Ques. 1NEET 2018
Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is
- CH CH
- CH2 = CH2
- CH3 - CH3
- CH4
Answer
(4) CH4
Solution
Alkenes and alkynes react with bromine by addition, so (A) must be an alkane.
Wurtz reaction joins two alkyl groups ⇒ the product has twice the carbon atoms of the alkyl bromide.
CH4 Br2, h CH3Br Na, dry ether CH3 - CH3 (2 C atoms, gas)
With CH3-CH3, the Wurtz product would be butane (4 C atoms), not less than four.
∴ (A) is CH4.
Answer: (4)