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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:
2014-04-02
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The study was conducted in accordance with OECD Test Guideline 102, but GLP compliance was not specified.
Qualifier:
according to guideline
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Deviations:
no
GLP compliance:
not specified
Type of method:
thermal analysis
Remarks:
Differential Thermal Analysis (DTA)
Key result
Melting / freezing pt.:
ca. 90.1 - ca. 93.4 °C
Atm. press.:
1 013 hPa
Melting / freezing pt.:
ca. 363.3 - ca. 366.6 K
Atm. press.:
1 013 hPa

In both experiments, an endothermic peak was observed around 91°C (364 K). Based on the literature data and experience from melting point measurement using the Capillary/Metal block method which indicated the melting point of 89.4°C, and the test substance was confirmed to be liquid above the temperature, the endothermic peak around 91°C definitely corresponds to the phase transition from solid to liquid.

Since the endothermic peaks start at 90.1°C (363.3 K) and ends at 93.4°C (366.6 K) on average, whose difference exceeds 0.5°C, the estimated accuracy for DSC given in the Guideline, it is appropriate to report the two temperatures as a melting range rather than to report melting point.

The differences between two measurements are within the accuracy of 0.5°C both for the start and the end of the peak. Therefore the testing was considered to be valid.

In conclusion, phase transition from solid to liquid was observed from 90.1°C to 93.4°C (from 363.3 K to 366.6 K) in a valid testing, and the melting range of the test substance was therefore from 90.1°C to 93.4°C (from 363.3 K to 366.6 K).

Conclusions:
A melting temperature range of 90.1°C to 93.4°C (363.3 - 366.6 K) was determined for the substance in accordance with OECD Test Guideline 102. The result is considered to be reliable.

Description of key information

Melting range: 90.1 - 93.4°C (363.3 - 366.6 K) (OECD 102)

Key value for chemical safety assessment

Additional information

A measured melting temperature range of 90.1 - 93.4°C (363.3 - 366.6 K) was determined for tert-butyl(chloro)dimethylsilane in accordance with OECD Test Guideline 102. The result is considered to be reliable and is selected as key study. The melting temperature range is supported by a reported melting point of 89.5°C in a handbook or collection of reliable data which has been subjected to peer-review and in which the original sources are traceable. A further study reports a melting range of 75-100°C, obtained in an OECD 103 study using differential scanning calorimetry.

The supporting data are in good agreement with the key study.