C₃H₆Cl₂ is treated with NaNH₂ to give compound P.

P on reaction with:

• HgSO₄/Dil. H₂SO₄ gives Q
• Red hot Fe tube gives R

Find the ratio of hydrocarbons present in R and Q.

Options:

1. 3 : 1
2. 2 : 3
3. 2 : 1
4. 3 : 2

Solution:

C₃H₆Cl₂ is a geminal dihalide.

NaNH₂ causes double dehydrohalogenation producing:

P = Propyne (CH₃C≡CH)

Hydration of propyne:

CH₃C≡CH

HgSO₄/H₂SO₄

→ CH₃COCH₃

Q = Acetone

Number of carbon atoms in Q = 3

When propyne is passed through a red hot iron tube, cyclotrimerization occurs:

3 CH₃C≡CH

→ Mesitylene (1,3,5-trimethylbenzene)

R = Mesitylene

Number of carbon atoms in R = 9

Required ratio:

R : Q = 9 : 3

= 3 : 1

Answer:

3 : 1 (Option 1)