7 - HETEROCYCLES
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what is the structure of indole?
present in tryptophan aromatic, has 10 pi electrons
what are the properties of pyrrole?
• aromatic and more reactive than benzene (often a catalyst is not needed) • weakly basic • high boiling point due to the intramolecular H bonding in pyrrole • undergoes electrophilic substitution reactions such as halogenation, nitration etc
how is pyrrole made from furan?
treatment of furan with ammonia in the presence of a catalyst such as Al2O3 it is a condensation reaction
what happens when pyrrole is subjected to a very strong acid?
protonated forms a conjugated red polymer
on which carbon does pyrrole preferentially react with electrophiles?
more preferentially on carbon 2 there are more possible resonance forms, which makes the intermediates more stable than with a reaction with C3
how can you do nitration and sulfonation of pyrrole?
cannot use nitric or sulfuric acid since those are strong acids, you’d get a polymer of pyrrole, which is not what you want
what are tautomers?
structural isomers of compounds that readily interconvert
does indole prefer to attack with C2 or C3?
attack at C3 gives the most stable cation the aromaticity of the 6 membered ring is preserved reaction at C2 would mean the disruption of the aromatic benzene ring, which we absolutely do not want
paal knorr synthesis of pyrrole
paal knorr synthesis of furan mechanism
pyrrole polymerisation when protonated mechanism
nitration of pyrrole mechanism
what is the structure of tetrephenylporphyrin? and what can it be used for?
can be used for the treatment for bladder cancer when activated by light careful!! this is the oxidised version, the reduced version has hydrogens on all 4 nitrogens
synthesis of porphyrin
Fischer indole Synthesis
structure of indole
