Question

Identify the reagent which can easily distinguish between but-1-yne and but-2-yne:

• A. bromine in $CC{l}_4$
• B. $H_2$, Lindlar's catalyst
• C. dilute $H_{2}S{O}_4,HgS{O}_4$
• D. ammoniacal $C{u}_{2}C{l}_2$

Answer 1

The correct option is D ammoniacal $C{u}_{2}C{l}_2$

But-1-yne contains acidic hydrogen and hence it reacts with ammonical $C{u}_{2}C{l}_2$ to form a red precipitate of $copper-1-butynide$ whereas but-2-yne does not react with ammonical $C{u}_{2}C{l}_2$ as it do not have acidic hydrogen.