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Partition coefficient

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Endpoint:
partition coefficient
Data waiving:
study technically not feasible
Justification for data waiving:
the study does not need to be conducted because the substance decomposes
Justification for type of information:
The substance is hydrolytically unstable
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Justification for type of information:
The substance is a reaction mass and the single components are hydtrolytically instable. The study is technically not feasible, therfore an accepted calculation QSAR method according to US EPA EPISUITE was used
Qualifier:
no guideline followed
Guideline:
other: US EPA QSAR Method KOWWIN
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.  Users unfamiliar with SMILES notations can consult the document "A Brief Description of SMILES Notation" (accessed by pressing the F1 key or selecting "Help" from the program menu).  SMILES can be entered into KOWWIN by several methods (see Section 5.1).  Structures in scientific file formats other than SMILES notations can be imported directly into KOWWIN see (section 5.3).

 

The KOWWIN program and estimation methodology were developed at Syracuse Research Corporation.  A journal article by Meylan and Howard (1995) describes the program methodology. Section 6.1 of this User’s Guide briefly discusses the "fragment constant" methodology of KOWWIN.  The accuracy of KOWWIN is described in Section 6.2.

 

The octanol-water partition coefficient is a physical property used extensively to describe a chemical's lipophilic or hydrophobic properties.  It is the ratio of a chemical's concentration in the octanol-phase to its concentration in the aqueous phase of a two-phase system at equilibrium.  Since measured values range from less than 10-4 to greater than 10+8 (at least 12 orders of magnitude), the logarithm (log P) is commonly used to characterize its value.  Log P is a valuable parameter in numerous quantitative structure-activity relationships (QSAR) that have been developed for the pharmaceutical, environmental, biochemical and toxicological sciences.  For example, additional estimation programs available in the EPI Suite (WSKOWWIN, BCFBAF, KOAWIN, ECOSAR and DERMWIN) use KOWWIN’s estimation methodology and experimental log P database retrieval system to predict water solubilities, bioconcentration-bioaccumulation, octanol-air partition coefficients, aquatic toxicity and dermal permeability coefficients, respectively (Meylan et al, 1996, 1999; Meylan and Howard, 2005, USEPA, 1992).

 
GLP compliance:
no
Type of method:
calculation method (fragments)
Partition coefficient type:
other: US EPA QSAR method program KOWWIN V1.68
Type:
log Pow
Partition coefficient:
3.7
Remarks on result:
other: QSAR estimation
Remarks:
S-(6-((3-(triethoxysilyl)propyl)thio)hexyl)ethylthioester
Type:
log Pow
Partition coefficient:
5.4
Remarks on result:
other: QSAR estimation
Remarks:
Hexamethylen-1,6-dithio-bis((3-triethoxysilyl) propane)
Type:
log Pow
Partition coefficient:
0.55
Remarks on result:
other: QSAR estimation hydrolysis product
Remarks:
S-(6-((3-(trihydroxysilyl)propyl)thio)hexyl)ethylthioester
Type:
log Pow
Partition coefficient:
-1.37
Remarks on result:
other: QSAR estimation hydrolysis product
Remarks:
Hexamethylen-1,6-dithio-bis((3-trihydroxysilyl) propane)
Type:
log Pow
Partition coefficient:
-0.14
Remarks on result:
other: QSAR estimation hydrolysis product
Remarks:
ethanol
Executive summary:

The study is technically not feasible, the substance decompose by hydrolysis in water.

The Partitions coefficient of the silanol hydrolysis products are 0.55 for S-(6-((3-(trihydroxysilyl)propyl)thio)hexyl)ethylthioester and -1.37 for Hexamethylen-1,6-dithio-bis((3-trihydroxysilyl) propane). The hydrolysis product ethanol has a Partitions coefficient of -0.14

Description of key information

The study is technically not feasible, the substance decompose by hydrolysis in water

The Partitions coefficient of the silanol hydrolysis products are 0.55 for S-(6-((3-(trihydroxysilyl)propyl)thio)hexyl)ethylthioester and -1.37 for Hexamethylen-1,6-dithio-bis((3-trihydroxysilyl) propane). The hydrolysis product ethanol has a Partitions coefficient of -0.14

Key value for chemical safety assessment

Additional information