The reagent which will be suitable to distinguish 1-methoxy-3-methyl-2-butene from isomeric 4-methyl-3-pentene -1-ol is

Options

A. bromine in chloroform
B. alkaline potassium permanganate
C. ammoniacal silver nitrate
D. sodium metal suspended in hexane

Answer

To distinguish between 1-methoxy-3-methyl-2-butene and 4-methyl-3-pentene-1-ol, we can analyze the structures and reactivity of these compounds with different reagents. Here’s a step-by-step solution:

### Step 1: Identify the Structures
1. **1-Methoxy-3-methyl-2-butene**: This compound has a methoxy group (-OCH3) attached to a double-bonded carbon chain. Its structure can be represented as:
- CH3-CH=CH-CH3 (with a methoxy group on the second carbon).

2. **4-Methyl-3-pentene-1-ol**: This compound has a hydroxyl group (-OH) and is an alcohol. Its structure can be represented as:
- CH3-CH2-CH=CH-CH3 (with an -OH group on the first carbon).

### Step 2: Analyze the Reagents
We need to evaluate the given reagents to find one that can distinguish between the two compounds:

1. **Bromine in Chloroform (Br2 in CHCl3)**: This reagent tests for unsaturation (double bonds). Both compounds have double bonds, so this reagent will not distinguish between them.

2. **Alcoholic KMnO4**: Similar to bromine, this reagent also tests for unsaturation. Both compounds will give a positive test, so it cannot distinguish between them.

3. **Ammonical Silver Nitrate**: This reagent is used primarily to test for aldehydes. Neither compound will react with this reagent, so it cannot be used for distinction.

4. **Sodium Metal in Hexane**: Sodium reacts with alcohols to produce hydrogen gas and sodium alkoxide. Since 1-methoxy-3-methyl-2-butene is an ether, it will not react with sodium, while 4-methyl-3-pentene-1-ol, being an alcohol, will react and release hydrogen gas.

### Step 3: Conclusion
The suitable reagent to distinguish between 1-methoxy-3-methyl-2-butene and 4-methyl-3-pentene-1-ol is **sodium metal suspended in hexane**. This is because it will react with the alcohol (4-methyl-3-pentene-1-ol) but not with the ether (1-methoxy-3-methyl-2-butene).