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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:
07 June 2018 to 10 July 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study was conducted in accordance with international guidelines and in accordance with GLP.
Qualifier:
according to
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.1 (Melting / Freezing Temperature)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 830.7200 (Melting Point / Melting Range)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Date of Inspection: 18 July 2017 - 20 July 2017 Date on Certfiicate: 28 November 2017
Type of method:
differential scanning calorimetry
Key result
Melting / freezing pt.:
ca. 176 °C
Decomposition:
yes
Decomp. temp.:
ca. 176 °C

The thermographic data fro the preliminary screen and determinations 1 to 4 are shown in the following tables:

Table 2: Thermographic Data - Preliminary Screen

Thermal Event

Interpretation

Temperature

°C

K

Endotherm

Onset of melting

202.3

475.5

Endotherm (left limit)

Melting of decomposition product (see Section 4.2.5)

From ~220

From ~493

After heating to 400  °C, the crucible had lost 57% of the original mass.

The residue in the crucible was observed to be a shiny black stain.

Table 3: Thermographic Data - Determinations 1 to 4

Thermal Event

Interpretation

Temperature

Determination 1

Determination 2

Determination 3

Determination 4

°C

K

°C

K

°C

K

°C

K

Endotherm (left limit)

Start of melting with decomposition

179.7

452.9

176.5

449.7

177.7

450.8

176.2

449.3

After heating to 220 °C, the crucibles had lost an average of 16% of their original mass.
The residue in the crucibles were observed to be shiny dark brown solid around the periphery.

Overall Result: Melting with decomposition from approximately 176 °C (449 K)

Visual Method - Metal Block

In support of the DSC determinations, a visual determination was performed using a metal block apparatus. Sample observations and temperatures are summarized in the following table:

Table 4: Visual Evaluation

Temperature (°C)

Observation

20

Test item is a light brown powder

190

Light brown powder. Small droplets beginning to form

195

No change

200

Test item starting to darken with lots of small droplets

202

Shrinkage point. Test item is a dark brown/black solid

205

Test item completely melted. Dark red/brown liquid

207

Test item has solidified to a dark red/brown solid

210

Test item lightened in colour to red/orange solid

230

Test item liquified to dark red/brown liquid

240

No change

260

Test item is dark red/brown solid

Result: Melting with decomposition from approximately 190 °C (463 K).

On heating in determinations 1 to 4, the broad melting endotherm with the resultant dark brown residue was indicative of melting with decomposition. This was affirmed in the visual determination with the test item melting to a dark red/brown liquid.

The overall result reported has been derived from the left limit temperature of the integrated baseline. The lowest temperature of the four determinations has been reported.

Similar thermograms were obtained under air and nitrogen atmospheres indicating thermal decomposition.

Conclusions:
The test item was determined to melt with decomposition from approximately 176°C (449 K).
Executive summary:

The determination of melting point was carried out by differential scanning calorimetry, using a procedure designed to be compatible with Methods A.1 Melting/Freezing Temperature, Method 102 of the OECD Guidelines for the Testing of Chemicals and Methods 830.7200 of the OCSPP Guidelines.

The test item was determined to melt with decomposition from approximately 176 °C

Description of key information

The test item was determined to melt with decomposition from approximately 176 °C

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
176 °C

Additional information

The determination of melting point was carried out by differential scanning calorimetry, using a procedure designed to be compatible with Methods A.1 Melting/Freezing Temperature, Method 102 of the OECD Guidelines for the Testing of Chemicals and Methods 830.7200 of the OCSPP Guidelines.

The test item was determined to melt with decomposition from approximately 176 °C. As the substance begins to melt (with decomposition) from this temperature, it is selected as the key value for chemical safety assessment.