Terephthalaldehyde

Boiling point

Administrative data

Endpoint:

boiling point

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 103 (Boiling Point)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method A.2 (Boiling Temperature)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Test material

Test material information

Constituent 1

Reference substance name:

Terephthalaldehyde

EC Number:

210-784-8

EC Name:

Terephthalaldehyde

Cas Number:

623-27-8

Molecular formula:

C8H6O2

IUPAC Name:

benzene-1,4-dicarbaldehyde

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Batch (Lot) Number: 180401
Expiry date: 01 April 2020 (retest date)
Physical Description: Light yellow powder
Purity/Composition: 99.6%
Storage Conditions: At room temperature

Results and discussion

Boiling point

Key result

Boiling pt.:

ca. 259 °C

Decomposition:

yes

Decomp. temp.:

ca. 259 °C

Any other information on results incl. tables

Preliminary test

The TGA curve of the test item is shown inFigure 1. Starting at 175°C, the weight of the sample decreased significantly. At 252°C, the sample weight had decreased by 25%.

After the experiment, a yellow molten residue remained in the sample container (original colour: light yellow). The change of the colour indicated reaction and/or decomposition of the test item.

Main Study

The DSC curve obtained with Experiment 1 is shown inFigure 2. A first endothermic effect was observed between 100°C and 125°C. A second an endothermic effect started at 175°C. The extrapolated onset temperature of the first effect was 113.189°C. This endothermic effect was most likely obtained due to melting of the test item. The second endothermic effect was probably partly due to boiling combined with reaction and/or decomposition of the test item since after the experiment, a yellow molten residue remained in the sample container (original colour: light yellow). 

In order to investigate the firstendothermiceffect, Experiment 2 was stopped directly after the effect. Figure 3shows the DSC curve obtained. Theextrapolated onset temperature was 113.444°C. After the experiment, a light yellow molten residue remained in the sample container (original colour: light yellow). It demonstrated that melting was the reason for the first endothermic effect.

In order to investigate the secondendothermiceffect, a higher heating rate of 50°C/minute and a higher end temperature was used in the Experiment 3. Figure 4shows the DSC curve obtained. Theextrapolated onset temperature of the melting effect was 114.473°C. Theextrapolated onset temperature of the second endothermic effect was 259.057°C. The effect had not shifted significantly to higher temperatures and was therefore attributed to boiling of the test item but since some yellow molten residue remained in the sample container (original colour: light yellow), it was concluded that during boiling some reaction and/or decomposition of the test item occurred. Since a higher heating rate was used, the extrapolated onset temperature was not used in the calculation of the boiling point.

Experiment 4 was performed with a heating rate of 20°C/minute. Figure 5shows the DSC curve obtained. Similar results as in Experiment 3 were obtained. The extrapolated onset of the melting effect was 113.930°C. The extrapolated onset of the second endothermic effect could not be determined sufficiently accurate.After the experiment, some yellow molten residue remained in the sample container (ori ginal colour: light yellow).

In order toobtain an accurate boiling temperature, a sample container with lid in which a was drilled by the supplier was used in the Experiment 5. Figure 6shows the DSC curve obtained. Theextrapolated onset temperature of the melting effect was 113.896°C. Theextrapolated onset temperature of the second effect was 258.864°C. After the experiment, some yellow molten residue remained in the sample container (original colour: light yellow).

Experiment 6 was performed as a duplicate of Experiment 5. Figure 7shows the DSC curve obtained. Similar results as in Experiment 5 were obtained. The extrapolated onset of the melting effect was 113.973°C. Theextrapolated onset temperature of the second effect was 259.141°C. After the experiment, some yellow molten residue remained in the sample container (original colour: light yellow).

The melting temperature was determined as the mean melting temperature of Experiment 1 (113.189°C), Experiment 2 (113.444°C), Experiment 4 (113.930°C), Experiment 5 (113.896°C) and Experiment 6 (113.973°C).

The boiling temperature was determined as the mean melting temperature of Experiment 5 (258.864°C) and Experiment 6 (259.141°C).

Applicant's summary and conclusion

Conclusions:

The melting and boiling temperature of Terephthaldehyde were determined by DSC.
The melting temperature of the test item was 113.7°C (386.8K).
The boiling temperature of the test item was 259.0°C (532.2K).
Reaction and/or decomposition of the test item was observed during boiling.