Hex-3-yne is converted separately by (i) H2/Lindlar catalyst and (ii) Na in liquid NH3. The main products are respectively

(Z)-hex-3-ene and (E)-hex-3-ene

(E)-hex-3-ene and (Z)-hex-3-ene

JEE Main levelSingle correct optionDifficulty 2 of 3ro117

Hex-3-yne is converted separately by (i) $H X_{2}$ /Lindlar catalyst and (ii) Na in liquid $NH X_{3}$ . The main products are respectively

Lindlar hydrogenation is a syn addition on the catalyst surface and gives the cis (Z) alkene. Na/liquid

NH X_{3}

proceeds through a radical anion that protonates to the more stable trans vinyl radical anion, giving the (E) alkene by anti addition.