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Henry's Law constant

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Reference
Endpoint:
Henry's law constant
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source
Justification for type of information:
US EPA. [2011]. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11 or insert version used]. United States Environmental Protection Agency, Washington, DC, USA. From
HENRYWIN v3.20 model: Bond method, Group method.
Calculations done with structures having different branching (number of terminal CH3), possible constituents of the substance.
See report.
Qualifier:
according to
Guideline:
other: HENRYWIN v3.20 model: Bond method, Group method.
Principles of method if other than guideline:
Applicability domain: not applicable to components with heavy substituents (C12-15). Therefore, only C9 estimates are shown.
H:
> 0.079 atm m³/mol
Remarks on result:
other: Group method, covering all components but exact upper value can not be indicated: it increases along substituent size and heaviest substituents are outside applicability domain

Influence of substituent weight and branching on HLC (atm.m3/mole) according to Bond and Group methods (HENRYWIN (v3.20)

Substituent

Weight (number of C)

9

12

14

Branching (number of terminal CH3)

3

0.057, 0.14

NA

NA

4

0.057, 0.079-0.14

0.13, 0.49

0.24, 0.97

5

NA

0.13, 0.27-0.48

0.24, 0.54-0.95

6

NA

0.13, 0.32

0.24, 0.64

NA : unlikely structure     Gray : less reliable value (outside the model’s applicability domain)

 

Influence of substituent weight on HLC estimates (according to Bond, Group and Water solubility + Log Kow methods) and experimental values for C10 linear substituent

Estimation method

Bond

Group

HLC (atm.m3/mol)

Experimental

0.153

Estimate

0.076

0.14

Bias

0.5x

0.9x

 

Based on this, the best estimates, to be retained, are those of the Group method. The good agreement suggests that no correction is necessary.

The HLC range (atm.m3/mol) retained for BAB is therefore: 0.079 to X.10-1(all BAB components).

Conclusions:
The final value of H for BAB is between 0.079 and X.10-1. As this H is greater than 10-3 atm.m3/mol, half of the substance is lost from a water phase-in a few (less than 3) hours by volatilisation.
Volatilisation is significant.
Executive summary:

A range of Henry's Law constant (H) has been estimated with HENRYWIN (atm.m3/mole) for C9 substituent according to bond method: H=0.057 and group method: H=0.079-0.14.

The validation with experimental data (in EPIsuite database) for linear decylbenzene gave experimental H= 0.153, according to bond method:=0.076 and to group method: H=0.14.

Therefore the Group method is more accurate and final value for BAB is: 7.9 10-2 to X.10-1 (covering all components but exact upper value can not be indicated: it increases along substituent size and heaviest substituents are outside applicability domain)

Description of key information

A range of Henry's Law constant (H) has been estimated with HENRYWIN (atm.m3/mole) for C9 substituent according to bond method: H=0.057 and group method: H=0.079-0.14.

The validation with experimental data (in EPIsuite database) for linear decylbenzene gave experimental H= 0.153, according to bond method:=0.076 and to group method: H=0.14.

Therefore the Group method is more accurate and final value for BAB is: 7.9 10-2 to X.10-1 (covering all components but exact upper value can not be indicated: it increases along substituent size and heaviest substituents are outside applicability domain)

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):
8 004
at the temperature of:
20 °C

Additional information