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Vapour pressure

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Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: full report not available
Principles of method if other than guideline:
Principle and procedure of the measurement:

An amount of sample is weighed into a small cup (70 micro litre) with a pierced lid. This cup is placed on one of the two measurement-spots on the delta_T -sensor in the DSC oven. Next to this cup, an empty reference cup with the same net weight is placed.
During heating the DSC oven, the temperature difference between the sample cup and the (empty) reference cup is measured. The heat flow to the sample is proportional to this temperature difference.
The experiment starts when the heater of the oven is activated. A linear heating rate (5 °C/minute) is applied. The pressure is kept constant during the entire experiment. After starting the oven heating the reference cup will heat up faster than the sample cup because the sample has to be heated too.
After a short period the temperature difference between the cups will be constant. This will continue till a physical or a chemical effect occurs in the sample cup.
At the boiling point of the sample, the sample temperature will level off. So, the temperature difference will increase. At the end of the boiling effect, the sample cup is also empty. The temperature difference between the empty sample cup and the oven will be larger than the temperature difference between the reference cup and the oven. At the moment at which the sample is evaporated completely, the sample cup temperature will be heated up rapidly till it reaches the T-level of the reference cup. During the evaporation the pressure in the oven is controlled at a constant value, by removing the sample vapour.
When this process is completed, the graph q(heat flow) versus temperature has shown a peak. The boiling peak at the pre-set pressure is measured. The onset temperature of the peak represents the boiling point. The controlled (applied) pressure then, is equal to the vapour pressure of the sample.
Correction factors are used to construct the real sample temperature plot.
Finally, the curve 10log p (p: mbara) versus T(K) is constructed. Extrapolated data can be calculated.





GLP compliance:
no
Type of method:
other: DSC at reduced pressure
Temp.:
25 °C
Vapour pressure:
ca. 33 mBar
Remarks on result:
other: Data is obtained by extrapolation of the measured values.
Conclusions:
The vapour pressure of di-tert-butyl peroxide is 33 mBar at 25°C
Executive summary:

The original report is not found.

So details are missing in this overview.

The vapour pressure of di-tert-butyl peroxide is 33 mBar at 25°C

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: no GLP
Reason / purpose for cross-reference:
reference to same study
Qualifier:
no guideline followed
Principles of method if other than guideline:
Principle and procedure of the measurement:

An amount of sample is weighed into a small cup (70 micro litre) with a pierced lid. This cup is placed on one of the two measurement-spots on the delta_T -sensor in the DSC oven. Next to this cup, an empty reference cup with the same net weight is placed.
During heating the DSC oven, the temperature difference between the sample cup and the (empty) reference cup is measured. The heat flow to the sample is proportional to this temperature difference.
The experiment starts when the heater of the oven is activated. A linear heating rate (5 °C/minute) is applied. The pressure is kept constant during the entire experiment. After starting the oven heating the reference cup will heat up faster than the sample cup because the sample has to be heated too.
After a short period the temperature difference between the cups will be constant. This will continue till a physical or a chemical effect occurs in the sample cup.
At the boiling point of the sample, the sample temperature will level off. So, the temperature difference will increase. At the end of the boiling effect, the sample cup is also empty. The temperature difference between the empty sample cup and the oven will be larger than the temperature difference between the reference cup and the oven. At the moment at which the sample is evaporated completely, the sample cup temperature will be heated up rapidly till it reaches the T-level of the reference cup. During the evaporation the pressure in the oven is controlled at a constant value, by removing the sample vapour.
When this process is completed, the graph q(heat flow) versus temperature has shown a peak. The boiling peak at the pre-set pressure is measured. The onset temperature of the peak represents the boiling point. The controlled (applied) pressure then, is equal to the vapour pressure of the sample.
Correction factors are used to construct the real sample temperature plot.
Finally, the curve 10log p (p: mbara) versus T(K) is constructed. Extrapolated data can be calculated.





GLP compliance:
no
Type of method:
other: DSC at reduced pressure
Temp.:
25 °C
Vapour pressure:
29 mBar
Temp.:
20 °C
Vapour pressure:
21 mBar

Vacuum DSC results of Trigonox B

measured Antoine fit

pressure

(mbar)

  

Tboiling point 

°C

   

calculated pressures 

after fit (mbar)
 

47

  

32.9

   

46
 

60

  

38.5

   

62
 

100

  

47.8

   

98
 

150

  

57.25

   

148
 

200

  

64.8

  

200

 
 

250

  

71.0

   

251

Antoine:

10log(p)=A -B/(C+T)

or

p=10{A -B/(e+T))

T=BI(A - 10log p) - C

where: A,B and C : constants

p: pressure (mbar)

T: temperature (K)

Conclusions:
The vapour pressure of Di-tert-butyl peroxide is 29 mBar at 25°C
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No GLP
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Principles of method if other than guideline:
Standard vapor pressure measurements were made by allowing an excess of liquid to equilibrate in an enclosed system resting in a Haake Model FK constant-temperature bath.Integral to the enclosed system was an MKS Model 144 Baratron for pressure measurements (accuracy 0.001 Torr for less than 11.500 Torr and O.O 1 Torr for greater than 11.500 Torr). Temperature was measured with a chromel-alumel thermocouple resting in the
liquid of the constant-temperature bath. The thermocouple was attached to a strip chart recorder and the pressure measurement was taken approximately 15 min after there was no detectable temperature change.
Type of method:
static method
Temp.:
20 °C
Vapour pressure:
24.73 Torr
Conclusions:
Di-tert-butyl peroxide has a vapour pressure of 24.73 torr (3297 Pa, 32.97 hPa) at a temperature of 20 °C.
Executive summary:

Di-tert-butyl peroxide has a vapour pressure of 24.73 torr (3297 Pa, 32.97 hPa) at a temperature of 20 °C.

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: no GLP, summary of Boerdijk G.B. 1999 data
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Principles of method if other than guideline:
Equipment:
The DSC (Differential Scanning Calorimeter) is applied. The vacuum DSC experiments were carried out at various controlled pressure levels. Pressure is measured accurately with an electronic micro membrane manometer.
Procedure:
Approximately 15 mg is weighed into a 70 micro litre aluminium cup with a pierced lid.
After reaching a constant pre-set pressure, the DSC temperature scan is started. The heating rate is 5°C/min. During this scan, the product will evaporate. A sudden increase in the endothermic heat flow is obtained at the initial boiling point of the mixture at the pre-set pressure. A condenser, cooled by CO2 ice, captures the gases. After at least 4 DSC scans at different pressures, a plot is constructed with 10log P (P in mBar) versus 1/T (T in K), the Antoine plot of the product.
GLP compliance:
no
Type of method:
other: DSC
Temp.:
71 °C
Vapour pressure:
252 mBar
Temp.:
33 °C
Vapour pressure:
47 mBar
Temp.:
-14 °C
Vapour pressure:
1 mBar
Conclusions:
The vapour pressure of di-tert-butyl peroxide at 71°C is 252 mBar, at 33°C is 47 mBar and at -14°C is 1 mBar.
Endpoint:
vapour pressure
Type of information:
other: calculation from data compiled from 3 references over -23 oC to 71 oC
Adequacy of study:
key study
Study period:
see supporting references
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: calculation based on summary of 3 WoE reports containing non-GLP data
Principles of method if other than guideline:
see WoE endpoints for further method information
GLP compliance:
no
Type of method:
other: see WoE endpoints for further method information
Temp.:
20 °C
Vapour pressure:
3 500 Pa
Conclusions:
The vapour pressure of di-tert-butyl peroxide is 35 mBar (3500 Pa) at 20°C
Executive summary:

The vapour pressure of di-tert-butyl peroxide is 35 mBar (3500 Pa) at 20°C

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No GLP
Qualifier:
no guideline followed
Principles of method if other than guideline:
isoteniscope
GLP compliance:
no
Type of method:
isoteniscope
Temp.:
20 °C
Vapour pressure:
32 mm Hg

The experimental values agree well with the literature values, especially above 30°C, so a reasonable reliability can be assigned to it.

32 mm Hg = 4266

Conclusions:
The vapour pressure of di-tert-butyl peroxide is 32mm Hg at 20 °C.
Executive summary:

The experimental values agree well with the literature values, especially above 30°C, so a reasonable reliability can be anouced to it.

The vapour pressure of Di-tert-butyl peroxide is 32mm Hg at 20 °C.

Description of key information

The vapour pressure of di-tert-butyl peroxide is 35 mBar (3500 Pa) at 20°C. The calculated vapour pressure is 96.5 mBar (9650 Pa) at 40 °C.

Key value for chemical safety assessment

Vapour pressure:
3 500 Pa
at the temperature of:
20 °C

Additional information

Based on weight of evidence and calculation: see Nuysink, 2010 and attachment.