2,2'-bipyridyl

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

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Principles of method if other than guideline:

The above-mentioned guidelines contain several different methods for the determination of the melting point / melting range. These are, among others, thermal analysis using a calorimeter and visual tests (e.g. capillary method), where the melting, respectively the freezing temperatures
were measured. During the present study the thermal analysis was used. A phase transformation, e.g. melting or evaporation, or a reaction, e.g. dissociation, usually is associated with a heat effect. In the calorimeter, two identical aluminum sample containers, one filled with the test item and
the other empty (used as the reference), were heated at a constant rate. During the experiment, the heat effect, i.e. the difference in heat flow between the sample container and the reference container, was registered.

A preliminary test was conducted according to the following brief description. A test item amount of 3.24 mg was heated up from 25 °C to 400 °C at a rate of 20 °C/min. The quantities of heat absorbed or released were measured and recorded. Before and after the test, the weight and the appearance of the sample were determined.

For the main test: As in the temperature range investigated, a peak was observed from which melting of the sample could be deduced, the thermal analysis was repeated in the immediate vicinity of the peak temperature with the temperature rise adjusted to 10 °C/min. For the actual determination of the melting point, 4.38 mg and 7.11 mg, respectively, of the test item were heated up from 50 °C to
100 °C. Before and after the test, the weight and the appearance of the samples were determined.

GLP compliance:

no

Type of method:

thermal analysis

Remarks:

DSC

Melting / freezing pt.:

69.2 °C

In the preliminary study several endothermic heat effects were observed, the first peak starting at 70.8 °C. After the experiment, the sample had lost all of its mass and no residue remained in the sample cup.

In order to determine the melting more precisely, further DSC-runs were recorded between 50 °C and 100 °C with a heating rate of 10 °C/min. In the first main test run, the melting was observed at 69.0, during the second main test run at 69.4 °C. During these runs, the samples lost no weight and a whitish melt remained in the sample cups.

The melting point of CA3610A was determined to be 69.2 °C, which is equal to 342.4 K. The estimated accuracy is ± 0.5 K. This result was obtained using Differential Scanning Calorimetry (Thermal Analysis) method.

Conclusions:

The melting point of CA3610A was determined to be 69.2 °C, which is equal to 342.4 K.
The estimated accuracy is ± 0.5 K.
This result was obtained using Differential Scanning Calorimetry (Thermal Analysis) method.

Description of key information

The melting point was found to be 69.2°C using DSC method.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

69.2 °C

Additional information

A very large body of experimental data exists in the literature for melting point. The range of melting points observed likely reflects experimental error, as well as the larger effect of different purities. The key study was chosen for classification and risk assessment purposes because the method is according to OECD guidleines without deviation.