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Boiling point

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Reference
Endpoint:
boiling point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 18 July to 23 August 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The study was conducted according to an internationally recognised method, and under GLP. The substance is considered to be adequately characterised. Therefore full validation applies.
Qualifier:
according to
Guideline:
OECD Guideline 103 (Boiling Point)
Version / remarks:
1995
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.2 (Boiling Temperature)
Version / remarks:
2008
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
GLP compliance programme (inspected on 13-14 October 2014 / signed on 8 April 2015)
Type of method:
dynamic method
Key result
Decomposition:
ambiguous
Remarks on result:
other: No defined boiling point of the test item could be determined using the dynamic method

RESULTS

Different methods were performed to determine the boiling point of this substance: Siwoloboff pre-test, DSC measurement and cottrell method (main test).

Pre-test for the boiling point following Siwoloboff

Table 4.3/1.- Observations Pre-test for the boiling point following Siwoloboff

Observations

Temperatures

At the bottom started to shrivel

Since 55 °C

Getting darker and more shrivelled

Since 60 °C

Completely melted to a red-brown liquid, the colour was very dark. Observations through the drilled-hole was difficult, only every now and then observed at the surface

80 °C

Some bubbles at the surface visible

Since 100 °C

The test item boiled / foamed at the surface and the foam rose upside. Lots of bubbles above liquid with individual bubble from the bottom.

Since 145 °C

Bubbles came often

Since 170 °C

Performance of heating and turned off the burner

Up to 200 °C,

No more bubbles and foam visible

170 °C

The test item was a red-brown solid. A part of the test item was taken to grind, the test item was visually looked like the original state

After cooling down

The colour was very dark and difficult to observe through the hole, only observation at the surface was performed.

DSC Method

Security Pre-test for the DSC instrument

Thecrucible was found visually unchanged after reaching a temperature of 420°C. The weight was recorded with 48.81 mg (2.72 mg residue). After further heating to 600°C and cooling down the crucible was bloated. The weight was recorded with 46.47 mg (0.38 mg residue). After heating and weighing of 600 °C the crucible was opened, a black residue (like charcoal) was visible.

Calibration

After calibration with indium and zinc the measurement of indium yielded the following values:

Table 4.3/2.-Values DSC Indium

ExpectedMelting point

Measured

Melting point

Expected

Energy

Measured

Energy

Assessment

156.6 ± 1.0°C

156.29 °C

28.45 ± 1.0 J/g

28.78 J/g

OK

The measurement of indium after calibration met the validity criteria.

Results with DSC method

Table 4.3/3.- Values Observations

Mass test item

Mass crucible (before measurement):

Mass crucible (after measurement):

Observations

First

Measurement

1.10 mg

46.29 mg

46.22 mg

After the test the crucible was visually unchanged. The crucible was opened, a red-brown glassy mass was visible.

Second

Measurement

2.96 mg

48.88 mg

48.84 mg

After the test the crucible was visually unchanged

Third

Measurement

3.12 mg

49.08 mg

48.97 mg

After the test the crucible was visually unchanged

Fourth

Measurement

3.00 mg

48.76 mg

48.63 mg

After the test the crucible was visually unchanged

DSC measurements show no events, for that raison boiling point was performed with the dynamic method with Cottrell Apparatus.

Results with dynamic method (main test)

Table 4.3/4.-Observation with Dynamic method with Cottrell Apparatus

Observations

First

determination

Second

determination

Test item melted to a red-brown liquid

-

-

Test item foamed

43.8 °C (in Cottrell-pump)

100.0 °C (in test item)

45.1 °C (in Cottrell-pump)

102.0 °C (in test item)

Started to boil with colourless condensate

55.0 °C (in Cottrell-pump)

146.0 °C (in test item)

56.1 °C (in Cottrell-pump)

130.0 °C (in test item)

Test item boiled with lots of condensate and vapour, some part splashed in the air, turned off burner

100.6 °C (in Cottrell-pump)

180.0 °C (in test item)

77.7 °C (in Cottrell-pump)

185.0 °C (in test item)

After cooling down

Test item was a dark red-brown solid

Test item was a dark red-brown solid

No calculation following Sydney-Young was carried out as no clear initial boiling point and initial decomposition was determined.

Validity boiling point Dynamic Method with Cottrell Apparatus

As decomposition occurred no valid criteria must be considered.

DISCUSION

Siwoloboff method was used in a pre-test but the colour of the test item was very dark and was difficult to observe through the hole. Only observation at the surface could be possible.

Three experiments were conducted via DSC (differential scanning calorimetry). As DSC measurements showed no events, other method was chosen.

Finally the determination of the Boiling Point with Dynamic Method - Cottrell Apparatus was performed.

Two experiments were performed using the dynamic method to determine the initial boiling point of the substance. At a test item temperature of approximately 100°C (resp. 102°C), the test item foamed and at 146°C (resp. 130°C), a colourless condensate was observed.This might be due to the evaporation / vaporisation of higher volatile components of the test item or to a decomposition of the substance.

Boiling of the major part of the substance, indicated by pumping of the Cottrell pump, was observed at a test item temperature of 180°C (resp. 185°C). These results are quite close to the results obtained in the pre-test using Siwoloboff method.

However, the thermometer in the Cottrell pump showed a much lower temperature than the temperature in the sample, eg. 100.6°C (first determination) and 77.7°C (second determination), while the temperature measured in the sample fluctuated between 180 and 185°C. This temperature difference between the thermometers was also observed when the test item foamed and when the condensate was observed. It can be a sign of decomposition of the substance.

 

Finally, the temperature of initial boiling point and / or initial decomposition of the test item cannot be determined using the dynamic method. Considering that the DSC didn’t allow to detect a potential decomposition or a phase transition of the substance (such as boiling point), no initial boiling point of the test could be determined using the standard methods reported in this report.

 

No observations were made which might cause doubts on the validity of the study outcome. Therefore, the result of the study is considered valid.

Conclusions:
No clear initial boiling point of the test item could be determined using the dynamic method and considering the complex nature of the substance.
Executive summary:

The boiling point of the test substance was determined under GLP by dynamic method according to EU A2 guideline.

Different methods were used to determine the boiling point of this substance: Siwoloboff pre-test, DSC measurement and Cottrell method (dynamic method) as a main test.

The pre-test with Siwoloboff method was difficult to perform considering the dark colour of the test item. As DSC measurement showed no events, Dynamic method was chosen as a main method.

Two experiments were conducted but no clear initial boiling point of the test item could be determined using this method and considering the complex nature of the substance. At a test item temperature of approximately 100°C (resp. 102°C), the test item foamed and at 146°C (resp. 130°C), a colourless condensate was observed.This might be due to the evaporation / vaporisation of higher volatile components of the test item or to a decomposition of the substance.

Boiling of the major part of the substance, indicated by pumping of the Cottrell pump, was observed at a test item temperature of 180°C (resp. 185°C). These results are quite close to the results obtained in the pre-test using Siwoloboff method.

However, the thermometer in the Cottrell pump showed a much lower temperature than the temperature in the sample, eg. 100.6°C (first determination) and 77.7°C (second determination), while the temperature measured in the sample fluctuated between 180 and 185°C. This temperature difference between the thermometers was also observed when the test item foamed and when the condensate was observed. It can be a sign of decomposition of the substance.

 

Finally, the temperature of initial boiling point and / or initial decomposition of the test item cannot be determined using the dynamic method. Considering that the DSC didn’t allow to detect a potential decomposition or a phase transition of the substance (such as boiling point), no initial boiling point of the test could be determined using the standard methods reported in this report.

 

No observations were made which might cause doubts on the validity of the study outcome. Therefore, the result of the study is considered valid.

Description of key information

No clear initial boiling point of the test item could be determined using the dynamic method and considering the complex nature of the substance.

Key value for chemical safety assessment

Additional information

A reliable experimental study, conducted according to a recognized OECD/EC, following the dynamic method and under GLP, is available. It is considered as a key study.

Different methods were used to determine the boiling point of this substance: Siwoloboff pre-test, DSC measurement and Cottrell method (dynamic method) as a main test.

The pre-test with Siwoloboff method was difficult to perform considering the dark colour of the test item. As DSC measurement showed no events, dynamic method was chosen as a main method.

Two experiments were conducted but no clear initial boiling point of the test item could be determined using this method and considering the complex nature of the substance. At a test item temperature of approximately 100°C (resp. 102°C), the test item foamed and at 146°C (resp. 130°C), a colourless condensate was observed.This might be due to the evaporation / vaporisation of higher volatile components of the test item or to a decomposition of the substance.

Boiling of the major part of the substance, indicated by pumping of the Cottrell pump, was observed at a test item temperature of 180°C (resp. 185°C). These results are quite close to the results obtained in the pre-test using Siwoloboff method.

Significant difference between the sample temperature and the temperature of the Cottrell pump when observed.

Therefore no key value is retained for this endpoint.