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Physical & Chemical properties

Melting point / freezing point

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melting point/freezing point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Testing was conducted between 31 March 2010 and 4 June 2010
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive and done to a valid guideline.
according to guideline
EU Method A.1 (Melting / Freezing Temperature)
GLP compliance:
Type of method:
differential scanning calorimetry
Key result
Melting / freezing pt.:
451 K
Remarks on result:
other: No atmospheric pressure was recorded for this endpoint.

Please see Attachment 1 as this information contains tables and graphs and it would be rendered less comprehensible separated within this section.

The test item has been determined to melt with decomposition from approximately 451 K.
Executive summary:


Methods employed are designed to be compatible with those specified in Commission Regulation (EC) No 440/2008 of 30 May 2008, Part A: Methods for the determination of physico-chemical properties.


The determination was carried out by differential scanning calorimetry (DSC) using the procedure specified in ASTM E537-86 designed to be compatible with Method A1 Melting/Freezing Temperature of Commission Regulation (EC) No 440/2008 of 30 May 2008.


The test item has been determined to melt with decomposition from approximately 451 K.

Description of key information

Melting point [ATMP-xNH4]: The acid form (ATMP-H) was observed to undergo thermal decomposition from approximately 178°C (451 K) (Tremain 2010). This conclusion is read across to the salt to indicate that ATMP-xNH4 will also undergo decomposition when heated.

Key value for chemical safety assessment

Additional information

The melting point of the anhydrous form of the parent acid (ATMP-H) was determined using differential scanning calorimetry (DSC) in accordance with EU Test Method A.1. ATMP-H (anhydrous form) was observed to undergo thermal decomposition from approximately 178°C (451 K). In addition to the DSC method, a visual assessment of melting temperature was performed using a metal block technique. In this visual assessment, ATMP-H was observed to start melting at 205°C, undergo phase transition (turn from solid to foam) at 210°C and then decompose at 215°C. The visual assessment was performed to assist with the interpretation of the thermographic profiles observed in the DSC. The result is considered to be reliable and is selected as key study.


In a supporting study (Vanesse 1992), ATMP-H was also observed to undergo thermal decomposition with no loss of mass from around 225°C in a study that used a thermogravimetric analysis/differential scanning calorimetry method.


Melting temperature values of 210 to 215°C and 195 to 210°C with decomposition were reported for ATMP-H in available handbooks or collections of reliable data (Beilstein 1966 and 1973).

The available results are read-across to the salt, ATMP-xNH4, to indicate that the salt will also undergo thermal decomposition when heated. Salts would be expected to melt at a higher temperature than the parent acid, and to decompose on heating.