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Physical & Chemical properties

Partition coefficient

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Administrative data

Endpoint:
partition coefficient
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 (at the moment no reliable determination method for surface-active substances is available)

Data source

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

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: OECD Guideline 122 (draft)
GLP compliance:
no
Type of method:
other: pH-metric method for ionisable substances
Partition coefficient type:
octanol-water

Test material

Constituent 1
Chemical structure
Reference substance name:
Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]
EC Number:
930-947-3
IUPAC Name:
Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]

Study design

Analytical method:
other: titration

Results and discussion

Partition coefficientopen allclose all
Type:
log Pow
Partition coefficient:
3
Temp.:
22 °C
Remarks on result:
other: Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]
Type:
log Pow
Partition coefficient:
3.3
Temp.:
22 °C
Remarks on result:
other: N-(3-(dimethylamino)propyl)dodecanoic acid amid
Type:
log Pow
Partition coefficient:
3.3
Temp.:
22 °C
Remarks on result:
other: N-(3-(dimethylamino)propyl)octanoic/decanoic acid amide
Details on results:
Due to its chemical nature as tertiary amine and its chain length distribution the test substance is not a unique substance but a variety of substances with individual log Kow values and pKa values. Thus, log Kow can only be determined as an average or as a range of individual data.

The log Kow of various amido-amines of different chain length were estimated to

Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]: 3.0
N-(3-(dimethylamino)propyl)dodecanoic acid amide: 3.3
N-(3-(dimethylamino)propyl)octanoic/decanoic acid amide: 3.3

Applicant's summary and conclusion

Conclusions:
In a study conducted according to OECD Guideline 122 the range of the n-octanol/water partition coefficient log Kow was determined to be 3.0 - 3.3 for Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl] at 22 °C. The measured pKa value, however, can only be a rough estimation of the log Kow value due the surface-active properties. However there is no more suitable method available for the determination of the log Kow of amido-amines.
Executive summary:

The n-octanol/water partition coefficient log Kow was investigated in a study conducted according to OECD Guideline 122 'Partition coefficient n-octanol/water, pH-metric method for ionisable substances' (draft). Although the method is only valid for pure substances it was applied to Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl] which represents a complex mixture. Thus, log Kow can only be determined as an average or as a range of individual data. In order to validate the log Kow estimation, the method was additionally applied to two of the main consituents which were available as pure substances. The log Kow of various amido-amines of different chain length were estimated to:

-Amides, C8-18 even numbered, N-[3-(dimethylamino)propyl]: 3.0

-N-(3-(dimethylamino)propyl)dodecanoic acid amide: 3.3

-N-(3-(dimethylamino)propyl)octanoic/decanoic acid amide: 3.3

According to guideline, the method can not be applied to surface-active substances: Amido-amines may provide a surface active behaviour in watery systems

-these influences might be the reason for the disturbed titration curves recorded under addition of n-octanol

-the measured pKa data did not correlate with the chain length of the alkyl moiety of the amido-amines, which would be expected in a way that shorter alkyl chains should correlate with lower pKa values.

Consequently the measured pKa value can only be an rough estimation of the log Kow value. At the moment, however, there is no more suitable method available for the determination of the log Kow of amido-amines.