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| Names | |||
|---|---|---|---|
| IUPAC name Piperidine | |||
| Preferred IUPAC name Piperidine[2] | |||
| Other names Hexahydropyridine Azacyclohexane Pentamethyleneamine Azinane | |||
| Identifiers | |||
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3D model (JSmol) | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.003.467 | ||
| EC Number |
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| KEGG | |||
| RTECS number |
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| UNII | |||
| UN number | 2401 | ||
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| Properties | |||
| C5H11N | |||
| Molar mass | 85.150 g·mol−1 | ||
| Appearance | Colorless liquid | ||
| Odor | Semen-like,[3] fishy-ammoniacal, pungent | ||
| Density | 0.862 g/mL | ||
| Melting point | −7 °C (19 °F; 266 K) | ||
| Boiling point | 106 °C (223 °F; 379 K) | ||
| Miscible | |||
| Acidity (pKa) | 11.22 (protonated)[4] | ||
| −64.2·10−6 cm3/mol | |||
| Viscosity | 1.573cP at 25 °C | ||
| Hazards | |||
| GHS labelling: | |||
   | |||
| Danger | |||
| H225,H311,H314,H331 | |||
| P210,P233,P240,P241,P242,P243,P260,P261,P264,P271,P280,P301+P330+P331,P302+P352,P303+P361+P353,P304+P340,P305+P351+P338,P310,P311,P312,P321,P322,P361,P363,P370+P378,P403+P233,P403+P235,P405,P501 | |||
| NFPA 704 (fire diamond) | |||
| Safety data sheet (SDS) | MSDS1 | ||
| Legal status | |||
| Related compounds | |||
Related compounds | Pyridine Pyrrolidine Piperazine Phosphorinane Arsinane | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Piperidine is anorganic compound with the molecular formula (CH2)5NH. Thisheterocyclicamine consists of a six-membered ring containing fivemethylene bridges (–CH2–) and one amine bridge (–NH–). It is a colorless liquid with an odor described as objectionable, typical ofamines.[6] The name comes from the genus namePiper, which is the Latin word forpepper.[7] Although piperidine is a common organic compound, it is best known as a representative structure element within many pharmaceuticals andalkaloids, such as natural-occurringsolenopsins.[8]
Piperidine was first reported in 1850 by the Scottish chemistThomas Anderson and again, independently, in 1852 by the French chemistAuguste Cahours, who named it.[9][10][11] Both of them obtained piperidine by reactingpiperine withnitric acid.
Industrially, piperidine is produced by thehydrogenation ofpyridine, usually over amolybdenum disulfide catalyst:[12]
Pyridine can also be reduced to piperidine via a modifiedBirch reduction usingsodium inethanol.[13]
Piperidine itself has been obtained fromblack pepper,[14][15] fromPsilocaulon absimile (Aizoaceae),[16] and inPetrosimonia monandra.[17]
The piperidine structural motif is present in numerous naturalalkaloids. These includepiperine, which givesblack pepper its spicy taste. This gave the compound its name. Other examples are thefire ant toxinsolenopsin,[18] thenicotine analoganabasine of tree tobacco (Nicotiana glauca),lobeline ofIndian tobacco, and the toxic alkaloidconiine frompoison hemlock, which was used to putSocrates to death.[19]
Piperidine prefers achair conformation, similar tocyclohexane. Unlike cyclohexane, piperidine has two distinguishable chair conformations: one with the N–H bond in anaxial position, and the other in an equatorial position. After much controversy during the 1950s–1970s, the equatorial conformation was found to be more stable by 0.72 kcal/mol in the gas phase.[20] Innonpolar solvents, a range between 0.2 and 0.6 kcal/mol has been estimated, but in polar solvents the axial conformer may be more stable.[21] The two conformers interconvert rapidly throughnitrogen inversion; the free energyactivation barrier for this process, estimated at 6.1 kcal/mol, is substantially lower than the 10.4 kcal/mol forring inversion.[22] In the case ofN-methylpiperidine, the equatorial conformation is preferred by 3.16 kcal/mol,[20] which is much larger than the preference inmethylcyclohexane, 1.74 kcal/mol.
 |  |
| axial conformation | equatorial conformation |
Piperidine is widely used to convertketones toenamines.[23] Enamines derived from piperidine are substrates in theStork enamine alkylation reaction.[24]
Upon treatment withcalcium hypochlorite, piperidine converts toN-chloropiperidine, achloramine with the formula C5H10NCl. The resulting chloramine undergoesdehydrohalogenation to afford the cyclic imine.[25]
Piperidine is used as asolvent and as abase. The same is true for certain derivatives:N-formylpiperidine is apolar aprotic solvent with better hydrocarbon solubility than other amide solvents, and2,2,6,6-tetramethylpiperidine is a highlysterically hindered base, useful because of its lownucleophilicity and high solubility inorganic solvents.
A significant industrial application of piperidine is for the production of dipiperidinyl dithiuram tetrasulfide, which is used as an accelerator of thesulfur vulcanization of rubber.[12]
Piperidine and its derivatives are ubiquitous building blocks in pharmaceuticals[26] and fine chemicals. The piperidine structure is found in, for example:
Piperidine is also commonly used in chemical degradation reactions, such as the sequencing ofDNA in the cleavage of particular modifiednucleotides. Piperidine is also commonly used as a base for thedeprotection ofFmoc-amino acids used in solid-phasepeptide synthesis.
Piperidine is listed as a Table II precursor under theUnited Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances due to its use (peaking in the 1970s) in the clandestine manufacture ofphencyclidine.[27]
L'alcali nouveau dérivé de la pipérine, que je désignerai sous le nom de 'pipéridine',… (The new alkali derived from piperine, which I will designate by the name of 'piperidine',…
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