Alkanes, fusion melting temperatures

The model substances for DSC were the same as those used for thermogravimetry (see section 3.1) such as the series of w-alkanes and some of the substances listed in ASTM D 2887-84. If an appropriate gas flow rate was used, then evaporation without residue of all the tested n-alkanes resulted, as already described for thermogravimetry. Fig. 3-39 demonstrates this behaviour for n-hexacontane. At a temperature of 99 °C there is a sharp fusion (melting) peak exhibiting a heat of fusion 243.3 J g. At 439 °C the maximum of energy resorption for the evaporation process appears, which has an onset temperature of 409 °C. The low energy resorption of 136 J g indicates the occurrence of an evaporation process. 

From DSC tests, data on the melting point MP and the heat of fusion (melting) are obtained. If the experiment is started at room temperature then data of the series of n-alkanes may be obtained, probably beginning with n-heptadecane (MP = 22 °C). If a commercial refrigerator (temperature range from -65 °C up to 250 °C) is used to cool the DSC cell, fusion and crystallization events my be recorded down to n-octane (MP = -56.8 °C). The cooling/heating rates should not exceed 5 K/min in order to measure... 

Adams catalyst, platinum oxide, Pt02 H20. Produced by fusion of H2PtCl6 with sodium nitrate at 500-550 C and leaching of the cooled melt with water. Stable in air, activated by hydrogen. Used as a hydrogenation catalyst for converting alkenes to alkanes at low pressure and temperature. Often used on Si02... 

---