Question

The correct statements(s) concerning the structures E, F, and G is (are):

• A. E, F and G are resonance structures.
• B. E, F and E, G are tautomers.
• C. F and G are geometrical isomers
• D. F and G are diastereomers.

Answer 1

Answer: (B), (C), (D)

F and G are diastereomers.

Tautomerism is a phenomenon where a single compound tends to exist in two or more structures which are interconvertible and differ in the relative position of one atomic nucleus.

In Keto-enol tautomerism, delocalisation takes place between a >C=O group and an alpha H where the equilibrium lies between a keto form and an enol form.


E, F and E, G are keto enol tautomers.

Geometrical Isomerism arises due to different arrangement of atoms/groups around a system where free rotation of bonds is restricted.
Compound F is cis isomer because similar groups are in same side about the $C-C$ double bond.
Compound G is trans isomer because similar groups are in opposite side about the $C-C$ double bond.

Geometrical isomers are diastereomers. Thus, F and G are diastereomers.

E, E and G are not resonance structures.

Hence, correct statements are (b), (c) and (d).