Pyrrolidine

Preparation

Pyrrolidine is formed by reduction of pyrrole. Via overall 5-endo-trig cyclizations of homoallylic tosylamides. Pyrrolidine can be produced from butanediol and ammonia, e.g., over an aluminum thorium oxide catalyst at 300°C or over a nickel catalyst at 200°C and 20 MPa under hydrogenation conditions. It can also be produced from THF and ammonia over aluminum oxide at 275-375°C.

Air & Water Reactions

Highly flammable. Very soluble in water.

Reactivity Profile

Tetrahydro pyrrole neutralizes acids in exothermic reactions to form salts plus water. May be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. May generate hydrogen, a flammable gas, in combination with strong reducing agents such as hydrides. An explosion occurred when a mixture of Tetrahydro pyrrole, benzaldehyde, and propionic acid was heated in an attempt to form porphyrins.

Hazard

Flammable, dangerous fire risk. Toxic by ingestion and inhalation.

Health Hazard

The acute toxicity of pyrrolidine is moderateon test animals. It is somewhat less toxicthan pyrrole. The vapors are an irritant tothe eyes and respiratory tract. The liquid iscorrosive to the skin. Contact with the eyescan cause damage. The oral LD50 value inrats is 300 mg/kg, while the inhalation LC50value in mice is 1300 mg/m3/2 h (NIOSH1986).

Fire Hazard

Flammable/combustible material. May be ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.

Flammability and Explosibility

Highlyflammable

Safety Profile

Poison by ingestion and intravenous routes. Moderately toxic by inhalation. Dangerous fire hazard when exposed to heat or flame; can react vigorously with oxidizing materials. To fight fire, use alcohol foam, CO2, dry chemical. When heated to decomposition it emits hghly toxic fumes of NOx.

Purification Methods

Dry pyrrolidine with BaO or sodium, then fractionally distil it, under N2, through a Todd column (p 11) packed with glass helices. [Beilstein 20 H 159, 20 I 36, 20 II 79, 20 III/IV 2072, 20/1 V 162.]

General Description

Pyrrolidine (Tetrahydro pyrrole) is a versatile heterocyclic amine widely used in organic synthesis, acting as a catalyst in asymmetric Michael additions, facilitating nitrone formation through iminium activation, and serving as a nucleophile in amidinoethylation and SNAr reactions. It is also employed in the microwave-assisted synthesis of antimicrobial pyrrolidine derivatives and plays a key role in regioselective imidazole formation and amphiphilic allylation reactions. Its recyclability, stereoselectivity, and cooperative effects with other reagents make it valuable in green chemistry and pharmaceutical applications.

Physical properties

Pyrrolidine has a penetrating amine-type odor, reminiscent of ammonia and piperidine. It is easy to turn yellow when exposed to light or humid air, easily soluble in water and ethanol. It is nauseating and diffusive.

Application

Pyrrolidine is a heterocyclic compound used as a building block in the synthesis of wide range of pharmaceutical compounds, namely matrix metalloprotein inhibitors (MMPIs) and aminopeptidase N inhibitors (APNIs). It has been used for the synthesis of N-benzoyl pyrrolidine from benzaldehyde via oxidative amination. It may be used as a catalyst for the synthesis of N-sulfinyl aldimines from carbonyl compounds and sulfonamides.Pyrrolidine can also be used to synthesize:Taddol-pyrrolidine phosphoramidite, a ligand for rhodium-catalyzed [2+2+2] cycloaddition of pentenyl isocyanate and 4- ethynylanisole.H,4 PyrrolidineQuin-BAM (′PBAM′), a selective catalyst for the aza-Henry addition of nitroalkanes to aryl aldimines.1,2,3,3a,4,9-Hexahydropyrrolo[2,1-b]quinazoline by reacting with o-aminobenzaldehyde.

Definition

ChEBI: Pyrrolidine is a cyclic amine whose five-membered ring contains four carbon atoms and one nitrogen atom; the parent compound of the pyrrolidine family. It is a saturated organic heteromonocyclic parent, a member of pyrrolidines and an azacycloalkane. It is a conjugate base of a pyrrolidinium ion.

Aroma threshold values

Detection: 20.2 ppm

Taste threshold values

Taste characteristics at 50 ppm: ammonia and fishy, amine-like with seaweed and shellfish nuances.