Registration Dossier

Administrative data

Endpoint:
Henry's law constant
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Data from guideline studies under GLP
Justification for type of information:
MTDID 22327 is a member of the Perfluorinated Organic Chemicals, C5-C18, category. Unlike most members of the category, MTDID 22327 is a UVCB consisting mostly of perfluoro-N-methylmorpholine, a mixture of C5-C7 perfluoroamines, and mixed perfluorohexanes. However, all of these chemicals stem from the same manufacturing process, have similar physicochemical properties including high vapor pressure and low water solubility relative to the hydrocarbon analogs (e.g., hexanes v. perfluorohexanes), and also lack any chemically reactive groups, which forms the technical basis for the category.  Members of this category are fully fluorinated, meaning that fluorine, rather than hydrogen, is bonded to all carbon atoms in the molecule.  Fluorine is the most electronegative of the elements (fluorine has an electronegativity of 3.98 on the Pauling scale, as compared to 2.55 for carbon, 3.04 for nitrogen or 2.20 for hydrogen).  This electronegativity is expected to dominate over all other aspects of substance chemistry and is the underlying basis for similarity of substances in this category.  For example, strong electron withdrawing in perfluorinated tertiary amines results in a molecule with essentially no lone pair reactivity or availability, and which has chemistry more similar to a branched, perfluorinated alkane than any other structure.  Because these substances exhibit similar physicochemical properties they can be considered to constitute a chemical category.  The data gap for HLC can therefore be addressed by many-to-one read-across between category members.

See section 13 for a fuller discussion of the category approach.

Data source

Reference
Reference Type:
other: Read across from other internal studies
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs and grouping of chemicals
Version / remarks:
May/July 2008
Deviations:
no
GLP compliance:
no
Remarks:
Source data were GLP compliant

Test material

Constituent 1
Reference substance name:
Reaction mass of perfluoro(dimethyl - N - Butylamine ) and perfluoro (methyl - di - N - propylamine) and perfluoro (dimethyl - N - propylamine and 2,2,3,3,5,5,6,6, octafluoro-4-(trifluoromethyl)morpholine and perfluoro-N-pentane
EC Number:
908-205-5
Cas Number:
2187449-42-7
IUPAC Name:
Reaction mass of perfluoro(dimethyl - N - Butylamine ) and perfluoro (methyl - di - N - propylamine) and perfluoro (dimethyl - N - propylamine and 2,2,3,3,5,5,6,6, octafluoro-4-(trifluoromethyl)morpholine and perfluoro-N-pentane
Specific details on test material used for the study:
Readacross is from category members:
Perfluorohexanes, PFHx, CAS# 1064697-81-9
Perfluoro-N-methylmorpholine, PMM, CAS# 382-28-5
Perfluoroheptanes, PFHp, CAS# 1064698-16-3
Perfluorotripropylamine, PTPA, CAS# 338-83-0
Perfluorotributylamines, PTBA, CAS# 1064698-37-8

Results and discussion

Henry's Law constant Hopen allclose all
Key result
H:
ca. 171 - ca. 1 021 atm m³/mol
Temp.:
22 °C
Remarks on result:
other: Upper limit defined by perfluorohexanes, lower limit by perfluoromethylmorpholine
H:
> 1 021 - < 4 020 atm m³/mol
Temp.:
22 °C
Remarks on result:
other: HLC range for tertiary amine constituents
Remarks:
bracketing by perfluorohexanes and perfluorotributyl amines

Any other information on results incl. tables

Experimental HLC data are available for two constituents of MTDID 22327. These two substances are comparable to MTDID 22327 as a whole based on the types of chemical functional groups (perfluorinated alkyl groups and perfluorinated amines); molecular weights (MTDID 22327 range = 288 - 421 g/mol; PFHx = 338 g/mol; and PMM =299 g/mol); vapor pressures (MTDID 22327 = 28.4 kPa; PFHx = 24 kPa; and PMM = 29 kPa); and water solubilities (MTDID 22327 = 0.679 - 758 µg/L; PFHx = 84 ug/L; and PMM = 758 ug/L). The respective dimensionless HLCs of these two substances are used to define the upper and lower bounds of the dimensionless HLC value which may be expected for MTDID 22327. A higher range of HLC values may be expected specifically for perfluorinated tertiary amines.

Applicant's summary and conclusion

Conclusions:
Henry's Law constant of MTDID 22327: 171 – 1021 atm∙m³/mol at 22 °C by read-across from category members. Perfluorinated tertiary amine constituents are expected to have a higher range (1021 – 4020 atm∙m³/mol at 22 °C).
Executive summary:

The Henry’s Law constant (HLC) for MTDID 22327 was determined using a category approach wherein the experimental HLCs of two constituent substances with similar physical properties are used to define the upper and lower bound of the HLC range.  The resulting HLC range is 171 – 1021 atm∙m³/mol at 22 °C.  This approach is considered reliable based on the validity of the experimental values provided. Based on the anticipated HLC range, the test substance is not expected to remain in aqueous solution in open systems and it will partition to the atmosphere.

The validity of this approach to categorically group these types of substances was determined to be reliable with restrictions based on the similarity of chemical functional groups, molecular weights, water solubilities, and vapor pressures. Since the source data are for constituents of MTDID 22327, they provide the best estimate of the range of partition coefficient for MTDID 22327. The source data are from GLP-compliant studies which used scientifically acceptable methods, and they are considered reliable. This study is pertinent to the fate of MTDID 22327 and may be used for risk assessment, classification and labelling, and PBT analysis.