Piperazine is an organic compound that consists of a six-membered ring containing two nitrogen
atoms at opposite positions in the ring.
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, part of the structure of piperine in the black
pepper plant.
It is important to note, however, that piperazines are not derived from plants in the Piper genus.
Chemistry Piperazine is freely soluble in water and
ethylene glycol, but insoluble in diethyl ether.
It is a weak base with two pKbs of 5.35 and 9.73 at 25°C.; the pH of a 10% aqueous solution
of piperazine 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.
A form in which piperazine is commonly available industrially is as the hexahydrate, C4H10N2.
6H2O, which melts at 44°C and boils at 125-130°C. Two common salts in the form of which piperazine
is usually prepared for pharmaceutical or veterinary purposes are the citrate, 3C4H10N2.2C6H8O7,
and the adipate, C4H10N2.C6H10O4.
Industrial production Piperazine is formed as a co-product in the
ammoniation of 1,2-dichloroethane or ethanolamine.
These are the only routes to the chemical used commercially.
The piperazine is separated from the product stream, which contains ethylenediamine, diethylenetriamine,
and other related linear and cyclic chemicals of this type.
As an anti-helmintic 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.
The neuromuscular effects are thought to be caused by blocking acetylcholine at the myoneural
junction.
This action is mediated by its agonist effects upon the inhibitory GABA 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 vertebrates' one.
Piperazine hydrate and piperazine citrate are the main anthelmintic 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, brake fluid and other industrial materials.
Piperazines, especially BZP and TFMPP were extremely common adulterants in the club and
rave scene, often being passed off as MDMA, although they do not share many similarities
in their effects.
Piperazine is also a fluid used for CO2 and H2S scrubbing in association with methyl diethanolamine.
Piperazine derivatives as drugs Many currently notable drugs contain a piperazine
ring as part of their molecular structure.
Examples include: Antianginals
Antidepressants
Antihistamines
Antipsychotics
Recreational Drugs
Urologicals
Others
Most of these agents can be classified as either phenylpiperazines, benzylpiperazines,
diphenylmethylpiperazines, pyridinylpiperazines, pyrimidinylpiperazines, or tricyclics.
See also Pyridine
Pyrazine Piperidine
References
External links Piperazine citrate at Chemicalland21