N-[3-(dimethylamino)propyl]dodecanamide

Water solubility

Administrative data

Endpoint:

water solubility

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
C8-C18 AAPA and C12 AAPA have the same functional groups, and general composition. The main variable resides in the alkyl chain distribution.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source chemical = C8-18 even numbered, N-[3-(dimethylamino)propyl]
Target chemical = C12 cocamidopropyl hydroxysultaine (EC 221-661-3)

3. ANALOGUE APPROACH JUSTIFICATION
The alkyl C-chain distribution of the source chemical significantly overlaps with the one of the target chemical, the C12-alkyl derivative being the major constituent in both chemicals. The structural differences in side C-chains is not expected to lead to significant differences on phys-chem properties.

4. DATA MATRIX: see "Documentation and scientific justification of the read-across approach" in section 13.2.
-

Cross-reference

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: comparable to guideline study. However, some difficulties in getting consistent results could not be resolved due to complex composition of the test substance.

Qualifier:

no guideline followed

Principles of method if other than guideline:

A known quantity above the limit of solubility of the test substance is weighed into water and slowly stirred for the duration of the experiment of at least 3 days. By slowly stirring on one hand the formation of foam and micro emulsions shall be prevented, and on the other hand the dissolution process shall be supported as good as possible. After well defined periods of time samples are taken, the non-dissolved material removed by pressure-filtration through a 0.05 .m filter and the concentration in the clear water phase is measured with a HPLC method. After reaching equilibrium the concentrations in the water phase should remain stable.

GLP compliance:

no

Type of method:

other: slow stirring method

Key result

Water solubility:

> 50 - < 1 000 mg/L

Incubation duration:

> 2 - < 7 d

Temp.:

21 °C

pH:

ca. 9.6

Remarks on result:

other:

Remarks:

The obtained experimental data are in-line with the estimated water solubilities of the individually component calculated by the modelling program EPIWIN v4.00 (WSKOW v1.41) and is in the range between slightly soluble (0.1 -100 mg/L) to moderately soluble (100-1000 mg/L).

Details on results:

As Product 205398 is a mixture of components the determination of the water solubility was referred to the particular main components. For the determination of the water samples six main components of the test substance were analysed.
The total water solubility of Product 205398 was calculated as their sum.

Test 1

The concentrations of the individual components in these samples are compiled in table. The average total solubility expressed as the sum of the individual concentrations are given below:

Sample	Average total solubility, mg/L	Weigt of the component in the product, %
N-(3-(dimethylamino)propyl)-octanamide	7.8	8.6
N-(3-(dimethylamino)propyl)- decanamide	5.9	6.3
N-(3-(dimethylamino)propyl)-dodecanamide	30.5	46.6
N-(3-(dimethylamino)propyl)-tetradecanamide	5.9	17.6
N-(3-(dimethylamino)propyl)-hexadecanamide	3.3	8.6
N-(3-(dimethylamino)propyl)-octadecanamide	3.2	9.6
Sum	56.5

 

 

Test 2

The first sample, taken after 24h, was analyzed. The total solubility (sum of the individual concentrations) increased by a factor of about 10. The rest of the second test with measurements after additional days of stirring was abandoned, because the concentration in the water phase turned out to be extremely dependent on the starting concentration.

Sample	Average total solubility, mg/L	Weigt of the component in the product, %
N-(3-(dimethylamino)propyl)-octanamide	64.3	8.6
N-(3-(dimethylamino)propyl)- decanamide	42.8	6.3
N-(3-(dimethylamino)propyl)-dodecanamide	279.7	46.6
N-(3-(dimethylamino)propyl)-tetradecanamide	104.7	17.6
N-(3-(dimethylamino)propyl)-hexadecanamide	50.9	8.6
N-(3-(dimethylamino)propyl)-octadecanamide	53.4	9.6
Sum	595.7

 

Conclusions:

Interpretation of results (migrated information): other:
The test performed clearly shows the effects of fractionated dissolution and the interaction between the individual components resulting in water solubilities depending on the start concentration.
Some difficulties in getting consistent results could not be resolved due to complex composition of the test substance.
The obtained experimental data are in-line with the estimated water solubilities of the individually component calculated by the modelling program EPIWIN v4.00 (WSKOW v1.41) and is in the range between slightly soluble (0.1-100 mg/L) to moderately soluble (100-1000 mg/L).

Executive summary:

The water solubility of Product 205398 was analysed by slow stirring method and subsequent analysis with HPLC/CAD. The two tests performed (the second only partially) clearly show the effects of fractionated dissolution and the interaction between the individual components resulting in water solubilities depending on the start concentration. Some difficulties in getting consistent results could not be resolved due to complex composition of the test substance. Hence the slow stirring method is also not applicable to product 205398, as it is also the case with the OECD 105 methods (column elution and flask).

The obtained experimental data are in-line with the estimated water solubilities of the individually component calculated by the modelling program EPIWIN v4.00 (WSKOW v1.41) and is in the range between slightly soluble (0.1 -100 mg/L) to moderately soluble (100-1000 mg/L).

Materials and methods

Test material

Test material information

Constituent 1

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]

Constituent 2

Reference substance name:

Amides, C6-18, N-[3-(dimethylamino)propyl]

EC Number:

308-484-8

EC Name:

Amides, C6-18, N-[3-(dimethylamino)propyl]

Cas Number:

98072-33-4

IUPAC Name:

98072-33-4

Details on test material:

- Name of test material (as cited in study report): Product 205398
- Batch: UB 3385
- Composition of test material, percentage of components:
N-(3-(dimethylamino)propyl)-hexanamide 200.3 g/mol 0.7 %
N-(3-(dimethylamino)propyl)-octanamide CAS 22890-10-4 228.4 g/mol 8.6 %
N-(3-(dimethylamino)propyl)- decanamide CAS 22890-11-5 256.4 g/mol 6.3 %
N-(3-(dimethylamino)propyl)-dodecanamide CAS 3179-80-4 284.5 g/mol 46.6 %
N-(3-(dimethylamino)propyl)-tetradecanamide CAS 45267-19-4 312.5 g/mol 17.6 %
N-(3-(dimethylamino)propyl)-hexadecanamide CAS 39669-91-1 340.6 g/mol 8.6 %
N-(3-(dimethylamino)propyl)-octadecanamide CAS 7651-02-7 368.6 g/mol 9.6 %
N-(3-(dimethylamino)propyl)-octadecenamide 0.4 %
Sum amides 98.4 %
Glycerol CAS 56-81-5 92.1 g/mol 0.05%
N,N-dimethylamino-propylamine (DMAPA) CAS 109-55-7 102.2 g/mol 6 mg/kg

Results and discussion

Water solubility

Key result

Water solubility:

> 50 - < 1 000 mg/L

Incubation duration:

> 2 - < 7 d

Temp.:

21 °C

pH:

ca. 9.6

Remarks on result:

other:

Remarks:

The obtained experimental data are in-line with the estimated water solubilities of the individually component calculated by the modelling program EPIWIN v4.00 (WSKOW v1.41) and is in the range between slightly soluble (0.1 -100 mg/L) to moderately soluble (100-1000 mg/L).