# Is this a feasible synthetic route for 1-(phenylethynyl)cyclopentan-1-ol?

From my notes $\ce{NaNH_2}$ is a good base for the deprotonation of alkynes. After the deprotonation I thought the alkyne would attack the carbon on the cyclopentanone because of the $\delta^+$ charge on the carbonyl carbon due to the EWG effects of the oxygen. Should the protonation of the $\ce{O^-}$ be carried out with conditions specified or can I just leave it as the addition of $\ce{H^+}$?

• There is no such compound as $\ce{NaNH3}$. It is easy to mix up sodium in liquid ammonia $\ce{Na}/\ce{NH3}$ with sodium amide $\ce{NaNH2}$. Make sure you know what you are writing. As for the final workup, you definitely need some kind of proton source. – orthocresol Dec 10 '15 at 17:04
• Thank you i must have taken that down incorrectly, ok so would $H_3O^+$ suffice? @orthocresol – MrLuke370 Dec 10 '15 at 17:20
• Again, please make sure you know what you are writing. If you treat the alkyne with $\ce{Na}/\ce{NH3}$, you are going to get a trans alkene, not the acetylide ion. For the final workup, it depends on how strict your marking scheme is, but I would recommend you write an actual compound like water. You can't go out and buy a bottle of "$\ce{H3O+}$" from Sigma-Aldrich. – orthocresol Dec 10 '15 at 17:21
• Ok so would the conjugate acid of the sodium amide protonate the $O^-$? @orthocresol – MrLuke370 Dec 10 '15 at 17:24
• Or would that be too weak an acid to do so? – MrLuke370 Dec 10 '15 at 17:43

• Make sure you actually have sodium amide $\ce{NaNH2}$ and not sodium in ammonia $\ce{Na/NH3}$. As pointed out in the question comments, they react very differently; the latter generates a trans-alkene.
• Typically in a lab setting, reactions with strong bases (as is the case here) are carefully quenched with something aquaeous. So you can be sure that there will be an aquaeous proton source ($\ce{H2O}$ or $\ce{H+/H2O}$, depending on your markers’ preferences) in the end. There should be no need to additionally specify conditions. It would make no sense to attempt to isolate the alcoholate anyway.