Di-tert-butyl sec-butylidene diperoxide

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 January 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Method 1:
In the first method, the DSC (differential scanning calorimeter) is applied. The pressure is measured accurately with an electronic micro membrane manometer. The vacuum DSC experiments were carried out at various controlled pressure levels.
Approximately 15 mg is weighed into a 70 micro litre aluminium cup with a pierced lid.
After reaching a constant 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 then obtained. This represents the initial boiling point of the mixture at the pre-set pressure. A condenser, cooled by CO2ice extrudates, captures the gases. After at least 4 DSC scans at different pressures, a plot is constructed with10log p (p: mbara) versus T(K), the Antoine plot of the product.
 
Method 2:
In the second method, a closed system is created. The headspace temperature of the system is set at the same value as the sample temperature. The system is equipped with a turbo molecular vacuum pump. This pump is additional to the 2-stage oil vacuum pump and is applied to give extra low initial pressure values. This pump is positioned in the line between the first pump and the flask.
Approximately 5 ml product is put into a clean, dry 500-ml flask. The flask is closed and the valve to the vacuum pumps is opened. The 2-stage vacuum pump is started. The dissolved gases are removed. When the substance gasses intensively, the boiling point is already reached. The temperature here, is lower then in the bath. The valve has to be closed and wait for constant temperature.
Again, the valve has to be opened. When the boiling point is reached again, immediately close the valve. If below 0.5 mbara still no boiling point is reached, the turbo molecular vacuum pump is started.
After reaching a constant value (boiling), the valve to the pumps is closed. The initial value p(initial), during the first few seconds, is close to the vapour pressure of the product. After closing the valve, the pressure rises slowly. This is partly the result of a small leakage. The leak-value determined is before, in an empty system and will be used later on for correction.
The decomposition products formed during the experiment will also contribute to the total pressure.

GLP compliance:

no

Other quality assurance:

other: ISO 9001

Type of method:

other: DSC method

Test no.:

#1

Temp.:

37 °C

Vapour pressure:

300 Pa

Remarks on result:

other: vp of Trigonox D-C50

Test no.:

#2

Temp.:

72 °C

Vapour pressure:

2 050 Pa

Remarks on result:

other: vp of Trigonox D-C50

Test no.:

#3

Temp.:

25 °C

Vapour pressure:

140 Pa

Remarks on result:

other: extrapolated vp of Trigonox D-C50

Test no.:

#4

Temp.:

25 °C

Vapour pressure:

180 Pa

Remarks on result:

other: vp of isododecane solvent control

Key result

Test no.:

#5

Temp.:

25 °C

Vapour pressure:

50 Pa

Remarks on result:

other: calculated vp of 2,2-di(tert-butylperoxy)butane in Trigonox D-C50

Derived Antoine equation for Trigonox D-C50:

log p (mbar) = 8.071-2157.5/(T-25.94) (T in K)

Derived Antoine equation for isododecane solvent control:

log p (mbar) = 7.036-1515.1/(T-74.70) (T in K)

At 25 oC, the vp of Trigonox D-C50 is 140 Pa.

At 25 oC, the vp of the isododecane used is 180 Pa.

As Trigonox D-C50 is 50 % 2,2-di(tert-butylperoxy)butane and 50 % isododecane, the vp of 2,2-di(tert-butylperoxy)butane in the Trigonox D-C50 can be calculated as (140 - 180/2) Pa = 50 Pa

Conclusions:

The extrapolated vapor pressure of commercially marketed Trigonox D-C50 at 25 oC is 140 Pa. From this, the vapor pressure of the contained 2,2-di(tert-butylperoxy)butane is calculated as 50 Pa @ 25 oC.

Executive summary:

The vapor pressure of the contained 2,2-di(tert-butylperoxy)butane is calculated as 50 Pa @ 25 oC.

Description of key information

The vapor pressure of the contained 2,2-di(tert-butylperoxy)butane is calculated as 50 Pa @ 25 oC.

Key value for chemical safety assessment

Vapour pressure:

50 Pa

at the temperature of:

25 °C