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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:

from 2018-03-16 to 2018-05-24

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

Qualifier:

according to guideline

Guideline:

other: CIPAC MT 1 (Freezing Point)

Version / remarks:

2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Remarks:

DSC results confirmed with a capillary method

Key result

Melting / freezing pt.:

-4 °C

Atm. press.:

>= 989 - <= 1 015 hPa

Decomposition:

no

Sublimation:

no

In the temperature range of -20 to +10 °C a first endothermic effect was observed.

Table 1: Results of DSC measurement

No.	Sample weight (mg)	Onset of Effect (°C)	Range of effect (°C)	Atmospheric pressure (hPa)
PN15220	9.26	-4.27	-20 – 10 (endo)	988.7
PN15221	16.33	-3.46	-20 – 10 (endo)	988.7
PN15248	10.17	-4.23	-20 – 10 (endo)	1015.2

During the cooling phase, a small endothermic effect could be observed at a temperature of approx. -20 °C. During the heating phase two small endothermic and one exothermic effect were observed, which couldn't be clearly assigned to melting of the test item. Thus, a test in a test tube was performed for a verification of the DSC measurement results.

First, the test item was filled in a test tube, together with a thermocouple, which was cooled with liquid nitrogen to -46.2 °C. At -45.7 °C the test item was still solid and white. During the heating up the test item melted at -16.4 °C. The test item was heated up in the test tube by means of a lighter.

Combining the results of the measurements, the first endothermic effect in the DSC in the temperature range of -20 to +10 °C can be assigned to a melting of the test item. As the onset temperatures in all three tests do not deviate by more than 0.5 K from their mean value of ‑4.0 °C, the test item has a melting point of -4.0 °C at air.

Conclusions:

The melting point of the test item was determined to be at -4 °C at 989 to 1015 hPa.

Executive summary:

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1, EPA OCSPP test guideline 830.7200 and CIPAC MT 1 to determine the melting point of the test item using differential scanning calorimetry. The test item was weighed into an aluminium crucible under air. Three tests were performed. As reference an empty aluminium crucible was used. During the cooling phase using DSC, a small exothermic effect was observed at a temperature of approx. -20 °C. During the heating phase three small endothermic effects were observed, which couldn't be clearly assigned to a melting of the test item. Thus, a test in a test tube was performed for verification of the DSC-measurements. The test item was filled into a test tube together with a thermocouple. While cooling down with liquid nitrogen to -46.2 °C the test item was observed and the melting point recorded. Finally, the melting point of the test item was determined to be -4.0 °C at 989 to 1015 hPa.

Description of key information

The melting point of the test item was determined to be at -4 °C at 1013.25 hPa.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

-4 °C

Additional information

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1, EPA OCSPP test guideline 830.7200 and CIPAC MT 1 to determine the melting point of the test item using differential scanning calorimetry. The test item was weighed into an aluminium crucible under air. Three tests were performed. As reference an empty aluminium crucible was used. During the cooling phase using DSC, a small exothermic effect was observed at a temperature of approx. -20 °C. During the heating phase three small endothermic effects were observed, which couldn't be clearly assigned to a melting of the test item. Thus, a test in a test tube was performed for verification of the DSC-measurements. The test item was filled into a test tube together with a thermocouple. While cooling down with liquid nitrogen to -46.2 °C the test item was observed and the melting point recorded. Finally, the melting point of the test item was determined to be -4.0 °C at 989 to 1015 hPa.