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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:
22-May to 30-Jun 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.1 (Melting / Freezing Temperature)
Qualifier:
according to guideline
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
GLP compliance:
not specified
Type of method:
differential scanning calorimetry
Melting / freezing pt.:
0 °C
Atm. press.:
ca. 1 013 hPa
Remarks on result:
other: Atmospheric pressure assumed to be close to normal.

Results of preliminary thermogravimetric measurements:

Two steps were registered with maxima at 184 °C and 201 °C. A total mass loss of 99.7 % at the final temperature could be observed, considering the initial mass loss from purging (ca.0.5 % before the start of the measurement): Mass change in the range until 192 °C: 98.0 % (97.5 % + 0.5 %); mass change in the range from 192 to 350 °C: 1.7 %.

After cooling, no residue was discernible.

Results of DSC measurements:

The cooling curve exhibits a very sharp exothermic crystallisation peak, and upon heating the heat flow curve shows an endothermic melting (extrapolated Onset-temperature: 0.3 / 0.3 °C, peak maximum temperature: 3 / 3 °C).

It is to be noted that crystallisation processes are often impaired by supercooling, due to a kinetic delay of the transformation caused by inhibited nucleation. Thus the measured transformation temperature does not necessarily correspond to the thermodynamic equilibrium temperature, but is strongly dependant on the thermal history of the sample and the applied cooling rate. Therefore cooling and heating cycle yield different enthalpy profiles.

Melting point: 0 °C

Conclusions:
A melting point value of 0 °C at approx. 1013 hPa was determined in a reliable study conducted according to an appropriate test protocol.

Description of key information

Trichloro(4-methylphenyl)silane: 0 °C at approx. 1013 hPa (Differential scanning calorimetry, EU method A.1)

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
0 °C

Additional information

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