1,3-bis(2-methylphenyl)guanidinium m-[[p-anilinophenyl]azo]benzenesulfonate

Melting point / freezing point

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2017-12-06

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Determination of the melting point by the thermoanalytical technique DSC

GLP compliance:

no

Type of method:

differential scanning calorimetry

Key result

Decomposition:

yes

Decomp. temp.:

ca. 248 °C

Remarks on result:

not determinable

Remarks:

The test item shows no melting point.

Conclusions:

The Substance has no a melting point and decomposes before boiling

Executive summary:

A determination of the thermal stability of the test item by DSC (Differential Scanning Calorimetry) was performed with a DSC Mettler TOLEDO DSC 1, using a perforated crucible.

The Substance has no melting point and starts decomposing at ca. 248°C.

Reference 2

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2017-12-06

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Determination of the melting point by the thermoanalytical technique DSC

GLP compliance:

no

Type of method:

differential scanning calorimetry

Key result

Decomposition:

yes

Decomp. temp.:

ca. 248 °C

Remarks on result:

not determinable

Remarks:

The test item shows no melting point.

Conclusions:

The Substance has no a melting point and decomposes before boiling.

Executive summary:

A determination of the thermal stability of the test item by DSC (Differential Scanning Calorimetry) was performed with a DSC Mettler TOLEDO DSC 1, using a closed crucible.

The Substance has no melting point and starts decomposing at ca. 248°C.

Reference 3

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Version / remarks:

similar to Kofler hot bar

Deviations:

yes

Remarks:

: hot bar PROLABO, temperature is homogenous on the hot bar

Principles of method if other than guideline:

Technic similar to the Kofler Hot bar.
Apparatus PROLABO, temperature is homegenous at every point of the hot bar. Use of a rheostat to slow down the increase of the temperature.

GLP compliance:

no

Type of method:

other: similar to Kofler hot stage

Key result

Melting / freezing pt.:

>= 115 °C

Atm. press.:

ca. 1 013 hPa

Remarks on result:

other: As the test stopped at 123.5°C, no decomposition occured.

Conclusions:

Under normal conditions of pressure, the Substance has a melting point of 115°C.

Executive summary:

Under normal conditions of pressure, the Substance has a melting point of 115°C. The assay was stopped after reaching 123°C (no decomposition occured).

Description of key information

Melting point temperature

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

115 °C

Additional information

3 tests were performed to determine the melting of the Substance :

- one hot bar test

- two DSC (with perforated and closed crucible)

Method used	Melting point temperature	Decomposition temperature
Hot bar method	115 °C	Test stopped at 123°C, no decomposition occurred
DSC n°1 with perforated crucible 2017 batch 708033	75.16°C	~ 248°C
DSC n° 2 with closed crucible 2021 batch 013431	76.10°C	~ 248°C

 

The DSC n°1 (perforated crucible) shows an endothermic reaction between 53.04 and 118.34°C, with a peak of – 20.39 kJ/kg at 75.16°C. Then an exothermic phase starts at around 248°C, consistent with the beginning of the decomposition of the test item.

The DSC n°2 (closed crucible) shows an endothermic reaction between 57.02 and 124.37°C, with a peak of – 18.68 kJ/kg at 76.10 °C. Then an exothermic phase starts at around 248°C, consistent with the beginning of the decomposition of the test item.

 

An endothermic peak in a DSC heating curve, performed with a Mettler Toledo apparatus is a melting peak if :

- sample weight does not decrease significantly over the course of the peak, and

- the sample appears to have visibly melted after the measurement, and

- the surface area of the peak is between about 120 Jg-1 to 170 Jg-1 for non-polymeric organic substances, and

- the half-width of the peak is significantly less than 10 K (i.e. 10°C).

The surface area of the peaks of the two DSC is very low (--20.39 kJ/kg), which is << of the 120 kJ/kg cut off value. However, no data is provided concerning the half-width of the peaks and concerning the weight and the appearance of the sample appearance after the endothermic peak and before the exothermic one.

Therefore, the endothermic peaks observed at 75/76°C do not fulfil all the criteria of a melting point.

Conclusion: The Substance has a melting point of 115°C and starts decomposing at temperature > 248°C.