Aromatic Heterocycles

Question 1

Huckel’s rule

Answer 1

Planar, fully conjugated, cyclic π-systems with (4n+2) π electrons

Question 2

Pyrrole structure

Answer 2

N lp contributes to delocalised π-system so can’t be used as base without destroying aromatic it’s

Question 3

Pyridine structure

Answer 3

N lp in sp2 hybridised orbital perpendicular to plane of delocalised electrons so can be used as a weak base

Question 4

Antiaromatic

Answer 4

Destabilisation due to aromaticity, only cylobutadiene