2-chloro-2-methylpropane

Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

from 2017-08-25 to 2017-11-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline 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:

no

Type of method:

differential scanning calorimetry

Key result

Melting / freezing pt.:

<= -20 °C

Atm. press.:

1 013.25 hPa

Decomposition:

no

Sublimation:

no

Individual results - melting point/range (DSC measurement)

One DSC measurement in an open crucible and two additional DSC measurements in closed glass crucibles were performed. In each case the test item was cooled down to -80 °C with a cooling rate of 10 K/min, -80 °C were kept for 30 min and afterwards the test item was heated up to 10 °C, 20 °C, and 25 °C, respectively, with a heating rate of 10 K/min. During the cooling down the DSC measurements showed an exothermal effect in the temperature range of -30 to -50 °C. During heating up the measurements showed two broad endothermal effects in the temperature range of -55 to -20 °C and in the temperature range of -20 to 0 °C, respectively. The onset temperature (see Table 1) was derived from the intersection of the tangent line with the highest slope of the endothermal peak with the baseline.

The results of the DSC measurements are summarized in Table 1.

Table 1: Melting point (DSC measurement)

Ident No.	Test item (mg)	Temperature range (endothermal) (°C)	Onset (°C)	Crucible	Observations after the measurement
36538	33.03	(-50) - (-20) (-20) - (0)	-46.68  -15.01	open glass	Test item was unchanged; mass loss: 61 %
36541	14.04	(-55) - (-30) (-30 - (-10)	-50.22  -22.89	closed glass	Test item was unchanged
36702	18.56	(-55) - (-30) (-30) - (-5)	-50.78  -22.36	closed glass	Test item was unchanged

Additionally to the DSC measurements, the liquid test item was brought to a temperature of approx. -26 °C with the help of a freezer. A visual check after around 12 h showed a solidified test item which however melted nearly spontaneously completely at room temperature. Taking both the DSC measurements and the visual check at approx. -26 °C into account it can be concluded that the melting point of the test item is below -20 °C.

In literature a polymorphism of the test item compounds is reported with different phases at low temperatures. The results of two endothermal effects in the DSC measurements agree with such phase transitions reported in literature. The latter describes the formation of an orientationally disordered plastic crystalline phase by colling down the test item below its freezing point of approximately -25 to -23 °C.

Conclusions:

The melting point/range of the test item was determined to be not above -20 °C.

Executive summary:

A study was performed according to OECD TG 102 and Commission Regulation (EC) No. 440/2008 method A.1 in order to determine the melting point/range of the test item by using differential scanning calometry method (DSC). One DSC measurement in an open crucible and two additional DSC measurements in closed crucibles were performed. The test item was cooled down to -80 °C with 10 K/min (kept for 30 min) and afterwards heated up to 10 °C, 20 °C and 25 °C with 10 K/min. During cooling down an exothermal effect was visible between -30 and -50 °C and during heating an endothermal effect was visible between -20 and 0 °C. During the measurements the test item remained unchanged. In addition to the DSC measurement the test item was cooled down to -26 °C with a freezer. After 12 hours at this temperature the test item was solidified. Under consideration of both the DSC measurements and the visual check at about -26 °C it was concluded that the melting point of the test item is below -20 °C. (reference 4.2-1).

Description of key information

The melting point of the substance is below -20 °C.

Additional information

In accordance with column 2 Annex VII section 7.2 of Regulation (EC) No 1907/2006 (REACH), the test on melting point does not need to be conducted as the melting point of the substance is below -20°C.

A study was performed according to OECD TG 102 and Commission Regulation (EC) No. 440/2008 method A.1 in order to determine the melting point/range of the test item by using differential scanning calometry method (DSC). One DSC measurement in an open crucible and two additional DSC measurements in closed crucibles were performed. The test item was cooled down to -80 °C with 10 K/min (kept for 30 min) and afterwards heated up to 10 °C, 20 °C and 25 °C with 10 K/min. During cooling down an exothermal effect was visible between -30 and -50 °C and during heating an endothermal effect was visible between -20 and 0 °C. During the measurements the test item remained unchanged. In addition to the DSC measurement the test item was cooled down to -26 °C with a freezer. After 12 hours at this temperature the test item was solidified. Under consideration of both the DSC measurements and the visual check at about -26 °C it was concluded that the melting point of the test item is below -20 °C. (reference 4.2 -2).