The most suitable reagent for the following conversion , is

Question : The most suitable reagent for the following conversion , is

(1) Na/liquid NH3

(2) H2 , Pd/C , quinoline

(3) Zn/HCl

(4) Hg2+  / H+ , H2O

answer : from all above options the correct answer is “(2) H2 , Pd/C , quinoline” . you must keep remember that Lindlar’s catalyst can be used to prepare cis-alkenes from the disubstituted alkynes and given reaction will follow this step as given below –

answer explanation : as we can see in the question reaction that in the resultant product “Cis-2-butene” is formed and we also know that Lindlar’s catalyst can be use to get cis-alkenes from the disubstituted alkynes. and keep remember that Lindlar’s catalyst is composed of palladium , and this Lindlar’s catalyst used to transform an alkyne to a cis-alkene¬†and the reason behind this reaction is that hydrogenation reaction occurred on the surface of the metal. that is why option “(2) H2 , Pd/C , quinoline” is correct answer.