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EC number: 215-170-3 | CAS number: 1309-42-8
Boiling point
Administrative data
Link to relevant study record(s)
- Endpoint:
- boiling point
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 19-03-2010 to 15-06-2010
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 103 (Boiling point/boiling range)
- Deviations:
- no
- 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
- Specific details on test material used for the study:
- - Name: Magnesium hydroxide
- Batch no. 20BR0026
- CAS No.: 1309-42-8
- Purity: 99.9 %
- Expiry date: 31 January 2012
- Storage Room Temp. in the dark - Key result
- Decomposition:
- yes
- Remarks:
- An exothermic point was observed at > 320°C - no visual changes observed in comparison to original test substance.
- Decomp. temp.:
- > 320 °C
- Conclusions:
- Reaction and/or decomposition of the test substance was observed at temperatures of > 320 °C (> 593 K).
An exothermic point was observed at 375.05°C (extrapolated from onset temperature 344.81 °C) - no visual changes observed in comparison to original test substance.
Boiling of the test substance was not observed below the temperature at which reaction/decomposition started.
The test substance has no boiling temperature. - Executive summary:
In a GLP guideline study according to OECD 103 and EEC A.2, the boiling point of Magnesium hydroxide was investigated.
The boiling point of Magnesium hydroxide was determined using DSC. Reaction and/or decomposition of the test substance was observed at temperatures of > 320 °C (> 593 K). Boiling of the test substance was not observed below the temperature at which reaction and/or decomposition started.
Based on this, the test substance has no boiling point.
Reference
Preliminary test:
6.15 mg of test substance was heated at a rate of 20 °C/minute from 25 °C to 550 °C. At this point 28 % weight loss of the test substance was observed. After the experiment the sample was cooled to 50 °C and the consistency of the test substance was determined.
Main study:
After each of the experiments, no visual changes could be observed when compared to the original test substance.
In the first experiment an endothermic peak was observed between 325 °C and 400 °C. The end temperature was set too low to obtain a complete endothermic peak. After the experiment, no visual changes could be observed when compared to the original test substance.
The second experiment investigated the endothermic peak between 325 °C and 400 °C, with the end temperature set to 500 °C. An endothermic peak was observed between 350 °C and 450 °C. The extrapolated onset temperature peak was 377.88 °C. A duplicate experiment was conducted and an endothermic peak was obtained between 325 °C and 450 °C. The extrapolated onset temperature of the peak was 372.03 °C.
In the fourth experiment, a repeated heating cycle was applied to investigate the exothermic peak between 325 °C and 450 °C. With the first heating the extrapolated onset temperature of the endothermic peak was 370.53 °C. During the cooling no exothermic peak was observed. This concluded that the endothermic peak is not obtained through the melting of the test substance. With the second heating no endothermic peak was observed. The endothermic peak in the first instance was probably due to reaction/decomposition of the test substance.
To further investigate the reaction/decomposition of the test substance a lower heating rate of 5 °C/minute was applied in the fifth experiment. The extrapolated onset temperature of the endothermic peak was 344.81 °C, so the endothermic peak shifted to lower temperatures. This demonstrates that reaction/decomposition of the test substance was the reason for the endothermic effect.
In order to obtain a temperature at which the reaction/decomposition starts the sixth experiment was a triplicate of the second and third experiments. The extrapolated onset temperature of the endothermic peak was 374.05 °C.
All relevant DSC figures are provided in the original study report.
Description of key information
The temperature of decomposition is greater than 320 °C.
Key value for chemical safety assessment
Additional information
Reaction and/or decomposition of the test substance was observed at temperatures of > 320 °C (> 593 K). Boiling of the test substance was not observed below the temperature at which reaction/decomposition started. Therefore, the test substance has no boiling temperature.
An exothermic point was observed at 375.05°C (extrapolated from onset temperature 344.81 °C) - no visual changes observed in comparison to original test substance.
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