Isobutyraldehyde

Henry's Law constant

Link to relevant study record(s)

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 valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

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): Propanal, 2-methyl-
- SMILES: O=CC(C)C

Key result

H:

12.1 Pa m³/mol

Temp.:

25 °C

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

CLASS	BOND CONTRIBUTION DESCRIPTION		COMMENT	VALUE
HYDROGEN	7	Hydrogen to Carbon (aliphatic) Bonds		-0.8377
HYDROGEN	1	Hydrogen to Carbonyl (C=O) Bonds		1.2103
FRAGMENT	2	C-C		0.2326
FRAGMENT	1	C-CO		1.7057
RESULT		Hydrogen to Carbon (aliphatic) Bonds		-0.8377
HENRYs LAW CONSTANT at 25 °C				1.20E-04 atm·m3/mole
				4.89E-03 unitless
				1.21E+01 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 (72.11 g/mol)
		2) Maximum number of instances of bond in any of the training set compounds (On-Line HENRYWIN User’s Guide, Appendix D)	Not 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*m^3/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:

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	7
CO-H	1.210289	25	1	Hydrogen bond	1
C-C	0.116304	200	9		2
C-CO	1.70572	41	2		1

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

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

Not applicable

 

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

Henry's Law constant is estimated to be 12.1 Pa·m³/mole at 25 °C by means of QSAR (EPISuite module EPIWIN v4.11 (2012)).

Substances with a Henry's Law constant of <100 Pa·m³/mole will not evaporate into the atmosphere from the water surface.

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. 

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 isobutyraldehyde (Q)SAR results were used for the 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.