N6-Benzoyl-5′-O-(4,4′-dimethoxytrityl)-2′-deoxyadenosine-3′-O-[O-(2-cyanoethyl)-N,N′-diisopropylphosphoramidite]

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:

2017-09-18 to 2018-02-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

Atm. press.:

ca. 1 atm

Decomposition:

yes

Decomp. temp.:

ca. 150 °C

Remarks on result:

other: No melting point could be determined. Substance only showed a softening effect in the temperature range between 35 - 95 °C, followed by decomposition at a temperature of approx. 150 °C.

Two DSC measurements with a heating rate of 10 K/min showed an endothermal effect in the temperature range of 35 – 95 °C.

The first DSC measurement additionally showed an exothermal effect starting at approx 150 °C indicating the decomposition of the test item. The decomposition of the substance was confirmed by the appearance of the sample after measurement (black residue) combined with a mass loss of 69 % of the initial weigh-in (see table).

The second measurement was terminated at 100 °C to ensure that the endothermal effect is the melting/softening effect. No decomposition was observed and the sample appeared as a white solified melt with a negligible mass loss (1 % of the initial weigh-in).

The results of the DSC measurements are summarized in the table below.

DSC run	Weigh-in / mg	Starting temperature	Final test temperature	Temperature range (endo-thermal) / °C	Onset / °C	Crucible	Observations after the measurement
1	9.32	25	500	35-95	37.92	Aluminium with hole	Black residue Mass loss: 69 %
2	13.88	25	100	35-95	38.80	Aluminium with hole	Test item was a white solified melt Mass loss: 1 %

The test item showed an unusually wide ranging endothermal effect (35 °C – 95 °C). Therefore it was concluded that the test item did not actually melt. The test item most likely softened in the temperature range of 35 °C – 95 °C. No additional endothermal effects were observed after the softening and before the exothermal effect at approximately 150 °C that indicated a decomposition of the test item.

Conclusions:

The test item showed an unusually wide ranging endothermal effect (35 °C – 95 °C). Therefore it was concluded that the test item did not actually melt. The test item most likely softened in the temperature range of 35 °C – 95 °C. No additional endothermal effects were observed after the softening and before the exothermal effect at approximately 150 °C that indicated a decomposition of the test item.

Executive summary:

The test item showed an unusually wide ranging endothermal effect (35 °C – 95 °C). Therefore it was concluded that the test item did not actually melt. The test item most likely softened in the temperature range of 35 °C – 95 °C. No additional endothermal effects were observed after the softening and before the exothermal effect at approximately 150 °C that indicated a decomposition of the test item.

Description of key information

The test item showed an unusually wide ranging endothermal effect (35 °C – 95 °C). Therefore it was concluded that the test item did not actually melt. The test item most likely softened in the temperature range of 35 °C – 95 °C.

Additional information

No additional endothermal effects were observed after the softening and before the exothermal effect at approximately 150 °C that indicated a decomposition of the test item.