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Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
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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 | |
3D model (JSmol)
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| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.003.463 |
| KEGG | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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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 their standard state (at 25 °C [77 °F], 100 kPa).
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Piperazine (/paɪˈpɛrəziːn/) is an organic compound with the formula (CH2CH2NH)2. In terms of its structure, it can be described as cyclohexane with the 1- and 4-CH2 groups replaced by NH.[3] Piperazine exists as a deliquescent solid with a saline taste. Piperazine is freely soluble in water and ethylene glycol, but poorly soluble in diethyl 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 of chemical compounds. Many piperazines have useful pharmacological properties, with prominent examples including sildenafil, ciprofloxacin, and ziprasidone.[5][6]
Piperazines were originally named because of their chemical similarity with piperidine, part of the structure of piperine in the black pepper plant (Piper nigrum).[7] The -az- infix added to "piperazine" refers to the extra nitrogen atom, compared to piperidine. However, piperazines are not in general derived from plants in the genus Piper.
Piperazine is formed by the ammoniation of either 1,2-dichloroethane or ethanolamine. This reaction is mainly used for production of ethylene 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 containing CH2CH2NH subunits, e.g. diethylenetriamine, aminoethylpiperazine, and other related linear and cyclic chemicals of this type.
Piperazine can also be synthesized by reduction of pyrazine with sodium in ethanol.[citation needed]
As confirmed by X-ray crystallography, piperidine is a centrosymmetric molecule. The ring adopts a chair conformation and the two N-H groups are equatorial.[10]
Its basicity is that of a typical amine. The pH of a 10% aqueous solution of piperazine is 10.8–11.8. The two pKa's are 5.35 and 9.73 at 25 °C.
Piperazine readily absorbs water and carbon dioxide from the air. Carbon dioxide produces a series of carbamates.[11] Some of the relevant equilibria are:
As a basic amine, piperazine forms a variety of coordination complexes, usually binding to metals as a unidentate ligand (bidentate binding would require the boat conformation). One example is the polymer [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 an anthelmintic in the early 20th century, and was featured in print ads alongside other popular Bayer products at the time, including heroin.[14] In fact, a large number of piperazine compounds have an anthelmintic action. Their mode of action is generally by paralysing parasites, which allows the host body to easily expel the invasive 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 use GABA only in the CNS, and the GABA receptor of helminths is of a different isoform from that of vertebrates.[15]
Piperazine hydrate, piperazine adipate and piperazine citrate (used to treat ascariasis and enterobiasis[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 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).[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 of filariasis.
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).
The antibacterial agent piperacillin takes its name from a piperazine ring substituted onto a penicillin core, conferring it activity against Pseudomonas aeruginosa.[19] Similarly, ciprofloxacin and levofloxacin are antipseudomonal fluoroquinolones by virtue of their piperazine rings.[19]
Piperazine is also a fluid used for CO2 and H2S scrubbing in association with methyl diethanolamine (MDEA).
Piperazines, such as BZP and TFMPP were common adulterants in the club and rave scene, often being passed off as MDMA, although they do not share many similarities in their effects.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
| Authority control databases: National |
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Piperazine () is an organic compound with the formula (CH2CH2NH)2. In terms of its structure, it can be described as cyclohexane with the 1- and 4-CH2 groups replaced by NH. Piperazine exists as a deliquescent solid with a saline taste. Piperazine is freely soluble in water and ethylene glycol, but poorly soluble in diethyl ether. Piperazine is commonly available industrially as the hexahydrate, (CH2CH2NH)2·6H2O, which melts at 44 °C and boils at 125–130 °C. Substituted derivatives of piperazine are a broad class of chemical compounds. Many piperazines have useful pharmacological properties, with prominent examples including sildenafil, ciprofloxacin, and ziprasidone.
1-[4-(Trifluoromethyl)phenyl]piperazine (pTFMPP) is a serotonergic releasing agent. It is rarely encountered as a designer drug but is much less common than the "normal" isomer meta-TFMPP.
3C-PEP, also known as 1-(3-chlorophenyl)-4-(2-phenylethyl)piperazine, is a designer drug of the piperazine class of chemical substances. 3C-PEP is related to meta-cholorophenylpiperazine (mCPP) and phenethylamine which can be thought of as mCPP having a phenylethyl group attached to the nitrogen atom at its 4-position. It was first described in 1994 in a patent disclosing a series of piperazine compounds as sigma receptor ligands. Later, it was discovered to be a highly potent dopamine reuptake inhibitor.
1-(2-Naphthyl)piperazine (2-NP), also known as 1-deazaquipazine, is a serotonin receptor modulator and putative serotonergic psychedelic of the arylpiperazine family related to quipazine. It shows affinity for the serotonin 5-HT1, 5-HT2, and 5-HT3 receptors and is known to act as a serotonin 5-HT2A receptor partial agonist. Conversely, it has negligible affinity for the serotonin 5-HT1D receptor. The drug produces the head-twitch response, a behavioral proxy of psychedelic effects, in rodents, although it was less efficacious than quipazine. This effect was absent in serotonin 5-HT2A receptor knockout mice. In addition, 2-NP fully generalizes to the psychedelic DOM in animal drug discrimination tests. Hence, it may have hallucinogenic effects in humans. Along with quipazine, the drug is one of a relatively small number of known psychedelics that is distinct from the tryptamine, phenethylamine, and lysergamide families. It was first described in the scientific literature by at least 1961.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.
