91Ó°ÊÓ

Lindlar catalyst is used mainly for the selective hydrogenation of alkynes to the alkene.It is the selective catalyst used for the hydrogenation of triple bonds to cis-double bonds.

Sodium in liquid ammonia is used to convert internal alkyne to trans alkene.Sodium is ionized to $N{a}^{+}$an electron.

${\mathbf{D}}_2\mathbf{O}$exchange is a hydrogen-deuterium exchange reaction in which covalently bonded hydrogen is replaced by deuterium.

Due to the acidic nature of hydrogen, they can be replaced by or exchanged by deuterium using ${\mathbf{D}}_2\mathbf{O}$as a reagent.

${\mathbf{D}}_2\mathbf{O}$exchange is a hydrogen-deuterium exchange reaction in which covalently bonded hydrogen is replaced by deuterium.

Due to the acidic nature of hydrogen, they can be replaced by or exchanged by deuterium using ${\mathbf{D}}_2\mathbf{O}$as a reagent.

a.

In this reaction, deuterium is passed in the presence of the Lindlar catalyst. So the Lindlar catalyst converts internal alkyne to the cis alkene.

b.

c.

d.