Question

What reagents would be required to synthesize hex-2-yne starting with acetylene?

a. NaNH₂ and CH₃l then NaNH₂ and CH₃CH₂l
b. NaNH₂ and CH₃l then NaNH₂ and CH₃CH₂CH₂l
c. NaNH₂ and CH₃CH₂CH₂l
d. NaNH₂ and CH₃l

Answer 1

To synthesize hex-2-yne from acetylene, one would use NaNH₂ and CH₃I for the initial step and NaNH₂ and CH₃CH₂CH₂I for the final step, making option b the correct answer.

Step-by-step explanation:

The reagents required to synthesize hex-2-yne starting with acetylene are NaNH₂ and CH₃I for the first step and then NaNH₂ and CH₃CH₂CH₂I for the second step. This process involves an initial alkylation step to lengthen the carbon chain followed by a final alkylation to achieve the hex-2-yne molecule.

The correct sequence of reagents and reactions is:

1. React acetylene with NaNH₂ to generate an acetylide ion.
2. Use CH₃I (methyl iodide) to add a methyl group to the acetylide ion, forming propyne.
3. React propyne with NaNH₂ again to form another acetylide ion.
4. Finally, alkylate with CH₃CH₂CH₂I (1-iodopropane) to form hex-2-yne.

The correct answer is therefore option b.