NEET Solved Paper 2016 Question 2

Question: In the reaction $ H-C\equiv CH\frac{(1)NaNH _2/liq.NH _3}{(2)CH _3CH _2Br}X\frac{(1)NaNH _2/liq.NH _3}{(2)CH _3CH _2Br}Y $ X and Y are:

Options:

A) X = 1-Butyne; Y = 3-Hexyne

B) X = 2-Butyne; Y = 3-Hexyne

C) X = 2-Butyne; Y = 2-Hexyne

D) X = 1-Butyne; Y = 2-Hexyne

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Answer:

Correct Answer: A

Solution:

  • $NaNH_2$ is a strong base which on reacting with terminal alkyne removes terminal acidic hydrogen leaving alkynyl carbanion, which on reaction with alkyl halide produces longer alkyne by nucleophilic addition. Thus, X is 1-Butyne and Y is 3-Hexyne.