Physical properties acyl halides

Identification of Alkyl Halides.—On account of their relative inertness at ordinary temperatures the alkyl halides are usually identified by the determination of their physical properties. They are insoluble in concentrated sulphuric acid, and, unlike the acyl halides, they do not react readily with water and alcohols. Unlike the compounds in which halogen is joined to nitrogen, they are not easily changed by an aqueous solution of sodium hydroxide. They are distinguished from many halogen derivatives of benzene and related hydrocarbons, which will be described later, by the fact that they are decomposed when boiled with an alcoholic solution of potassium hydroxide —... 

Acyl halides, such as acetyl chloride, and acid anhydrides, such as acetic anhydride, are used exclusively as reagents rather than as solvents. Consequently, their physical properties, such as boiling points and dielectric constants, are of less interest than those of other acyl derivatives. Because neither acyl hahdes nor acid anhydrides form tntermolecular hydrogen bonds, their boiling points are similar to structurally related carbonyl compounds of approximately the same molecular weight. 

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