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Physical & Chemical properties

Partition coefficient

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partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12-08-2011 -> 22-08-2011
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
GLP compliance:
But performed at GLP lab under comparable conditions
Type of method:
other: Slow stirring
Partition coefficient type:
Analytical method:
other: LC-MS/MS
log Pow
Partition coefficient:
25.3 °C
log Pow
Partition coefficient:
25.3 °C
Remarks on result:
other: pH range was 3 - 4
Details on results:
The Pow values are calculated from the ratio between the concentration of the substance in octanol and water. The logarithmic value of the ratio is presented for each compound and for the sum. Log Pow for the di (2-hydroxypropyl) tallow amine is calculated as the logarithm of the sum of the individual compound concentrations in the octanol phase divided by the sum of the concentrations in the corresponding water phase. The recovery is calculated from the sum of the mass found in the water phase and the corresponding octanol phase. This sum is divided by the mass added in the octanol phase at the start of the experiment and the resulting recovery is given in the green field in the lower table.
The Log Pow was calculated by using the results from the SPE concentrated water phases. The Log Pow values for each homologue are also calculated using the SPE water phases.

Substance Log Pow Sampling time Log Pow individual values Recovery
(average) (days) Flask 1 Flask 2 Flask 3 (%)
Di (2-hydroxypropyl) tallow amine 6.2 7 6.23 6.07 6.17 87
Di (2-hydroxypropyl) tallow amine Acidified water phase 3.7 7 3.65 3.65 3.67 91

Substance Log Pow Log Pow
pH = 7 Acidified water phase pH = 3-4
Di (2-hydroxypropyl) tallow amine 6.2 3.7

With the following results of its components:

C16 2PO 5.7 3.3
C18’ 2PO 6.1 3.6
C18 2PO 6.9 4.4
The test is considered valid as all validity criteria have been fulfilled; Based on the test setup (Guideline study) and detailed results presented, the results are considered to be reliable. Finally, the test result is considered adequate for the evaluation of the log Kow (log Pow) but because the substance evaluated is a surface active substance, it is not clear if this log Kow has any meaning for predicting the bioaccumulation potential or sorption potential of this substance.
Executive summary:

The octanol-water partition coefficient for di (2-hydroxypropyl) tallow amine, CAS no: 68951 -72 -4, has been determined according to OECD Guidelines for the Testing of Chemicals, 'Partition coefficient (l-octanol/water): Slow stirring method', no 123.

The Log Kow has been determined at two test conditions, at pH 7 and at reduced pH (3-4) as the substance is a tertiary amine with a calculated pKa of 5.7 (SPARC). At pH 7 a log Kow of 6.2 was observed where at pH 3-4 a log Kow of 3.7 was observed.

Description of key information

The partition coefficient of the substance is 6.2 (log Pow).

Key value for chemical safety assessment

Log Kow (Log Pow):
at the temperature of:
25.3 °C

Additional information

The registered substance is a surface active with a surface tension of 30 mN/m at 20 °C and 200 mg/L. For surfactants, measurement of the Kow is challenging or in most cases infeasible (see REACH Guidance R.7.8.1.). The registrant has managed to measure the Kow under the conditions described in the end-point robust study summary with the slow-stirring method. Other conditions were found to be infeasible. The conditions used in the slow-stirring test are environmentally relevant (pH range to be considered is 4-9). Based on the pKa of 8.8, the registered substance does not exist exclusively in a neutral form within this environmentally relevant pH range. The partition coefficient of the registered substance is 6.2 (log Kow).


In addition, the log Kow of the substance is estimated using the KOWWIN model, the log Kow is 7.2, calculated from its major constituents.