Disodium 3-[[2,2'-dimethyl-4'-[[4-[[(p-tolyl)sulphonyl]oxy]phenyl]azo][1,1'-biphenyl]-4-yl]azo]-4-hydroxynaphthalene-2,7-disulphonate

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:

From September 14th, 2017 to January 31st, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Version / remarks:

1995

Qualifier:

according to guideline

Guideline:

other: OECD Test Guideline 113: Thermal Stability

Version / remarks:

1981

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Remarks:

and capillary method

Decomposition:

yes

Decomp. temp.:

210 °C

MELTING POINT - DSC method

The test item showed a broad endothermic effect starting at a temperature of ca 55 °C and an exothermic effect starting from 210 °C with an average energy release of -221 J/g and another endothermic effect starting at a temperature of 359 °C.

During the heating phase two broad endothermic effects were detected, which both cannot be clearly assigned to a melting or a boiling of the test item.

Results of DSC analysis

No.	Sample weight / mg	Onset of Effect / °C	Energy / (J/g)	Weight loss / mg	Atmospheric pressure / hPa
1	14.38	79	103	5.68	1001
		260	-174
		359	193
2	10.63	54	127	4.13	1001
		210	-268
		400	50

MELTING POINT - capillary method

According to the observations during the tests with the capillary method, the broad endothermic effect starting at 50 °C in the DSC measurements with open crucibles cannot be assigned to the melting of the test item, since the test item did not change its appearance. Since the test item contains 5.3 wt.-% water, it can be assumed, that the endothermic effect is caused by the drying of the test item. Starting at a temperature of approx. 290 °C the test item becomes black and starts to decompose. The decomposition was accomplished at a temperature of approx. 370 °C. Due to the fact that a sharp exothermic effect was observed in the DSC measurements starting at a temperature of approx. 250 °C, the effect cannot be associated with a melting or boiling. It can be stated that the test item has no melting point and no boiling point up to its decomposition.

THERMAL STABILITY

The test item showed an endothermic effect from 110 °C. A first exothermic effect was observed starting at 160 °C with an averaged energy release of -460 J/g. A second exothermic effect was detected starting from 430 °C with an energy release of more than -60 J/g. Because of the test end at 500 °C the second exothermic effect was not fully recorded and the associated energy release cannot be fully quantified.

No.	Sample weight / mg	Start of effect / °C	Energy / (J/g)
1	7.48	110	+8 (endothermic)
		160	-370 (exothermic)
		430	higher than -58 (exothermic)
2	8.25	110	+8 (endothermic)
		160	-551 (exothermic)
		430	higher than -63 (exothermic)

Conclusions:

The substance decomposes before melting (210 °C).

Executive summary:

The thermal behaviour of test item was assessed using the DSC analysis, according to the OECD guideline 102 and OECD guideline 113. To verify the results of the DSC measurement, three additional measurements with the capillary method were performed in the temperature range of 25 – 400 °C with a heating rate of 10 K/min.

The test item has no melting/boiling point up to its decomposition starting at a temperature of approx. 210 °C as determined by differential scanning calorimetry and capillary method.

The test item showed an endothermic effect from 110 °C. A first exothermic effect was observed starting at 160 °C with an averaged energy release of -460 J/g. A second exothermic effect was detected starting from 430 °C with an energy release of more than -60 J/g. Because of the test end at 500 °C the second exothermic effect was not fully recorded and the associated energy release cannot be fully quantified.

Conclusion

The substance decomposes before melting (210 °C).

Description of key information

The substance decomposes before melting (210 °C).

Additional information

OECD 102 and OECD 113 - DSC analysis and capillary method