Sodium 6-amino-5-[[2-[(ethylphenylamino)sulphonyl]phenyl]azo]-4-hydroxynaphthalene-2-sulphonate

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 12th, 2017 to August 16, 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:

adopted in 1995

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

GLP compliance:

no

Type of method:

differential scanning calorimetry

Remarks:

and capillary method

Decomposition:

yes

Decomp. temp.:

ca. 120 °C

DSC ANALYSIS

A broad endothermic effect was observed in the temperature range of 110 – 170 °C and an exothermic effect in the temperature range of 250 – 330 °C, directly followed by an endothermic effect in the temperature range of 330 – 370 °C.

Sample weight / mg	Onset of effect / °C	Range of effect / °C	Energy / J/g	Weight loss / mg
12.86	135.1	120 – 170 (endo)	26.72	5.92
	---	260 – 330 (exo)	-73.45
	330.4	330 – 370 (endo)	24.64
9.5	129.2	110 – 170 (endo)	27.45	3.93
	---	250 – 330 (exo)	-81.5
	322.1	330 – 370 (endo)	24.13

During the heating phase an untypical broad endothermic effect was observed in the temperature range of 110 – 170 °C, which cannot be assigned to a melting of the test item. The broad endothermic effect starting at approx. 110 °C was caused by another endothermic process (e.g. drying, gas evolution).

 

CAPILLARY METHOD

Above approx. 120 °C the test item became darker and rise in the capillary. The item showed no melting until the the maximum test temperature of 400 °C.

Conclusions:

The substance decomposes before melting.

Executive summary:

The thermal behaviour of the test item was investigated using Differential Scanning Calorimetry analysis and Capillary Method, according to the OECD guideline 102.

The substance was placed into the DSC apparatus and the temperature was increased up to 500 °C at a constant heating rate of 10 K/min under air.

In addition, 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 25 to 400 °C at a heating rate of 10 K/min.

During the heating phase an untypical broad endothermic effect was observed in the temperature range of 110 – 170 °C, which cannot be assigned to a melting of the test item. The broad endothermic effect starting at approx. 110 °C was caused by another endothermic process (e.g. drying, gas evolution). An exothermic effect occurred in the temperature range of 250 – 330 °C, directly followed by an endothermic effect in the temperature range of 330 – 370 °C.

During the capillary analysis, above approx. 120 °C the test item became darker and rise in the capillary; the item showed no melting until the maximum test temperature of 400 °C.

Conclusion

The substance decomposes before melting.

Description of key information

The substance decomposes before melting/boiling (at ca 250 °C)

Additional information

Differential Scanning Calorimetry analysis and Capillary Method - OECD 102