Which of the following reagent used to identify fructose ?

Options

A. Neutral `FeCl_3`
B. `CHCl_3` / alc KOH
C. Ammoniacal `AgNO_3`
D. Iodine

Answer

To identify fructose, we need to determine which reagent can specifically react with it. Here's a step-by-step solution:

### Step 1: Understand the structure of fructose.
Fructose is a ketohexose, meaning it has a ketone functional group. Its structure can be represented as:
\[ \text{C}_6\text{H}_{12}\text{O}_6 \]
with a ketone group at the second carbon.

### Step 2: Review the given reagents.
The options provided are:
1. Neutral FeCl3
2. CHCl3
3. Alcoholic OH
4. Ammonical AgNO3
5. Iodine

### Step 3: Analyze each reagent.
- **Neutral FeCl3**: This reagent is typically used to detect phenols, not sugars.
- **CHCl3**: This is used in reactions involving ketones but is not specific for fructose.
- **Alcoholic OH**: This reagent is not specific for detecting fructose.
- **Ammonical AgNO3**: This reagent is known as Tollen's reagent, which is used to detect reducing sugars.
- **Iodine**: This reagent is used to test for starch, not fructose.

### Step 4: Identify the reducing property of fructose.
Fructose is a reducing sugar, meaning it can reduce certain reagents. Tollen's reagent (ammonical AgNO3) can react with fructose due to its ability to form an enol, which can then reduce the silver ion to metallic silver.

### Step 5: Conclusion.
The reagent that can be used to identify fructose is **Ammonical AgNO3**.

### Final Answer:
Ammonical AgNO3 is the correct reagent used to identify fructose.

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