Heteroaromatic systems

Question 1

Is pyridine a good or bad nucleophile?

Based on this give an example of a reaction in which pyridine would be a good catalyst.

Answer 1

Yes

acylation

Question 2

Can pyridine readily react with electrophiles?

Question 3

Name two ways of activating a pyridine ring to react with electrophiles. Give the reagents needed for both.

Answer 3

1) Add an electron donating group e.g. NO2
reagents: C. H2SO4 and HNO3
2) Make N-Oxide
See topic 8 card 3

Question 4

How does pyridine react with nucleophiles?

Answer 4

Very well —> pyridine halides particularly reactive to SnAR

Question 5

What are the reagents for the Chichibabin reaction?

Answer 5

1) NaNH2
2) H2O

Question 6

What are the reagents for the bromination of a 5 ring heterocyclic aromatic?

Answer 6

XS Br2, EtOH, ) degrees C

Question 7

What does the Vismeier reaction add to 5 membered rings?

Answer 7

Aldehyde group in ortho position

Question 8

What are the reagents for the Vismeier reaction?

Answer 8

1) Me2NCHO (DMF), POCl3
2) H2O