Sodium salts of [[(phosphonomethyl)imino]bis[ethane-2,1-diylnitrilobis(methylene)]]tetrakisphosphonic acid (5-7 Na:1)

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:

Testing was conducted between 31 March 2010 and 24 August 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

yes

Type of method:

differential scanning calorimetry

Key result

Melting / freezing pt.:

723 K

Decomposition:

yes

Remarks:

Test item gradually decomposed upon heating

Sublimation:

no

Remarks on result:

other: No atmospheric pressure was recorded for this endpoint.

Please see Attachment 1 for Results.

Conclusions:

The melting/freezing temperature of the test item has been determined to be not less than 450°C (723K). The test item was determined to gradually decompose upon heating.

Executive summary:

Two physico-chemical properties of the test item have been determined.

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.

Method

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.

Conclusion

The melting/freezing temperature of the test item has been determined to be not less than 450°C (723K). The test item was determined to gradually decompose upon heating.

Description of key information

Melting point: The acid form [DTPMP-H] was observed to have a melting/freezing temperature of >450°C (723 K) and to gradually decompose when heated (Tremain 2010). This conclusion is read across to the salt to indicate that DTPMP (5 -7Na) will also undergo decomposition when heated.

Additional information

The melting point of the anhydrous form of the parent acid (DTPMP-H) was determined using differential scanning calorimetry (DSC) in accordance with EU Method A.1 test method. DTPMP-H (anhydrous form) was observed to have a melting/freezing temperature of >450°C (723 K) and undergo gradual decomposition when heated.

This result is read-across to the salt, DTPMP (5-7Na); that the salt will have a higher melting point than the parent acid and also undergoes thermal decomposition when heated. Salts would be expected to melt at a higher temperature than the parent acid, and to decompose on heating.