Fundamentals of Organic ChemistryChemistryGeneral Organic Chemistry
Which of the following compounds are aromatic? (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x) (xi) (xii)
Options
- A(i), (ii), (iii), (vi), (viii), (x), (xi), (xii)
- B(i), (ii), (iii), (v), (vii), (viii), (ix), (x), (xii)
- C(i), (ii), (iii), (iv), (v), (vi), (viii), (x), (xii)
- D(i), (ii), (iii), (iv), (v), (vi), (vii), (x), (xii)
Correct answer
D. (i), (ii), (iii), (iv), (v), (vi), (vii), (x), (xii)
Step-by-step solution
According to Huckel's rule, a compound is aromatic if it is cyclic, planar, completely conjugated, and has (4n + 2) electrons. (i) Pyrrole: 4 electrons from double bonds + 2 electrons from N lone pair = 6 electrons. Aromatic. (ii) Imidazole: 4 electrons from double bonds + 2 electrons from one N lone pair = 6 electrons. Aromatic. (iii) Furan: 4 electrons from double bonds + 2 electrons from O lone pair = 6 electrons. Aromatic. (iv) Thiophene: 4 electrons from double bonds + 2 electrons from S lone pair = 6 electron