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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:
18 May 2016 - 20 Jan 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
reference to other study
Related information:
Composition 1
Reference:
Composition 0
Qualifier:
according to
Guideline:
EU Method A.1 (Melting / Freezing Temperature)
Version / remarks:
adopted in 2008
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Version / remarks:
adopted in 1995
Deviations:
no
GLP compliance:
no
Type of method:
differential scanning calorimetry
Test material information:
Composition 1
Specific details on test material used for the study:
Storage conditions: ambient temperature (10 to 30 °C)
Atm. press.:
1 013 hPa
Decomposition:
yes
Decomp. temp.:
169 °C

Results
Melting point/melting range: DSC measurement
Two DSC measurements showed a 1st endothermal effect in the temperature range of 95 to 125 °C and a 2nd endothermal effect in the range of 150 to 210 °C. A 3rd endothermal effect (265 to 295 °C) was seen only in the second measurement. The onset temperature was derived from the intersection of the tangent line with the highest slope of the endothermal peak with the baseline.

Table 1 – Melting point – DSC measurements

Test item [mg]

Starting temperature [°C]

Final test temperature [°C]

Temperature range [°C]

Onset [°C]

Observations after the measurement

11.81

25

500

95 – 125
150 - 205

103.13
169.78

Black residue, mass loss: 50%

4.42

500

95 – 120
150 – 210
265 – 295

105.93
168.43
288.93

Black residue, mass loss: 48%

12.41

120

95 - 120

102.80

Test was caked, mass loss: 7%

 

Melting point/melting range: Capillary tube in a metal block
An additional measurement with the capillary method was carried out so as to clarify the DSC measurement results.

Table 2 – Capillary method results

Set point [°C]

Endpoint [°C]

Remarks

50

410

Start 50 °C: test item unchanged (white powder)
Approx. 187 °C: test item discoloured to yellow; start melting
Approx. 195 °C: turbid, yellow melt
Approx. 202 °C: dark bubbles, foam formation, colour changed to orange
Approx. 215 °C: dark orange, clear melt
Approx. 249 °C: formation of bubbles; colour changed to amber
Approx. 297 °C: colour changed to black
End 410 °C: no further changes

 

Conclusion
The test item melted under decomposition starting at 169 °C. The first endothermal effect was most likely due to a partial evaporation of water of crystallization.

Description of key information

Substance melted under decomposition starting at 169 °C (OECD 102, DSC).

Key value for chemical safety assessment

Additional information