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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:
2010-07-06 to 2010-07-20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted in accordance to an appropriate test method and in compliance with ISO 17025 quality system
Qualifier:
according to guideline
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Version / remarks:
27 July 1995
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.1 (Melting / Freezing Temperature)
Version / remarks:
30 May 2008
Deviations:
no
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
differential scanning calorimetry
Key result
Melting / freezing pt.:
-66 °C
Atm. press.:
1 013 hPa

Result:

The DSC measurements were performed twice. After cooling to -125°C at a rate of 5 K/min the sample was heated to 35°C at a rate of 10 K/min. The cooling curve exhibits only one sharp exothermic crystallisation peak. Upon heating the heat flow curve shows several small thermal effects (two endothermic maxima at -75/-76°C and -66/-67°C and one exothermic maximum at -72/-72°C, indicating thermal conversions) as well as an endothermic melting with a peak maximum temperature at -62/-62°C and an extrapolated onset temperature of -65/-66°C.

It is to be noted that crystallisation processes are often impaired by supercooling, due to a kinetic delay of the transformation caused by inhibited nucleation. Thus the measured transformation temperature does not necessarily correspond to the thermodynamic equilibrium temperature, but is strongly dependant on the thermal history of the sample and the applied cooling rate. Therefore cooling and heating cycle yield different enthalpy profiles.

Melting temperature: -66°C

The DSC curves are attached

Conclusions:
A melting temperature value of -66°C at 1013 hPa was determined for the substance using a relevant test method and in compliance with ISO 17025. The result is considered to be reliable.

Description of key information

Melting Point: -66°C at 1013 hPa (OECD 102)

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
-66 °C

Additional information

A melting temperature of -66°C at 1013 hPa was determined for the substance using differential scanning calorimetry (DSC) in accordance with OECD Test Guideline 102 and in compliance with ISO 17025 quality system. The result is considered to be reliable and is selected as key study.