Trisodium bis[4-[4,5-dihydro-4-[(2-hydroxy-5-nitrophenyl)azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]benzene-1-sulphonato(3-)]cobaltate(3-)

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Version / remarks:

1995

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 103 (Boling point)

Version / remarks:

1995

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 113 (Thermal stability)

Version / remarks:

1981

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Decomposition:

yes

Decomp. temp.:

220 - 380 °C

Remarks on result:

other: - 760 J/g (thermal stability assay)

Melting and boiling point (DSC)

In the thermograms of the DSC runs in a perforated aluminium crucible under air, test item showed first a broad endothermic effect in the temperature range of 90 °C to 210 °C. An exothermic effect could be detected in the temperature range of 290 – 450 °C with an average energy of -620 J/g.

sample weight / mg	range of effect / °C	weight loss / mg	atm pressure / hPa
15.4	90-210 (endo) 290-460 (exo)	5 33 %	1007
18.18	90-210 (endo) 290-450 (exo)	5.95 33 %	1007

It is not possible to assign the observed endothermic effect definitely to melting or boiling of the test item.

Due to the fact that the measured weight loss of each sample was approx. 33 % of the initial sample weight, none of the observed endothermic effects can be assigned to boiling of test item. The endothermic effect might be a drying of the test item. The exothermic effect can be attributed to the decomposition of the test item.

Measurements by the capillary method

To verify the results of the DSC measurement, one additional measurement with the capillary method was performed in the temperature range of 25 – 400 °C with a heating rate of 10 K/min. The test item showed no optical change up to a temperature of 210 °C. At a temperature of 250 °C the color of the test item changed to grey / brown. At a temperature of 285 °C the test item is grey and changed its color to dark grey at 340 °C.The measurement was stopped at 400 °C with a black residue solid in the capillary. Neither a melting nor a boiling of the test item could be observed. Due to this fact, it can be stated that the test item has no melting and boiling point up to its decomposition starting at approx. 220 °C.

Thermal stability (DSC)

In the DSC runs, in the temperature range from 220 °C to 380 °C, an exothermic effect could be observed with an average decomposition energy of -760 J/g. After the measurement a black residual of the test item remained in the crucible.

sample weight / mg	start of effect / °C	energy J/g
4.27	220 - 380	-790 (exothermic)
4.35	220 - 380	-730 (exothermic)

Final Results

Melting and boiling point

The test item has no melting point up to its decomposition starting at a temperature of approx. 220 °C as determined by differential scanning calorimetry and capillary method.

The test item has no boiling point up to its decomposition starting at a temperature of approx. 220 °C as determined by differential scanning calorimetry.

Thermal stability

In the DSC-measurements the test item showed an exothermic effect from 220 °C with an average energy release of -760 J/g.

Conclusions:

The test item has no melting point up to its decomposition starting at temperature of ca. 220 °C, as determined by DSC and capillary method.
The test item has no boiling point up to its decomposition starting at temperature of ca. 220 °C, as determined by DSC.
In DSC-measurements, the test item showed an exothermic effect between 220 and 380 °C with an average energy release of -760 J/g.

Executive summary:

Melting and boiling point

Acid Brown 303 has no melting point up to its decomposition starting at a temperature of approx. 220 °C as determined by differential scanning calorimetry (perforated crucible) and capillary method according to OECD guideline 102 (1995).

Acid Brown 303 has no boiling point up to its decomposition starting at a temperature of approx. 220 °C as determined by differential scanning calorimetry according to OECD guideline 103 (1995).

Thermal stability

In the DSC-measurements (closed crucible), Acid Brown 303 showed an exothermic effect between 220 and 380 °C with an average energy release of -760 J/g.

Description of key information

No melting point up to decomposition starting at ca. 210 °C.

Exothermic decomposition between 220 and 380 °C with an average energy release of - 760 J/g.

Additional information

Melting and boiling point: OECD guideline 102, 103.

Thermal stability: OECD guideline 113.