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Henry's Law constant

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Endpoint:
Henry's law constant
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
The number of carbon-oxygen bonds was exceeded by two (maximum number per structure: 4). Therefore, the estimation might be less accurate.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Calculation using HENRYWIN (v3.20) Bond Method
GLP compliance:
no
Specific details on test material used for the study:
- Substance name (as in EPISuite CAS inventory): Ethanol, 2,2 -[1,2-ethanediylbis(oxy)]bis-
- SMILES: O(CCOCCO)CCO
H:
0 Pa m³/mol
Temp.:
25 °C

Result table for Bond Contribution Method from HENRYWIN v3.20:

CLASS

BOND CONTRIBUTION DESCRIPTION

COMMENT

VALUE

HYDROGEN

12

Hydrogen to Carbon (aliphatic) Bonds

 

-1.4361

HYDROGEN

2

Hydrogen to Oxygen Bonds

 

6.4635

FRAGMENT

3

C-C

 

0.3489

FRAGMENT

6

C-O

 

6.5128

FACTOR

1

Additional aliphatic alcohol -OH(s)

 

-3.0000

RESULT

 

Bond estimation method for LWAPC value

 

8.889

 

HENRYs LAW CONSTANT at 25 °C

3.16E-011 atm·m3/mole

1.29E-009 unitless

3.20E-006 Pa·m3/mole

Executive summary:

QPRF: HENRYWIN v3.20: Bond contribution method

1.

Substance

See “Test material identity”

2.

General information

 

2.1

Date of QPRF

See “Data Source (Reference)”

2.2

QPRF author and contact details

See “Data Source (Reference)”

3.

Prediction

3.1

Endpoint
(OECD Principle 1)

Endpoint

Degree of volatilisation of substances from the aquatic environment

Dependent variable

Henry’s Law Constant

3.2

Algorithm
(OECD Principle 2)

Model or submodel name

HENRYWIN: Bond contribution method

Model version

v. 3.20

Reference to QMRF

Henry’s Law constant (HLC) using HENRYWIN v3.2: Estimation Accuracy (QMRF)

Predicted value (model result)

See “Results and discussion: Henry’s Law constant H”

Input for prediction

Chemical structure via CAS number or SMILES

Descriptor values

- Bond contribution values

- Correction factors

3.3

Applicability domain
(OECD principle 3)

Domains:

1) Molecular weight (range of test data set: 26.04 to 451.47 g/mol, mean: 144.64 g/mol) (On-Line HENRYWIN User’s Guide, Ch. 7.4 Estimation Domain and Appendix G)

Substance within range (150.18 g/mol)

2) Maximum number of instances of bond in any of the training set compounds (On-Line HENRYWIN User’s Guide, Appendix D)

Exceeded

3) Maximum number of instances of correction factor in any of the training set compounds (On-Line HENRYWIN User’s Guide, Appendix E)

Not exceeded

3.4

The uncertainty of the prediction
(OECD principle 4)

According to REACH Guidance Document R.7a, Appendix R.7.1-1 (Nov. 2012), measurement of HLC is not highly accurate, especially for very high or very low HLC values. The bond contribution method regarded by Altschuh et al. (1999) to produce the most reliable results with the exception of organochlorine pesticides. However, for some compounds, the method can yield a Henry's Law constant of 1.0x10-12atm*m3/mol or smaller. Numbers which are smaller than this value may be unrealistically low.

3.5

The chemical mechanisms according to the model underpinning the predicted result
(OECD principle 5)

The compound is split into a summation of individual bonds which comprise the compound. The summation of these bonds (= bond contribution values) is set equal to LWPAC. Correction factors were developed to correct for polar interactions and other deviations from the regression curve, which are applied to members of some chemical classes.

References:

Altschuh, J.R., Bruggemann, H. Santl, G. Eichinger, and O.G. Piringer.1999. Henry’s law constants for a diverse set of organic chemicals: experimental determination and comparison of estimation methods. Chemosphere 39: 1871-87.

Identified number of bonds and correction factors for the current substance:

HLC Appendix D, Table D-1: Bond Contribution Values Derived by Least-Square Regression Analysis

Bond

Coefficient
Value

No. Compounds
 in Training Set
containing
the Bond

Maximum No.
of instances of
each Bond
occurring in any
single compound

Comment

No. of instances
of each bond
found for the
current substance

C-H

-0.119677

284

27

Hydrogen bond

12

O-H

3.23177

42

3

Hydrogen bond

2

C-C

0.116304

200

9

 

3

C-O

1.085473

83

4

 

6

HLC Appendix D, Table D-2: Bond Contribution Values from a Subsequent Regression

Not applicable

 

HLC Appendix D, Table D-3: Additional Bond Contribution Values Used HENRYWIN

Not applicable

 

HLC Appendix E, Table E-1: Bond Correction Factors Derived from the Original Regression

Bond Correction Factor

Coefficient
Value

No. Compounds
in Training Set
containing
the Factor

Maximum No.
of instances of
each Factor
occurring in any
single compound

Comments

No. of instances
of each factor
found for the
current substance

Each additional aliphatic alcohol function (-OH) above one

-3.00

2

1

 

1

 

HLC Appendix E, Table E-2: Bond Correction Factors Derived from the Second Regression

Not applicable

 

HLC Appendix E, Table E-3: Bond Correction Factors Derived Individually

Not applicable

Endpoint:
Henry's law constant
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
The number of carbon-oxygen bonds was exceeded by four (maximum number per structure: 4). Therefore, the estimation might be less accurate.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Calculation using HENRYWIN (v3.20) Bond Method
GLP compliance:
no
Specific details on test material used for the study:
- Substance name (as in EPISuite CAS inventory): Ethanol, 2,2 -[oxybis(2,1-ethanediyloxy)]bis-
- SMILES: OCCOCCOCCOCCO
Key result
H:
0 Pa m³/mol
Temp.:
25 °C

Result table for Bond Contribution Method from HENRYWIN v3.20:

CLASS

BOND CONTRIBUTION DESCRIPTION

COMMENT

VALUE

HYDROGEN

16

Hydrogen to Carbon (aliphatic) Bonds

 

-1.9148

HYDROGEN

2

Hydrogen to Oxygen Bonds

 

6.4635

FRAGMENT

4

C-C

 

0.4652

FRAGMENT

8

C-O

 

8.6838

FACTOR

1

Additional aliphatic alcohol -OH(s)

 

-3.0000

RESULT

 

Bond estimation method for LWAPC value

 

10.698

 

HENRYs LAW CONSTANT at 25 °C

4.91E-013 atm-m3/mole

2.01E-011 unitless

4.97E-008 Pa-m3/mole

Executive summary:

QPRF: HENRYWIN v3.20: Bond contribution method

1.

Substance

See “Test material identity”

2.

General information

 

2.1

Date of QPRF

See “Data Source (Reference)”

2.2

QPRF author and contact details

See “Data Source (Reference)”

3.

Prediction

3.1

Endpoint
(OECD Principle 1)

Endpoint

Degree of volatilisation of substances from the aquatic environment

Dependent variable

Henry’s Law Constant

3.2

Algorithm
(OECD Principle 2)

Model or submodel name

HENRYWIN: Bond contribution method

Model version

v. 3.20

Reference to QMRF

Henry’s Law constant (HLC) using HENRYWIN v3.2: Estimation Accuracy (QMRF)

Predicted value (model result)

See “Results and discussion: Henry’s Law constant H”

Input for prediction

Chemical structure via CAS number or SMILES

Descriptor values

- Bond contribution values

- Correction factors

3.3

Applicability domain
(OECD principle 3)

Domains:

1) Molecular weight (range of test data set: 26.04 to 451.47 g/mol, mean: 144.64 g/mol) (On-Line HENRYWIN User’s Guide, Ch. 7.4 Estimation Domain and Appendix G)

Substance within range (194.23 g/mol)

2) Maximum number of instances of bond in any of the training set compounds (On-Line HENRYWIN User’s Guide, Appendix D)

Exceeded

3) Maximum number of instances of correction factor in any of the training set compounds (On-Line HENRYWIN User’s Guide, Appendix E)

Not exceeded

3.4

The uncertainty of the prediction
(OECD principle 4)

According to REACH Guidance Document R.7a, Appendix R.7.1-1 (Nov. 2012), measurement of HLC is not highly accurate, especially for very high or very low HLC values. The bond contribution method regarded by Altschuh et al. (1999) to produce the most reliable results with the exception of organochlorine pesticides. However, for some compounds, the method can yield a Henry's Law constant of 1.0x10-12atm*m3/mol or smaller. Numbers which are smaller than this value may be unrealistically low.

3.5

The chemical mechanisms according to the model underpinning the predicted result
(OECD principle 5)

The compound is split into a summation of individual bonds which comprise the compound. The summation of these bonds (= bond contribution values) is set equal to LWPAC. Correction factors were developed to correct for polar interactions and other deviations from the regression curve, which are applied to members of some chemical classes.

References:

Altschuh, J.R., Bruggemann, H. Santl, G. Eichinger, and O.G. Piringer.1999. Henry’s law constants for a diverse set of organic chemicals: experimental determination and comparison of estimation methods. Chemosphere 39: 1871-87.

Identified number of bonds and correction factors for the current substance:

 

HLC Appendix D, Table D-1: Bond Contribution Values Derived by Least-Square Regression Analysis

Bond

Coefficient
Value

No. Compounds
 in Training Set
containing
the Bond

Maximum No.
of instances of
each Bond
occurring in any
single compound

Comment

No. of instances
of each bond
found for the
current substance

C-H

-0.119677

284

27

Hydrogen bond

16

O-H

3.23177

42

3

Hydrogen bond

2

C-C

0.116304

200

9

 

4

C-O

1.085473

83

4

 

8

 

HLC Appendix D, Table D-2: Bond Contribution Values from a Subsequent Regression

Not applicable

 

HLC Appendix D, Table D-3: Additional Bond Contribution Values Used HENRYWIN

Not applicable

 

HLC Appendix E, Table E-1: Bond Correction Factors Derived from the Original Regression

Bond Correction Factor

Coefficient
Value

No. Compounds
in Training Set
containing
the Factor

Maximum No.
of instances of
each Factor
occurring in any
single compound

Comments

No. of instances
of each factor
found for the
current substance

Each additional aliphatic alcohol function (-OH) above one

-3.00

2

1

 

1

 

HLC Appendix E, Table E-2: Bond Correction Factors Derived from the Second Regression

Not applicable

 

HLC Appendix E, Table E-3: Bond Correction Factors Derived Individually

Not applicable

Description of key information

For CAS 112-27-6, the Henry's Law constant is calculated to be 3.20E-006 Pa·m³/mole based on the Bond method. For CAS 112-60-7, the Henry's Law constant is calculated to be 4.97E-008 Pa·m³/mole based on the Bond method. Substances with a Henry's Law constant of <100 Pa·m³/mole will not evaporate into the atmosphere from the water surface.

Key value for chemical safety assessment

Additional information

QSAR-disclaimer

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met. Furthermore according to Article 25 of the same Regulation testing on vertebrate animals shall be undertaken only as a last resort.

 

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

 

For the assessment of Reaction mass of 2,2'-(Ethylenedioxy)diethanol and 3,6,9-Trioxaundecane-1,11-diol, (Q)SAR results of its main constituents were used for Henry's Law constant. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment. Although the substances (CAS 112-27-6 and CAS 112-60-7) did not fall entirely within the applicability domain of this QSAR, the additional carbon-oxygen bond is not expected to have significantly influenced the calculation.