Question

Which of the following reagents maybe used to distinguish between but-2-yne and but-1-yne.

• A. $B{r}_2$ in $CC{l}_4$
• B. Dilute $KMn{O}_4$
• C. Concentrated $H_{2}S{O}_4$
• D. Ammonical $CuCl$

Answer 1

Answer: (D)

Ammonical $CuCl$

There will be no reaction between $butyne-2$ and $Cu,Cl$ because it has no acidic hydrogen. In $butyne-1$ the terminal hydrogen is acidic ($CH,CH,-CCH$) so it will give a real ppt with Ammonical $C{u}_{2}C{l}_2$ or $CuCl$