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Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Dec. 2009
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: unsuitable test system due to the surface-active properties of the test substance

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report date:
2009

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
In a study conducted according to OECD Guideline 122 'Partition coefficient n-octanol/water, pH-metric method for ionisable substances' log Kow was estimated based on pKa measurements. The pKa was determined in pure 0.15 M KCl: 300 mg of the sample were weighed to next 0.1 mg into a titration glass beaker. Subsequently 150 mL of 0.15 M KCl were added. The sample was dissolved shaking. The slightly turbid solution was titrated against 0.5 N HCl. Monotone titration in steps of 0.05mL was applied. A record delay time of 10 sec was maintained. The pKa value was estimated from the point of half neutralization determined by the TIAMO titration software. The determination was performed at least as a threefold repeated test.
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]
EC Number:
930-947-3
Cas Number:
146987-98-6
Molecular formula:
R-CO(NH)(CH2)(CH2)(CH2)N(Me2), whereas R=C8-18 (even numbered)
IUPAC Name:
Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]

Results and discussion

Dissociating properties:
yes
Dissociation constantopen allclose all
No.:
#1
pKa:
8.55
Temp.:
22 °C
No.:
#2
pKa:
8.38
Temp.:
22 °C

Any other information on results incl. tables

In a study conducted according to OECD Guideline 122 'Partition coefficient n-octanol/water, pH-metric method for ionisable substances' log Pow was estimated based on pKa measurements. The pKa value was estimated from the point of half neutralization determined by the TIAMO titration software. For the test substance amides, coco, N-(3 -(dimethylamino)propyl) a pKa=8.547 +/- 0.043 was determined. For the pure components (main components of amides, coco, N-(3 -(dimethylamino)propyl)) N-(3-(dimethylamino)propyl)dodecanoic acid amide and N-(3-(dimethylamino)propyl)octanoic/decanoic acid amide pKa values of 8.38 each were obtained. The measured pKa data, however, did not correlate with the chain length of the alkyl moiety of the amido-amines, which wold be expected in a way that shorter alkyl chains should correlate with lower pKa values. This might be related to the surface-active properties of the amido-amines.

Applicant's summary and conclusion

Conclusions:
In a study conducted according to OECD Guideline 122 'Partition coefficient n-octanol/water, pH-metric method for ionisable substances' log Pow was estimated based on pKa measurements. The pKa value was estimated from the point of half neutralization determined by the TIAMO titration software. For the test substance amides, coco, N-(3 -(dimethylamino)propyl) a pKa=8.547 +/- 0.043 was determined. For the pure components (main components of amides, coco, N-(3 -(dimethylamino)propyl)) N-(3-(dimethylamino)propyl)dodecanoic acid amide and N-(3-(dimethylamino)propyl)octanoic/decanoic acid amide pKa values of 8.38 each were obtained. The measured pKa data, however, did not correlate with the chain length of the alkyl moiety of the amido-amines, which wold be expected in a way that shorter alkyl chains should correlate with lower pKa values. This might be related to the surface-active properties of the amido-amines.
Executive summary:

In a study conducted according to OECD Guideline 122 'Partition coefficient n-octanol/water, pH-metric method for ionisable substances' log Pow was estimated based on pKa measurements. The pKa value was estimated from the point of half neutralization determined by the TIAMO titration software. For the test substance amides, coco, N-(3 -(dimethylamino)propyl) a pKa=8.547 +/- 0.043 was determined. For the pure components (main components of amides, coco, N-(3 -(dimethylamino)propyl)) N-(3-(dimethylamino)propyl)dodecanoic acid amide and N-(3-(dimethylamino)propyl)octanoic/decanoic acid amide pKa values of 8.38 each were obtained. The measured pKa data, however, did not correlate with the chain length of the alkyl moiety of the amido-amines, which wold be expected in a way that shorter alkyl chains should correlate with lower pKa values. This might be related to the surface-active properties of the amido-amines.