Bis(acetato-O)hydroxyaluminium

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:

from 2015-03-31 to 2015-06-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Key result

Decomposition:

yes

Decomp. temp.:

> 280 - < 440 °C

One measurement in an aluminium crucible with a hole showed a first endothermal effect in temperature range of 90 - 170 °C with an onset temperature of 131.7 °C and a second one in the temperature range of 280 - 440 °C with an onset temperature of 321.6 °C. No further endothermal or exothermal effects were observed up to the final temperature of 500 °C. The mass loss after the DSC measurements amounted to 69 %. A second DSC measurement in aluminium crucible with a hole showed an endothermal effect in the temperature range of 105 - 165 °C with an onset of 133.1 °C. No further endothermal or exothermal effects were observed up to the final temperature of 250 °C. The mass loss after the DSC measurements amounted to 12 %.

 

Table 1: Melting point (DSC measurements)

 

Ident No.	Test item / mg	Final test temperature / °C	Temperature range / °C	Onset / °C	Crucible	Observations
34961	11.63	500	90 – 170 280 – 440	131.7 321.6	Aluminium with a hole	Test item was discoloured to beige-brown after the measurement
34967	9.22	250	105 - 165	133.1	Aluminium with a hole	Test item appeared unchanged after the measurement

 

According to the certificate of analysis (CoA) of the test item, it has a moisture content of 6.0 - 15.0 %. Therefore and according to the observed mass loss, it was assumed that the first endothermal effect was caused by evaporation of water. Considering the mass loss and the observation after the measurement with a final temperature 500 °C, the second endothermal peak could be assigned to decomposition under release of acetate. Thus it was concluded that the test item had no melting point, it decomposed first.

Conclusions:

An endothermal effect at approximately 130 °C due to water release was observed. A second endothermal effect at around 320 °C due to release of acetate was observed. A mass loss in the range of 12 - 69 % was observed in all tests which a sign of decomposition. Therefore, the item decomposes above 280 °C before it starts to melt.

Executive summary:

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1 and EPA OPPTS test guideline 830.7200 to determine the melting point of the test item using differential scanning calorimetry. The test item was weighed out into an aluminium crucible with a hole under an inert atmosphere (nitrogen). Two tests with 9 – 12 mg of the test item were performed. As reference crucible, an empty aluminium crucible with a hole was used. The substance is solid at ambient conditions. The crucibles were heated up to 500 °C (second test up to maximum 250 °C) at a constant heating rate of 10 K/min. In the temperature range of 90 – 170 °C, an endothermal effect was observed in the two tests. A second endothermal effect was observed in the first run at a temperature range of 280 - 440 °C. Mass loss in the range of 12 – 69 % was observed in both tests. In consideration of the mass loss detected after the second measurement, it can be assumed that the first endothermal effect is decomposition under release of water and the second one, under release of acetate. Therefore, the test item has no melting point up to 500 °C. No observations were made which cause doubt of the validity of the outcome of the study.

Description of key information

An endothermal effect at approximately 130 °C due to water release was observed. A second endothermal effect at around 320 °C due to release of acetate was observed. A mass loss in the range of 12 - 69 % was observed in all tests which a sign of decomposition. Therefore, the item decomposes above 280 °C before it starts to melt.

Additional information

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1 and EPA OPPTS test guideline 830.7200 (reference 4.2-1) to determine the melting point of the test item using differential scanning calorimetry. The test item was weighed out into an aluminium crucible with a hole under an inert atmosphere (nitrogen). Two tests with 9 – 12 mg of the test item were performed. As reference crucible, an empty aluminium crucible with a hole was used. The substance is solid at ambient conditions. The crucibles were heated up to 500 °C (second test up to maximum 250 °C) at a constant heating rate of 10 K/min. In the temperature range of 90 – 170 °C, an endothermal effect was observed in the two tests. A second endothermal effect was observed in the first run at a temperature range of 280 - 440 °C. Mass loss in the range of 12 – 69 % was observed in both tests. In consideration of the mass loss detected after the second measurement, it can be assumed that the first endothermal effect is decomposition under release of water and the second one, under release of acetate. Therefore the test item has no melting point up to 500 °C. No observations were made which cause doubt of the validity of the outcome of the study.