In the hydrogenation of $1_{\text{decyne}}$ to $\text{decane}$, how many equivalents of ${H2}_{\text{gas}}$ are required for complete reduction?

• A. $0.5$ equivalent
• B. $1$ equivalent
• C. $3$ equivalents
• D. $2$ equivalents

Answer: (D)

Verified step by step guidance

1. Identify the type of bond present in 1-decyne. Since it is an alkyne, it contains a carbon-carbon triple bond (C\equiv C).
2. Understand that hydrogenation involves adding hydrogen (H\_2) across multiple bonds to convert them into single bonds. Each equivalent of H\_2 adds two hydrogen atoms.
3. Determine how many hydrogen molecules are needed to fully saturate the triple bond. A triple bond consists of one sigma and two pi bonds, and each pi bond requires one equivalent of H\_2 to be converted into a single bond.
4. Calculate the total equivalents of H\_2 required: since there are two pi bonds in the triple bond, two equivalents of H\_2 are needed to convert the alkyne into an alkane (decane).
5. Conclude that 2 equivalents of H\_2 gas are required for the complete hydrogenation of 1-decyne to decane.