0003M solutions.

Table 1: Determination of the ionization constant of the primary amino group of TRAE

Analytical wavelength: 286nm. Cell: 1 cm. Absorbance of neutral molecule (AM) = 0.3987 @ pH 6.48 Absorbance of cation (AO = 0.027115 @ pH 0.53

sample

pH

A

pKa

1

3.62

0.35742

2.717

2

3.18

0.2973

2.754

3

3.02

0.26465

2.772

4

2.85

0.23405

2.751

5

2.63

0.18666

2.754

6

2.4

0.13551

2.785

7

2.19

0.098648

2.813

Average: 2.76

StDev: 0.03

%COV: 1.09

Table 2: Determination of the ionization constant of the secondary amino group of TRAE

Analytical wavelength: 306nm. Cell: 1 cm. Absorbance of neutral molecule (AM) = 0.52893 @ pH 11.81 Absorbance of cation (A,) = 0.013687 @ pH 0.61

Sample

pH

A

pKa

1

7.73

0.46965

6.844

2

7.40

0.41489

6.854

3

7.22

0.37952

6.831

4

7.02

0.33464

6.802

5

6.85

0.29483

6.770

6

6.59

0.25795

6.635

7

6.40

0.2281

6.547

Average: 6.75

StDev: 0.12

%COV: 1.75

Applicant's summary and conclusion

Conclusions:
The dissociation constants for TRAE at 20 ± 1 °C are:
Primary amino group pKa = 2.76 COV = 1.09%
Secondary amino group pKa = 6.75 COV = 1.75%
Executive summary:

The dissociation constants for the substance were determined by Ultraviolet Spectrophotometry in accordance with OECD Guideline 112.

The dissociation constants for TRAE at 20 ± 1 °C are:

Primary amino group pKa = 2.76 COV = 1.09%

Secondary amino group pKa = 6.75 COV = 1.75%