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Published byColin Stephens Modified over 9 years ago
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Heterocyclic Rings Pyridne, quinoline and isoquinoline
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Pyridne Pyridine is a water -miscible liquid, b. p. 115 oC with an unpleasant odour An Excelent polar solvent, A base (pka = 5.23) Pyrrole is less basic than pyridine becuase the lone pair of electrons in pyrrole is part of the aromatic ring, while that in pyridine is free.
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1) The Hantzsch Synthesis 1,3-dicarbonyl compound + ammonia + aldehyde
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2) Reaction of Ammonia + 1,5-diketone
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3) Diels-Alder Reaction
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4) Kroehnke Synthesis
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Chemistry of Pyridine
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Electrophilic Substitution Pyridine is million times less reactive than benzene Nitration (less than 5%, Chlorination in moderate yield, Bromination in a good yield) 3-position is usually attacked preferably
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ChiChibabin Reaction (Nucleophilic Substitution)
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Quinoline and Isoquinoline
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Quinoline Skraup Synthesis
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Combes Synthesis
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Isoquinoline Synthesis, Bischler-Napierlaski
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Pictet-Spengler Synthesis
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Pomeranz-Fritsch Synthysis
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Chemistry of Quinoline and Isoquinoline Nucleophilic Substitution (ChiChibabin Reaction)
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Electrophilic Substitution Occurs at the 5- or 8-positions, or both
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Quinoline N-Oxides can be nitrated at the 4-position or photoisomerize as follows
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