2-[[4-[ethyl(2-hydroxyethyl)amino]phenyl]azo]-6-methoxy-3-methylbenzothiazolium chloride

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:

August 05, 2016 - August 30, 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

no

Type of method:

differential scanning calorimetry

Key result

Melting / freezing pt.:

> 90 °C

Atm. press.:

ca. 1 010 mBar

Decomposition:

yes

Decomp. temp.:

> 150 °C

  Individual results

 Melting point / melting range: DSC measurement

Two DSC measurements in aluminium crucibles with a hole showed a multistage endothermal effect in the temperature range of 90 – 150 °C with no clear melting point (onset). Afterwards exothermal decomposition started.

The results of the DSC measurements are summarized in Table 1.

Table 1: Melting point (DSC measurements)

Ident No.	Test item / mg	Starting temperature / °C	Final test temperature / °C	Temperature range (melting) / °C	Onset / °C	Crucible	Observations after the measurement
35739	12.61	25	450	90 –150	Multi-stage	Aluminium with a hole	Test item was black after the measurement
35817	10.03	25	400	90 – 145	Multi-stage	Aluminium with a hole	Test item was black after the measurement

An additional measurement with the capillary method was performed in order to clarify the melting range.

 

 Melting point / melting range: capillary tube in a metal block

A measurement with the capillary method was performed to clarify the results of the DSC measurements. Since this measurement was performed only as a verifying screening a high heating rate of 10 K/min was chosen and therefore the absolute temperature values derived with the capillary method are not as accurate as the DSC results. The filling height of the test item was approximately 5 mm.

The results are summarized in Table 2.

Table 2: Results of the capillary method

No.	Set point / °C	Heating rate / K/min	End point / °C	Remarks
1	60	10	200	Approx. 60°C: sample appeared unchanged. Approx. 104 °C: sample started to melt. Approx. 123 °C: sample completely melted and discoloured to black. Approx. 145 °C: formation of bubbles started. Approx. 180 °C: formation of bubbles deceased. Approx. 200 °C: no further change observed.

The capillary method measurement showed that the test item melted within a wide temperature range followed by decomposition.

Under consideration of the results from the thermal stability (ambiguous onset), the DSC measurements and the capillary method it was concluded that the test item started to melt at 90 °C followed by decomposition.

Conclusions:

The test item started to melt at 90 °C followed by decomposition.

Executive summary:

The melting point / melting range of the test substance was determined via Differential Scanning Calorimetry (DSC) and capillary tube in a metal block according to OECD 102.

For DSC, 12.61 mg and 10.03 mg of the test substance were heated constantly until the final temperature (450°C) is reached, while measuring the quantity of heat absorbed or released. The substance melted from 90°C to 150°C and was observed to be black after measurement.

For the capillary tube method, the test item was filled to a height of approx. 5 mm into the test tube and heated to the maximum temperature (410°C), while any changes of the substance are observed and recorded. The substance started to melt from 104°C. At 123°C the substance was completely melted and turned black.

According to these results the substance starts to melt at 90°C followed by decomposition.

Description of key information

The melting point / melting range of the test substance was determined via Differential Scanning Calorimetry (DSC) and capillary tube in a metal block according to OECD 102.

The test substance started melting at 90°C, followed by decomposition.