Return to Contents  Chapter 9 : Alkynes  Ch 9 contents

Dissolving Metal Reduction of Alkynes
Reaction Type: Addition

Summary

Related reactions:
MECHANISM FOR THE REDUCTION OF ALKYNES WITH Na / NH3
Step 1:
Sodium transfers an electron to the alkyne giving a radical anion.
mechanism for the dissolving metal reduction of an alkyne
Step 2:
The radical anion removes a proton from the ammonia in an acid / base reaction.
Step 3:
A second atom of sodium transfers another electron to the alkyne giving a vinly carbanion. The stereochemistry is established at this step - the alkyl groups being trans.
Step 4:
The carbanion removes a proton from the ammonia in an acid / base reaction to give the trans-alkene.

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  Dr. Ian Hunt, Department of Chemistry, University of Calgary