Chloral

Chloral, also known as trichloroacetaldehyde, is the organic compound with the formula Cl₃CCHO. This aldehyde is a colourless oily liquid that is soluble in a wide range of solvents. It reacts with water to form chloral hydrate, a once widely used sedative and hypnotic substance.

Production

Chloral is produced commercially by the chlorination of acetaldehyde in hydrochloric acid, producing chloral hydrate. Ethanol can also be used as a feedstock. This reaction is catalyzed by antimony trichloride:

The chloral hydrate is distilled from the reaction mixture. The distillate is then dehydrated with concentrated sulfuric acid, after which the heavier acid layer (containing the water) is drawn on"

The resulting product is purified by fractional distillation. Small amounts of chloral hydrate occur in some chlorinated water.

Key reactions

Chloral tends to form adducts with water (to give chloral hydrate) and alcohols.

Aside from its tendency to hydrate, chloral is notable as a building block in the synthesis of DDT. For this purpose, chloral is treated with chlorobenzene in the presence of a catalytic amount of sulfuric acid: