Chemistry · Alkynes: Acidic character, addition of hydrogen, halogens, water and hydrogen halides, polymerization

The reagent used for the following reaction is: \[ \mathbf{R}-\mathbf{C}=\mathbf

The reagent \( \boldsymbol{X} \) used for the following reaction is: \[ \mathbf{R}-\mathbf{C}=\mathbf{C R}^{\prime}+\mathbf{H}_{2} \stackrel{\mathbf{X}}{\longrightarrow} \underset{\mathbf{H}^{\prime}}{\mathbf{C}} \mathbf{C}=\mathbf{C}_{\mathbf{H}}^{\prime \mathbf{R}^{\prime}} \]

  • A. \( N i \)
  • B. \( P d / C \)
  • C. LiAlH\( _{4} \)
  • D. \( N a / \)Liquid \( N H_{3} \)

Step-by-step solution

The reaction is the reduction of an alkyne to a trans-alkene. Na in liquid NH3 is a specific reagent for this transformation, giving the trans-alkene via a dissolving metal reduction. Ni and Pd/C typically lead to over-reduction to alkanes, and LiAlH4 is not used for alkyne reduction.
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