Willow, Salix alba, ext.

Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2019-01-16 to 2019-02-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Version / remarks:

Adopted on 27th July 1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Version / remarks:

European Commission Regulation (EC) No. 440/2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Key result

Melting / freezing pt.:

> 160 °C

Atm. press.:

1 013 hPa

Decomposition:

yes

Remarks:

Decomposition before melting

Decomp. temp.:

>= 160 °C

Sublimation:

no

The DSC measurement in an aluminium crucible with a hole and an open glass crucible showed an ambiguous course of the baseline.

Both measurements showed after the measurement an expanded foamy mass. ln case of the aluminium crucible this led to clogging of the hole and subsequent destruction of the lid. This behaviour most likely caused a movement of the crucible on the sensor leading to several spikes in the course of the measurement.

The results of the DSC measurements are summarized in following Table, details are given in the attached illustration.

Ident No.	Test item / mg	Starting temperature / °C	Final test temperature / °C	Temperature range / °C	Crucible	Observations after the measurement
38459	10.87	25	500	---	Aluminium with a hole	Test item was an expanded grey to black mass
38462	9.64	25	500	---	Open glass	Test item was an expanded grey to black mass

Capillary tube in a metal block

A measurement with the capillary method was performed to clarify the results of the DSC measurements. 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.

Results are given in the following table:

No.	Set point / °C	Heating rate / K/min	End point / °C	Remarks
1	25	10	400	Approx. 116 °C: small droplets condensed on the capillary Approx. 122 °C: test item started to discolour to a darker shade Approx. 165 °C: test item discoloured to a lighter shade Approx. 178 °C: test item was discoloured to brown to black Above 178 °C: no further changes visible

Conclusions:

The test item had no melting point and no boiling point at atmospheric conditions (decomposition before melting; DSC and capillary method; OECD 102).

Executive summary:

To determine the melting and boiling point of the submission substance, differential scanning calorimetry in open crucibles was applied (aluminium with a hole; open glass crucible). At finalisation, both measurements showed an expanded foamy mass. ln case of the aluminium crucible this led to clogging of the hole and subsequent destruction of the lid. This behaviour most likely caused a movement of the crucible on the sensor leading to several spikes in the course of the measurement. To confirm observations from DSC, an additional measurement with the capillary method was performed in order to clarify the melting range.

Results / conclusions

Under consideration of the results from the thermal stability (see report PS20180395-10; DSC in closed crucibles), the DSC measurements and the capillary method it is concluded that the test item decomposed before melting or boiling could occur. Therefore, it was concluded that the test item had no melting point and no boiling point at atmospheric conditions.

From experiments with open crucibles, the onset temperature of decomposition is difficult to estimate due to the unusual peak shape but is around 160 °C.

Description of key information

The test item had no melting point and no boiling point at atmospheric conditions (decomposition before melting; DSC and capillary method; OECD 102).

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

160 °C

Additional information

To determine the melting and boiling point of the submission substance, differential scanning calorimetry in open crucibles was applied (aluminium with a hole; open glass crucible). At finalisation, both measurements showed an expanded foamy mass. ln case of the aluminium crucible this led to clogging of the hole and subsequent destruction of the lid. This behaviour most likely caused a movement of the crucible on the sensor leading to several spikes in the course of the measurement. To confirm observations from DSC, an additional measurement with the capillary method was performed in order to clarify the melting range.

Results / conclusions

Under consideration of the results from the thermal stability (see report PS20180395-10; DSC in closed crucibles), the DSC measurements and the capillary method, it is concluded that the test item decomposed before melting or boiling could occur. Therefore, it was concluded that the test item had no melting point and no boiling point at atmospheric conditions.

From experiments with open crucibles, the onset temperature of decomposition is difficult to estimate due to the unusual peak shape but is around 160 °C. Accordingly, the theoretical melting point is >160 °C, and thus 160°C is given as the key value for chemical safety assessment.