Question

An organic compound (A) on ozonolysis followed by treatment with Zn dust and water gives product P, which can be used to preserve biological specimens. Identify A.

• A. 1
• B. 2
• C. 3
• D. 4

Hint:

Ethene is the simplest alkene. On ozonolysis followed by reductive workup \((Zn/H_2O)\), it yields two molecules of methanal \((HCHO)\), whose aqueous solution (formalin) is used for preserving biological specimens.

Answer 1

The Correct Option is C

Step 1: Identify product \(P\).
The compound used for preservation of biological specimens is formaldehyde (methanal).
Its aqueous solution is known as formalin.
Therefore, \[ P=HCHO \]

Step 2: Recall ozonolysis of ethene.
Ethene undergoes ozonolysis followed by reductive workup \((Zn/H_2O)\) as \[ CH_2=CH_2 \xrightarrow[\text{Zn/H}_2O]{O_3} 2HCHO \] Thus, ethene produces methanal directly.

Step 3: Check the remaining options.
Option (1): \[ (CH_3)_2C=C(CH_3)_2 \] on ozonolysis gives acetone. \[ (CH_3)_2CO \] not methanal.
Option (2): \[ CH_3CH=CHCH_3 \] gives ethanal. \[ CH_3CHO \] not methanal.
Option (4): Cyclohexene gives a dialdehyde product, not methanal.

Step 4: Final conclusion.
The compound that produces methanal on ozonolysis is \[ \boxed{CH_2=CH_2} \] Therefore, compound \(A\) is ethene and the correct option is (3).