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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:

04 Apr - 08 May 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

GLP compliance:

no

Type of method:

differential scanning calorimetry

Remarks:

followed by capillary method

Atm. press.:

1 013 hPa

Decomposition:

yes

Decomp. temp.:

ca. 280 °C

Results

The test item shows two endothermic effects in the temperature ranges of 110 °C – 180 °C and 290 °C – 340 °C and an exothermic in the temperature range of 320 °C – 360 °C with a mean energy release of -50 J/g.

In Table 1 the results of the DSC measurements are summarized.

Table1:     Results of the DSC-measurements

No.	Sample weight / mg	Onset of Effect / °C	Range of effect / °C	Weight loss / mg	Atmospheric pressure / hPa
PN17567	12.34	120.60 308.47 ---	110 – 180 (endo) 290 – 340 (endo) 360 – 420 (exo)	4.76	987.3
PN17568	10.38	125.63 309.98 ---	110 – 170 (endo) 290 – 340 (endo) 360 – 400 (exo)	4.11	987.3

 

Due to the fact that none of the observed endothermic effects can be clearly associated with a melting of the test item further measurements were carried out with the capillary method.

Capillary Method

For verification of the results the test item was additionally tested three times according to the capillary method. In the three tests, the test item showed no change in its appearance in the temperature range of 110 °C – 180 °C. The first endothermic effect in the DSC measurements can therefore be assigned to a drying of the test item since it contains 4.45% water. This is also confirmed by a residue of a clear liquid at the top of the capillaries after the test. Starting at a temperature of approx. 280 °C the colour of the test item gets darker. At a temperature of 370 °C the test item turned brown and started to swell up the capillary at a temperature of 380 °C. At the final test temperature of 400 °C the test item was dark brown to black. Due to this result, the second endothermic effect in the temperature range of 290 °C – 340 °C can be assigned to the decomposition of the test item accompanied by an evaporation of gaseous decomposition products.

The measurement carried out with the capillary method showed that none of the endothermic effects observed in the DSC measurements can be assigned to a melting point of the test item. Due to this result, the test item has no melting point up to its decomposition starting at a temperature of 280 °C.

Conclusion:

The test item DMPSA-K₂ has no melting point up to its decomposition starting at a temperature of approx. 280 °C as determined by differential scanning calorimetry and capillary method according to Regulation EC No. 440/2008 Method A.1. and OECD Test Guideline 102 (1995).

 

Description of key information

Decomposition starting at ca. 280 °C under ambient conditions (DSC, OECD 102).

Additional information

No melting point up to its decomposition starting at ca. 280 °C.