Dipotassium hexacyanocobalt(II)-ferrate(II)

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

Study period:

24.5.-11.9.2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

A differential scanning calorimetry method compatible with Method A1 Melting/Freezing Temperature of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 102 of the OECD Guidelines for Testing of Chemicals, 27 July 1995 was used. The study is GLP compliant.

Reason / purpose for cross-reference:

reference to other 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)

Remarks:

Certificate included in the study report.

Type of method:

thermal analysis

Remarks:

Differential scanning calorimetry

Melting / freezing pt.:

> 450 °C

Atm. press.:

1 atm

Decomposition:

yes

Remarks:

According to studies performed by J. Lehto, S. Haukka, P. Koskinen and M. Blomberg the substance starts decomposing at 230 °C.

Decomp. temp.:

> 230 - < 300 °C

No evidence of melting below 450 °C (723 K). The broad endotherms from approximately 40 to 250 °C indicate a gradual loss of a volatile component, most likely water.

Conclusions:

The melting point study determined that the substance does not melt at temperatures below 450 °C. Visually, the samples did not change during the study. A supporting thermal decomposition study performed by J. Lehto et al. (1990) suggests that the substance starts to decompose at 230 °C. At 300 °C the substance has completely decomposed.

Executive summary:

The melting point was determined using differential scanning calorimetry in accordance with EU Method A.1 and OECD Guideline 102. According to the study, the substance does not melt at temperatures below 450 °C. According to a supporting study by J. Lehto et al. (1990) the substance starts to decompose at 230 °C. At 300 °C the substance has completely decomposed.

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:

other: The results from the decomposition study performed by J. Lehto, S. Haukka, P. Koskinen and M. Blomberg were published in the noted journal Thermochimica Acta in 1990. The article does not refer to any standard methods.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The test item was synthesized in the laboratory and the composition of the product was determined by atomic absorption spectrophotometry from samples dissolved in boiling concentrated sulphuric acid. The water content was calculated from the weight loss after heating the samples at 170 Celsius.

The thermograms (TG, DTG, DTA and EGD) were determined using a thermobalance.

The heated samples were analysed with X-ray diffraction. The samples were heated in an oven and the temperature was determined with a chromel-alumel thermocouple. The annealings were carried out in porcelain (< 650 degrees Celsius) and platinum crucibles (900 degrees Celsius).

GLP compliance:

not specified

Type of method:

thermal analysis

Decomposition:

yes

Decomp. temp.:

> 230 - < 300 °C

Remarks on result:

other: The decomposition begins at 230 Celsius. At approximately 300 Celsius all the product has decomposed. The study results show that the decomposition products themselves decompose as the temperature is gradually increased to above 900 Celsius.

The determination indicated that there were four different weight-loss ranges:

- 20 - 170 ⁰C: loss of water

- 230 - 300 ⁰C: decomposition of product

- 350 - 900 ⁰C: decomposition of the decomposition products and loss of gases

- > 900 ⁰C: decomposition of the decomposition products and loss of gases

The decomposition reaction has been determined to be the following:

K2CoFe(CN)6 x 1.4 H2O -> K3Fe(CN)6 + K3Co(CN)6 + K2CO3 + Co3O4 + Fe2O3 + CoFe2O4

At temperatures over 350 ⁰C, the decomposition reaction continues.

Conclusions:

Potassium cobalt hexacyanoferrate(II) has been shown to decompose before melting. The decomposition begins at 230 ºC and proceeds gradually as the temperature is raised until it has completely decomposed at 300 ºC.

Description of key information

 Thermal analysis (differential scanning calorimetry (DSC)):  Melting point > 450 °C at 1,013 hPa (OECD 102, EU Method A.1, GLP)

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

450 °C

Additional information

The melting point study determined that the substance does not melt at temperatures below 450 °C. Visually, the samples did not change during the study. A supporting thermal decomposition study by J. Lehto et al. (1990) suggests that the substance starts to decompose at 230 °C, and at 300 °C the substance has completely decomposed.