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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:
2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study performed under GLP. All relevant validity criteria were met.
Qualifier:
according to
Guideline:
EU Method A.1 (Melting / Freezing Temperature)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 830.7200 (Melting Point / Melting Range)
Deviations:
no
GLP compliance:
yes
Type of method:
thermal analysis
Melting / freezing pt.:
>= -58 °C
Atm. press.:
1 atm
Sublimation:
no
Remarks on result:
other: mean result of two DSC determinations; thermal event was a glass transition temperature

Main study

- Experiment 1: During cooling, a glass transition between -50°C and -90°C was observed (results are archived in the raw data). During heating a glass transition between -40°C and -75°C was observed. The inflection point of the glass transition was -58.14°C. Additionally, an unknown endothermic peak between 25°C and 50°C was observed.

 

- Experiment 2: To investigate the unknown peak between 25°C and 50°C a repeated heating cycle was applied also to yield a duplicate glass transition temperature. During first cooling a glass transition between -50°C and -90°C was observed. With the first heating a glass transition between -40°C and -75°C was observed. The inflection point of the glass transition was -57.30°C. An unknown peak was observed between 25°C and 65°C. During second cooling a glass transition between -50°C and -90°C was observed. With the second heating a glass transition between -40°C and -75°C was observed. This temperature was not used in the calculation. No endothermic effect was observed between 25°C and 50°C. After the experiment, a yellow molten residue remained in the sample container.

 

The glass transition was determined as the average glass transition temperature obtained from Experiment 1 (-58.14°C) and Experiment 2 (-57.30°C).

Conclusions:
The melting temperature (glass transition temperature) was observed at – 58 °C (or 215 K). At this temperature the substance is considered to be liquid.
Executive summary:

The melting/freezing temperature was determined using EU Method A.1 and OECD TG 102 - Differential Scanning Calorimetry. The guideline defines the melting temperature as: the temperature at which the phase transition from solid to liquid state occurs at atmospheric pressure and this temperature ideally corresponds to the freezing temperature. The glass transition was determined as the average glass transition temperature obtained from Experiment 1 (-58.14°C) and Experiment 2 (-57.30°C) and was determined to be -58°C (215K) by using DSC. Applicant assessment indicates the substance should be considered a liquid at temperatures in excess of - 20°C and/or at environmentally relevant conditions.

Description of key information

Mp: Glass transition temperature - 58°C (or 215 K) at 1 atm, substance is liquid, EU Method A.1 - Thermal Analysis Method, 2016

Key value for chemical safety assessment

Additional information

The melting/freezing temperature was determined using EU Method A.1 and OECD TG 102 - Differential Scanning Calorimetry. The guideline defines the melting temperature as: the temperature at which the phase transition from solid to liquid state occurs at atmospheric pressure and this temperature ideally corresponds to the freezing temperature. The glass transition was determined as the average glass transition temperature obtained from Experiment 1 (-58.14°C) and Experiment 2 (-57.30°C) and was determined to be -58°C (215K) by using DSC.

Applicant assessment of the DSC curve indicates: the substance appears to have constituents that possess amorphous solid properties at low temperatures (< 20 °C) and possesses a Glass Transition Temperature (Tg) analogous to the conventional ‘melting point’ as defined under the OECD TG 102 guideline. This is a temperature point where the substance possesses glass form as opposed to possessing super-cooled liquid form. Although the second thermal event at between 25°C and 65°C was not identified; it was clearly not boiling, evaporation or decomposition of the test item and would by expert judgement be considered to be a second thermal event where suspended amorphous solid within the bulk liquid undergoes a final supercooled-liquid to liquid transition. For hazard assessment the substance should be treated as a liquid. This is based on the bulk properties of the test item being clearly ‘liquid’ as defined in Regulation (EC) 1272/2008: Annex I, section 1.0. In that the substance is not gaseous and has a vapour pressure < 300 kPa at 50°C and/or has an ‘initial melting point’ at < 20°C. The test substance was also observed to flow as a liquid at temperatures between -20°C and up to 25°C. Therefore for hazard assessment purposes the substance should be considered a liquid at temperatures in excess of - 20°C and/or at environmentally relevant conditions.