4,5-bis(hydroxymethyl)-2-phenyl-1H-imidazole

Boiling point

Link to relevant study record(s)

Reference

Endpoint:

boiling point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 01 September 2021 to 10 March 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 103 (Boiling Point/Boiling Range)

Version / remarks:

1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.2 (Boiling Temperature)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Specific details on test material used for the study:

Actual storage conditions: Stored in original plastic bag in a ventilated closed cupboard at normal laboratory temperature.

Decomposition:

yes

Decomp. temp.:

180 °C

Remarks on result:

other: based on DSC-TG curves drop, under inert atmosphere

Key result

Decomposition:

yes

Decomp. temp.:

120 °C

Remarks on result:

other: based on colour change, in air atmosphere

First Pre-test

No peak assigned to the melting and/or boiling of the substance was clearly observed. Therefore, measurement was stopped at 550°C.
A peak was observed from 218.3°C with a corresponding mass loss of 13.46 %.
Mass continues decreasing after the peak and perturbations on the DSC signal are observed. Considering the aspects of the crucible and substance at the end of measurement, the substance decomposed during the test and spilled out of the crucible.
Oxidative degradation is discarded as the measurement was performed under inert atmosphere (nitrogen). As the peak observed at 218.3°C is endothermic, a possible melting could occur before degradation of the test item. To verify this hypothesis, a new pre-test was performed.

Second Pre-test

The DSC signal looks similar with the first pre-test. The onset of the endothermic peak is observed from 214.3°C (start of both TG and DSC curves drop around 180°C) and a comparable mass-loss (-12.60%) is observed.
However, by looking at the test item appearance after cooling of the crucible, degradation already occurred even if the substance seems to have melted at the same time.

Muffle Furnace Observation

A first test was performed. By heating up to 200°C in the muffle furnace, the test item is already degraded and started to melt.
The endothermic peak observed from 214.3°C (onset temperature) during the second pre-test could eventually correspond with the melting of the test item but degradation occurs before.

Another test using the muffle furnace was performed. The test item was observed at least every 10°C up to 200°C.
Relevant observations are summarised below (pictures are available in the experimental report):

Temperature	Description
20°C to 110°C	The test item remains light-pink/white.
120°C	The test item starts to turn slightly pink-red (probably oxidative degradation).
130-140°C	The colouring becomes more and more pronounced.
150°C	The test item colour is now orange.
160°C	The test item becomes darker and start to « crack ».
170°C	The test item colour turns red.
180-185-190°C	The test item colour continues to darken.
200°C	The test item is completely black and seems to start melting (little « spheres » appear).

Based on the appearance of the substance during heating and combining this information with the results obtained from the TG-DSC thermograms, it appears that the test item degrades before melting. From the second pre-test results, the test item mass starts decreasing from 180°C and the DSC curve increases from the same temperature due to the degradation of the test item. An oxidative degradation is suspected to occur earlier from 120°C based on the test item colour change.

Considering the degradation of the test item, boiling point is “not determinable”.

Executive summary:

The boiling point of the test item was determined according to OECD 103 / EU A2 guidelines, using differential scanning calorimetry (DSC) method, and under GLP.

In the DSC pre-tests (under nitrogen atmosphere) no peak assigned to the melting or boiling of the substance was clearly observed up to 550°C. The aspect at the end of measurement showed degradation before 280°C, and partial mass loss started from ca 180°C. Additional test in the muffle furnace (in air atmosphere) showed visual colour change starting from 120°C, therefore oxidative degradation is suspected.

The boiling temperature of the test item is not determinable, due to decomposition before melting transition.

Description of key information

Not determinable: decomposition before boiling (and melting), starting from 120°C in air atmosphere. (OECD 103, DSC, GLP; Noel Y., 2022)

Key value for chemical safety assessment

Temperature of decomposition (state purity):

120 °C