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Environmental fate & pathways

Henry's Law constant

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Endpoint:
Henry's law constant
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Scientifically acceptable method
GLP compliance:
no
H:
0 atm m³/mol
Temp.:
25 °C
Remarks on result:
other: model result
Remarks:
bond contribution method
H:
0 atm m³/mol
Temp.:
25 °C
Remarks on result:
other: model result
Remarks:
group contribution method
H:
0.496 Pa m³/mol
Temp.:
25 °C
Remarks on result:
other: comments
Remarks:
bond contribution method
H:
0.375 Pa m³/mol
Temp.:
25 °C
Remarks on result:
other: comments
Remarks:
group contribution method

 Descriptor values:

Class

Bond contribution description

Value

Hydrogen

11 hydrogen to carbon (aliphatic) bonds

-1.3164

Hydrogen

1 hydrogen to oxygen bonds

3.2318

Fragment

6 C-C

0.6978

Fragment

1 C-O

1.0855

Result

Bond estimation method for LWAPC (Log Water-to-Air Partition Coefficient) value

3.699

 

 

Group contribution description

Value

 

5 CH2 (C)(C)

-0.75

 

1 CH (C)(C)(O)

0.12

 

1 O-H (C)

4.45

Result

Group estimation method for LWAPC (Log Water-to-Air Partition Coefficient) value

3.82

 

 

Conclusions:
QSAR by HENRYWIN v3.20, EPI Suite v4.10: The predicted Henry’s law constant at 25 °C is 0.496 Pa · m3/mole based on the bond contribution methodology. The predicted Henry’s law constant is 0.375 Pa · m3/mole based on the group contribution methodology.
Executive summary:

HENRYWIN v3.20, EPI Suite v4.10 was used: The predicted Henry’s law constant at 25 °C is 0.496 Pa · m3/mole based on the bond contribution methodology. The predicted Henry’s law constant is 0.375 Pa · m3/mole based on the group contribution methodology.

No formal QMRF is currently available for the two methodologies used in the model. The original bond contribution methodology is published in Hine and Mookerjee (1975). The QSAR model has been updated with more data in the training set and expanded since the original publication as described in Meylan and Howard (1991).

The substance falls within the QSAR applicability domain. The prediction is considered reliable as supporting information given further information demonstrating a good prediction for cyclohexanol in the validation set. The prediction for cyclohexanol is considered to be adequate for the purposes of environmental exposure assessment.

Endpoint:
Henry's law constant
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Thermodynamic method
GLP compliance:
no
Specific details on test material used for the study:
cyclohexanol, no further information
Key result
H:
0 dimensionless
Temp.:
25 °C

The dimensionless HLC for the theoretical value is estimated according to:

H = M*pv / ( R*T*Cw)

M is the molecular weight, pv is the vapor pressure; Cw is the aqeous solubility, R is the gas constant, and T is the absolute temperature. pv and Cw are taken from literature.

Conclusions:
Thermodynamic method resulted in a Henry's Law Constant of 1.8 x 10^-4
Executive summary:

Henry's law constant for cyclohexanol was experimentally determined by a thermodynamic method decribed in a publication from S.Brunner et al. (1990). The measured result is 1.8* 10E-4 (dimensionless).

Description of key information

0.446 Pa * m3/mol at 25 °C, thermodynamic method, Altschuh et al. (1999)

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
0.446
at the temperature of:
25 °C

Additional information

Henry´s Law constant as measured by Altschuh et al. (1999), was very low 0.00018 (dimensionless, corresponding to 0.446 Pa * m3 / mol, 25 °C). This is supported by a calculation using SRC HENRYWIN v3.10, resulting in a Henry’s Law Constant of 0.496 Pa * m3 / mol at 25 °C (Wormuth 2017). Cyclohexanol is expected to partially evaporate from the water surface to the atmosphere.