Piperidine

chembox
References= [ [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc03/icsc0317.htm International Chemical Safety Card 0317] ]
Name = Piperidine
ImageFileL1 = Piperidine.svg
ImageSizeL1 = 100px
ImageFileR1 = Piperidine-equatorial-3D-balls-B.png ImageSizeR1 = 120px
ImageFile2 = Piperidine-3D-vdW.png ImageSize2 = 150px
IUPACName = Piperidine
OtherNames = Hexahydropyridine Azacyclohexane, pentamethyleneamine
Section1 = Chembox Identifiers
SMILES = C1CCCCN1
CASNo = 110-89-4
RTECS = TM3500000
InChI=1/C5H11N/c1-2- 4-6-5-3-1/h6H,1-5H2
Section2 = Chembox Properties
Formula = C₅H₁₁N
MolarMass = 85.15 g/mol
Appearance = colourless liquid
Density = 0.862 g/ml, liquid
Solubility = miscible
MeltingPt = −7 °C
BoilingPt = 106 °C
pKa = 11.24
Viscosity = 1.573 cP at 25 °C
Section7 = Chembox Hazards
NFPA-H = 3
NFPA-F = 3
NFPA-R = 3
EUClass = Flammable (F) Toxic (T)
RPhrases = R11, R23/24, R34
Section8 = Chembox Related
OtherCpds = pyridine
pyrrolidine
piperazine

Piperidine is an organic compound with the molecular formula (CH₂)₅NH. This heterocyclic amine consists of a six-membered ring containing five methylene units and one nitrogen atom. It is a colorless fuming liquid with an odor described as ammoniacal, pepper-like; [cite book |title=Organic Analytical Reagents
author=Frank Johnson Welcher |year=1947 |publisher=D. Van Nostrand |pages=149] the name comes from the genus name "Piper", which is the Latin word for pepper. [cite book |author=Alexander Senning |title=Elsevier's Dictionary of Chemoetymology |p [ublisher=Elsevier |year=2006 |isbn=0444522395] Piperidine is a widely used building block and chemical reagent in the synthesis of organic compounds, including pharmaceuticals.

Production

Industrially, piperidine is produced by the hydrogenation of pyridine, usually over a molybdenum sulfide catalyst:Karsten Eller, Erhard Henkes, Roland Rossbacher, Hartmut Höke “Amines, Aliphatic” Ullmann's Encyclopedia of Industrial Chemistry 2002 Wiley-VCH. DOI|10.1002/14356007.a02_001]

: C₅H₅N + 3 H₂ → C₅H₁₀NH

Pyridine can also be reduced to piperidine by sodium in ethanol. [OrgSynth | author = C. S. Marvel and W. A. Lazier| title = Benzoyl Piperidine| collvol = 1 | collvolpages = 99 | year = 1941| prep = CV1P0099]

Natural occurrence of piperidine and derivatives

Piperidine itself has been obtained from pepper [ Spaeth and Englaender, Ber.1935,68, 2218; cf. Pictet and Pictet, Helv. Chim. Acta, 1927, 10, 593] , from Psilocaulon absimile N.E.Br (Aizoaceae) [ Rimington, S. Afr. J. Sci, 1934, 31, 184 ] , and in Petrosimonia monandra. [ Juraschewski and Stepanov, J. Gen. Chem., U.R.S.S., 1939, 9, 1687]

The piperidine structural motif is present in numerous natural alkaloids. These include piperine, which gives black pepper the hot taste. This gave the compound its name. Other examples are the fire ant toxin solenopsincite journal | author = Arbiser JL, Kau T, Konar M et al. | title = Solenopsin, the alkaloidal component of the fire ant (Solenopsis invicta), is a naturally occurring inhibitor of phosphatidylinositol-3-kinase signaling and angiogenesis | journal = Blood | year = 2007 | volume = 109 | issue = 2 | pages = 560–5 | doi = 10.1182/blood-2006-06-029934 | pmid = 16990598] , the nicotine analog anabasine of the Tree Tobacco (Nicotiana glauca), lobeline of the indian tobacco, the toxic alkaloid coniine from poison hemlock, which was used to put Socrates to death. [ The Plant Alkaloids, Thomas Anderson Henry, 4th ed. 1949, The Blakiston Company]

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, 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.cite journal |title=Influence of calculation level and effect of methylation on axial/equatorial equilibria in piperidines |journal=Journal of Computational Chemistry |volume=19 |issue=8 |year=1998 |pages=961–976 |author=Luis Carballeira, Ignacio Pérez-Juste |doi=10.1002/(SICI)1096-987X(199806)19:8<961::AID-JCC14>3.0.CO;2-A] In nonpolar 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. [cite journal |title=Conformation of piperidine and of derivatives with additional ring hetero atoms |author=Ian D. Blackburne, Alan R. Katritzky, Yoshito Takeuchi |journal=Acc. Chem. Res. |year=1975 |volume=8 |issue=9 |pages=300–306 |doi=10.1021/ar50093a003] 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. [cite journal |title=Nitrogen inversion in piperidine|author=F.A.L. Anet, Issa Yavari |journal=J. Am. Chem. Soc. |year=1977 |volume=99 |issue=8 |pages=2794–2796 |doi=10.1021/ja00450a064] 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 secondary amine. It is widely used to convert ketones to enamines. [OrgSynth | author = Vinayak V. Kane and Maitland Jones Jr | title = Spiro [5.7] trideca-1,4-dien-3-one| collvol = 7 | collvolpages = 473 | year = 1990 | prep = CV7P0473] Enamines derived from piperidine can be used in the Stork enamine alkylation reaction. ["March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure" Michael B. Smith, Jerry March Wiley-Interscience, 5th edition, 2001, ISBN 0-471-58589-0 ]

Piperidine can be converted to the chloramine C₅H₁₀NCl with calcium hypochlorite. The resulting chloramine undergoes dehydrohalogenation to afford the cyclic imine. [OrgSynth | author = George P. Claxton, Lloyd Allen, and J. Martin Grisar | title = 2,3,4,5-Tetrahydropyridine trimer| collvol = 6 | collvolpages = 968 | year = 1988 | prep = CV6P0968]

Uses

Piperidine is used as a solvent 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 highly sterically hindered 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 a rubber vulcanization accelerator.

Otherwise piperidine and its derivatives are ubiquitous building blocks in the synthesis of pharmaceuticals and fine chemicals. The piperidine structure is e.g. found in the pharmaceuticals risperidone, raloxifene, minoxidil, thioridazine, haloperidol, droperidol, mesoridazine, meperidine, melperone the psychochemical agents Ditran-B (JB-329), N-methyl-3-piperidyl benzilate (JB-336) and in many others.

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-amino acids 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 (also known as angel dust). [ [http://www.incb.org/pdf/e/list/red.pdf List of Precursors and Chemicals Frequently Used in the Illicit Manufacture of Narcotic Drugs and Psychotropic Substances Under International Control] , International Narcotics Control Board]

References