1,6-Hexanediamine, N1,N6-bis(1,2,2-trimethylpropyl)-

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Followed guideline and GLP requirements.

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

GLP compliance:

yes (incl. QA statement)

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

gas chromatography

Type:

Pow

Partition coefficient:

>= 125

Temp.:

22 °C

pH:

ca. 9

Remarks on result:

other: Pow standard deviation 14.7

Type:

log Pow

Partition coefficient:

ca. 2.1

Temp.:

22 °C

pH:

ca. 9

Total Weights and Analyzed Concentrations of Respective Phases

Sample number	Total Weight (mg)*	Organic Phase Analyzed Concentration (x 10^3mg/l)	Organic Phase Weight (mg)#	Aqueous Phase Analyzed Concentration (mg/l)	Aqueous Phase Weight (mg)#	pH
1	176	2.48	174	21.0	1.47	9.1
2	150	2.47	148	21.0	1.26	9.1
3	105	2.47	104	23.6	1.99	9.1
4	113	2.50	112	18.2	1.64	9.1
5	75	2.39	71.8	16.5	1.98	9.1
6	55	2.43	53.4	19.1	1.68	9.1

pH of pH 9 buffered n-octanol saturated water 9.0

Temperature 22.0 +/- 0.5 degrees C

* From analysis of stock solution        # From analysis of respective phase

Partition coefficient determined for each sample

Sample Number	Organic/Aqueous Volume Ratio	Partition coefficient	Log10Pow	Mean Partition Coefficient
1	1.1	118	2.07	118
2	1.1	117	2.07	118
3	1.2	105	2.02	121
4	1.2	137	2.14	121
5	1.4	145	2.16	136
6	1.4	127	2.10	136

Mean P_ow= 1.25      Standard Deviation = 14.7     Log₁₀P_ow = 2.10

Conclusions:

In a shake-flask n-octanol partition coefficient test, test article mean Pow was 125 (SD 14.7) with log Pow 2.10

Executive summary:

A partition coefficient value of 125 at 22.0 degrees C +/- 0.5, and log₁₀P_ow 2.10 was determined for the test article using the shake-flask method (Method A8 Partition Coefficient of Commission Regulation (EC) No. 440/2008 of 30 May 2008 and Method 830.7550 of the OPPTS Guideline). 

In conducting the test, the n-octanol saturated water was buffered to pH 9 to ensure the test material was partitioned in the least ionized form possible within the environmentally relevant pH range of 5 to 9. The dissociation constants of the two amine groups were estimated to be 10.91 +/- 0.29 and 11.56 +/- 0.29 (ACD/l-lab Web Service, ACD/pKa 8.03). Due to a pH of at least 13 being required to give the un-ionized molecule, it was considered impractical to perform the test at such a high pH as well as exceeding the environmentally relevant range.

Substances having a and log₁₀P_ow2.10 of greater than 3 are regarded as having the potential to bioaccumulate in the environment, but as the overall test result was log₁₀P_ow2.10, this suggests that the test article is not a bioaccumulation risk. In addition, the partition coefficient is anticipated to decrease further at neutral and weakly acidic pH’s as the degree of ionization will increase. Although the preliminary estimate of partition coefficient based on visual solubilities resulted in a log value greater than 3, this value was believed to be artificially high due to the miscibility of the test material in n-octanol. As the method guidelines limit the maximum stock concentration at 0.01 M, such a value could not be achieved for a definitive test with the constraints of the guidelines. 

Description of key information

The partition coefficient of the test article was determined by using the shake-flask method (Method A8 Partition Coefficient of Commission Regulation (EC) No. 440/2008 of 30 May 2008 and Method 830.7550 of the OPPTS Guideline). The partition coefficient value (Kow) of the test article was estimated at 125 at 22.0°C =/-0.5 (LogKow = 2.10). The current value suggests that the test article do not display any bioaccumulation risk. In addition, the partition coefficient is anticipated to decrease further at neutral and weakly acidic pH’s as the degree of ionization will increase.

Key value for chemical safety assessment

Log Kow (Log Pow):

2.1

at the temperature of:

22 °C