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Piperazine Structural Formula V1.svg
IUPAC name
Other names
Hexahydropyrazine; Piperazidine; Diethylenediamine; 1,4-diazinane
110-85-0 YesY
ChemSpider 13835459 N
DrugBank DB00592 YesY
Jmol 3D model Interactive image
KEGG D00807 YesY
PubChem 4837
Molar mass 86.136 g/mol
Appearance White crystalline solid
Melting point 106 °C (223 °F; 379 K)[1]
Boiling point 146 °C (295 °F; 419 K)[1] Sublimates
Freely soluble[1]
Acidity (pKa) 9.8
Basicity (pKb) 4.19[1]
P02CB01 (WHO)
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuel Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

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[edit]

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 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.[2]

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).[2]

Industrial production[edit]

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.[3] 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[edit]

Piperazine was first introduced as an anthelmintic in 1953[citation needed]. 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 vertebrates' one.

Piperazine hydrate, piperazine adipate and piperazine citrate (used to treat ascariasis and enterobiasis[4]) are the most common anthelmintic piperazine compounds. (These drugs are often referred to simply as "piperazine" which may cause confusion between the specific anthelmintic drugs, the entire class of piperazine-containing compounds), and the compound itself. Diethylcarbamazine, a derivative of piperazine, is used to treat some types of filariasis.

Other uses[edit]

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).

Amine blends that are activated by concentrated piperazine are used extensively in commercial CO2 removal for carbon capture and storage (CCS) because piperazine advantageously allows for protection from significant thermal and oxidative degradation at typical coal flue gas conditions.[5] The CO2 absorption rates and solvent capacities are increased through the addition of piperazine to amine gas treating solvents, the most common of which is MDEA due to its unmatched high rate and capacity efficiency when paired with piperazine.[6] Piperazine can be thermally regenerated through distillation and other methods after being used in operating temperatures up to 150°C and provides for higher overall energy performance in amine gas treating processes.[7]

Piperazine derivatives as drugs[edit]

Many currently notable drugs contain a piperazine ring as part of their molecular structure. Examples include:






Recreational Drugs



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[edit]


  1. ^ a b c d e Merck Index, 11th Edition, 7431
  2. ^ a b The Merck index, 10th Ed. (1983), p. 1076, Rahway:Merck & Co.
  3. ^ Ashford’s Dictionary of Industrial Chemicals, 3rd edition, 7332
  4. ^ "Helminths: Intestinal nematode infection: Piperazine". WHO Model Prescribing Information: Drugs Used in Parasitic Diseases - Second Edition. WHO. 1995. Retrieved 2015-08-29. 
  5. ^ Closmann, Fred; Nguyen, Thu; Rochelle, Gary T. (February 2009). "MDEA/Piperazine as a solvent for CO2 capture". Energy Procedia 1 (1): 1351–1357. Retrieved 15 April 2016. 
  6. ^ Li, Le; Voice, Alexander K.; Li, Han; Namjoshi, Omkar; Nguyen, Thu; Du, Yang; Rochelle, Gary T. (2013). "Amine blends using concentrated piperazine". Energy Procedia 37: 353–369. Retrieved 15 April 2016. 
  7. ^ Rochelle, Gary; Chen, Eric; Freeman, Stephanie; Wagener, David V.; Xu, Qing; Voice, Alexander (15 July 2011). "Aqueous piperazine as the new standard for CO2 capture technology". Chemical Engineering Journal 171 (3): 725–733. Retrieved 15 April 2016. 

External links[edit]