Dimethoxydimethylsilane

Vapour pressure

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10-Oct-2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Version / remarks:

1.5.2 Static method

GLP compliance:

no

Other quality assurance:

ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)

Type of method:

static method

Temp.:

20 °C

Vapour pressure:

86.6 hPa

Temp.:

40 °C

Vapour pressure:

205 hPa

Results

 

Raw data

Data point	Time [min]*	Temperature T [°C]	Vapor pressure p [hPa]
1	15	20	86.0
2	20	25	109.0
3	20	30	136.3
4	20	40	204.4

*  Time for equilibration

 

Conversion of Raw Data

Data point	T [K]	1fT [1/K]	log p [hPa]
1	293.15	0.003411	1.93450
2	298.15	0.003354	2.03743
3	303.15	0.003299	2.13450
4	313.15	0.003193	2.31048

 

Results from Calculation

Estimated vapour pressure	Temperature
86.6 hPa	20°C
205 hPa	40°C

The estimated value is calculated using the formula of regression

 

Formula of regression: log p [hPa] = -1722.81 1/T [1/K] = 7.81418

Conclusions:

Vapour pressure values of 86.6 hPa at 20 °C and 205 hPa at 40 °C was determined in a reliable study conducted according to an appropriate test protocol.

Reference 2

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

2018

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 v4.11 (June 2017) Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11 (June 2017). US EPA, United States Environmental Protection Agency, Washington, DC, USA.

2. MODEL (incl. version number)
Mpbpwin v. 1.44

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

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 (June 2017)
- Model(s) used: Mpbpwin Model version 1.44
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.
In the updated version from June 2017, more data for organosilicon compounds have been included. A subset of 149 organosilicon substances is present in the current version of Mpbpwin (v1.44). The correlation coefficient evaluated on this subset is 0.952, which is a significant improvement in estimation accuracy, compared to the correlation coefficient calculated on the same subset with the previous version of the model (r2 = 0.742, v. 1.43).

- 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:

10 700 Pa

Remarks on result:

other: Mean of Antoine and 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"

Conclusions:

A vapour pressure 10700 Pa at 25 °C was obtained for the substance using an appropriate calculation method. The result is considered to be reliable.

Description of key information

86.6 hPa at 20°C, 205 hPa at 40°C (OECD 104, vapour pressure curve, static method)

 

 

Key value for chemical safety assessment

Vapour pressure:

86.6 hPa

at the temperature of:

20 °C

Additional information

The key study is supported by a value of 74.0 hPa at 25°C determined using an appropriate calculation method (QSAR). The higher value determined for the measured result may due to residual amounts of (more volatile) solvent.