An aldohexose (e.g., glucose) and 2 - oxohexose (e.g., fructose) can be distinguished with the help of

Options

A. Tollen's reagent
B. Fehling's solution
C. Benedict solution
D. `Br_(2)+H_(2)O`

Answer

To distinguish between an aldohexose (like glucose) and a 2-oxohexose (like fructose), we can use bromine water as a reagent. Here’s a step-by-step explanation of the reasoning:

### Step 1: Understanding Aldohexose and 2-Oxohexose
- **Aldohexose**: This is a six-carbon sugar that contains an aldehyde group (-CHO). Glucose is a common example.
- **2-Oxohexose**: This is also a six-carbon sugar but contains a ketone group (C=O) at the second carbon. Fructose is a common example.

### Step 2: Identifying the Functional Groups
- Aldohexoses can be oxidized to form carboxylic acids due to the presence of the aldehyde group.
- 2-Oxohexoses (ketoses) do not have an aldehyde group and thus do not react in the same way.

### Step 3: Choosing the Right Reagent
- **Bromine Water**: This is a mild oxidizing agent that can oxidize aldehydes to carboxylic acids but does not oxidize ketones.
- **Tollens' Reagent, Fehling's Solution, and Benedict's Solution**: These reagents can oxidize both aldehydes and ketones, making them unsuitable for distinguishing between aldohexoses and 2-oxohexoses.

### Step 4: Performing the Test
- When bromine water is added to glucose (an aldohexose), it will oxidize the aldehyde group to a carboxylic acid, resulting in a color change (the brown color of bromine will disappear).
- When bromine water is added to fructose (a 2-oxohexose), there will be no reaction because the ketone group does not get oxidized by bromine water.

### Conclusion
Thus, by using bromine water, we can distinguish between an aldohexose (like glucose) and a 2-oxohexose (like fructose) based on the reaction that occurs.

### Final Answer
The correct reagent to distinguish between an aldohexose and a 2-oxohexose is **Bromine water**.

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