Praseodymium trinitrate

Boiling point

Link to relevant study record(s)

Reference

Endpoint:

boiling point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2012-02-23 to 2012-03-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

EU Method A.2 (Boiling Temperature)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 103 (Boiling point/boiling range)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Key result

Remarks on result:

not determinable

Remarks:

The substance did not show boiling behavior over the temperature range tested. The substance changed into a white solid which is concluded to correspond to anhydrous praseodymium trinitrate.

Assay No. 1:

Neither endothermic peak nor exothermic peak was recorded.

Assay No. 2:

An endothermic peak was observed at 88.2°C. This endothermic event reflected the fact that the rare earth salt solubilised in its hydration water. The hydrated rare earth salts, such as the hydrated form of praseodymium trinitrate, loose their water of hydration when heated. As these water molecules are loosely bound and as the amount of water in the substance is significant, the attached water is released and as a result the rare earth salt solubilizes in water. It is thus concluded that praseodymium trinitrate did not melt over the temperature range tested.

Assay No. 5:

An endothermic peak was observed at 85.5°C. As for the second preliminary assay, this revealed the solubilisation of the rare earth salt in its hydration water.

Assay No. 6:

A second endothermic peak was observed at 83.4°C. As for the previous assays, this revealed the solubilisation of the rare earth salt in its hydration water.

Assay No. 7:

An endothermic peak was observed at 82.9°C. As for previous assays, this revealed the solubilisation of the rare earth salt in its hydration water.

The assay No. 5 was not taken into account in the calculation of the endothermic peak value as it was not in compliance with the criterion (i.e. out of the range of the estimated accuracy of the method: no more than 0.5°C of variation between two assays up to 326.9°C).

The mean value of the endothermic peak was thus calculated from assays No. 6 and 7 (i.e. 83.2°C).This endothermic peak was in all cases preceded by a small endothermic peak at approx 60°C.

A complementary test with a Köfler bench was performed to better understand this phenomenon. From about 50 to 85 -90°C, the appearance of praseodymium trinitrate did not change. Then the salt solubilised in its hydration water and turned into a white solid at about 135 -140°C. It appeared this could not reflect the decomposition into praseodymium oxide as the oxide is a dark solid whose formation occurs at higher temperatures. Instead, the white solid observed during the Köfler bench assay should correspond to anhydrous praseodymium trinitrate.

No boiling point was determined under the experimental conditions.

Conclusions:

The DSC curve revealed an endothermic peak at 83.2°C ± 0.5°C. This endothermic event reflected the fact that the rare earth salt solubilised in its hydration water. As a result, praseodymium trinitrate did not boil over the temperature range tested. The substance changed into a white solid which is concluded to correspond to anhydrous praseodymium trinitrate. No boiling point was determined under the experimental conditions of the test.

Description of key information

A GLP boiling point study with praseodymium trinitrate was conducted according to EU method A.2 and OECD Guideline 103 by Differential Scanning Calorimetry (Demangel, 2012). Praseodymium trinitrate does not boil below 600°C.

Additional information

The DSC curve revealed an endothermic peak at 83.2°C ± 0.5°C. This endothermic event reflected the fact that the rare earth salt solubilised in its hydration water. As a result, praseodymium trinitrate did not boil over the temperature range tested. The substance changed into a white solid which is concluded to correspond to anhydrous praseodymium trinitrate. No boiling point was determined under the experimental conditions of the test.