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Vapour pressure

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Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Detailed report, by using the ASTM E1782-03 method
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
other: ASTM E1782-03
Deviations:
no
GLP compliance:
no
Type of method:
other: DSC (differential scanning calorimetry)
Temp.:
20 °C
Vapour pressure:
0 Pa
Key result
Temp.:
25 °C
Vapour pressure:
0 Pa

Measured Temperature (°C)

Pressure (mbars)

Pressure-corrected temperature (°C)

120.09

4

115.53

121.49

7

118.65

123.33

10

121.23

130.33 drift of the signal
(decomposition)

13

128.65 (drift of the signal –
decomposition)

Decomposition detected

18

Decomposition detected

 

 

Data treatment to establish Clausius-Clapeyron relationship leads to the following data.

Pression P
(Bar)

Ln(P)

Onset Temperature (°C)

Pressure-corrected temperature (°C)

T (K)

-1/T

0.004

-5.52146092

120.09

115.53

388.53

-0.00257384

0.007

-4.96184513

121.49

118.65

391.65

-0.00255329

0.010

-4.60517019

123.33

121.23

394.23

-0.00253657

 

The Clausius-Clapeyron equation resulting is:

y = 24685x + 58.029 (correlation coefficient R2= 0.9954)

with y= ln(P)

x= -1/T

 

Extrapolated data – with high uncertainty- at 20°C and 25°C are :

-Pressure vapour at 20°C is determined to 4 10-9mbars ;

-Pressure vapour at 25°C is determined to 1.7 10-8mbars.

Conclusions:
The vapour pressure of the substance is determined to be close to 0.000001Pa at 25°C .
With DSC method, the impurities more volatile than the substance are evaporated, and thus, will not affect the vapour pressure determination.
Executive summary:

A detailed study report on the measurement of vapour pressures according to ASTM E-1782 -03 is available. The relationship between vapour pressure and temperature was established with the Clausius-Clapeyron equation.

With this method, the volatile impurities do not have an effect on the vapour pressure determination

The vapour pressure of OO-tert-butyl O-(2-ethylhexyl) peroxycarbonate is determined to be close to 10-8 mbars at 25°C. However, this value may be underestimated due to decomposition that occured during the testing. Thus, a calculated value (with EPISUITE) was needed to confirm that the substance has a low vapour pressure and a very low fugacity.

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study, with detailed report
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
no
Type of method:
static method
Temp.:
20 °C
Vapour pressure:
13.6 mBar
Key result
Temp.:
25 °C
Vapour pressure:
16.9 mBar

Temperature (°C) Pressure (mbar)
18,5 12,4
19,8 13,4
21,1 14,4
23,1 15,6
24,1 16,6
26,1 18
27,1 18,7
28,7 19,9
30,6 21,4
33,3 23,5

The Clausius-Clapeyron equation resulting is:

Ln (P[mbar]) = 3,8487 *(-1000/T[K]) + 15,744 (correlation coefficient R2=0,9957)

Extrapolated data at 20°C and 25°C are :

- pressure vapour at 20°C is determined to 13.6 mbar s ;

- pressure vapour at 25°C is determined to 16.9 mbar s.

Conclusions:
The vapour pressure of the test material is determined to be 16.9 mbars, or 1690 Pa, at 25°C.
The test material contains volatile impurity (tert-butyl hydroperoxide) that may have affected the vapour pressure determination (small amounts of volatile impurities may increase the vapour pressure by several orders of magnitude)
Executive summary:

A guideline and well detailed study is available. The vapour pressure of the substance was measured using the static method. The relationship between vapour pressure and temperature was established with the Clausius-Clapeyron equation.

The vapour pressure of the test material is determined to be 16.9 mbars, or 1690 Pa, at 25°C. The presence of volatile impuritiy (tert-butyl hydroperoxide, with vapour pressure ~50hPa) may have increased the vapour pressure.

Endpoint:
vapour pressure
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Accepted calculation method
Principles of method if other than guideline:
Method: estimated by calculation with MPBPWIN v1.43
GLP compliance:
no
Type of method:
other:
Key result
Temp.:
25 °C
Vapour pressure:
0.57 Pa

CAS Number: 34443-12-4

SMILES : CCCCC(CC)COC(=O)OOC(C)(C)C

CHEM  : OO-tert-butyl O-(2-ethylhexyl) peroxycarbonate

MOL FOR: C13 H26 O4

MOL WT : 246.35

 

Vapor Pressure Estimations (MPBPVP v1.43):

   VP(mm Hg,25 deg C): 0.00431 (Modified Grain method)

   VP (Pa, 25 deg C) : 0.574 (Modified Grain method)

Conclusions:
The vapour pressure of OO-tert-butyl O-(2-ethylhexyl) peroxycarbonate was estimated with EPISUITE Software (MPBPWIN v1.43). The vapour pressure value is 0.57 Pa at 25°C.
Executive summary:

In order to confirm the data determined by DSC method, the vapour pressure was estimated with EPISUITE software.

The calculated data confirms the substance has a low vapour pressure, and thus a very low potential of fugacity.

Description of key information

The vapour pressure of the substance is <1 Pa at 25 °C (using DSC method, in order to limit the effect of volatile impurities on the vapour pressure determination; in line with calculated value).

Key value for chemical safety assessment

Vapour pressure:
1 Pa
at the temperature of:
25 °C

Additional information

Well detailed studies are available.

The vapour pressure was firstly determined with static method. The vapour pressure was determined to be 16,9hPa at 25°C, but the presence of a volatile impurity (tert-butyl hydroperoxide, vapour pressure ~50hPa) may have affected the vapour pressure determination (small amounts of volatile impurities may increase the vapour pressure by several orders of magnitude).

The DSC method was then used, and the vapour pressure was determined to be 0.000001 Pa at 25°C (more representative of the substance as impurities more volatile than the substance are evaporated). The vapour pressure determined by DSC may be understimated, due to decomposition that occured during the test.

In both methods, the relationship between vapour pressure and temperature was fitted with the Clausius-Clapeyron equation.

In order to confirm the very low potential of fugacity of OO-tert-butyl O-(2-ethylhexyl) peroxycarbonate, EPISUITE was used to calculate the vapour pressure. The result confirms that the vapour pressure of the substance is very low, and that can be reasonably considered <1Pa. For the risk assessment, the value of 1Pa was considered, as it represents a worst-case.