5'-O-(p,p'-dimethoxytrityl)thymidine

Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-09-19 to 2018-02-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

GLP compliance:

no

Type of method:

differential scanning calorimetry

Key result

Melting / freezing pt.:

142.7 °C

Atm. press.:

ca. 1 atm

Decomposition:

yes

Decomp. temp.:

ca. 240 °C

Two DSC measurements with a heating rate of 10 K/min showed an endothermal effect (melting) in the temperature range of 130 °C – 170 °C.

The first DSC measurement with final temperature 500 °C additionally showed a slight exothermal effect starting at approx. 240 °C, indicating the decomposition of the substance. The decomposition of the substance was confirmed by the appearance of the sample after measurement (black residue) combined with a mass loss of 87% of the initial weigh-in (see table).

The second DSC measurement was terminated at 200 °C to ensure that the endothermal effect is the melting/softening effect. No decomposition was observed and the sample appeared as a yellow melt with no mass loss.

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

Table 1: DSC measurements

DSC run	Weigh-in / mg	Starting temperature / °C	Final test temperature / °C	Temperature range (endothermal) / °C	Onset / °C	Crucible	Observations after the measurement
1	9.58	25	500	130 -170	143.2	Aluminium with hole	Black residue, mass loss: 87%
2	8.97	25	200	130 - 160	142.2	Aluminium with hole	Test item was a yellow solified melt, no mass loss

Conclusions:

The test item melted in the temperature range between 130 – 170 °C under atmospheric conditions and started to decompose at a temperature of approx. 240 °C. The mean melting point was 142.7 °C under atmospheric conditions.

Executive summary:

The melting point / melting range of the test item DMT-dT was determined by DSC measurement according to OECD 102. The test item melted in the temperature range between 130 - 170 °C under atmospheric conditions and the mean melting point was 142.7 °C. At approx. 240 °C decomposition of the test item started.

Description of key information

The melting point / melting range of the test item DMT-dT was determined by DSC measurement according to OECD 102. The test item melted in the temperature range between 130 - 170 °C under atmospheric conditions and the mean melting point was 142.7 °C. At approx. 240 °C decomposition of the test item started.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

142.7 °C