Pyrrolidine, also known as tetrahydropyrrole, is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the molecular formula (CH₂)₄NH. It is a cyclic secondary

amine In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

, also classified as a saturated

heterocycle A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...

. It is a colourless liquid that is miscible with water and most organic solvents. It has a characteristic odor that has been described as "ammoniacal, fishy, shellfish-like". In addition to pyrrolidine itself, many substituted pyrrolidines are known.

Production and synthesis

Industrial production

Pyrrolidine is prepared industrially by the reaction of 1,4-butanediol and

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

at a temperature of 165–200 °C and a pressure of 17–21 MPa in the presence of a cobalt- and nickel oxide catalyst, which is supported on

alumina Aluminium oxide (or aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formula . It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium oxide. It is commonly ...

. :

The reaction is carried out in the liquid phase in a continuous tube- or tube bundle reactor, which is operated in the cycle gas method. The catalyst is arranged as a fixed-bed and the conversion is carried out in the downflow mode. The product is obtained after multistage purification and separation by extractive and

azeotropic distillation In chemistry, azeotropic distillation is any of a range of techniques used to break an azeotrope in distillation. In chemical engineering, ''azeotropic distillation'' usually refers to the specific technique of adding another component to genera ...

Laboratory synthesis

In the laboratory, pyrrolidine was usually synthesised by treating 4-chlorobutan-1-amine with a strong base: : Pyrrolidine synthesis

Furthermore, 5-membered ''N''-heterocyclic ring of the pyrrolidine derivatives can be synthesized via

cascade reaction A cascade reaction, also known as a domino reaction or tandem reaction, is a chemical process that comprises at least two consecutive reactions such that each subsequent reaction occurs only in virtue of the chemical functionality formed in the p ...

Occurrence

Many modifications of pyrrolidine are found in natural and synthetic drugs and drug candidates. The pyrrolidine ring structure is present in numerous natural

alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...

s ''i.a.''

nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...

and hygrine. It is found in many drugs such as

procyclidine Procyclidine is an anticholinergic medication, drug principally used for the treatment of drug-induced parkinsonism, akathisia and acute dystonia, Parkinson's disease, and idiopathic or secondary dystonia. Medical uses It is used in patients ...

and

bepridil Bepridil (trade name Vascor) is an diamine calcium channel blocker once used to treat angina pectoris. It is no longer sold in the United States. It is nonselective. It has been discussed as a possible option in the treatment of atrial fibri ...

. It also forms the basis for the

racetam Racetams, also sometimes known simply as pyrrolidones, are a class of drugs that share a pyrrolidone nucleus. Many, but not all, specifically have a 2- oxo-1- pyrrolidine acetamide (piracetam) nucleus. Some racetams, such as piracetam, aniracet ...

compounds (''e.g.''

piracetam Piracetam is a drug that has efficacy in cognitive disorders, vertigo, cortical myoclonus, dyslexia, and sickle cell anemia; sources differ on its usefulness for dementia. Piracetam is sold as a medication in many European countries. Piracetam ...

aniracetam Aniracetam (brand names Draganon, Sarpul, Ampamet, Memodrin, Referan), also known as ''N''-anisoyl-2-pyrrolidinone, is a racetam which is sold in Europe as a prescription drug. It is not approved by the Food and Drug Administration for use in t ...

). The

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

proline Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the p ...

and

hydroxyproline (2''S'',4''R'')-4-Hydroxyproline, or L-hydroxyproline ( C5 H9 O3 N), is an amino acid, abbreviated as Hyp or O, ''e.g.'', in Protein Data Bank. Structure and discovery In 1902, Hermann Emil Fischer isolated hydroxyproline from hydrolyzed gela ...

are, in a structural sense, derivatives of pyrrolidine. : Nicotine

Reactions

Pyrrolidine is a base. Its basicity is typical of other dialkyl amines. Relative to many secondary amines, pyrrolidine is distinctive because of its compactness, a consequence of its cyclic structure. Pyrrolidine is used as a building block in the synthesis of more complex organic compounds. It is used to activate

ketone In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

s and

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

s toward nucleophilic addition by formation of

enamine An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the r ...

s (e.g. used in the Stork enamine alkylation): : Enamine

References

External links

*{{Commonscat-inline Amine solvents