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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:
01 September - 18 September 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.1 (Melting / Freezing Temperature)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Deviations:
no
GLP compliance:
no
Type of method:
differential scanning calorimetry
Key result
Melting / freezing pt.:
> 90.5 - < 129.8 °C
Atm. press.:
ca. 1 013.25 hPa
Decomposition:
no

Two DSC measurements with a heating rate of 10 K/min showed two endothermal effects in the temperature ranges of 75 - 110 °C and 120 - 140 °C (two stage effect: the first part from approximately 120 - 130 °C and the second effect from approximately 130 - 140 °C). The first measurement showed another endothermal effect after these endothermal effects. The onset temperature (see Table 1) was derived from the intersection of the tangent line with the highest slope of the endothermal peak with the baseline.

 

Tabel 1: Melting point (DSC measurements)

Ident No.

Test item/ mg

Starting temperature / °C

Final test temperature / °C

Temperature range (melting) /°C

Onset / °C

Crucible

Observations

35238

10.41

25

500

75 – 110

120 – 140

370 - 415

90.65

124.93/129.79

n.d.

Aluminium with a hole

Measurement continued after melting

35240

9.77

25

200

80 – 105

120 - 135

90.43

124.97/129.90

Aluminium with a hole

Test item was a solidified melt after the measurement

 

An additional measurement with the capillary method was performed in order to clarify the melting point.

Since this measurement was performed only as a verifying screening a high heating rate of 10 K/min was chosen and therefore the absolute temperature values derived with the capillary method are not as accurate as the DSC results. The filling height of the test item was approximately 5 mm.

Table 2: Results of the capillary method

No.

Set point/°C

Heating rate/ K/min

Endpoint/ °C

Remarks

1

40

10

140

Approx. 80°C: test item started to melt

Approx. 127°C: test item appeared melted and turbid

Approx. 131°C: test item appeared melted and clear

2

40

10

140

Approx. 80°C: test item started to melt

Approx. 127°C: test item appeared melted and turbid

Approx. 131°C: test item appeared melted and clear

Conclusions:
The DSC measurements showed that the test item had a melting range of 90.5 - 129.8 °C.
Executive summary:

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1. The melting range was determined by differential scanning calorimetry. The test item and the reference are heated up from the starting temperature to the final temperature at a constant heating rate in a defined atmosphere (nitrogen). Open crucibles are used as containers for the test item and as empty reference crucible. The quantity of heat absorbed or released is measured and recorded. A measurement with the capillary method was performed to clarify the results of the DSC measurements.

The test item showed three endothermal effects. The first was observed with an onset temperature of 90.5 °C in the DSC-measurement (optical observation: test item started to melt) The second endothermal effected consisted of two phases. During the first phase (onset temperature 125.0 °C) the test item changed from a solid to a turbid liquid. During the second phase (onset temperature 129.8 °C) the test item changed from a turbid liquid to a clear liquid.

Description of key information

The test item had a melting point/range of 90.5 to 129.8 °C.

Key value for chemical safety assessment

Additional information

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1. The melting range was determined by differential scanning calorimetry. The test item and the reference are heated up from the starting temperature to the final temperature at a constant heating rate in a defined atmosphere (nitrogen). Open crucibles are used as containers for the test item and as empty reference crucible. The quantity of heat absorbed or released is measured and recorded. A measurement with the capillary method was performed to clarify the results of the DSC measurements.

The test item showed three endothermal effects. The first was observed with an onset temperature of 90.5 °C in the DSC-measurement (optical observation: test item started to melt) The second endothermal effected consisted of two phases. During the first phase (onset temperature 125.0 °C) the test item changed from a solid to a turbid liquid. During the second phase (onset temperature 129.8 °C) the test item changed from a turbid liquid to a clear liquid.