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Physical & Chemical properties

Water solubility

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Reference
Endpoint:
water solubility
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:
guideline study with acceptable restrictions
Remarks:
Data from guideline studies under GLP or ISO 17025
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 influence, 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 water solubility can therefore be addressed by many-to-one read-across between category members.

See section 13 for a fuller discussion of the category approach.
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 studies were GLP or ISO 17025 compliant
Specific details on test material used for the study:
Readacross is from category members:
Perfluoro-N-methylmorpholine, PMM, CAS# 382-28-5
reaction mass of perfluoro (methyl - di - N - propylamine) and mono (perfluoro ethyl), di (perfluoro-n-propyl) amine and tri (perfluoro-n-propyl) amine and perfluoro N-methyl N-isopropyl n-propylamine and perfluoro N-methyl, Nisopropyl butamine, MTDID 50908, EC# 920-778-3
Perfluorohexanes, PFHx, CAS# 1064697-81-9
Water solubility:
758 µg/L
Conc. based on:
other: Constituent
Remarks:
2,2,3,3,5,5,6,6-octafluoro-4-(trifluoromethyl)morpholine
Temp.:
23 °C
Remarks on result:
other: read across from category member PMM
Water solubility:
1.84 µg/L
Conc. based on:
other: Constituent
Remarks:
1,1,2,2,3,3,3-heptafluoro-N-(heptafluoropropyl)-N-(trifluoromethyl)propan-1-amine (isomers)
Temp.:
23.6 °C
Remarks on result:
other: read across from category MTDID 50908
Water solubility:
0.679 µg/L
Conc. based on:
other: Constituent
Remarks:
1,1,2,2,3,3,4,4,4-nonafluoro-N,N-bis(trifluoromethyl)butan-1-amine
Temp.:
23.6 °C
Remarks on result:
other: read across from category member MTDID 50908
Water solubility:
84.1 µg/L
Conc. based on:
other: Constituent
Remarks:
tetradecafluorohexane (isomers)
Temp.:
23.7 °C
Remarks on result:
other: read across from category member PFHx
Details on results:
Data from PMM and PFHx (isomers) are available from individual substances. Other constituents are common with MTDID 50908. Similar to MTDID 50908, the water solubility of other materials present below 1% may be greater, such that water solubility of the primary components does not reflect total amount of material in water solution at high loading rates.

Experimental water solubility are available for two constituents of MTDID 22327 (perfluoromethylmorpholine, PMM) and (perfluorohexanes; PFHx). In addition, two constituents are common to MTDID 22327 and MTDID 50908. Excess water solubility was observed for constituents of MTDID 50908 present below 1% of composition. This possibility cannot be excluded in the case of MTDID 22327.

Conclusions:
Water solubilities for components of MTDID 22327 ranged from 0.679 µg/L to 758 µg/L at ca. 23 - 24 °C. The predominant constituent had the highest measured solubility. Constituents present below 1% may have excess water solubility.
Executive summary:

The water solubility of MTDID 22327 was determined using a category approach wherein the experimental water solubilities of known constituents are used to define the range. The resulting range was 0.679 µg/L to 758 µg/L at ca. 23 - 24 °C.  The predominant constituent had the highest measured solubility.  Constituents present below 1% may have excess water solubility. As a result, compositions of water solutions may not reflect composition as registered, especially at high loading rates.

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, and vapor pressures. Since the source data are for constituents of MTDID 22327, they provide the best estimate of the range of water solubility for MTDID 22327. The source data are from GLP-compliant or ISO 17025-compliant studies which used national standard test guidelines, and they are considered reliable or reliable with restriction. It may be used for Risk Assessment, Classification & Labelling, and PBT Analysis.

Description of key information

Water solubilities for components of MTDID 22327 ranged from 0.679 μg/L to 758 µg/L at ca. 23 - 24 °C. The predominant constituent had the highest measured solubility. Constituents present below 1% may have excess water solubility.

Key value for chemical safety assessment

Additional information

The water solubility of MTDID 22327 was determined by read-across using category members which are consitutents of MTDID 22327 to define the range. The resulting range was 0.679 μg/L to 758 µg/L at ca. 23 - 24 °C. The predominant constituent had the highest measured solubility. Constituents present below 1% may have excess water solubility. As a result, compositions of water solutions may not reflect composition as registered, especially at high loading rates. Since the source data are for constituents of MTDID 22327, they provide the best estimate of the range of water solubility for MTDID 22327. The source data were collected in guideline studies and are GLP- or ISO 17025-compliant. The read- across is considered reliable with restrictions. Please see IUCLID section 13 for the category justification and a matrix of physicochemical data for members of the Perfluorinated Organic Chemicals C5-C18 category.