Ethylcyclohexane

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption, other

Remarks:

Adsorption modelling

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

For calculation of the soil adsorption coefficient (koc) of ethylcyclohexane the EPI (Estimation Programs Interface) Suite™, a Windows®-based suite of physicall-chemical property and environmental fate estimation programs developed by the EPA’s Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC), was used. The included program KOCWIN estimates the koc using two different estimation methodologies:
1. the Sabljic molecular connectivity method with improved correction factors
2. the traditional method based on log KOW
The Sabljic molecular connectivity method is solely based on the Molecular Connectivity Index (MCI) which is a method that runs directly from structure to activity. Molecular Connectivity Indices are representation of molecular structure. The molecule is regarded as a sum of the bonds connecting pairs of atoms
which are encoded by the cardinal number (delta) and represents the count of all bonded atoms other than hydrogen. The molecule is than splitted into fragments which are encoded by the corresponding delta values. The delta value of each atom forming a bond pair designate a bond value and these values are then summed over all the bonds to calculate the molecular connectivity index. The traditional method using measured Kow values uses correlations between the log Kow and the Koc. For polar and non-polar compunds separate regression equations are used.

Qualifier:

according to guideline

Guideline:

other: Guidance on information requirements and chemical safety assessment, Chapter R.6: QSARs and grouping of chemicals, ECHA, May 2008

Deviations:

not applicable

GLP compliance:

not specified

Type of method:

other: QSAR

Media:

other: not applicable

Radiolabelling:

not specified

Test temperature:

not applicable

Details on study design: HPLC method:

not applicable

Analytical monitoring:

not required

Details on sampling:

not applicable

Details on matrix:

not applicable

Details on test conditions:

not applicable

Computational methods:

See "Principles of method if other than guideline"

Key result

Sample No.:

#1

Type:

log Koc

Value:

446.1 L/kg

Remarks on result:

other: MCI method, pH, temp. and %carbon not applicabel

Key result

Sample No.:

#2

Type:

log Koc

Value:

9 062 L/kg

Remarks on result:

other: log Kow method, pH, temp. and %carbon not applicabel

Transformation products:

not specified

SMILES : CCC1CCCCC1

CHEM  :

MOL FOR: C8 H16

MOL WT : 112.22

--------------------------- KOCWIN v2.00 Results ---------------------------

 

 Koc Estimate from MCI:

 ---------------------

        First Order Molecular Connectivity Index ........... : 3.932

        Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 2.6495

        Fragment Correction(s) --> NONE                     :  ---

        Corrected Log Koc .................................. : 2.6495

 

                        Estimated Koc: 446.1 L/kg  <===========

 

 Koc Estimate from Log Kow:

 -------------------------

        Log Kow (experimental DB) ......................... : 4.56

        Non-Corrected Log Koc (0.8679 logKow - 0.0004) ..... : 3.9572

        Fragment Correction(s) --> NONE                     :  ---

        Corrected Log Koc .................................. : 3.9572

 

                        Estimated Koc: 9062 L/kg  <===========

Validity criteria fulfilled:

yes

Conclusions:

It can be concluded that ethylcyclohexane is very likely to adsorb to soil or sediment (Koc = 446 and 9062 L/kg; log Koc = 2.65 and 3.96). The KOC values derived with EPISuite™, based on the MCI-model and the Kow method, can be considered reliable for both modelling and environmental fate assessments.

Executive summary:

The adsorption coeffcient log Koc of ethylcyclohexane was determined by a non-experimental calculation method.

Ethylcyclohexane is a slightly water soluble, non-polar organic substance.

As a very hydrophobic substance, supported by its measured Kow of 4.56, it is expected that ethylcyclohexane would strongly adsorb to organic matter in soil to an appreciable extent.

This is confirmed by the estimated log KOC values of 2.65 and 3.96.

According to the EPI SUITE User's Guide, the MCI methodology is somewhat more accurate than the Log Kow methodology, although both methods yield good results.

For risk assessment purposes the calculated log Koc of 3.96 is used as a worst case value.

Description of key information

The adsorption coeffcient log Koc of ethylcyclohexane was determined by a non-experimental calculation method.

Ethylcyclohexane is a slightly water soluble, non-polar organic substance.

As a very hydrophobic substance, supported by its measured Kow of 4.56, it is expected that ethylcyclohexane would strongly adsorb to organic matter in soil to an appreciable extent.

This is confirmed by the estimated log KOC values of 2.65 and 3.96.

According to the EPI SUITE User's Guide, the MCI methodology is somewhat more accurate than the Log Kow methodology, although both methods yield good results.

For risk assessment purposes the calculated log Koc of 3.96 is used as a worst case value.

Key value for chemical safety assessment

Koc at 20 °C:

9 062

Additional information

[LogKoc: 3.96]