Which of the following reagents can be used to differentiate `1^(@)` and
`3^(@)` alcohols ?

Options

A. PCC
B. `K_(2)Cr_(2)O_(7)//H^(oplus)`
C. Jones reagent
D. `Br_(2)-H_(2)O`

Answer

To differentiate between 1° (primary) and 3° (tertiary) alcohols, we can use specific reagents that will react differently with these types of alcohols. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the reagents
The reagents provided in the question are:
1. PCC (Pyridinium chlorochromate)
2. K2Cr2O7 (Potassium dichromate) in acidic medium
3. Jones reagent (CrO3 in aqueous H2SO4)
4. Bromine water

### Step 2: Analyze the reactivity of 1° alcohols
1° alcohols can be oxidized to aldehydes using:
- **PCC**: It oxidizes 1° alcohols to aldehydes.
- **K2Cr2O7**: In acidic conditions, it oxidizes 1° alcohols to aldehydes and further to carboxylic acids.
- **Jones reagent**: Similar to K2Cr2O7, it oxidizes 1° alcohols to carboxylic acids.

### Step 3: Analyze the reactivity of 3° alcohols
3° alcohols are generally resistant to oxidation under neutral or alkaline conditions. However:
- **K2Cr2O7** and **Jones reagent** can oxidize 3° alcohols in strong acidic conditions, but this is not a typical differentiation method since both types of alcohols can react under these conditions.
- **Bromine water** does not react with alcohols in a way that differentiates between 1° and 3° alcohols.

### Step 4: Conclusion
From the analysis, we conclude that:
- **PCC**, **K2Cr2O7**, and **Jones reagent** can differentiate between 1° and 3° alcohols since 1° alcohols will react and 3° alcohols will not under typical conditions.
- **Bromine water** is not suitable for this differentiation.

### Final Answer
The reagents that can be used to differentiate 1° and 3° alcohols are **PCC, K2Cr2O7, and Jones reagent**.

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