24 PRACTICAL ORGANIC CHEMISTRY they are volatile or non-volatile. The commonest impurity in liquid compounds, namely water, should however be removed before distillation whenever conveniently possible. Drying of Liquid Compounds. Liquids are almost invariably dried by being kept in contact with a suitable powdered solid dehydrating agent, the dehydration being occasionally facilitated by boiling the liquid gently under reflux. When dehydration is complete, the liquid is either de-canted or (better) filtered from the dehydrating agent, and can then at once be further purified by distillation. The commonest dehydrating agents, with their practical limitations, are: Calcium chloride Cannot be used for alcohols, phenols or amines, (granular). with all of which it combines. Not advisable for acidic liquids, as ordinary calcium chloride always contains some calcium hydroxide owing to partial hydrolysis during preparation. Usually used for alcohols (see p. 88). Cannot
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.