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Unit 3 Pyrrole
- 1. UNIT 3 SYNTHESIS REACTIONS& MEDICINAL USES OF PYRROLE Presented by SOWMIYA PERINBARAJ Assistant Professor Dept. of Pharmaceutical Chemistry SVCP
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- 3. PYRROLE WHAT IS PYRROLE? Pyrrole is an unsaturated five membered heterocyclic compound consists of nitrogen as heteroatom at 1st position. One of the important heterocyclic compound because many naturally occurring substances contain pyrrole ring. Eg: Alkaloids, haemoglobin, chlorophyll Its name derived from the fact that its vapours produce a bright red colour when brought in contact with a pine splint moistened with con. HCl. Greek word- Pyrros which means fiery oil Molecular formula: C4 H5 N
- 4. SOURCE: Pyrrole occursin coal- tar and in bone oil. Obtained from dry distillation or pyrolysis of animal by-products such as horns, hooves and bones. Ehrlich Test: Pyrrole + p-dimethylaminobenzaldehyde Intense Red colour PYRROLE Steam distillation Potassium salt of pyrrole formed Pyrrole removed by boiling with KOH Fractional distillation Washing with dil.alkali to remove acidic substances Washing with Sulphuric acid to remove basic substances Isolated Bone oil
- 5. SYNTHESIS PREPARATION 1) Paal-Knorrsynthesis 1,4-dicarbonyl compounds reacts with ammonia or primary amines to give pyrrole derivatives. CH2 CH2 C C O O R1 R C NH C CH CH R1 R NH3 -2H2O
- 6. 2) Hantzsch pyrrolesynthesis Reaction of α-haloketones with β-ketoester in presence of ammonia gives pyrrole derivatives. C CH3 O C H C H3 Cl + C H2 C O CH3 COOC2H5 NH3 -HCl -2H2O C NH C C C CH3 C H3 C H3 COOC2H5
- 7. 3) Knorr synthesis Cycliccondensation of α-aminoketone with β-ketoester gives pyrrole derivatives. C CH3 O C H C H3 NH2 + C H2 C O CH3 COOC2H5 C NH C C C CH3 C H3 C H3 COOC2H5 -2H2O
- 8. 4) From Furan(Commercial method) Furan passing over ammonia in presence of Aluminium oxide catalyst at high temperature 480-490 °C gives Pyrrole. O C H CH CH CH NH3 Al2O3 Δ NH C H CH CH CH O NH3 Al2O3 Δ NH Furan Pyrrole
- 9. 5) From acetylene Bypassing a mixture of acetylene and ammonia through a red hot tube. CH CH CH CH + NH3 Δ NH Acetylene Pyrrole
- 10. REACTIONS 1.ELECTROPHILIC SUBSTITUTION: Pyrrole undergoeselectrophilic substitution reaction at 2nd position C2 attack gives more resonance structures than C3 C2 Attack – more stable C3 attack – less stable
- 11. NH HNO3 (CH3CO)2O Nitration NH NO2 SO3 inpyridine Sulphonation NH SO3H Pyrrole 2-nitropyrrole 2-pyrrolesulphonic acid SO2Cl2 Chlorination NH Cl Cl Cl Cl 2,3,4,5-tetrachloropyrrole NH I I I I I2 aq.KI Iodination 2,3,4,5-tetraiodopyrrole CH3COOH +
- 12. NH (CH3COO)2O Friedel- Crafts Acylation NH COCH3 CH3COOH + 2-acetylpyrrole aq.K2CO3 Kolbe- schmitt Reaction NH COOH Pyrrole-2-carboxylicacid CHCl3 aq.KOH Reimer- Tiemann Reaction NH CHO 2-formylpyrrole Diazo coupling reaction NH N N N + N + Cl 2-phenylazopyrrole + HCl Pyrrole
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- 14. 4) Ring expansionreaction NH + 2CH3ONa CH2I2 + N 2NaI 2CH3OH + + Pyrrole Sodium methoxide Pyridine Methylene iodide
- 15. MEDICINAL USES 1. Proline ✓A major amino acid found in cartilage and is important for maintaining youthful skin as well as repair of muscle, connective tissue and skin damage. ✓ An essential component of collagen and is important for proper functioning of joints and tendons. 2. Nicotine ✓ A stimulant and potent parasympathomimetic (Cholinergic) alkaloid. It is used for smoking cessation to relieve withdrawal symptoms.
- 16. 3. Procyclidine An anticholinergicdrug used to treat the stiffness, tremors (involuntary movements) and poor muscle control of Parkinson's disease.
- 17. 4. Glycopyrrolate An anticholinergicdrug which is used in peptic ulcer. 5. Atorvastatin Belongs to a group of drugs known as Statins. Used to reduce high cholesterol level in blood and also reduce the risk of heart attack and stroke.