[[(phosphonomethyl)imino]bis[hexamethylenenitrilobis(methylene)]]tetrakisphosphonic acid

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:

2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

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, done to a valid guideline and the study was conducted under GLP conditions, however no formal claim of GLP compliance was made.

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

no

Type of method:

differential scanning calorimetry

Key result

Decomposition:

yes

Remarks:

The test item has been determined to undergo decomposition from approximately 80°C.

Decomp. temp.:

ca. 80 °C

Sublimation:

no

Results

Thermograms and thermographic data can be found in Attachment 1 of this Summary.

Please see results of the visual assessment in the table below:

Table: Results of visual assessment

Reading Number	Temperature (°C)	Observations
1	20	Test item is a white powder.
2	39	No change.
3	71	No change.
4	91	Test item is a white powder that is shrinking.
5	94	Vapour droplets on the capillary tube; test item is still a white powder.
6	103	Vapour droplets on the wall of the capillary tube; test item is still a white powder.
7	108	Test item is a white powder that is expanding up the capillary tube with vapour droplets still present.
8	116	Test item is a white solid inside white bubbles/foam.
9	134	Test item is a white solid inside white bubbles/foam; bubbles are becoming larger.
10	152	Amount of bubbles have decreased from previous observation.
11	162	Test item is a white solid inside white bubbles/foam.
12	174	White foam is rising up the capillary tube.
13	238	Test item is white foam.
14	255	Foam bubbles are bursting.
15	263	Small amount of bubbles/foam remaining.
16	281	Small amount of foam/bubbles.
17	314	Test item has risen up capillary tube and out of sight.

Conclusions:

The test item has been determined to undergo decomposition from approximately 80°C in a study using a relevant test method. The result is considered to be reliable.

Executive summary:

The determination was carried out by differential scanning calorimetry (DSC) using a procedure designed to be compatible with Method A1 Melting/Freezing Temperature of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 102 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.

Conclusion

The test item has been determined to undergo decomposition from approximately 80°C.

Description of key information

Melting point (BHMT-H): Decomposition at approximately 80°C (Atwal, 2012).

Additional information

A decomposition temperature of approximately 80°C was determined for BHMT-H using an appropriate test method. A recent, reliable DSC test demonstrates that the anhydrous form of the acid decomposes from approximately 80°C at 1013 hPa. In addition to the DSC method, a visual assessment was performed by heating an aliquot of the registered substance in a capillary tube from room temperature to 314°C. In the visual assessment, decomposition of the substance was observed from approximately 100°C. The result of the visual assessment indicates that the onset of the endotherm observed at approximately 80°C is likely a result of decomposition of the substance.

Melting point of -8°C was reported for the substance in secondary sources to which no reliability could be assigned; these results likely refer to aqueous solution products.

HMDTMP-H is a named impurity in the registered substance. The melting point of the anhydrous form of the HMDTMP-H was determined using differential scanning calorimetry (DSC) in accordance with EU Method A.1 test method. HMDTMP-H (anhydrous form) was observed to undergo thermal decomposition from approximately 200°C. In addition to the DSC method, a visual assessment was performed by heating an aliquot of HMDTMP-H in a capillary tube from room temperature to 350°C. The visual assessment was performed to assist with the interpretation of the thermographic profiles observed in the DSC. In the visual assessment, HMDTMP-H was observed to undergoes a colour change at approximately the same temperature at which HMDTMP-H starts to melt, i.e. HMDTMP-H undergoes simultaneous melting and decomposition.