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PIPERAZINE
Piperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste.
The piperazines are a broad class of chemical compounds, many with important pharmacological properties, which contain a core piperazine functional group.
Origin and naming
Piperazines were originally named because of their chemical similarity with piperidine, a constiuent of piperine in the black pepper plant (Piper nigrum).
Chemistry
Piperazine is freely soluble in water and ethylene glycol, but insoluble in diethyl ether. It is a strong base with a pKa of 4.19; the pH of a 10% aqueous solution is 10.8-11.8. Piperazine readily absorbs water and carbon dioxide from the air. Although many piperazine derivatives occur naturally, piperazine itself can be synthesized by reacting alcoholic ammonia with 1,2-dichloroethane; by the action of sodium and ethylene glycol on ethylene diamine hydrochloride; or by reduction of pyrazine with sodium in ethanol.
Medicinal Use
Piperazine was originally introduced into medicine as a solvent for uric acid. When taken into the body the drug is partly oxidized and partly eliminated unchanged. Outside the body, piperazine has a remarkable power to dissolve uric acid and producing a soluble urate, but in clinical experience it has not proved equally successful. Lycetol, lysidine and sidonal are compounds having similar action. Many piperazines are notable successful drugs, including:
As an anthelmintic
Piperazine was first introduced as an anthelmintic in 1953. A large number of piperazine compounds have anthelmintic action. Their mode of action is generally by paralysing parasites, which allows the host body to easily remove or expel the invading organism. This action is mediated by its agonist effects upon the inhibitory GABA (γ-aminobutyric acid) receptor. Its selectivity for helminths is because vertebrates only use GABA in the CNS and the helminths' GABA receptor is a different isoform to the vertebrate's one. Piperazine hydrate and piperazine citrate are the main anthelminthic piperazines. These drugs are often referred to simply as "piperazine" which may cause confusion between the specific anthelmintic drugs and the entire class of piperazine-containing compounds.
Other uses
Piperazines are also used in the manufacture of plastics, resins, pesticides, and other industrial materials.
References
- Merck Index, 11th Edition, 7431.
External links
This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
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