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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:
2016-01-27 to 2016-02-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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
Key result
Melting / freezing pt.:
< -80 °C
Atm. press.:
1 013 hPa
Decomposition:
yes
Decomp. temp.:
> 275 °C

Preliminary test:

The TGA-curve of the test item is shown in Figure 1 (attached). From 275°C upwards the weight of the sample decreased significantly. At 347°C the sample weight had decreased by 25%.

After the experiment, a yellowish residue remained in the sample container (original colour: light yellow). The change of the colour indicated reaction and/or decomposition of the test item.

Main study:

The DSC-curve obtained during Experiment 1 is shown in Figure 2 (attached). During cooling no effects were observed which could be attributed to crystallization of the test item. During heating, an endothermic peak started from 275°C. The effect was due to reaction and/or decomposition of the test item. Also, during heating a glass transition seemed to be present at -50°C. Since a glass transition was not observed during cooling the experiment was repeated. After the experiment, an orange/pink residue remained in the sample container.

Experiment 2 was performed as a duplicate of Experiment 1 with a similar temperature program. Figure 3 (attached) shows the DSC-curve obtained. During heating, no glass transition was observed. An obvious decrease in heat flow was observed from 200°C onwards. After the experiment, an orange/pink residue remained in the sample container.

To further investigate the melting temperature of the test substance, two samples of the test substance were stored for 69 hours at -22.4 ± 0.6°C and for 70 hours at -83.0 ± 2.1°C, respectively. It was assessed by visual inspection after storage that the test substance was a viscous liquid (-20°C freezer) and a very viscous liquid (-80°C freezer), without any crystals or other type of precipitation. According to this it was

concluded that the melting temperature of the test substance is <-80°C (< 193K).

Conclusions:
A freezing temperature of <-80°C was determined for the substance using a relevant test method and in compliance with GLP. The result is considered to be reliable.

Description of key information

Freezing point: <-80°C at 1013 hPa (OECD 102)

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
-80 °C

Additional information

The freezing temperature of the test substance was investigated using Differential Scanning Calorimetry (DSC) in accordance with OECD Test Guideline 102 and in compliance with GLP. During the DSC experiment, crystallisation and melting of the test substance were not observed. Therefore, to further investigate the melting temperature of the test substance, two samples of the test substance were stored for 69 hours at -22.4 ± 0.6°C and for 70 hours at -83.0 ± 2.1°C and the consistency of the test substance was determined by visual inspection after the experiment.

At -20°C, the test substance was observed to be a viscous liquid and at -80°C, the test substance was observed to be a very viscous liquid, without any crystals or other type of precipitation. Thus, the freezing temperature is considered to be <-80°C (< 193K). The result is considered to be reliable.