Conhydrine
Encyclopedia
Conhydrine is a poisonous alkaloid
found in poison hemlock
in small quantities.
-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.
, 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
.
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 seemed to be excluded, since neither of the two forms of this product prepared by Löffler and Tschunke 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. 157-9 °C@744 mmHg, and a crystalline substance, C8H16O2, mp. 75-6 °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. 94-6 °C. On oxidation with permanganate
in dilute sulfuric acid
, propionaldehyde
and succinic acid
are produced, whilst the saturated substance, mp. 94-6 °C, is oxidised to n-valeric acid
. These results indicate that the substance of mp. 75-6 °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.
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
found in poison hemlock
Conium
Conium is a genus of two species of highly poisonous perennial herbaceous flowering plants in the family Apiaceae, native to Europe and the Mediterranean region as Conium maculatum, and to southern Africa as Conium chaerophylloides....
in small quantities.
Isolation and properties
This oxygenated alkaloid was isolated by Wertheim. It crystallises in colourless leaflets, has a coniineConiine
Coniine is a poisonous alkaloid found in poison hemlock and the yellow pitcher plant, and contributes to hemlock's fetid smell. It is a neurotoxin which disrupts the peripheral nervous system. It is toxic to humans and all classes of livestock; less than 0.2g is fatal to humans, with death caused...
-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
Benzoyl
In organic chemistry, benzoyl is the acyl of benzoic acid, with structure C6H5CO-. It should not be confused with benzyl, which is the radical or ion formed from the removal of one of the methyl hydrogens of toluene...
derivative mp. 132 °C.
Constitution
On oxidation with chromic acidChromic acid
The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. This kind of chromic acid may be used as a cleaning mixture for glass. Chromic acid may also refer to the...
, 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
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
at 180 °C or by hydrogenation of the mixture of coniceines produced, when it is dehydrated by phosphorus pentoxide
Phosphorus pentoxide
Phosphorus pentoxide is a chemical compound with molecular formula P4O10 . This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant.-Structure:...
in toluene
Toluene
Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...
.
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 seemed to be excluded, since neither of the two forms of this product prepared by Löffler and Tschunke 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
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
in ethyl alcohol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
of 2-pyridyl ethyl ketone, and that conhydrine on dehydrogenation over platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
or palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
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. 157-9 °C@744 mmHg, and a crystalline substance, C8H16O2, mp. 75-6 °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
Palladium on carbon
Palladium on carbon, often referred to as Pd/C, is a form of palladium used for catalysis. It is usually used for catalytic hydrogenations in organic chemistry...
absorbs enough to saturate one double bond producing a new substance, mp. 94-6 °C. On oxidation with permanganate
Potassium permanganate
Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...
in dilute sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
, propionaldehyde
Propionaldehyde
Propionaldehyde or propanal is the organic compound with the formula CH3CH2CHO. It is a saturated 3-carbon aldehyde and is a structural isomer of acetone...
and succinic acid
Succinic acid
Succinic acid is a dicarboxylic acid. Succinate plays a biochemical role in the citric acid cycle. The name derives from Latin succinum, meaning amber, from which the acid may be obtained....
are produced, whilst the saturated substance, mp. 94-6 °C, is oxidised to n-valeric acid
Valeric acid
Valeric acid, or pentanoic acid, is a straight-chain alkyl carboxylic acid with the chemical formula C5H10O2. Like other low-molecular-weight carboxylic acids, it has a very unpleasant odor. It is found naturally in the perennial flowering plant valerian , from which it gets its name. Its...
. These results indicate that the substance of mp. 75-6 °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.