Question

What is the product when $2$ -butyne is treated with liquid $N{H}_3$ in presence of lithium ?

• A. n -butane
• B. cis- 2 -butene
• C. trans- 2 -butene
• D. 1 -butene

Answer 1

Answer: (C)

$\underset{\text{2-butyne}}{C{H}_3—C}\equiv CH+2[H]\underset{liq.N{H}_3}{\overset{Li}{\to }}$

But, in presence of Lindlar’s catalyst
$(Pd-CaC{O}_3)$ $2$-butyne reacts with hydrogen giving cis-2-butene
$\underset{\text{2-butyne}}{C{H}_3—C}CH+H_2\stackrel{pd.CaC{O}_3}{\to }$