Question

Butyne-1 and butyne-2 can be distinguished by:

• A. Benedicts reagent
• B. alkaline $KMn{{O}_{4}}$
• C. ammonical cuprous chloride
• D. bromine water

Answer 1

Answer: (C)

ammonical cuprous chloride

Answer 2

Butyne-1 and butyne-2 can be distinguished by using ammonical cuprous chloride as only butyne-1 reacts with this reagent to give red ppt. (because it contains active hydrogen) while butyne-2 does not react with it. $C{{H}_{3}}--C{{H}_{2}}--C\equiv \equiv CH\xrightarrow[\underset{\text{red}\,\text{ppt}\text{.}}{\mathop{C{{H}_{3}}\cdot C{{H}_{2}}C\equiv \equiv C\cdot Cu\,\downarrow }}\,]{C{{u}_{2}}C{{l}_{2}}/N{{H}_{4}}OH}$ $C{{H}_{3}}--C\equiv \equiv C--C{{H}_{3}}\underset{\text{no}\,\text{reaction}}{\mathop{\xrightarrow{C{{u}_{2}}C{{l}_{2}}/N{{H}_{4}}OH}}}\,$