Question

Identify the reagent from the following list which can easily distinguish between 1- butyne and 2- butyne.

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

Answer 1

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

In 1- butyne, terminal hydrogen is acidic where as in 2- butyne there is no terminal hydrogen. Thus, 2- butyne will not react with ammonical $C{u}_{2}C{l}_2$ while 1- butyne, being terminal alkyne, will give red precipitate with ammonical curprous chloride. Hence, the correct answer is option (d).