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Physical & Chemical properties

Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30 March - 14 April, 2022
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
effusion method: Knudsen cell
Test no.:
#1
Temp.:
20 °C
Vapour pressure:
0.02 Pa
Test no.:
#2
Temp.:
25 °C
Vapour pressure:
0.04 Pa

First trial

 Mass loss (mg)  Mass loss duration (s)  Vapour pressure (Pa)  Temperature (K)  1/T (K-1) log10 (p) 
 0.061  600  0.5190  320.25  3.123 x 10-3  -0.2849
0.097  600  0.8297  323.75  3.089 x 10-3  -0.0811
 0.322  600  2.7995  334.45  2.990 x 10-3  -0.4471
 1.034  600  9.1349  345.35  2.896 x 10-3  0.9607
 3.115  600  27.9702  356.75  2.803 x 10-3  1.4467

A plot of Log10 (p) versus reciprocal temperature (1/T) (with p in Pa and T in K) gives the following statistical data using an unweighted least square treatment.

Slope -5404.6

Intercept 16.603

R² 0.9998

The results obtained indicate the following vapour pressure relationship:

Log10 (p (Pa)) = -5404.6/ T (K) + 16.603

Second trial

 Mass loss (mg)  Mass loss duration (s)  Vapour pressure (Pa)  Temperature (K)  1/T (K-1) log10 (p) 
 0.075  600  0.6371  319.25  3.132 x 10-3  -0.1958
0.109  600  0.9306  322.55  3.100 x 10-3  -0.0312
 0.339  600  2.9398  332.75  3.005 x 10-3  -0.4683
 1.049  600  9.2406  343.35  2.912 x 10-3  0.9657
 3.165  600  28.3314  354.55  2.820 x 10-3  1.4523

A plot of Log10 (p) versus reciprocal temperature (1/T) (with p in Pa and T in K) gives the following statistical data using an unweighted least square treatment.

Slope -5292.9

Intercept 16.380

R² 1.0000

The results obtained indicate the following vapour pressure relationship:

Log10 (p (Pa)) = -5292.9 / T (K) + 16.380

Third trial

 Mass loss (mg)  Mass loss duration (s)  Vapour pressure (Pa)  Temperature (K)  1/T (K-1) log10 (p) 
 0.066  600  0.5603  318.85  3.136 x 10-3  -0.2516
0.106  600  0.9045  322.15  3.104 x 10-3  -0.0436
 0.341  600  2.9544  332.15  3.011 x 10-3  -0.4705
 1.088  600  9.5757  342.75  2.918 x 10-3  0.9812
 3.236  600  28.9383  353.85  2.826 x 10-3  1.4615

A plot of Log10 (p) versus reciprocal temperature (1/T) (with p in Pa and T in K) gives the following statistical data using an unweighted least square treatment.

Slope -5499.6

Intercept 17.016

R² 0.9995

The results obtained indicate the following vapour pressure relationship:

Log10 (p (Pa)) = -5499.6 / T (K) + 17.016

Summary of results

 Trial  Vapour pressure at 293.15 K (Pa) Vapour pressure at 298.15 K (Pa)
 1 NP  1.47 x 10 -2   2.99 x 10-2
2 NP  2.11 x 10 -2   4.24 x 10-2
3 NP  1.80 x 10 -2   3.72 x 10-2
Mean from trials 2 NP and 3 NP  1.96 x 10 -2  3.98 x 10-2

The test item did not change in appearance under the conditions used in the determination.

 Mass loss duration (s)  Vapour pressure (Pa)  Temperature (K)  1/T (K-1) log10 (p) 
 0.066  600  0.5603  318.85  3.136 x 10-3  -0.2516
0.106  600  0.9045  322.15  3.104 x 10-3  -0.0436
 0.341  600  2.9544  332.15  3.011x 10-3  -0.4705
 1.088  600  9.5757  342.75  2.918 x 10-3  0.9812
 3.236  600  28.9383  353.85  2.826 x 10-3  1.4615
Executive summary:

A study was performed to determine the vapour pressure of the test item N,N-dimethyl dodec-9-enamide. The method followed was designed to be compliant with the OECD guideline for the Testing of Chemicals No. 104, "Vapour pressure" (2006), 23 March 2006 and Commission Regulation No 440/2008 on test methods, Method A.4 (2009 version). As the test item prediction (EPIWEB predictions) for vapour pressure is 0.0237 Pa at 25°C (Modified Grain Method), the Knudsen effusion method was conducted.

In this method, the mass of the test substance flowing out per unit of time of a Knudsen cell in the form of vapour, through a micro-orifice under ultra-vacuum conditions was determined at various specified temperatures (from 23.7°C to 48.9°C). However, the mass loss observed was of the same order of magnitude as the baseline mass variation. Therefore, other tests with higher temperatures were performed. With these new tests, temperature was varied between 45.7°C and 83.6°C. The Hertz-Knudsen equation was used to calculate the vapour pressure corresponding to the mass loss rate.

The Log10 (Vapour Pressure (Pa)) was plotted against 1/T (K) and a linear function was obtained. With this equation, the vapour pressure has been calculated for temperatures of 20°C and 25°C.

Three trials were conducted and five points were recorded for each trial. Log10 (Vapour Pressure (Pa)) was plotted against reciprocal temperature and values of vapour pressure were calculated at 20°C and 25°C. Calculated values from the second and third trials respect validity criteria (less than 20% of difference) and the linear functions obtained gave a correlation coefficient R² over 0.95.

In conclusion, the vapour pressure of N,N-dimethyl dodec-9-enamide is 1.96x10-2 Pa at 20°C and 3.98x10-2 Pa at 25°C.

Description of key information

The vapour pressure was determined to be 1.96x10-2 Pa at 20°C and 3.98x10-2 Pa at 25°C in a study performed according to OECD TG 104 and EU Method A.4 using the the Knudsen effusion method.

Key value for chemical safety assessment

Vapour pressure:
0.02 Pa
at the temperature of:
20 °C

Additional information