Pyrrolidine, also known as tetrahydropyrrole, is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

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

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...

, also classified as a saturated

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

. 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 1,4-Butanediol, colloquially known as BD or BDO, is a primary alcohol, and an organic compound, with the formula HOCH2CH2CH2CH2OH. It is a colorless viscous liquid. It is one of four stable isomers of butanediol. Synthesis In industrial sy ...

and

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

at a temperature of 165–200 °C and a pressure of 17–21 MPa in the presence of a cobalt- and

nickel oxide Nickel oxide may refer to: * Nickel(II) oxide, NiO, green, well-characterised oxide * Nickel(III) oxide Nickel (III) oxide is the inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydr ...

catalyst, which is supported on alumina. : Industrial synthesis of pyrrolidine

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 class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...

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 drug principally used for the treatment of drug-induced parkinsonism, akathisia and acute dystonia, Parkinson's disease, and idiopathic or secondary dystonia. Uses It is used in patients with parkinsonism and ...

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 fibrilla ...

. It also forms the basis for the

racetam Racetams are a class of drugs that share a pyrrolidone nucleus. Some, such as piracetam, aniracetam, oxiracetam, pramiracetam and phenylpiracetam are considered nootropics. Others such as levetiracetam, brivaracetam, and seletracetam are ant ...

compounds (''e.g.''

piracetam Piracetam is a drug marketed as a treatment for myoclonus. It is also used as a cognitive enhancer to improve memory, attention, and learning. Evidence to support its use is unclear, with some studies showing modest benefits in specific populat ...

, aniracetam). The

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

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 prot ...

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 gelatin. ...

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 a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

s and

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

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 th ...

s (e.g. used in the

Stork enamine alkylation The Stork enamine alkylation involves the addition of an enamine to a Michael acceptor (e.g, an α,β -unsaturated carbonyl compound) or another electrophilic alkylation reagent to give an alkylated iminium product, which is hydrolyzed by dilute ...

): :

References

External links

*{{Commonscat-inline Amine solvents