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Partition coefficient

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Reference
Endpoint:
partition coefficient
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 partition coefficient can therefore be addressed by many-to-one read-across between category members.

See section 13 for a fuller discussion of the category approach.
Reason / purpose for cross-reference:
other: composition of substance
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
Partition coefficient type:
octanol-water
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
Type:
log Pow
Partition coefficient:
4.3
Temp.:
23 °C
Remarks on result:
other: Constituent 2,2,3,3,5,5,6,6-octafluoro-4-(trifluoromethyl)morpholie
Remarks:
read across from category member PMM
Type:
log Pow
Partition coefficient:
6.14
Temp.:
25 °C
Remarks on result:
other: Constituent 1,1,2,2,3,3,3-heptafluoro-N-(heptafluoropropyl)-N-(trifluoromethyl)propan-1-amine (isomers)
Remarks:
read across from category members MTDID 50908
Type:
log Pow
Partition coefficient:
5.46
Temp.:
25 °C
Remarks on result:
other: Constituent 1,1,2,2,3,3,4,4,4-nonafluoro-N,N-bis(trifluoromethyl)butan-1-amine
Remarks:
read across from category member MTDID 50908
Type:
log Pow
Partition coefficient:
5
Temp.:
23.3 °C
Remarks on result:
other: Constituent tetradecafluorohexane (isomers)
Remarks:
read across from category member PFHx

Experimental partition coefficient data 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. The four constituents described have the highest typical concentrations (>1%) in MTDID 22327. Average Kow values are not reported in all of the source studies. Individual Kow ratios are reported below, with average Kow calculated where necessary

Table, Kow values from source studies

n-octanol: water volume ratio

replicate

PMM

MTDID 50908 Components A and H¹

MTDID 50908 Component D²

PFHx

1:1

1

21300

1520000

315000

86200

 

2

21100

1550000

331000

102000

1:2

1

20400

1330000

288000

98800

 

2

22600

1330000

276000

108000

1120000

214000

2:1

1

outlier, disregarded

1340000

280000

125000

 

2

21800

1450000

317000

106000

1420000

288000

average Kow

21400

1380000

289000

104000

1, data for unresolved isomeric mixture of constituent 1,1,2,2,3,3,3-heptafluoro-N-(heptafluoropropyl)-N-(trifluoromethyl)propan-1-amine and impurity 1,1,2,2,3,3,3-heptafluoro-N-(1,1,1,2,3,3,3-heptafluoropropan-2-yl)-N-(trifluoromethyl)propan-1-amine

2, constituent is 1,1,2,2,3,3,4,4,4-nonafluoro-N,N-bis(trifluoromethyl)butan-1-amine

3, Only two replicatate were done for PMM and PFHx

Conclusions:
Log n-octanol:water coefficient for components of MTDID 22327 ranged from 4.3 - 6.14 at ca. 23 - 25 °C. The predominant constituent had the lowest measured measured log Kow.
Executive summary:

The Log n-octanol:water coefficient of MTDID 22327 was determined using a category approach wherein the coefficients of known constitituents are used to define the range. The resulting range was 4.3 to 6.14 at ca. 23 - 25 °C. The predominant constituent had the lowest measured log Kow.

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 or ISO 17025-compliant studies which used national standard test guidelines, and they are considered reliable or reliable with restriction. This study is pertinent to the fate of MTDID 22327 and may be used for Risk Assessment, Classification & Labelling, and PBT Analysis.

Description of key information

Log n-octanol:water coefficient for components of MTDID 22327 ranged from 4.3 - 6.14 at ca. 23 - 25 °C. The predominant constituent had the lowest measured log Kow.

Key value for chemical safety assessment

Additional information

The Log n-octanol:water coefficient of MTDID 22327 was determined by read-across using category members which are constituents of MTDID 22327 to define the range. The resulting range was 4.3 to 6.14 at ca. 23 - 25 °C. The predominant constituent had the lowest measured log Kow. 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 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.