7 - HETEROCYCLES Flashcards

1
Q

what is the structure of indole?

A

present in tryptophan
aromatic, has 10 pi electrons

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2
Q

what are the properties of pyrrole?

A
  • 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
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3
Q

how is pyrrole made from furan?

A

treatment of furan with ammonia in the presence of a catalyst such as Al2O3
it is a condensation reaction

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4
Q

what happens when pyrrole is subjected to a very strong acid?

A

protonated
forms a conjugated red polymer

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5
Q

on which carbon does pyrrole preferentially react with electrophiles?

A

more preferentially on carbon 2
there are more possible resonance forms, which makes the intermediates more stable than with a reaction with C3

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6
Q

how can you do nitration and sulfonation of pyrrole?

A

cannot use nitric or sulfuric acid
since those are strong acids, you’d get a polymer of pyrrole, which is not what you want

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7
Q

what are tautomers?

A

structural isomers of compounds that readily interconvert

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8
Q

does indole prefer to attack with C2 or C3?

A

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

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9
Q

paal knorr synthesis of pyrrole

A
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10
Q

paal knorr synthesis of furan mechanism

A
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11
Q

pyrrole polymerisation when protonated mechanism

A
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12
Q

nitration of pyrrole mechanism

A
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13
Q

what is the structure of tetrephenylporphyrin? and what can it be used for?

A

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

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14
Q

synthesis of porphyrin

A
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15
Q

Fischer indole Synthesis

A
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16
Q

structure of indole

A