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What is the product obtained on the reaction of but-2-yne with $\ce{Na}$ in ethanol?

I know that $\ce{Na}$ in liquid $\ce{NH3}$ converts an alkyne to an alkene by anti addition, and $\ce{Na}$ in ethanol is the principle reagent in Bouveault Blanc Reduction, but what about this reaction.

The answer given in my book is a trans-alkene. Is this a standard reaction? Also does it depend if it is a terminal alkyne or not? (I guess yes, because the terminal alkyne will try to deprotonate)

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    $\begingroup$ Do you correctly decipher the question? The reduction by Na in liquid ammonia is followed by addition of ethanol as a source of protons. If you insist on your reaction process, addition of sodium metal into but-2-yne in ethanol will lead to formation of sodium ethanoate, which can add on the triple bond, leading to trans alkene. For further references see Houben-Weyl, books.google.de/… $\endgroup$ – ssavec Feb 16 '16 at 10:18
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the reduction of alkynes using Na, proceeds through the anion radical, which can obtain trans conformation for the stability. Now considering the usage of NH3 and ethanol are proton donors. So, there is no effect on trans conformation altering the proton donors.

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    $\begingroup$ Hey, welcome to Chem.SE! Can you please cite some references to back your answer up? $\endgroup$ – Gaurang Tandon Jun 14 '18 at 14:14
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That's actually an example of Birch reduction of internal alkynes.

It's given in detail on this website.

Also, you're completely right in your reasoning that a terminal alkyne will not show this reaction.

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    $\begingroup$ Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. $\endgroup$ – Gaurang Tandon Jun 14 '18 at 14:09
  • $\begingroup$ Also, the citation on that article seems dubious. While the mechanism looks plausible, both the papers by Zimmerman cited therein make no mention of alkynes at all! $\endgroup$ – Gaurang Tandon Jun 14 '18 at 14:17

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