Cobalt(II) 4-oxopent-2-en-2-olate

Melting point / freezing point

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

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

GLP compliance:

no

Type of method:

thermal analysis

Melting / freezing pt.:

>= 170 - <= 180 °C

Reference 2

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

Michelin analysis proved that these results are not correct (see endpoint study record "Melting point-Michelin-Thermal analysis").

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Remarks:

No incident, which could have affected the quality or the interpretation of the results obtained, was observed.

GLP compliance:

yes (incl. QA statement)

Type of method:

thermal analysis

Melting / freezing pt.:

>= 115.8 - <= 116.8 °C

Atm. press.:

101.325 kPa

Decomposition:

no

Sublimation:

no

Description of key information

The report edited by Defitrace indicates a melting point of 116 °C for this substance.

We contest the conclusions of this study as melting point is defined in TGA-DSC as an endothermic peak without weight variation.

We conducted TGA measurements to follow  weight losses of the product as function of temperature. DSC measurements were then performed to characterize potential thermal phenomena.

Near 100 °C, losses due to water vaporisation are observed. Then important losses between 150 and 370 °C without significant thermal exchanges are probably due to product decomposition (loss of organic matter). At 750 °C, the residue is about 13 % meaning that there was also no complete vaporisation of the product but mainly a degradation and loss of the organic matter.

Additional information

Discussion:

 

- Phenomenon considered as Melting point by Defitrace: endothermic peak at 116 °C under Argon (DSC).

 

We observed the phenomenon near 100 °C. It is associated in ATGcurves to a weight loss of about 15 % (water). This matches the chemical composition of the substance: Peconal H is a dehydrated molecule that contains about 11 % water.

There is no melting of cobalt acetylacetonate at 116 °C.

 

An endothermic peak is observed near 180 °C without weight variation. It could correspond to a melting point (DH = 197 J/g).Under air, we could see the melting of the substance by this temperature, followed by an apparent oxidation (browning).

 

Under nitrogen, an important weight loss was observed in the DSC curve above 200 °C without significant thermal exchanges, which confirms product degradation from this temperature. The degradation goes on until more than 400 °C.

 

At 750 °C, the residue is about 13 % meaning that there was also no complete vaporisation of the product but mainly a degradation and loss of the organic matter.

 

Conclusions:

 

The endothermic phenomenon near 116 °C does not correspond to product melting but to “water of constitution” vaporisation.

The presence of an endothermic peak near 180 °C/ 190 °C could be interpreted as melting of the substance. Degradation of the product seems to begin near 200 °C.

 

No boiling point was identified.