Question

Which one of the following compounds show geometrical isomerism?

• A. 1,1-dibromoprop-1-ene
• B. propene
• C. 2-methylprop-1-ene
• D. 1,2-dibromobut-2-ene

Answer 1

The correct option is D 1,2-dibromobut-2-ene

Conditions for geometrical isomers:
1) Free rotation must be restricted.
2) Both the terminals must be attached with different groups.
3) Terminals must not be in perpendicular planes.
a has two same groups(Br) attached to the terminal carbon of the double bond so it can't show geometrical isomerism.

b has two same groups (H) attached to the terminal carbon of the double bond so it can't show geometrical isomerism.

c has two same groups (H) attached to the terminal carbon of the double bond so it can't show geometrical isomerism.

d has two different groups attached to the terminal carbons of the double bond so it will show geometrical isomerism