Conhydrine

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title: "Conhydrine" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["piperidine-alkaloids", "neurotoxins", "2-piperidinyl-compounds"] topic_path: "general/piperidine-alkaloids" source: "https://en.wikipedia.org/wiki/Conhydrine" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 401682942 | Name = Conhydrine | ImageFile = (+)-alpha-Conhydrine.png | ImageClass = skin-invert | ImageSize = 180px | ImageName = Conhydrine | PIN = (1R)-1-[(2S)-Piperidin-2-yl]propan-1-ol |Section1= {{Chembox Identifiers | SMILES=OC@H[C@H]1NCCCC1 | CASNo_Ref = | CASNo = 495-20-5 | UNII_Ref = | UNII = Q21EOC14Q2 | ChemSpiderID_Ref = | ChemSpiderID = 9919452 | PubChem = 10314 | EC_number = 207-798-1 | StdInChI_Ref = | StdInChI = 1S/C8H17NO/c1-2-8(10)7-5-3-4-6-9-7/h7-10H,2-6H2,1H3/t7-,8+/m0/s1 | StdInChIKey_Ref = | StdInChIKey = VCCAAURNBULZRR-JGVFFNPUSA-N | Section2 = {{Chembox Properties |C=8|H=17|N=1|O=1 |MeltingPtC = 121 |BoilingPtC = 226 |SpecRotation = +10° (natural) |Solubility = moderate |Solubility2=good |Solvent2 = ethanol |Solubility3=good |Solvent3 = chloroform |Solubility4=moderate |Solvent4 = diethylether

Conhydrine is a poisonous alkaloid found in poison hemlock (Conium maculatum) in small quantities.

Isolation and properties

This oxygenated alkaloid was isolated by Wertheim from C. maculatum. It crystallises in colourless leaflets, has a coniine-like odour, can be sublimed, and is strongly basic. It crystallises readily from ether. The salts are crystalline; the aurichloride small rhombs or prisms, mp. 133 °C; the benzoyl derivative mp. 132 °C.

Constitution

On oxidation with chromic acid, conhydrine yields L-piperidyl-2-carboxylic acid. It is converted into L-coniine either by reduction of the iodo-derivative (iodoconiine), C8H16IN, formed by the action of hydriodic acid and phosphorus at 180 °C or by hydrogenation of the mixture of coniceines produced, when it is dehydrated by phosphorus pentoxide in toluene.

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These and other observations indicate that the oxygen atom must occur as a hydroxyl group, in the *n-*propyl side chain in either the α- or β-position, since the γ-position would involve the production of piperidyl-2-propionic acid on oxidation. 2-β-Hydroxypropyl-piperidine suggested by Willstätter resembled conhydrine, and these authors suggested the α-position as probably representing the alkaloid. Support for this view was provided by Hess and coworkers , who showed that DL--*N-*methylconhydrone is *N-*methyl-2-piperidyl ethyl ketone, that DL-conhydrine (mp. 69–70 °C), produced by a somewhat indirect method, is identical with the product, mp. 69.5–71.5 °C, prepared by Engler and Bauer by the reduction with sodium in ethyl alcohol of 2-pyridyl ethyl ketone, and that conhydrine on dehydrogenation over platinum or palladium asbestos gives rise to a mixture of tetrahydropyridyl 2-ethyl ketone and 2-α-hydroxypropyl-pyridine. Späth and Adler have shown that conhydrine can be degraded in two stages by exhaustive methylation to trimethylamine, and a mixture of two products, an oil, C8H14O, bp. 157–159 °C@744 mmHg, and a crystalline substance, C8H16O2, mp. 75–76 °C. The oil, when heated with water at 170 °C is converted, by addition of a molecule of water, into the crystalline substance. The latter contains two active hydrogen atoms (Zerewitinoff estimation), and on exposure to hydrogen over Pd/C absorbs enough to saturate one double bond producing a new substance, mp. 94–96 °C. On oxidation with permanganate in dilute sulfuric acid, propionaldehyde and succinic acid are produced, whilst the saturated substance, mp. 94–96 °C, is oxidised to n-valeric acid. These results indicate that the substance of mp. 75–76 °C is εζ-dihydroxy-Δα-n-octene, that the oil, C8H14O, is the corresponding oxide, and that the representation of conhydrine as 2-α-hydroxypropyl-pyridine accounts for their production.

References

References

  1. (1856). "Ueber ein neues Alkaloïd in Conium maculatum". Annalen der Chemie und Pharmacie.
  2. (1901). "Oxydation des Conydrins". Berichte der Deutschen Chemischen Gesellschaft.
  3. (1885). "Zur Kenntniss der Coniin-Gruppe". Berichte der Deutschen Chemischen Gesellschaft.
  4. (1890). "Ueber die Coniceïne". Justus Liebig's Annalen der Chemie.
  5. (1909). "Die Synthese des β-Coniceins (l-α-Allyl-piperidin)". Berichte der Deutschen Chemischen Gesellschaft.
  6. (1933). "Zur Konstitution des Konhydrins". Monatshefte für Chemie.
  7. (1909). "Über die Konstitution des Conhydrins (optisch-aktives α-Äthyl-piperidyl-alkin)". Berichte der Deutschen Chemischen Gesellschaft.
  8. (1917). "Über die Alkaloide des Granatapfelbaumes. IV. Ein Trennungsgang für die Reindarstellung der Pelletierin-Alkaloide. Aufklärung der Konstitution des Methyl-isopelletierins (Methyl-pelletierin, Isomethyl-pelletierin). Umwandlung des Conhydrins in Methylisopelletierin. Die Konstitution des Conhydrins". Berichte der Deutschen Chemischen Gesellschaft.
  9. (1919). "Über die Beziehung von Methyl-isopelletierin, d,l-Methyl-conhydrinon und (N-Methyl-piperidyl)-propan-1-on. Ein Isomeriefall von Verbindungen mit einem asymmetrischen dreiwertigen Stickstoffatom. VI. Mitteilung über die Alkaloide des Granatapfelbaumes". Berichte der Deutschen Chemischen Gesellschaft (A and B Series).
  10. (1920). "Über die Fähigkeit der Pflanze, optische Antipoden aufzubauen". Berichte der Deutschen Chemischen Gesellschaft (A and B Series).
  11. (1925). "Neue Umwandlungen von Conhydrin und Methylisopelletierin. (V. Mitteilung zur Frage des asymmetrischen dreiwertigen Stickstoffatoms)". Justus Liebig's Annalen der Chemie.
  12. (1928). "Über das Methyl-isopelletierin. (VIII. Mitteilung zur Stereochemie des gesättigten dreiwertigen Stickstoffatoms)". Justus Liebig's Annalen der Chemie.
  13. (1891). "Ueber das α-Aethylpyridylketon und dessen Ueberführung in Pseudoconhydrin". Berichte der Deutschen Chemischen Gesellschaft.
  14. (1894). "Die Reductionsproducte des α-Methylpyridylketons und die Nichtidentität des α-Aethyl-Piperylalkins mit dem activen Pseudoconhydrin". Berichte der Deutschen Chemischen Gesellschaft.

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piperidine-alkaloidsneurotoxins2-piperidinyl-compounds