Trifluoro(trifluoromethoxy)ethylene

Henry's Law constant

Link to relevant study record(s)

Reference

Endpoint:

Henry's law constant

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

QMRF and QPRF are attached

Guideline:

other: REACH guidance on QSARs R.6

Principles of method if other than guideline:

HENRYWIN estimates Henry's Law Constant (HLC) by two separate methods that yield two separate estimates. The first method is the Bond Contribution Method and the second is the Group Contribution Method. The Bond Method is able to estimate many more types of structures than the Group Method because it has a more extensive library of bond contribution values

GLP compliance:

no

Specific details on test material used for the study:

SMILE: FC(F)(F)OC(F)=C(F)F

H:

32 100 Pa m³/mol

Temp.:

25 °C

Remarks on result:

other: Bond Contribution Method

Description of key information

The Henry’s Law Constant of PMVE was estimated by QSAR (HENRYWIN model v.3.20, EPI Suite v 4.0). The model predicts a Henry’s Law constant = 32100 Pa.m3/mol indicating that PMVE is expected to rapidly distribute from the water to the atmosphere.

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):

32 100

at the temperature of:

25 °C

Additional information

According to Appendix R.7.1-4 “Henry’s law constant and evaporation rate” from the Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint Specific Guidance, Henry’s law constant is one of the most important factors in determining the environmental fate of chemicals. This physical law states that the mass of gas dissolved by a given volume of solvent is proportional to the pressure of the gas with which it is in equilibrium. The relative constant quantifies the partitioning of chemicals between the aqueous phase and the gas phase such as rivers, lakes and seas with respect to the atmosphere (gas phase). Indeed, this constant is a fundamental input for fugacity models that estimate the multimedia partitioning of chemicals (Mackay, 1991). According to RAECH guidance R.7.a for substances with HLC values around 100 Pa·m3/mol the volatilisation will be rapid.  

PMVE is a gas at ambient conditions which boils at -26 °C (Yaws, Carl L. ©2010 Knovel). In order to evaluate the Henry’s Law constant of PMVE a QSAR evaluation was applied (HENRYWIN model v.3.20, EPI Suite v 4.0). The model predicts a Henry’s Law constant = 32100 Pa.m3/mol indicating that PMVE is expected to rapidly distribute from the water to the atmosphere.