PYRROLE Kota.Swathi Assistant Professor Department of Pharmaceutical Chemistry St. Peters institute of pharmaceutical sciences Pyrrole is an unsaturated five membered heterocyclic compound with nitrogen as heteroatom at 1st position. It is
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Presentation Transcript
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PYRROLE Kota.Swathi
Assistant Professor
Department of Pharmaceutical Chemistry
St. Peter’s institute of pharmaceutical sciences<br>
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Pyrrole is an unsaturated five membered heterocyclic compound with nitrogen as heteroatom at 1st position.
It is a word derived from Greek, which pyrros means fiery oil.
Molecular fomula: C₄H₅N.
One of the important heterocyclic compound because many naturally
occuring compounds contain pyrrole ring.
E.g: Alkaloids, haemoglobin, chlorophyll….
It produces a bright red color when brought in contact with a pine splint moistened with conc. HCl.
Source:
Occurs in bone oil, coal tar & also derived from proteins.
Obtained from dry distillation or pyrrolysis of animal byproducts such as horns, hooves & bones.<br>
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Synthesis 1. FROM BONE OIL
Bone oil dil. Alkali bone oil free from acidic impurities
dil.acid
bone oil free from basic impurities
fractional distillation
Pyrrole ring fraction obtained (373K-423K)
fused with KOH
Potassium salt of Pyrrole
steam distillation
Pure Pyrrole (C₄H₅N)
2. FROM ACETYLENE (COMMERCIAL METHOD): Pyrrole can be synthesized commercially by passing a mixture of acetylene & ammonia through a red hot tube.
HC≡CH + HC≡CH NH₃<br>
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3. FROM SUCCINIMIDE: when succinimide is distilled with Zn dust, it reduced to pyrrole.
4. FROM FURAN: Furan on heating with ammonia in the presence of alumina (Al₂O₃) gives pyrrole over 400˚C.
5. PAAL-KNORR SYNTHESIS: By heating 1,4-dicarbonyl compounds with ammonia / primary amines/ hydrazines to give pyrrole derivatives is known as paal knorr synthesis.<br>
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Electrophilic Substitution Reactions Pyrrole undergoes substitution reaction predominantly at C₂ providing thermodynamically stable product. Although substitution also occurs at C₃ in some kinetically controlled reactions.<br>
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Acetylation: Pyrrole treated with acetic anhydride at 200˚C gives 2-acetyl pyrrole
while N-acetyl pyrrole cane be obtained by heating with N-acetyl imidazole.
Oxidation & Reduction: Pyrrole oxidized to maleinimide by chromium trioxide (CrO₃) in presence of acetic acid where as it catalytically reduced completely hydrogenate the ring system & produce pyrrolidine.<br>
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Medicinal Uses: Pyrrole has many variety of uses as follows<br>
