Disodium [6-[(2-anilino-1-naphthyl)azo]-2,4-dinitrophenolato(2-)][3-hydroxy-4-[(2-hydroxy-1-naphthyl)azo]naphthalene-1-sulphonato(3-)]chromate(2-)

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 December 18th, 2017 to August 15th, 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)

GLP compliance:

no

Type of method:

differential scanning calorimetry

Decomposition:

yes

Decomp. temp.:

250 °C

DIFFERENTIAL SCANNING CALORIMETRY

A broad endothermic effect was observed in the temperature range of 40 – 210 °C, followed by two exothermic effects in the temperature range of 250 – 450 °C.

Sample weight / mg	Onset of Effect / °C	Range of effect / °C	Energy / J/g	Weight loss / mg
7.92	45.4	40 – 210 (endo)	274.73	2.28
	---	250 – 450 (exo)	-476.07
8.2	57.2	40 – 200 (endo)	163.63	2.09
	---	250 – 440 (exo)	-345.51

During the heating phase the test item showed no distinct endothermic signal, which can be assumed with a melting point. The broad endothermic effect starting at approx. 40 °C was caused by another endothermic process (e.g. drying, gas evolution).

CAPILLARY METHOD

To verify the results of the DSC measurements, three additional measurements with the capillary method were performed in the temperature range of 30 – 400 °C with a heating rate of 10 K/min. The test item showed no melting in the temperature range from ambient temperature to 400 °C.

The item showed no melting until the decomposition starting at a temperature of approx. 250 °C.

Conclusions:

The substance decomposes before melting/boiling (starting approx. 250 °C).

Executive summary:

The thermal behaviour of the substance was assessed by Differential Scanning Calorimetry and capillary method.

The prepared crucibles (crucible with test item and reference crucible) were placed in the DSC apparatus and the temperature was increased up to 500 °C at a constant heating rate of 10 K/min under air.

The melting behaviour of the test item was confirmed by a measurement with the capillary method; for three measurements the capillary and a thermometer were heated from 30 °C to 400 °C at a heating rate of 10 K/min.

During the heating phase the test item showed no distinct endothermic signal, associated to a melting point. A broad endothermic effect was observed in the temperature range of 40 – 210 °C, followed by two exothermic effects in the temperature range of 250 – 450 °C. The broad endothermic effect starting at approx. 40 °C was caused by another endothermic process (e.g. drying, gas evolution).

During the capillary method analysis, the test item showed no melting in the temperature range from ambient temperature to 400 °C.

The item showed no melting until decomposition starting at a temperature of approx. 250 °C.

Conclusion

The substance decomposes before melting/boiling (starting approx. 250 °C).

Description of key information

The substance decomposes before melting/boiling (starting approx. 250 °C).

Additional information

OECD 102 - Differential Scanning Calorimentry and capillary methods