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Environmental fate & pathways

Henry's Law constant

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Description of key information

The hydrolysis product 2 -ethylhexanoic acid will not evaporate into the atmosphere from the water surface.

Key value for chemical safety assessment

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

Additional information


In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

For the assessment of 2-ethylhexanoil chloride (Q)SAR results were used for the estimation of the Henry’s Law constant. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

Therefore, further experimental studies on the Henry’s Law Constant are not provided.



The parent substance rapidly decomposes in water and forms 2-ethylhexanoic acid (CAS 149-57-5) and hydrochloric acid (HCl, CAS 7647 -01 -0). Due to this, the assessment of the Henry's Law Constant of the parent compound is considered to be of low relevance. Therefore, the assessment of the HLC is based solely on the hydrolysis product 2 -ethylhexanoic acid (CAS 149 -57 -5).


A HLC value was calculated for the hydrolysis product 2 -ethylhexanoic acid using the bond estimation method of HENRYWIN v3.20 (EPISuite v 4.11; BASF SE 2021) the HLC was calculated to be 0.304 Pa*m³/mol. This estimation refers to the uncharged molecule. The substance is within the applicability domain of the model.

In conclusion, based on the available calculated data, 2 -ethylhexanoyl chloride and its hydrolysis product will not evaporate into the atmosphere from the water surface.