Bipridine derivatives:
A-1-methyl-4-phenylpipridine carboxylic acid.
B - Ester ethyl acid - 1 - methyl - 3 - phenylpiperedine - 3 - Carboxylic.
C - Ester ethyl acid 1 - Methyl - 3 - phenylpiperedine - 4 - Carboxylic (bethidine).
D-Quito Pimidone (INN) (1-4) Methydroxy Vinyl (1-Methyl-4-Pibridil Propane-1-En).
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Piperidine is an organic compound of molecular formula C5H11N, whose chemical structure corresponds to a six-membered saturated heterocyclic amine.
It was first described in 1850 by Scottish chemist Thomas Anderson and then, independently, by the Frenchman Auguste Cahours in 1852, who gave it its name.
The term "piperidine" comes from the word Piper, a genus of magnoliopsid plants that includes pepper.
Physical and chemical characteristics:
At room temperature, piperidine is a colorless or pale yellow smoking liquid.
It gives off a characteristic smell of ammonia, pepper or fish, also defined as nauseating.6 Its flavor has been described as "burning pepper"
It has its boiling point at 105 ºC and its melting point at -11 ºC. Less dense than water (ρ = 0.862 g / cm3), it is soluble in ethanol, ether, acetone, benzene and chloroform.
Its solubility in water - estimated citra - is 250 g / L. The logarithm value of its distribution coefficient, logP = 0.84, indicates a higher solubility in apolar solvents than in polar solvents.
Its vapor is three times denser than air.
Piperidine is a weak base (pKa = 11,28) .7 Therefore, it neutralizes acids in exothermic reactions forming salts and water.
When combined with strong reducing agents such as hydrides, it can generate hydrogen gas.
Conformation:
Piperidine adopts various spatial conformations, specifically a chair conformation similar to that presented by cyclohexane.
But unlike this, piperidine has two distinguishable chair conformations: one with the N-H bond in axial position, and the other in equatorial position.
After some controversy in the mid-twentieth century, it was concluded that the equatorial conformation is more stable (by 0.72 kcal / mol) in the gas phase.
Such conformation also seems to be the most stable in solutions of piperidine in apolar solvents, although in polar solvents the preferred conformation may be the opposite.
The two conformers quickly interconvert through the so-called nitrogen inversion (oscillation of the nitrogen atom from one to the other side of the plane formed by the groups to which it is attached); The estimated free energy for this process is 6.1 kcal / mol, substantially lower than the 10.4 kcal / mol necessary for the inversion of the ring (more global oscillation than if it retains the shape of the ring, it changes the positions space between atoms).
In the case of 1-methylpiperidine, the equatorial conformation is preferred by 3.16 kcal / mol, much greater energy than in the case of methylcyclohexane (1.74 kcal / mol).
Sources of piperidine and its derivatives:
Piperidine has been obtained from black pepper, from the natural varieties Psilocaulon absimile N.E.Br (Aizoaceae) and Petrosimonia monandra.
Likewise, the structure of piperidine is present in numerous natural alkaloids such as piperine - which gives black pepper its spicy flavor - the toxin of red ants Solenopsis invicta, the nicotine analogue known as anabasin - from the Nicotiana glauca shrub - Lobelia inflata lobelin or the toxic alkaloid cicutina from the genus of Conium plants.
Synthesis:
On an industrial level, piperidine is produced by hydrogenation of pyridine, normally catalyzed by molybdenum disulfide:
C5H5N + 3 H2 → C5H10NH
Pyridine can also be reduced to piperidine by sodium in ethanol in a modified Birch reduction, or using as a catalyst ruthenium nanoparticles on magnesium oxide.
Another route of synthesis consists in a dehydrogenation of 5-amino-1-pentanol using osmium and ruthenium complexes as catalysts.
Piperidine can also be obtained from cyclization of cadaverine at 180 ° C in the presence of a ruthenium catalyst in diphenyl ether.
A-1-methyl-4-phenylpipridine carboxylic acid.
B - Ester ethyl acid - 1 - methyl - 3 - phenylpiperedine - 3 - Carboxylic.
C - Ester ethyl acid 1 - Methyl - 3 - phenylpiperedine - 4 - Carboxylic (bethidine).
D-Quito Pimidone (INN) (1-4) Methydroxy Vinyl (1-Methyl-4-Pibridil Propane-1-En).
------------------------
Piperidine is an organic compound of molecular formula C5H11N, whose chemical structure corresponds to a six-membered saturated heterocyclic amine.
It was first described in 1850 by Scottish chemist Thomas Anderson and then, independently, by the Frenchman Auguste Cahours in 1852, who gave it its name.
The term "piperidine" comes from the word Piper, a genus of magnoliopsid plants that includes pepper.
Physical and chemical characteristics:
At room temperature, piperidine is a colorless or pale yellow smoking liquid.
It gives off a characteristic smell of ammonia, pepper or fish, also defined as nauseating.6 Its flavor has been described as "burning pepper"
It has its boiling point at 105 ºC and its melting point at -11 ºC. Less dense than water (ρ = 0.862 g / cm3), it is soluble in ethanol, ether, acetone, benzene and chloroform.
Its solubility in water - estimated citra - is 250 g / L. The logarithm value of its distribution coefficient, logP = 0.84, indicates a higher solubility in apolar solvents than in polar solvents.
Its vapor is three times denser than air.
Piperidine is a weak base (pKa = 11,28) .7 Therefore, it neutralizes acids in exothermic reactions forming salts and water.
When combined with strong reducing agents such as hydrides, it can generate hydrogen gas.
Conformation:
Piperidine adopts various spatial conformations, specifically a chair conformation similar to that presented by cyclohexane.
But unlike this, piperidine has two distinguishable chair conformations: one with the N-H bond in axial position, and the other in equatorial position.
After some controversy in the mid-twentieth century, it was concluded that the equatorial conformation is more stable (by 0.72 kcal / mol) in the gas phase.
Such conformation also seems to be the most stable in solutions of piperidine in apolar solvents, although in polar solvents the preferred conformation may be the opposite.
The two conformers quickly interconvert through the so-called nitrogen inversion (oscillation of the nitrogen atom from one to the other side of the plane formed by the groups to which it is attached); The estimated free energy for this process is 6.1 kcal / mol, substantially lower than the 10.4 kcal / mol necessary for the inversion of the ring (more global oscillation than if it retains the shape of the ring, it changes the positions space between atoms).
In the case of 1-methylpiperidine, the equatorial conformation is preferred by 3.16 kcal / mol, much greater energy than in the case of methylcyclohexane (1.74 kcal / mol).
Sources of piperidine and its derivatives:
Piperidine has been obtained from black pepper, from the natural varieties Psilocaulon absimile N.E.Br (Aizoaceae) and Petrosimonia monandra.
Likewise, the structure of piperidine is present in numerous natural alkaloids such as piperine - which gives black pepper its spicy flavor - the toxin of red ants Solenopsis invicta, the nicotine analogue known as anabasin - from the Nicotiana glauca shrub - Lobelia inflata lobelin or the toxic alkaloid cicutina from the genus of Conium plants.
Synthesis:
On an industrial level, piperidine is produced by hydrogenation of pyridine, normally catalyzed by molybdenum disulfide:
C5H5N + 3 H2 → C5H10NH
Pyridine can also be reduced to piperidine by sodium in ethanol in a modified Birch reduction, or using as a catalyst ruthenium nanoparticles on magnesium oxide.
Another route of synthesis consists in a dehydrogenation of 5-amino-1-pentanol using osmium and ruthenium complexes as catalysts.
Piperidine can also be obtained from cyclization of cadaverine at 180 ° C in the presence of a ruthenium catalyst in diphenyl ether.
Applications:
Piperidine is used as a solvent and as a base.
The same applies to some of its derivatives, such as N-formylpiperidine, an aprotic solvent with greater solubility for hydrocarbons than other solvents in the amide group, and 2,2,6,6-tetramethylpiperidine, a very useful base due to its low Nucleophilia and high solubility in organic solvents.
Another important industrial application of piperidine is in the production of dipiperidinyl ditiuram tetrasulfide, used as an accelerator in the vulcanization of rubber.
Piperidine and its derivatives are widely used in the synthesis of pharmaceutical products.
The structure of piperidine is found in compounds such as paroxetine, risperidone, methylphenidate, raloxifene, minoxidil, thioridazine, haloperidol, droperidol, mesoridazine, pethidine, melperone, the psychochemical agents Ditran-B (JB-329), N-methyl-3- piperidyl benzylate (JB-336) and many others.
Piperidine, as a secondary amine, is used to convert ketones into enamines, or as a basis in the condensation of Knoevenagel.
The enamines thus made can be used in alkylation reactions of Stork enamines.
Likewise, piperidine is widely used in chemical degradation reactions, such as DNA sequencing and subsequent excision of some specifically modified nucleotides.
On the other hand, this cycloamine appears, as a precursor substance, in Table II of the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, due to its use in the 1970s in the clandestine phencyclidine industry ( compound also known as "angel dust").
Precautions:
Piperidine is a flammable compound that burns toxic nitrogen oxides on burning.
Its flash point is 3 ° C.
Mixtures of this amine's vapor with air are explosive at room temperature.
It is a strong irritant that can cause permanent damage after a short exposure even in small quantities.
Ingestion may involve both reversible and irreversible changes.
Doses of 30-60 mg / kg can cause symptoms in the human body.
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Carboxylic acids