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Environmental fate & pathways

Henry's Law constant

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Henry's law constant
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Principles of method if other than guideline:
Calculation according to REACH Guidance Document R7a, Appendix R.7.1-2 pH correction of partition coefficients for ionisable substances, p. 189, May 2008
GLP compliance:
0 Pa m³/mol
25 °C
Remarks on result:
other: pH 5
Key result
0.023 Pa m³/mol
25 °C
Remarks on result:
other: pH 7
2.23 Pa m³/mol
25 °C
Remarks on result:
other: pH 9

The data refer to the charged molecule (calculated pKa value: 10.59)

Description of key information

No data are available for the test substance EC 401 -280 -0. As the substance hydrolyses almost immediately in contact with water, the degradation products are therefore considered.

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
at the temperature of:
25 °C

Additional information

Hydrolysis products:

bis(2 -ethylhexyl)amine

The Henry's law constant at 25 °C was estimated to be 89 Pa*m³/mol using SRC HENRYWIN v3.20 (BASF, 2013). The substance was within the estimation domain of the model, but the estimate is less accurate since the maximum number of occurrence of two bonds was exceeded by the substance. The HENRYWIN estimate refers to the uncharged molecule. This estimate is supported by a calculated HLC based on measured data for vapour pressure and water solubility. The resulting HLC is 6.7 Pa*m³/mol (BASF, 2013). The estimated HLC values indicate that the substance will slowly evaporate into the atmosphere. However, most of the molecules of the test item will be present in a protonated form under environmental relevant pH conditions (pKa = 10.56). Considering that, the range of the HLC was calculated to be 2.29E-4 to 2.23 Pa*m³/mol under environmentally relevant conditions with pH values from 5 to 9. Therefore, the substance will slowly evaporate into the atmosphere from the water surface at pH 9.0 but not at pH 7 and lower


From the water surface the substance is not expected to evaporate into the atmosphere (Betterton 1988)

1H-1,2,4 -triazole

No data on Henry's Law constant is available