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Environmental fate & pathways

Henry's Law constant

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Description of key information

Parent compound methyl chloroformate (CAS 79 -22 -1): From the water surface, the product methanol will not evaporate into the atmosphere. However, methyl chloroformate hydrolyses rapidly in contact with water to form methanol. Therefore, this model calculation may be of low relevance.

Hydrolysis product methanol (CAS 67 -56 -1): From the water surface, the hydrolysis product methanol will not evaporate into the atmosphere.

Key value for chemical safety assessment

Additional information

The parent compound methyl chloroformate (CAS 79-22-1) rapidly hydrolyses in contact with water and forms methanol (CAS 67-56-1). Considering the Henry’s Law Constant, the assessment is, therefore, predominantly based on information available for the hydrolysis product metanol.

Parent compound methyl chlorformate:

No experimental data are available. Therefore, the Henry's Law constant (HLC) was calculated using the bond estimation method of HENRYWIN v3.20 (EPISuite v 4.11; BASF SE 2019). The model estimated the HLC of the substance to be 238 Pa*m³/mol. This estimate refers to the uncharged molecule. The substance is within the applicability domain of the model.

This indicates a volatile character of the parent compound. However, methyl chloroformate hydrolyses rapidly in contact with water to form methanol. Therefore, this model calculation may be of low relevance.

Hydrolysis product methanol:

A value of 0.461 Pa m³/mol for the Henry’s Law constant indicates that volatilization is not a significant removal process from the aquatic compartment (Gaffney et al. 1987).

Based on the available experimental data, the hydrolysis product methanol (CAS 67-56-1) will not evaporate into the atmosphere from the water surface.

QSAR-disclaimer

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 methyl chloroformate (CAS 79-22-1) (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.