Question

Which is the most suitable reagent among the following to distinguish compound (3) from rest of the compounds?
$1.C{H}_3-C\equiv C-C{H}_3$
$2.C{H}_3-C{H}_2-C{H}_2-C{H}_3$
$3.C{H}_3-C{H}_{2}C\equiv CH$
$4.C{H}_3-CH=C{H}_2$

• A. Bromine in carbon tetrachloride
• B. Bromine in acetic acid
• C. Alk $KMn{O}_4$
• D. Ammonical silver nitrate

Answer 1

The correct option is D Ammonical silver nitrate

$\left(a\right)\Rightarrow B{r}_2$ in $CC{l}_4$ ,
$\left(b\right)\Rightarrow B{r}_2$ in $C{H}_{3}COOH$ and
$\left(c\right)\Rightarrow \text{alkaline}KMn{O}_4$ will react with all unsaturated compounds ( double bonds and triple bonds) i.e., 1, 3 and 4. While $\left(d\right)\Rightarrow \text{ammonical}AgN{O}_3$ reacts only with terminal alkynes, because terminal alkynes are more acidic i.e., 3. Hence, compound 3 can be distinguished from 1, 2 and 4 by ammonical $AgN{O}_3$.