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Boiling point

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Reference
Endpoint:
boiling point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
04 May to 17 August 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, with experiments conducted according to appropriate and valid guidelines and conducted under GLP conditions.
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
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7220 (Boiling Point / Boiling Range)
Deviations:
no
GLP compliance:
yes
Type of method:
differential scanning calorimetry
Key result
Boiling pt.:
220 °C
Atm. press.:
1 012
Remarks on result:
other: atm pressure ± 3 hPa; decomposition was not noted during the experiment

From the DSC-curve obtained from experiment 1, an endothermic peak was observed between 210°C and 250°C. The extrapolated onset temperature of the peak was 220.15°C. The effect was most likely obtained due to evaporation of the test material. After the experiment it was observed that the test material was evaporated from the sample container.

 

To investigate the evaporation peak a closed sample container was applied in experiment 3 and a DSC-curve was obtained. The extrapolated onset temperature of the melting evaporation peak was 107.02°C. The similar value obtained demonstrated that melting of the test material was the reason for the endothermic effect. As can be seen the endothermic peak shifted to higher temperatures. It demonstrated that evaporation of the test material was the reason for the endothermic effect. After the experiment it was observed that the test material was evaporated from the sample container.

 

Experiment 4 was performed to determine the duplicate melting temperature of the test material. However in addition to the observed melting peak at 107.44ºC another endothermic peak was observed between 210°C and 250°C. The extrapolated onset temperature of the peak was 220.26°C. The effect was due to evaporation of the test material. After the experiment it was observed that the test material was evaporated from the sample container.

Conclusions:
Under the conditions of the test, the boiling point of the test material was determined to be 220ºC at an atmospheric pressure of 1012 ± 3hPa.
Executive summary:

The boiling point of the test material was determined in a differential scanning calorimetry study performed in accordance with GLP and to the standardised guidelines OECD 103, EU method A.2 and EPA OPPTS 830.7220.

The boiling temperature was determined in three independent tests, and under the conditions of the test, an endothermic peak was observed between 210°C and 250°C in all three tests. When extrapolated the peak corresponded to an onset temperature of 220°C.

Description of key information

The boiling point of 3,5-Dimethylpyrazole was determined to be 220 ºC in a key study (Baltussen, 2012) performed according to OECD 103, EU  method A.2 and EPA OPPTS 830.7220; all other sources have been provided as supporting data.

Key value for chemical safety assessment

Boiling point at 101 325 Pa:
220 °C

Additional information

The boiling point of the test material has been addressed by providing one key study and seven supporting studies.

Baltussen (2012) has been provided as the key study, where the boiling point was determined by the differential scanning calorimetry method to be 220 ºC. The study was performed to GLP and in line with standardised guidelines and had thus been assigned a reliability score of 1 using the principles for assessing data quality as set out in Klimisch (1997).

The seven supporting studies provide consistent data, reporting the boiling point to be within the range 212 - 218 ºC. The consistency of the supporting data and proximity to the key study result provides verification of the endpoint conclusion. The supporting data consist of one peer reviewed handbook (Lide, 2010), three material safety data sheets (Alfa Aesar MSDS, 2007; Sigma Aldrich MSDS, 2010 and Fisher Scientific, 2008), two internet sources (chemBlink, 2012 and Wacker, 2012) and an experimental result taken from the QSAR EPISuite (MPBPVP v.1.43 EPISuite, 2012). Lide (2010) was assigned a reliability score of 2, whereas all other sources were assigned a reliability score of 4, according to the principles set out by Klimisch (1997) for assessing data quality.