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Physical & Chemical properties

Vapour pressure

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Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Sep 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Cross-referenceopen allclose all
Reason / purpose:
reference to other study
Reference
Endpoint:
vapour pressure
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
Justification for type of information:
1. SOFTWARE
ARChem SPARC. version 4.6

2. MODEL
Properties - Vapor Pressure

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables".

5. APPLICABILITY DOMAIN
See information provided in "Any other information of materials and methods incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
Calculation based on SPARC version v4.6, "Properties" calculation type

- Software tool(s) used including version: SPARC v4.6
- Model(s) used: Properties - Vapor Pressure (Pa)
The model utilizes a conventional LFER (Linear Free Energy Relationships), SAR (Structure Activity Relationships) and PMO (Perturbed Molecular Orbital) theory. For the complete method's description see field 'Any other information on materials and methods incl. tables'.
The datasets used for the model development (315 molecules) and for the external validation (747 molecules) are described in the field 'Any other information on materials and methods incl. tables'.
- Model description: see field 'Any other information on materials and methods incl. tables'.
- Justification of QSAR prediction: see field 'Justification for type of information' and 'overall remarks'.
GLP compliance:
no
Type of method:
other: QSAR
Temp.:
20 °C
Vapour pressure:
0 Pa

QSAR result; transition/decomposition is not specified/reported. For detailed description of the model and its applicability, see "Any other information on materials and methods incl. tables".

Reason / purpose:
reference to other study
Reference
Endpoint:
vapour pressure
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
Justification for type of information:
1. SOFTWARE
EPI Suite version 4.11

2. MODEL (incl. version number)
Mpbpwin v. 1.43

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: EPI Suite v4.11
- Model(s) used: Mpbpwin Model version 1.43
The model estimates vapour pressure by three different methods:
- the Antoine equation (Lyman WJ, Reehl WF and Rosenblatt DH. 1990. Handbook of Chemical Property Estimation Methods. Washington, DC: American Chemical Society);
- the Modified Grain Method (Lyman WJ. 1985. In: Environmental Exposure From Chemicals. Volume I. Neely WB and Blau GE (eds). Boca Raton, FL: CRC Press, Inc., Chapter 2);
- the Mackay Method (Lyman WJ. 1985. In: Environmental Exposure From Chemicals. Volume I. Neely WB and Blau GE (eds). Boca Raton, FL: CRC Press, Inc.).
MPBPWIN selects a “suggested” vapour pressure: the modified Grain for solids and the average of the Antoine and the modified Grain for liquids and gases.
A dataset of 3037 compounds with experimentally determined vapour pressure values has been used to evaluate the model (using the “suggested” values as outcome), giving a correlation coefficient of 0.914. The evaluation clearly shows that the model reliability decrease for vapour pressure below 0.0001 Pa.
The dataset contains 1642 compounds with available experimental Boiling points and Melting points. The correlation coefficient evaluated on this subset (0.949) indicates that VP estimates are more accurate when experimental BP and MP are available.

- Model description: see field 'Justification for type of information', 'Attached justification' and 'any other information on Material and methods'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'
GLP compliance:
no
Type of method:
other: QSAR
Temp.:
25 °C
Vapour pressure:
0.001 Pa
Remarks on result:
other: Modified Grain method

QSAR result; transition/decomposition is not specified/reported. For detailed description of the model and its applicability, see "Any other information on materials and methods incl. tables”

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report Date:
2019

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The vapour pressure was determined by extrapolation using the Clausius-Clapeyron formula.
Vapour pressure at different temperatures were measured using a distillation method according to BS4591, Method A.2 Boiling Temperature of Commission Regulation (EC) No 440/2008 of 30 May 2008 and in accordance with Method 103 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.
GLP compliance:
no
Type of method:
other: distillation method, associated with pressure measurement.

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Vapour pressure
Key result
Temp.:
20 °C
Vapour pressure:
1 Pa

Any other information on results incl. tables

The results are shown in the following table:

 

Observed vapor pressure

Test 1

48 Pa (352.45 K)

Test 2

80 Pa (361.35 K)

Test 3

108 Pa (368.15 K)

 

By the least-squares method fitting, the values of Clausius-Clapeyron formula were obtained:

 

Log10 P = -2926.3 * (1/(t+273.15)) + 9.989

(R² = 0.9965)

 

P: vapor pressure (Pa)

t: temperature (°C)

 

By the formula, the extrapolated vapor pressure at 20 °C is 1 Pa.

Applicant's summary and conclusion

Conclusions:
The vapour pressure of the substance has been determined to be 1 Pa at 20 °C.
Executive summary:

The vapour pressure of the test material has been determined to be 48 Pa at 352.45 K, 80 Pa at 361.35 K, 108 Pa at 368.15 K.

The extrapolated vapor pressure at 20 °C is 1 Pa.

 

The following QSAR-estimated vapour pressure values are taken as supporting information for the low vapour pressure of the substance.

- VP = 5.81E-5 Pa at 20 °C (ARChem SPARC v4.6)

- VP = 8.17E-4 Pa at 25 °C (EPI Suite v4.11 / Mpbpwin Model v1.43 - Modified Grain Method)