Solution

Partial hydrogenation of an alkyne with Lindlar-type catalyst ($H_2$, Pd/C, quinoline) gives a cis-alkene by syn addition. $H_3C-C\equiv C-CH_3\xrightarrow{H_2,\ Pd/C,\ quinoline}$ cis-2-butene (Na/liquid $NH_3$ would give trans-2-butene.)

Concept syn addition of hydrogen to an alkyne

Hydrocarbons in past papers

75 questions from this chapter have appeared across 26 exam years.