Alkynes on reduction with sodium

Question:

Alkynes on reduction with sodium in liquid ammonia form trans alkenes. Will the butene thus formed on the reduction of the 2-butyne show the geometrical isomerism?

Solution:

The negative charged developed on one carbon attacks the proton from NH3 and another sodium atom lose its electron to develop a second negative charge on the

atom. This negative charge is finally neutralised by the attack of the second proton to give a trans-but-2-ene.

This but-2-ene produced shows geometrical isomers as cis and trans.

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