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Physical & Chemical properties

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:
2020-09-09 - 2020-09-17 (experimental phase)
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
GLP compliance:
yes (incl. QA statement)
Type of method:
other: differential scanning calorimetry and capillary method
Key result
Atm. press.:
1 007.3 hPa
Remarks on result:
other: no defined freezing or melting point in the temperature range of -90°C to room temperature

DSC

During cooling down to -90 °C no thermic effect could be observed. During the heating phase, the test item showed a very small endothermic effect in the temperature range of approx. -50 to -40 °C, which can’t clearly be assigned to the melting of the test item.

In the temperature range of 170 – 450 °C two exothermic effects can be observed.

In the DSC-measurement neither a freezing nor a melting point could be observed.

Table: Results of the DSC-measurements

Sample weight / mg

Onset of effect / °C

Range of effect / °C

Weight loss / mg

Atmospheric pressure / hPa

9.93

-49.24

-50 to -40 (endo)


170 -290

and

290 - 450 (exo)

6.86

1007.3

10.44

-53.56

-50 to -40 (endo)


170 -280

and

280 - 450 (exo)

7.40

1007.3

Capillary method

To verify the results of the DSC measurements, an additional measurement in a test tube was performed in the temperature range of -97 °C to room temperature.

After cooling down to -97 °C the test item was frozen. During the heating phase up to room temperature a softening of the test item could be observed, starting at a temperature of approx. -22 °C.

Combining the results of the DSC-measurement and the capillary method, no melting of the test item could be observed. The small endothermic effect in the DSC could be the beginning of a phase transformation of the test item. The test item started to soften at approx. -22 °C.

Conclusions:
THPO has no defined freezing or melting point in the temperature range of -90°C to room temperature at atmospheric pressure (1007 hPa)
Executive summary:

The test item Tris(hydroxymethyl)phosphine (THPO) has no defined freezing or melting point in the temperature range of -90°C to room temperature at atmospheric pressure (1007 hPa) as determined by Differential Scanning Calorimetry (DSC) and Capillary Method according to Regulation (EC) No 440/2008 Method A.1. and OECD Test Guideline 102 (1995).

Description of key information

melting / freezing point (determined using EU Method A.1 / OECD 102; GLP): no defined freezing or melting point in the temperature range of -90°C to room temperature at atmospheric pressure (1007 hPa)

Key value for chemical safety assessment

Additional information

The determination of the melting / freezing point was carried out by Differential Scanning Calorimetry (DSC) and Capillary Method according to Regulation (EC) No 440/2008 Method A.1. and OECD Test Guideline 102 (1995).

A reliability score of 1 was assigned, in accordance with the criteria for assigning data quality in line with the principles described by Klimisch (1997).