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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:
11 February - 9 April 2002
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:
not specified
Type of method:
differential scanning calorimetry
Specific details on test material used for the study:
- Batch n°: ZR027180PUG231
- Analytical purity: 99.3%
- Expiration date: 9 November 2006
- Storage condition: at room temperature, 10 to 30°C
Key result
Melting / freezing pt.:
>= 128.6 - <= 132.6 °C
Atm. press.:
1 013.25 hPa
Decomposition:
no

Initial Scan

Two thermal events were observed. A sharp endothermic peak was observed between ca. 129 and 133°C and was assumed to be the melting point. A broad endotherm commencing at 235°C was also present, and its shape, together with the appearance of a red-brown residue in the pan after testing, indicating that the test substance had boiled with a chemical change.

It was decided to proceed with a second scan to identify whether or not the former represented a true melting.

Additional Scan - Melting Event

This scan showed a sharp endotherm between ca. 128 and 133°C and replicates well the values observed in the initial scan. Results from the scans are detailed in table below

Table: Summary of Thermal Properties

Scan

Segment

Onset temp (°C)

Peak temp (°C)

Enthalpy

(J/g)

1

-

128.8

132.7

-71.3

2

Segment 1

128.4

132.4

-71.6

2

Segment 4

130.2

133.7

-64.8

Mean of 1 and 2.1

 

128.6

132.6

-71.4

The first endotherm is assumed to be the melting point of the test material. This peak is "clean" in appearance (no additional peaks) suggesting that the test material does not decompose at its melting temperature.

Conclusions:
A melting endotherm with a mean onset of 128.6°C and a mean peak at 132.6°C was observed.

Description of key information

In a key study (K1, Bates, 2002) according to the OECD guideline 102 and EC method A.1 assessing the thermal behaviour of the test substance by differential scanning calorimetry, a melting endotherm with a mean onset temperature of 128.6°C  and a mean peak temperature of 132.6°C was observed.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
130.6 °C

Additional information

Based on the observed mean onset temperature of 128.6°C and a mean peak temperature of 132.6°C, the mean value was calculated for the melting point used in the CSA.