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Environmental fate & pathways

Henry's Law constant

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Description of key information

From the water surface, the substance will not evaporate into the atmosphere.

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
0.195
at the temperature of:
25 °C

Additional information

QSAR-disclaimer

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 assessmentof the1,8-diazabicyclo [5.4.0] undec-7-ene (CAS 6674-22-2) (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.

 

Assessment

The Henry's law constant at 25 °C was estimated to be 0.195 Pa*m³/mol using the bond estimation method of HENRYWIN v3.20 (BASF, 2017). The substance was not completely within the estimation domain of the model as the maximum number of one fragment was exceeded. The HENRYWIN estimate refers to the uncharged molecule. The calculation of the Henry's Law constant via measured data for vapour pressure and water solubility is not taken into consideration as the method is not valid for substances like DBU which are miscible with water. The resulting HLC is 4.57E-4 Pa*m³/mol (BASF, 2017), but the value is disregarded. The estimated HLC value of the bond estimation method indicates that the substance will not evaporate into the atmosphere. However, the substance will be predominantly present in a protonated form under environmentally relevant pH conditions (pH 4 -9; pKa = 11.6).

It can be concluded that the substance will not evaporate into the atmosphere from the water surface as the HLC is < 1 Pa*m³/mol.