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Piperidine is an
organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon- hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
with the molecular formula (CH2)5NH. This heterocyclic
amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent su ...
consists of a six-membered ring containing five methylene bridges (–CH2–) and one amine bridge (–NH–). It is a colorless liquid with an odor described as objectionable, and typical of
amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent su ...
s. The name comes from the genus name '' Piper'', which is the Latin word for
pepper Pepper or peppers may refer to: Food and spice * Piperaceae or the pepper family, a large family of flowering plant ** Black pepper * ''Capsicum'' or pepper, a genus of flowering plants in the nightshade family Solanaceae ** Bell pepper ** Chili ...
. Although piperidine is a common organic compound, it is best known as a representative structure element within many pharmaceuticals and
alkaloid Alkaloids are a class of basic BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Th ...
s, such as natural-occurring solenopsins.


Production

Piperidine was first reported in 1850 by the Scottish chemist Thomas Anderson and again, independently, in 1852 by the French chemist Auguste Cahours, who named it. Both of them obtained piperidine by reacting piperine with nitric acid. Industrially, piperidine is produced by the
hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate org ...
of
pyridine Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakl ...
, usually over a molybdenum disulfide catalyst: : C5H5N + 3 H2 → C5H10NH Pyridine can also be reduced to piperidine via a modified Birch reduction using
sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...
in
ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a h ...
.


Natural occurrence of piperidine and derivatives

Piperidine itself has been obtained from black pepper, from '' Psilocaulon absimile'' ( Aizoaceae), and in '' Petrosimonia monandra''. The piperidine structural motif is present in numerous natural
alkaloid Alkaloids are a class of basic BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Th ...
s. These include piperine, which gives black pepper its spicy taste. This gave the compound its name. Other examples are the fire ant toxin solenopsin, the nicotine analog anabasine of tree tobacco ('' Nicotiana glauca''),
lobeline Lobeline is a pyridine alkaloid found in a variety of plants, particularly those in the genus '' Lobelia'', including Indian tobacco ('' Lobelia inflata''), Devil's tobacco ('' Lobelia tupa''), great lobelia ('' Lobelia siphilitica''), '' Lobeli ...
of Indian tobacco, and the toxic alkaloid coniine from poison hemlock, which was used to put
Socrates Socrates (; ; –399 BC) was a Greek philosopher from Athens who is credited as the founder of Western philosophy and among the first moral philosophers of the ethical tradition of thought. An enigmatic figure, Socrates authored no te ...
to death.


Conformation

Piperidine prefers a chair conformation, similar to cyclohexane. Unlike cyclohexane, piperidine has two distinguishable chair conformations: one with the N–H bond in an
axial position In organic chemistry, cyclohexane conformations are any of several three-dimensional shapes adopted by molecules of cyclohexane. Because many chemical compound, compounds feature structurally similar six-membered Ring (chemistry), rings, the stru ...
, 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. In
nonpolar solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for p ...
s, a range between 0.2 and 0.6 kcal/mol has been estimated, but in polar solvents the axial conformer may be more stable. The two conformers interconvert rapidly through nitrogen inversion; the free energy activation barrier for this process, estimated at 6.1 kcal/mol, is substantially lower than the 10.4 kcal/mol for ring inversion. In the case of ''N''-methylpiperidine, the equatorial conformation is preferred by 3.16 kcal/mol, which is much larger than the preference in methylcyclohexane, 1.74 kcal/mol.


Reactions

Piperidine is a widely used to convert
ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bon ...
s to enamines. Enamines derived from piperidine are substrates in the Stork enamine alkylation reaction. Upon treatment with calcium hypochlorite, piperidine converts to N-chloropiperidine, a chloramine with the formula C5H10NCl. The resulting chloramine undergoes dehydrohalogenation to afford the cyclic imine.


NMR chemical shifts

* 13C NMR: ( CDCl3, ppm) 47.27.2, 25.2 * 1H NMR: (CDCl3, ppm) 2.79, 2.19, 1.51


Uses

Piperidine is used as a
solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
and as a base. The same is true for certain derivatives: ''N''-formylpiperidine is a polar aprotic solvent with better hydrocarbon solubility than other amide solvents, and 2,2,6,6-tetramethylpiperidine is a highly
sterically hindered Steric effects arise from the spatial arrangement of atoms. When atoms come close together there is a rise in the energy of the molecule. Steric effects are nonbonding interactions that influence the shape ( conformation) and reactivity of ions ...
base, useful because of its low nucleophilicity and high solubility in organic solvents. A significant industrial application of piperidine is for the production of dipiperidinyl dithiuram tetrasulfide, which is used as an accelerator of the sulfur vulcanization of rubber.


List of piperidine medications

Piperidine and its derivatives are ubiquitous building blocks in pharmaceuticals and fine chemicals. The piperidine structure is found in, for example: * Icaridin (Insect repellent) *SSRIs ( selective serotonin reuptake inhibitors) ** Paroxetine * Stimulants and
nootropic Nootropics ( , or ) ( colloquial: smart drugs and cognitive enhancers, similar to adaptogens) are a wide range of natural or synthetic supplements or drugs and other substances that are claimed to improve cognitive function or to promote re ...
s: ** Methylphenidate ** Ethylphenidate ** Pipradrol ** Desoxypipradrol * Histamine 3 (H3) receptor antagonists/ inverse agonists: ** Pitolisant *SERM ( selective estrogen receptor modulators) ** Raloxifene * Vasodilators ** Minoxidil *
Antipsychotic Antipsychotics, also known as neuroleptics, are a class of psychotropic medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought), principally in schizophrenia but also in a range o ...
medications: **
Droperidol Droperidol (Inapsine, Droleptan, Dridol, Xomolix, Innovar ombination with fentanyl">fentanyl.html" ;"title="ombination with fentanyl">ombination with fentanyl is an antidopaminergic medication, drug used as an antiemetic (that is, to prevent o ...
** Haloperidol ** Melperone **
Mesoridazine Mesoridazine (Serentil) is a piperidine neuroleptic drug belonging to the class of drugs called phenothiazines, used in the treatment of schizophrenia. It is a metabolite of thioridazine. The drug's name is derived from the methylsulfoxy and pipe ...
** Risperidone ** Thioridazine *
Opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioi ...
s: ** Dipipanone ** Fentanyl and analogs ** Loperamide ** Pethidine (meperidine) **
Prodine Prodine (trade names Prisilidine and Nisentil) is an opioid analgesic that is an analog of pethidine (meperidine). It was developed in Germany in the late 1940s. There are two isomers of the trans form of prodine, alphaprodine and betaprodine ...
* Arylcyclohexylamines: ** PCP and analogs * anticholinergic
chemical weapons A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as ...
** Ditran ** ''N''-Methyl-3-piperidyl benzilate (JB-336, BZ) Piperidine is also commonly used in chemical degradation reactions, such as the sequencing of DNA in the cleavage of particular modified nucleotides. Piperidine is also commonly used as a base for the deprotection of
Fmoc The fluorenylmethoxycarbonyl protecting group (Fmoc) is a base-labile protecting group used in organic synthesis. Protection & Formation Fmoc carbamate is frequently used as a protecting group for amines, where the Fmoc group can be introduce ...
-
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
s used in solid-phase peptide synthesis. Piperidine is listed as a Table II precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances due to its use (peaking in the 1970s) in the clandestine manufacture of PCP (1-(1-phenylcyclohexyl)piperidine, also known as angel dust, sherms, wet, etc.).


References


External links

* {{Authority control Amine solvents Foul-smelling chemicals