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

Options

A. Bromine water
B. Baeyer's reagent
C. Dilute `H_(2)SO_(4)+HgSO_(4)`
D. Ammoniacal `Cu_(2)Cl_(2)`

Answer

To identify the reagent that can easily distinguish between 1-butyne and 2-butyne, we can follow these steps:

### Step 1: Understand the Structures
1-butyne (C4H6) has the structure CH3C≡CCH, while 2-butyne (C4H6) has the structure CH3C≡CCH3. The key difference is that 1-butyne has a terminal triple bond, while 2-butyne has an internal triple bond.

### Step 2: Analyze the Reagents
We need to evaluate the reagents provided to see which one can differentiate between the two compounds.

#### Option A: Bromine Water
- Both 1-butyne and 2-butyne can react with bromine water to form dibrominated products. Therefore, bromine water cannot distinguish between them.

#### Option B: Baeyer's Reagent (Alkaline KMnO4)
- Both 1-butyne and 2-butyne will react with Baeyer's reagent to oxidize the triple bond, resulting in similar products (1,2-diol). Thus, this reagent also cannot distinguish between the two.

#### Option C: Dilute H2SO4 and Mercurous Sulfate (HgSO4)
- When treated with dilute H2SO4 and HgSO4, both 1-butyne and 2-butyne undergo hydration to form ketones. The products are similar, so this reagent cannot differentiate between them either.

#### Option D: Ammoniacal Cuprous Chloride (Cu2Cl2)
- 1-butyne, being a terminal alkyne, has an acidic hydrogen that can react with ammoniacal cuprous chloride, leading to the formation of a red precipitate of copper. In contrast, 2-butyne does not have an acidic hydrogen and will not react, resulting in no precipitate. This allows us to distinguish between 1-butyne and 2-butyne.

### Conclusion
The reagent that can easily distinguish between 1-butyne and 2-butyne is **ammoniacal cuprous chloride (Cu2Cl2)**.

### Final Answer:
**Ammoniacal cuprous chloride (Cu2Cl2)** is the reagent that can distinguish between 1-butyne and 2-butyne.

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