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| Names | |
|---|---|
| Preferred IUPAC name Piperazine[1] | |
| Systematic IUPAC name 1,4-Diazacyclohexane | |
| Other names Hexahydropyrazine Piperazidine Diethylenediamine 1,4-Diazinane | |
| Identifiers | |
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3D model (JSmol) | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
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| DrugBank |
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| ECHA InfoCard | 100.003.463 |
| KEGG |
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| UNII | |
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| Properties | |
| C4H10N2 | |
| Molar mass | 86.138 g·mol−1 |
| Appearance | White crystalline solid |
| Melting point | 106 °C (223 °F; 379 K)[2] |
| Boiling point | 146 °C (295 °F; 419 K)[2] Sublimes |
| Freely soluble[2] | |
| Acidity (pKa) | 9.8 |
| Basicity (pKb) | 4.19[2] |
| −56.8·10−6 cm3/mol | |
| Pharmacology | |
| P02CB01 (WHO) | |
| Pharmacokinetics: | |
| 60-70% | |
| Hazards | |
| NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Piperazine (/paɪˈpɛrəziːn/) is anorganic compound with the formula(CH2CH2NH)2. In terms of its structure, it can be described ascyclohexane with the 1- and 4-CH2 groups replaced by NH.[3] Piperazine exists as adeliquescent solid with asaline taste. Piperazine is freely soluble in water andethylene glycol, but poorly soluble indiethyl ether. Piperazine is commonly available industrially as the hexahydrate,(CH2CH2NH)2·6H2O, which melts at 44 °C and boils at 125–130 °C.[4]
Substituted derivatives of piperazine are a broad class ofchemical compounds. Many piperazines have useful pharmacological properties, with prominent examples includingsildenafil,ciprofloxacin, andziprasidone.[5][6]
Piperazines were originally named because of their chemical similarity withpiperidine, part of the structure ofpiperine in theblack pepper plant (Piper nigrum).[7] The -az- infix added to "piperazine" refers to the extra nitrogen atom, compared to piperidine. However, piperazines arenot in general derived from plants in thegenusPiper .
Piperazine is formed by the ammoniation of either1,2-dichloroethane orethanolamine. This reaction is mainly used for production ofethylene diamine, but piperazine is a side product.[8][9] The piperazine is separated from the product stream, which, in addition to ethylenediamine, also contains various derivatives containingCH2CH2NH subunits, e.g.diethylenetriamine,aminoethylpiperazine, and other related linear and cyclic chemicals of this type.
Piperazine can also be synthesized by reduction ofpyrazine with sodium inethanol.[citation needed]
As confirmed byX-ray crystallography, piperidine is acentrosymmetric molecule. The ring adopts achair conformation and the two N-H groups are equatorial.[10]
Itsbasicity is that of a typical amine. ThepH of a 10% aqueous solution of piperazine is 10.8–11.8. The twopKa's are 5.35 and 9.73 at 25 °C.
Piperazine readily absorbs water andcarbon dioxide from the air. Carbon dioxide produces a series ofcarbamates.[11] Some of the relevant equilibria are:
As a basic amine, piperazine forms a variety ofcoordination complexes, usually binding to metals as a unidentate ligand (bidentate binding would require the boat conformation). One example is thepolymer [CoCl2(piperazine)]n, which features tetrahedral cobalt centers linked by bridging piperazine ligands.[12]
Piperazine is easily N-alkylated. Depending on conditions mono- or dialkyl derivatives are obtained.[13]
Piperazine was marketed by Bayer as ananthelmintic in the early 20th century, and was featured in print ads alongside other popular Bayer products at the time, includingheroin.[14] In fact, a large number of piperazine compounds have an anthelmintic action. Their mode of action is generally byparalysingparasites, which allows the host body to easily expel the invasive organism. The neuromuscular effects are thought to be caused by blockingacetylcholine at the myoneural junction. This action is mediated by itsagonist effects upon the inhibitoryGABA (γ-aminobutyric acid) receptor. Its selectivity forhelminths is becausevertebrates useGABA only in theCNS, and the GABA receptor of helminths is of a different isoform from that of vertebrates.[15]
Piperazine hydrate,piperazine adipate andpiperazine citrate (used to treatascariasis andenterobiasis[16]) 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.
Two common salts in the form of which piperazine is usually prepared for pharmaceutical orveterinary purposes are the citrate, 3C4H10N2·2C6H8O7 (i.e. containing 3 molecules of piperazine to 2 molecules ofcitric acid), and the adipate, C4H10N2·C6H10O4 (containing 1 molecule each of piperazine andadipic acid).[4]
Many notable drugs contain a piperazine ring as part of their molecular structure. They may be used as antiparasitic drugs.[17] Other examples include:[18]Diethylcarbamazine, a derivative of piperazine, is used to treat some types offilariasis.
Most of these agents can be classified as eitherphenylpiperazines,benzylpiperazines,diphenylmethylpiperazines (benzhydrylpiperazines),pyridinylpiperazines,pyrimidinylpiperazines, ortricyclics (with the piperazinering attached to theheterocyclicmoiety via aside chain).
Piperazine is also a fluid used for CO2 and H2S scrubbing in association withmethyl diethanolamine (MDEA).
Piperazines, such asBZP andTFMPP were common adulterants in the club and rave scene, often being passed off asMDMA, although they do not share many similarities in their effects.
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