Disodium 4,5-dihydroxybenzene-1,3-disulphonate

Melting point / freezing point

Administrative data

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 Jan - 25 Apr 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht Kaiser-Friedrich-Straße 7, 55116 Mainz, Germany

Type of method:

differential scanning calorimetry

Test material

Test material information

Constituent 1

Reference substance name:

Disodium 4,5-dihydroxybenzene-1,3-disulphonate

EC Number:

205-741-5

EC Name:

Disodium 4,5-dihydroxybenzene-1,3-disulphonate

Cas Number:

149-45-1

Molecular formula:

C6H6O8S2.2Na

IUPAC Name:

disodium 4,5-dihydroxybenzene-1,3-disulphonate

Results and discussion

Melting / freezing point

Key result

Decomposition:

yes

Decomp. temp.:

393.39 °C

Any other information on results incl. tables

Pre-Test Results

Since 370 °C the colour of the test item was darker. Heating was performed up to 400 °C, the colour was black and the test item was still solid. The test item decomposed.

 

Security Pre-test Result for the DSC instrument

The crucible was found visual unchanged after reaching a temperature of 420°C. The weight was recorded with 52.66 mg. The crucible was opened after the heating process; the test item had changed from white to brown powder. The test item decomposed.

 

Calibration Results

After calibration with indium and zinc the measurement of indium yielded the following values:

Expected Melting Point	Measured     Melting point	Expected Heatflow	Measured Heatflow	Assessment
156.6±1.0°C	156.73°C	28.45±1.0J/g	28.24J/g	OK

Final results

Two events were detected and are presented in the following table.

Solid-solid Transition	in °C	in K
1.Determination	197,12	470,27
2.Determination	195,83	468,98
3.Determination	197,31	470,46
Mean	197,22	470,37
sd	0,13	0,13
For the calculation of the mean and the standard deviation, only the first and third determinations were taken into account.
Decomposition	in °C	in K
1.Determination	393,36	666,51
2.Determination	393,41	666,56
Mean	393,39	666,54
sd	0,04	0,04

Description for results evaluation

The first event should be considered as “solid-solid transition” confirmed by opening the crucible of the third measurement after DSC-measuring, the test item was still solid and no colour change was observed. Also in the pre-test it was observed that the test item was still solid after heating up to 400 °C.

 

The second event should be considered as “decomposition” confirmed by opening the crucible of the first measurement after DSC-measuring, the test item was a black powder.

 

Validity of Results

As the difference between the two evaluated determinations was below 0.5 K the result can be considered valid.

 

Results Discussion

The determination of the melting point of AF-378 was performed via DSC (differential scanning calorimetry. In the runs two events was detected for the first and the second de- terminations. The events are endotherm and are stated as the solid-solid transition for the first even and as decomposition temperature for the second event.

 

The results of the study should be stated as follows:

 

Event 1: was indicated as solid-solid transition with: 197.22 ± 0.13 °C (470.37 ± 0.13 K)

Event 2: was indicated as decomposition with: 393.39 ± 0.04 °C (666.54 ± 0.04 K)

 

These values are the means of two independent determinations ± standard deviations.

As the test item decomposed, no melting point could be determined under these circumstances.