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Vapour pressure

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Description of key information

The estimated vapour pressure values for the test item constituents ranged from 1.23 x 10-25 Pa to 3.96 x 10-16 Pa.

Key value for chemical safety assessment

Additional information

The vapor pressure of Fatty acids, C18 unsaturated, reaction products with diethylenetriamine, acetate salts has been estimated. The results are summarized below:

The vapor pressure of each of the test item constituents was estimated using a computer-based atom fragment contribution method, MPBPWIN v1.43 (September 2010), © 2000 U.S. Environmental Protection Agency.

The estimated vapor pressure values are presented in the following table:

Constituent

Estimated vapour pressure at 25°C (Pa)

1

6.8 x 10-23

2

1.23 x 10-25

3

1.45 x 10-19

4

9.93 x 10-23

5

3.96 x 10-16

6

2.73 x 10-20

7

9.28 x 10-17

In order to confirm that these predictions are valid for use for in the chemical safety assessment, the following validation was compiled.

The acetate salts are anticipated to be less volatile than the un-salted forms (i.e. the Tall oil diethylenetriamine imidazoline constituents).

Therefore, predictions using MPBPWIN v1.43 (September 2010), © 2000 U.S. Environmental Protection Agency,

were also run for the constituents in their un-salted forms for comparison with the acetate salts forms. The data is presented in the table below:

Constituent

Acetate Salt

Unsalted (base imidazoline)

1

6.8 x 10-23 Pa

5.04 x 10-6 Pa

2

1.23 x 10-25 Pa

7.23 x 10-15 Pa

3

1.45 x 10-19 Pa

1.8 x 10-8 Pa

4

9.93 x 10-23 Pa

1.9 x 10-17 Pa

5

3.96 x 10-16 Pa

7.8 x 10-7 Pa

6

2.73 x 10-20 Pa

8.1 x 10-9 Pa

7 (DETA)

DETA acetate: 9.28 x 10-17 Pa

DETA: 34 Pa

As anticipated, the estimated vapour pressures for the acetate salts are lower (less volatile) than the corresponding unsalted forms.

The prediction for Diethylenetriamine (DETA) gave a vapour pressure of 34 Pa. A search of data for the vapour pressure of DETA (including details on the ECHA website) showed that most values given for the vapour pressure of DETA are within a similar range to the predicted value of 34 Pa at 25°C.

A prediction was also run for the vapour pressue of acetic acid, which gave an estimated vapour pressure of 17.2 mm Hg (2290 Pa). This is within a similar range as known data on acetic acid (including details on the ECHA website).

In addition, an experimentally measured vapour pressure for Tall oil diethylenetriamine imidazoline was obtained of 7.9 x 10-8 Pa at 20°C and 1.7 x 10-7 Pa at 25°C. The predicted estimates for the Tall oil diethylenetriamine imidazoline constituents (i.e. the unsalted constituents) show a similar range of vapour pressure (for constituents 1, 3, 5, 6) as obtained experimentally.

Based on the above information, it is considered that the vapour pressure predictions obtained from the MPBPWIN v1.43 (September 2010), © 2000 U.S. Environmental Protection Agency program (computer-based atom fragment contribution method) are suitable for use, as they follow expected trends and have been shown to be sufficiently similar to known vapour pressure data.

Therefore the vapour pressure predictions for the acetate salt constituents are valid predictions and suitable for use in the assessment of the substances vapour pressure.

For the purposes of the chemical safety assessment the substances vapour pressure will be identified as the lowest vapour pressure obtained for the predictions on the constituents, which is 3.96 x 10-16 Pa (obtained for constituent 5).