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Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11-07-2019 to 18-12-2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study performed under GLP. All relevant validity criteria were met.

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7200 (Melting Point / Melting Range)

Deviations:

no

GLP compliance:

yes

Type of method:

differential scanning calorimetry

Melting / freezing pt.:

<= -80.4 °C

Atm. press.:

ca. 1 011 hPa

Decomposition:

no

Sublimation:

no

Remarks on result:

other: mean melting point (n = 2)

Main study

- Experiment 1: During cooling, an exothermic effect between -90°C and -85°C was observed. The effect was obtained due to crystallization of the test item. During heating an exothermic effect directly followed by an endothermic effect was observed between -90°C and -75°C followed by an endothermic effect between 250°C and 375°C. The peak maximum of the first effect was -80.88°C. The extrapolated onset temperature of the second effect was 328.76°C. The first endothermic effect was obtained due to melting of the test item. The second endothermic effect was considered likely to have been obtained due to boiling of the test item. After the experiment it was observed that the test item had evaporated from the sample container. The extrapolated onset temperature of the second effect was not used for calculations since the test item had evaporated before boiling temperature was reached.

- Experiment 2: Was conducted to examine the extrapolated onset of the melting temperature peak.Additionally, a higher heating rate was used to investigate the boiling peak.An extrapolated onset temperature could not be determined for the melting peak. The peak maximum of the melting peak was -80.39°C. The extrapolated onset temperature of the endothermic effect was 345.67°C and since it had shifted to a higher temperature it was concluded that it is due to the boiling of the test item, within this experiment. At the end, it was observed that the test item had evaporated from the sample container.

- Experiment 3: Was conducted to further examine the melting and boiling temperature of the test item. The peak maximum of the melting peak was -80.32°C. The extrapolated onset of the boiling effect was 335.70°C. The boiling peak temperature increased as compared to the peak obtained under the same heating rate in Experiment 1. At the end, it was observed that the test item had evaporated from the sample container.

- Experiment 4: Was conducted to further examine the boiling temperature of the test item. An endothermic peak was observed. The extrapolated onset of the peak was 336.57°C. At the end, it was observed that the test item had evaporated from the sample container.

 

The melting temperature was determined as the mean melting temperature of Experiment 2 (-80.39°C) and Experiment 3 (-80.32°C). Mean (n=2) : -80.4°C.

The boiling temperature was determined as the mean boiling temperature of Experiment 3 (335.70°C) and Experiment 4 (336.57°C). Mean (n=2) : 336.1°C.

Conclusions:

The melting temperature of the test item has been determined to be < -80.4 °C (or < 192.8 K). At above this temperature the substance is considered to be liquid.

Executive summary:

The melting temperature was determined using OECD TG 102 and EU Method A.1 with the Differential Scanning Calorimetry method under GLP. 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. During DSC cooling an exothermic effect was observed which were due to crystallization of the test item between -90°C and -75°C. Subsequently upon heating an endothermic effect was seen indicating melting of the test item. The melting temperature was determined as the mean melting temperature of Experiment 2 (-80.39°C) and Experiment 3 (-80.32°C), respectively. It was concluded that the melting temperature of the test item is -80.4°C (or 192.8K). At above this temperature the substance is considered to be liquid.

Description of key information

Mp: -80.4 °C (or 192.8 K) at 1 atmosphere, OECD TG 102 : DSC Method, 2019

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

-80.4 °C

Additional information

Key Study : OECD TG 102, 2019 : The melting temperature was determined using OECD TG 102 and EU Method A.1 with the Differential Scanning Calorimetry method under GLP. 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. During DSC cooling an exothermic effect was observed which were due to crystallization of the test item between -90°C and -75°C. Subsequently upon heating an endothermic effect was seen indicating melting of the test item. The melting temperature was determined as the mean melting temperature of Experiment 2 (-80.39°C) and Experiment 3 (-80.32°C), respectively. It was concluded that the melting temperature of the test item is -80.4°C (or 192.8K). At above this temperature the substance is considered to be liquid.