Chloral hydrate

Overview
Chloral hydrate, also known as trichloroacetaldehyde monohydrate, 2,2,2-trichloro-1,1-ethanediol, and under the tradenames Aquachloral, Novo-Chlorhydrate, Somnos, Noctec, and Somnote, is a sedative and hypnotic drug as well as a chemical reagent and precursor. Its chemical formula is C2H3Cl3O2.

It was discovered through the chlorination of ethanol in 1832 by Justus von Liebig in Gießen. It was widely abused and misprescribed in the late 19th century. Chloral hydrate is soluble in both water and alcohol, readily forming concentrated solutions. A solution of chloral hydrate in alcohol called "knockout drops" was used to prepare a Mickey Finn.

It is a minor side-product of the chlorination of water, concentrations rarely exceeding 5 micrograms per litre (µg/l).

Uses
It is used for the short-term treatment of insomnia and as a sedative before minor medical or dental treatment. It has been largely displaced by the development of benzodiazepines. It was also formerly used in veterinary medicine as a general anesthetic. Today, it is commonly used as an ingredient in the veterinary anesthetic Equithesin.

In therapeutic doses for insomnia it is effective within sixty minutes, it is metabolized within 4 minutes into trichloroethanol by erythrocytes and plasma esterases and many hours later into trichloroacetic acid. Higher doses can depress respiration and blood pressure. An overdose is marked by confusion, convulsions, nausea and vomiting, severe drowsiness, slow and irregular breathing, cardiac arrhythmia and weakness. It may also cause liver damage. It is moderately addictive. Chronic use can cause dependency and withdrawal symptoms. It can potentiate various anticoagulants and is weakly mutagenic in vitro and in vivo.

The corresponding anhydrous aldehyde, chloral, is used as an intermediate in insecticide and herbicide manufacture (including DDT, dichlorvos, and naled). Chloral reacts rapidly with water to form chloral hydrate.

Chloral hydrate is now illegal in the United States without a prescription. Chloral hydrate is a schedule IV controlled substance in the United States. Its properties sometimes lead to its use as a date rape drug.

Chloral in fiction

 * Jimmy Breslin, "The Gang That Couldn't Shoot Straight," 1969


 * Sarah Waters. Affinity. London: Virago Press, 1999.


 * Caleb Carr "The Alienist"   Random House,     1994


 * Edith Wharton. "The House of Mirth." New York: Holt, Rhinehart, and Winston, 1962.


 * Agatha Christie. "And Then There Were None." St. Martin's Minotaur, 1966.


 * From Russia with Love, Movie 1963


 * The Living Daylights, Movie 1987


 * Evelyn Waugh, Vile Bodies


 * Margery Allingham, Campion - The Case of the Late Pig


 * Brock Sampson, The Venture Brothers Episode 104 The Incredible Mr. Brisby