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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:
02.03.2018 - 06.04.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.2 (Boiling Temperature)
GLP compliance:
no
Type of method:
differential scanning calorimetry
Key result
Decomposition:
yes
Decomp. temp.:
>= 240 °C

Performance of measurements with capillary method

The boiling behavior of the test item was confirmed by measurements with the capillary method:

A small quantity of the test item was filled up to 4 – 5 mm into a capillary and compacted by tapping on the capillary. The capillary and a thermometer were heated in the Büchi melting point apparatus from 120 to 400 °C at a heating rate of 10 K/min. The test item was watched while having been heated. When the test item started to melt or boil, the actual temperature was recorded.

Results

The test item shows an endothermic effect in the temperature range of 120 – 150 °C, which can be associated with a melting of the test item (melting point according to the certificate of analysis 127.1 °C). A second endothermic effect was observed in the temperature range of
230 – 310 °C, which cannot be clearly assigned to a boiling of the test item. No further thermal effects could be observed up to the maximum test temperature of 500 °C.

Table: Results of the DSC-measurements

No.

Sample weight / mg

Onset of Effect / °C

Range of effect / °C

Weight loss / mg

Atmospheric pressure / hPa

Remark

1

11.60

126.49
283.30

120 – 150 (endo)
230 – 310 (endo)

11.38

998.0

2

11.91

126.94
284.53

120 – 150 (endo)
230 – 300 (endo)

11.84

997.0

Due to the fact that the second endothermic effect could not be assigned to a boiling of the test item, due to its decomposition starting at 240 °C (see capillary method), the test item has no boiling point before its decomposition starting at a temperature of approx. 240 °C.

Conclusions:
Methylhydroquinone has no boiling point. Decomposition starts at approx. 240°C.
Executive summary:

The test item Methylhydroquinone has no boiling point up to its decomposition starting at approx. 240°C as determined by differential scanning calorimetry and capillary method according to Regulation EC No. 440/2008 Method A.2. and OECD Test Guideline 103 (1995).

Description of key information

According to Annex VII section 7.3, Column 2 of regulation (EC) 1907/2006, the study does not need to be conducted because the test item Methylhydroquinone decomposes before boiling. Decomposition starts at approx. 240 °C as determined by differential scanning calorimetry and capillary method according to Regulation EC No. 440/2008 Method A.2. and OECD Test Guideline 103 (1995).

C

Key value for chemical safety assessment

Additional information