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Physical & Chemical properties

Melting point / freezing point

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Reference
Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 2009 – March 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well conducted study, performed under the Internal Management System. Certificate of analysis included in the report.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Deviations:
yes
Remarks:
See Principles of method if other than guideline
Principles of method if other than guideline:
The crystallizing tube is not put into an outer protection tube.
- A 20 mm magnetic driven Teflon coated steel bar is used as stirrer instead of a mechanically driven stirrer with a loop of 20 mm.
- The temperature in the substance and in the cooling bath is measured with thermocouples instead of thermometers.
- A 500 ml insulating cooling bath made of glass and containing ethanol as cooling liquid is used for cooling the substance instead of a Dewar vessel. The bath is continuously stirred with a magnetic stirrer and its temperature is controlled via an external thermostatted
bath.
- The substance is cooled down in steps of 5°C to below -25°C or until crystallization occurs, instead of a one-step cooling to a temperature of 3 to 5°C below the expected crystallizing point.
It is not expected that these deviations will have affected the outcome of the study.
GLP compliance:
no
Type of method:
method to determine freezing temperature
Remarks:
After Thermal analysis
Melting / freezing pt.:
< -29 °C

Accuracy check DSC

The measured values for Indium are mentioned below.

- onset temperature : 156.48°C

- enthalpy of melting : 28.55 J/g

The measured values are within the acceptance limits.

Test method 1:

Thermal analysis method

The DSC curve of the measurement is shown in the report. No heat peak was measured. This means that the substance did not solidify or crystallize during the cooling step to -50°C, and consequently did neither melt during the heating step back to 20°C. This means that the melting point could not be determined with this method.

Test method 2:

Method for determination of the freezing temperature

Cooling was done in seven steps from 0°C to -29°C.

The appearance of the sample at each temperature level is mentioned below.

- at 0°C : clear liquid, thin fluid

- at -5°C : clear liquid, thin fluid

- at -10°C : clear liquid, thin fluid

- at -15°C : clear liquid, thin fluid

- at -20°C : clear liquid, thin fluid

- at -25°C : clear liquid, thin fluid

- at -29°C : clear liquid, thin fluid

Conclusions:
Di-tert-butyl peroxide has a freezing point lower than -29°C.
Executive summary:

The freezing point of di-tert-butyl peroxide was determined according to OECD guideline 102. Two methods were used for the determination of the melting/freezing point, a thermal analysis method (Differential Scanning Calorimetry, DSC) and a method for the determination of the freezing temperature. The first method is based on ASTM E537-07 and the second on ISO 1392. Both methods are mentioned in the list of standards of Guidelines EC A.1 and OECD 102.

No crystallization or freezing was observed. Also the temperature profile did not show any indication of crystallization or freezing. Since the substance remained liquid in the temperature range from 0°C to -29°C, it can be concluded that the melting/freezing point of di-tert-butyl peroxide is below -29°C.

Description of key information

 Di-tert-butyl peroxide has a freezing point lower than -29°C.

Key value for chemical safety assessment

Additional information

This data is supported by one old report and five literature endpoints.