Pyrrolidine, also known as tetrahydropyrrole, is an organic compound

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with the molecular formula C₄H₉N. It is a cyclic secondary amine

Amine

Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

 with a five-membered heterocycle containing four carbon

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 atoms and one nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 atom. It is a clear liquid with an unpleasant odor that is ammoniacal, fishy, shellfish-like and seaweed-like.

Pyrrolidine is found naturally in the leaves of tobacco

Tobacco

Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...

 and carrot

Carrot

The carrot is a root vegetable, usually orange in colour, though purple, red, white, and yellow varieties exist. It has a crisp texture when fresh...

. The pyrrolidine ring structure is present in numerous natural alkaloid

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...

s such as nicotine

Nicotine

Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...

 and hygrine

Hygrine

Hygrine is a pyrrolidine alkaloid, found mainly in coca leaves . It was first isolated by Carl Liebermann in 1889 as an alkaloid accompanying cocaine in coca. Hygrine is extracted as a thick yellow oil, having a pungent taste and odor....

. It is found in many pharmaceutical drugs such as procyclidine and bepridil

Bepridil

Bepridil is a calcium channel blocker once used to treat angina. 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 fibrillation....

. It also forms the basis for the racetam

Racetam

Racetams are a class of nootropic drugs that share a pyrrolidone nucleus.-Mechanism:There is no generally accepted mechanism for racetams. They generally show no affinity for the most important receptors, although modulation of most important central neurotransmitters, including acetylcholine and...

 compounds (e.g. piracetam

Piracetam

Piracetam is a nootropic drug. Piracetam's chemical name is 2-oxo-1-pyrrolidine acetamide; it shares the same 2-oxo-pyrrolidone base structure with 2-oxo-pyrrolidine carboxylic acid . Piracetam is a cyclic derivative of GABA. It is one of the group of racetams...

, aniracetam

Aniracetam

Aniracetam is an ampakine and nootropic of the racetam chemical class purported to be considerably more potent than piracetam. It is lipid-soluble and has possible cognition-enhancing effects. It has been tested in animals extensively, Alzheimer's patients, and temporarily-impaired healthy subjects...

).

A pyrrolidine ring is the central structure of the amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

s proline

Proline

Proline is an α-amino acid, one of the twenty DNA-encoded amino acids. Its codons are CCU, CCC, CCA, and CCG. It is not an essential amino acid, which means that the human body can synthesize it. It is unique among the 20 protein-forming amino acids in that the α-amino group is secondary...

 and hydroxyproline

Hydroxyproline

-4-Hydroxyproline, or L-hydroxyproline , is a common non-proteinogenic amino acid, abbreviated as HYP, e.g., in Protein Data Bank.-Structure and discovery:...

.

Pyrrolidine is a strong base and is by its basicity one of the strongest simple amines known.

In organic chemistry, pyrrolidine is used to activate ketone

Ketone

In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

s and aldehyde

Aldehyde

An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

s toward nucleophilic addition by formation of the imine

Imine

An imine is a functional group or chemical compound containing a carbon–nitrogen double bond, with the nitrogen attached to a hydrogen atom or an organic group. If this group is not a hydrogen atom, then the compound is known as a Schiff base...

.