Purifying and drying solid reagents

If the purity of the reagent is not up to the level required, standard solid purification techniques (chromatography, recrystallization, sublimation) should be used to purify it (see Chapter 11 for more details). 

Purification of some common solid reagents AIBN(a,a -Azobis(isobutyronitrile)) 

Recrystallize from diethyl ether and dry under vacuum, over P2O5 at room temperature. Store under inert atmosphere, in the dark, at -10 C. 

Para-toluenesulphonyl chloride often contains a considerable quantity of pam-toluenesulphonic acid. This can be removed by placing the reagent in the thimble of a soxhlet apparatus containing dry petroleum ether. After several hours of extraction under an inert atmosphere, the chloride will have dissolved in the solvent and the unwanted acid will be left behind in the soxhlet thimble. On cooling the solvent mixture, the acid chloride crystallizes and can be collected by filtration. The purified material should be stored under an inert atmosphere. 

Wash with ether, to remove grease from the surface of the metal, dry at 100°C under vacuum and cool in a desiccator. For a more active form of magnesium, stir the turnings under nitrogen overnight. They will turn almost black as the oxide coat is removed from the surface. The material produced is very active and should be used immediately or stored for a short period under inert atmosphere. 

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