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|Jmol-3D images||Image 1|
|Molar mass||86.14 g mol−1|
|Appearance||White crystalline solid|
106 °C, 379 K, 223 °F ()
146 °C, 419 K, 295 °F ()
|Solubility in water||Freely soluble|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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.
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 (Piper nigrum). It is important to note, however, that piperazines are not derived from plants in the Piper genus.
Piperazine is freely soluble in water and ethylene glycol, but insoluble in diethyl ether. It is a weak base with a pKb of 4.19; 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.
Two common salts in the form of which piperazine is usually prepared for pharmaceutical or veterinary purposes are the citrate, 3C4H10N2.2C6H8O7 (i.e. containing 3 molecules of piperazine to 2 molecules of citric acid), and the adipate, C4H10N2.C6H10O4 (containing 1 molecule each of piperazine and adipic acid).
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 (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 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 (MDEA).
Piperazine derivatives as drugs 
Many currently notable drugs contain a piperazine ring as part of their molecular structure. Examples include:
- 4-Bromo-2,5-dimethoxy-1-benzylpiperazine (2C-B-BZP)
- 1-Benzylpiperazine (BZP)
- 2,3-Dichlorophenylpiperazine (DCPP)
- 1,4-Dibenzylpiperazine (DBZP)
- 4-Methyl-1-benzylpiperazine (MBZP)
- 3-Chlorophenylpiperazine (mCPP)
- 3,4-Methylenedioxy-1-benzylpiperazine (MDBZP)
- 4-Methoxyphenylpiperazine (MeOPP)
- 4-Chlorophenylpiperazine (pCPP)
- 4-Fluorophenylpiperazine (pFPP)
- 3-Trifluoromethylphenylpiperazine (TFMPP)
Most of these agents can be classified as either phenylpiperazines, benzylpiperazines, diphenylmethylpiperazines (benzhydrylpiperazines), pyridinylpiperazines, pyrimidinylpiperazines, or tricyclics (with the piperazine ring attached to the heterocyclic moiety via a side chain).
See also 
|Wikisource has the text of the 1911 Encyclopædia Britannica article Piperazin.|