Reduction of an alkyne to the double bond stage can yield a cis alkene or trans alkene (except in cases where triple bond is at the end of the chain ) Reduction of alknes with sodium or lithium in liquid NH_(3) yields predominantly trans alkene. Hydrogenation of alkynes with Lindlar's catalyst or a nickel boride called P_(2) catalyst yeilds is alkene (as high as 98%) If Pd/C/H_(2) is used in the absence of a catalyst poison, two equivlanet of H_(2) are added forming alkanes.Reduction of alkynes to trans alkene by Li//NH_(3) is carried out in the presence of dry ice. This is because of

Reduction of an alkyne to the double bond stage can yield a cis alkene

1.	Reduction of an alkyne to the double bond stage can yield a cis alkene or trans alkene (except in cases where triple bond is at the end of the chain ) Reduction of alknes with sodium or lithium in liquid NH_(3) yields predominantly trans alkene. Hydrogenation of alkynes with Lindlar's catalyst or a nickel boride called P_(2) catalyst yeilds is alkene (as high as 98%) If Pd/C/H_(2) is used in the absence of a catalyst poison, two equivlanet of H_(2) are added forming alkanes.Reduction of alkynes to trans alkene by Li//NH_(3) is carried out in the presence of dry ice. This is because of
Answer» radical anion is formed at the temperature of dry ice intermediate if formed with dry ice `NH_(3)` REMAINS inliquidstate at the temperature of dry ice Li remains in liquid STATE at the temperature of dry ice ANSWER :C