Registration Dossier
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EC number: 200-609-3 | CAS number: 65-45-2
Melting point / freezing point
Administrative data
Link to relevant study record(s)
- Endpoint:
- melting point/freezing point
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Brief but adequate details of experimental setup, guideline equivalent. Purity reported. Instrument calibration reported. Large number of repeat experiments.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 102 (Melting point / Melting Range)
- Deviations:
- no
- GLP compliance:
- no
- Type of method:
- thermal analysis
- Melting / freezing pt.:
- 138.7 °C
- Atm. press.:
- ca. 1 atm
- Decomposition:
- no
- Remarks on result:
- other: ±0.5°C, melting point onset; ambient atmospheric pressure
- Melting / freezing pt.:
- 140 °C
- Atm. press.:
- ca. 1 atm
- Decomposition:
- no
- Remarks on result:
- other: ±0.4°C, melting point peak; ambient atmospheric pressure
- Conclusions:
- Carefully conducted literature study. The study is considered to be adequate and reliable.
- Endpoint:
- melting point/freezing point
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Similar to guideline study, well documented. Not conducted under GLP. Only the results from a preliminary test available; high heating rate may reduce accuracy.
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 102 (Melting point / Melting Range)
- Deviations:
- yes
- Remarks:
- high heating rate
- GLP compliance:
- no
- Type of method:
- thermal analysis
- Remarks:
- DSC
- Melting / freezing pt.:
- 140.88 °C
- Atm. press.:
- 98.7 kPa
- Decomposition:
- no
- Remarks on result:
- other: Melting point onset
- Melting / freezing pt.:
- 141.95 °C
- Atm. press.:
- 98.7 kPa
- Decomposition:
- no
- Remarks on result:
- other: Melting point peak
- Conclusions:
- The study is considered to be reliable with some restrictions.
- Endpoint:
- melting point/freezing point
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Similar to guideline study for melting point determination, very limited documentation on experimental details, sample purity was addressed.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 102 (Melting point / Melting Range)
- Deviations:
- not specified
- Principles of method if other than guideline:
- Survey of various pharmaceutical standards and an evaluation of their solubility and purity.
- GLP compliance:
- no
- Type of method:
- thermal analysis
- Remarks:
- DSC
- Melting / freezing pt.:
- 140.9 °C
- Atm. press.:
- ca. 1 atm
- Decomposition:
- no
- Remarks on result:
- other: Ambient atmospheric pressure
Referenceopen allclose all
Estimated errors at 95% confidence interval. Only the monoclinic structure was observed.
Description of key information
138.7±0.5°C, OECD 102, DSC, Nordström 2006
140.88°C, OECD 102, DSC, Weissenfeld 2010
140.9°C, similar to OECD 102, DSC, Grady 1973
142°C, no guideline, hotstage, sublimation observed, McCrone 1953
Key value for chemical safety assessment
- Melting / freezing point at 101 325 Pa:
- 139 °C
Additional information
A very large body of experimental data exists in the literature for melting point, which is not reproduced here (see literature search). The range of melting points observed likely reflects experimental error, as well as the larger effect of different purities. Of the available literature data, a subset was selected based on the best documented reports.
A recent study conducted to ascertain the boiling point also reported the melting point, although under sub-optimal experimental conditions (Weissenfeld, 2010). This was in close agreement with an older study reporting the melting points of various pharmaceutical standards (Grady, 1973). The highest reported value (McCrone, 1953) was by the least precise technique; a hotstage measurement. The most precise (although not necessarily most accurate) measurement was that conducted by Nordström et al (Nordström, 2006), which was based on the average of 13 replicate DSC scans. This is the value (rounded) which is selected and carried forward for risk assessment, classification and labelling.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
