Question

An alcohol A, when heated with concentrated $H_{2}S{O}_4$ gives an alkene B. When B is bubbled through bromine water and the product obtained is dehydrohalogenated with excess of sodamide, a new compound C is obtained. The compound C gives D when treated with warm dilute $H_{2}S{O}_4$ in presence of $HgS{O}_4$. D can also be obtained either by oxidising A with $KMn{O}_4$ or from acetic acid through its calcium salt. Identify D.

• A. A = Ethylene, B = Ethyl alcohol,
  C = Acetylene, D = Acetaldehyde
• B. A = Ethyl alcohol, B = Ethylene,
  C = Acetylene, D = Acetaldehyde
• C. A = Ethylene, B = Ethyl alcohol,
  C = Acetaldehyde, D = Acetylene
• D. A = Propan-2-ol, B = Propene,
  C = Propyne, D = Acetone

Answer 1

The correct option is D A = Propan-2-ol, B = Propene,

C = Propyne, D = Acetone
The facts given in the problem can be summarised as follows:

From the above it appears that C is an alkyne and D is an aldehyde or ketone. Since D can be obtained from acetic acid through its calcium salt it must be either acetaldehyde or acetone. Hence proceeding backwards A must be isopropyl alcohol.