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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Study period:
N/A
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:
In accordance with section 2 of REACH Annex XI, as the substance reacts with water, it is technically not feasible to perform the study Partition coefficient n-octanol/water (section 7.8). In accordance with column 2 of REACH Annex VII, the Partition coefficient n-octanol/water has been calculated.
Qualifier:
no guideline followed
Principles of method if other than guideline:
KOWWIN (the Log Octanol-Water Partition Coefficient Program) estimates the logarithmic octanol-water partition coefficient (log P) of organic compounds. KOWWIN requires only a chemical structure to estimate a log P. Structures are entered into KOWWIN by SMILES (Simplified Molecular Input Line Entry System) notations.

The KOWWIN program and estimation methodology were developed at Syracuse Research Corporation.

KOWWIN uses a "fragment constant" methodology to predict log P. In a "fragment constant" method, a structure is divided into fragments (atom or larger functional groups) and coefficient values of each fragment or group are summed together to yield the log P estimate. KOWWIN’s methodology is known as an Atom/Fragment Contribution (AFC) method. Coefficients for individual fragments and groups were derived by multiple regression of 2447 reliably measured log P values. KOWWIN’s "reductionist" fragment constant methodology (i.e. derivation via multiple regression) differs from the "constructionist" fragment constant methodology of Hansch and Leo (1979) that is available in the CLOGP Program (Daylight, 1995). See the Meylan and Howard (1995) journal article for a more complete description of KOWWIN’s methodology.

The KOWWIN training and validation datasets can be downloaded from the Internet at:
http://esc.syrres.com/interkow/KowwinData.htm

References:
Hansch, C and Leo, A.J. 1979. Substituent Constants for Correlation Analysis in Chemistry and Biology; Wiley: New York, 1979.
Daylight. 1995. CLOGP Program. Daylight Chemical Information Systems. Von Karman Ave., Irvine, CA 92715. (web-site as of March 2008: http://www.daylight.com/)
Meylan, W.M. and P.H. Howard. 1995. Atom/fragment contribution method for estimating octanol-water partition coefficients. J. Pharm. Sci. 84: 83-92.
GLP compliance:
no
Type of method:
other: QSAR
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
3.92
Temp.:
25 °C
pH:
ca. 7
Remarks on result:
other: Calculated value

Log Kow (estimated) : 3.92

Log Kow (experimental): not available from database

Log Kow used by Water solubility estimates: 3.92

Conclusions:
By using the estimation program KOWWIN (version 1.68), the log Kow of 1,3-H6XDI is calculated to be 3.92.
Endpoint:
partition coefficient
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
In accordance with section 2 of REACH Annex XI, as the substance reacts with water, it is technically not feasible to perform the study Partition coefficient n-octanol/water (section 7.8). In accordance with column 2 of REACH Annex VII, the Partition coefficient n-octanol/water has been calculated.

Description of key information

As the substance reacts with water, it is technically not feasible to perform a study on the Partition coefficient n-octanol/water. In accordance with column 2 of REACH Annex VII, the Partition coefficient n-octanol/water has been calculated using EPISuite v.4.11.

Key value for chemical safety assessment

Log Kow (Log Pow):
3.92
at the temperature of:
25 °C

Additional information