Adenine

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:

2017-11-14

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

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7200 (Melting Point / Melting Range)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Key result

Melting / freezing pt.:

358.4 °C

Atm. press.:

1 013.25 hPa

Decomposition:

yes

Decomp. temp.:

> 360 °C

Sublimation:

no

In the temperature range of 350 – 400 °C, two endothermic effect (melting and decomposition) was observed.As the onset temperatures in both tests do not deviate by more than 0.5 K from their mean value of 358.37 °C, this temperature can be used as melting point.

The confirmation by means of the capillary method showed, that the test item started to melt at 350 °C. At this temperature the test item changed its colour to brown. Starting at 360 °C the test item rised to the top of the capillary, and was not in the visual field anymore. The capillary was black after the measurement. Thus, it was concluded that the test item start to decompose after melting.

 

Conclusions:

The test substance melted at 358 °C followed by decomposition.

Executive summary:

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1 and EPA OCSPP test guideline 830.7200 to determine the melting point of the test item using differential scanning calorimetry. The test item was weighed out into an aluminium crucible under an inert atmosphere (nitrogen). Two tests with about 11 mg of the test item were performed. As reference crucible, an empty aluminium crucible was used. Both crucibles were heated up from room temperature to 300 °C with a heating rate of 3 K/min. In the temperature range of 350 – 400 °C, two endothermic effects were observed which can be attributed to the melting and decomposition of the test item. As the onset temperatures in both tests do not deviate by more than 0.5 K from their mean value of 358.37 °C, this temperature was set as melting point. The confirmation by means of the capillary method showed, that the test item started to melt at about 350 °C. At this temperature the test item changed its colour to brown. The change of colour was the indication for thermal decomposition.

Description of key information

The substance is melting at 358 °C followed by decomposition.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

358 °C

Additional information

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1 and EPA OCSPP test guideline 830.7200 to determine the melting point of the test item using differential scanning calorimetry. The test item was weighed out into an aluminium crucible under an inert atmosphere (nitrogen). Two tests with about 11 mg of the test item were performed. As reference crucible, an empty aluminium crucible was used. Both crucibles were heated up from room temperature to 300 °C with a heating rate of 3 K/min. In the temperature range of 350 – 400 °C, two endothermic effects were observed which can be attributed to the melting and decomposition of the test item. As the onset temperatures in both tests do not deviate by more than 0.5 K from their mean value of 358.37 °C, this temperature was set as melting point. The confirmation by means of the capillary method showed, that the test item started to melt at about 350 °C. At this temperature the test item changed its colour to brown. The change of colour was the indication for thermal decomposition (reference 4.2 -1).