Which one of the following alcohols cannot be oxidized by `K_(2)CrO_(4)`?

Options

A. Ethanol
B. Tert butyl alcohol
C. Isopropyl alcohol
D. allyl alcohol

Explanation

To determine which alcohol cannot be oxidized by potassium dichromate (K₂Cr₂O₇), we need to understand the oxidation behavior of different types of alcohols:

### Step-by-Step Solution:

1. **Identify the Types of Alcohols**:
- Alcohols can be classified into three categories based on the number of alkyl groups attached to the carbon bearing the hydroxyl (-OH) group:
- **Primary (1°) Alcohols**: The carbon with the -OH group is attached to one other carbon.
- **Secondary (2°) Alcohols**: The carbon with the -OH group is attached to two other carbons.
- **Tertiary (3°) Alcohols**: The carbon with the -OH group is attached to three other carbons.

2. **Understand the Oxidation Reactions**:
- Potassium dichromate is a strong oxidizing agent that can oxidize:
- Primary alcohols to carboxylic acids.
- Secondary alcohols to ketones.
- **Tertiary alcohols cannot be oxidized** by potassium dichromate.

3. **Analyze the Given Options**:
- **Ethanol**: This is a primary alcohol (1°).
- **Tertiary Butyl Alcohol**: This is a tertiary alcohol (3°).
- **Isopropyl Alcohol**: This is a secondary alcohol (2°).
- **Allyl Alcohol**: This is a primary alcohol (1°).

4. **Determine the Alcohol That Cannot Be Oxidized**:
- Among the options, tertiary butyl alcohol is the only tertiary alcohol, which cannot be oxidized by potassium dichromate.

5. **Conclusion**:
- The alcohol that cannot be oxidized by K₂Cr₂O₇ is **Tertiary Butyl Alcohol**.

### Final Answer:
**Tertiary Butyl Alcohol** cannot be oxidized by potassium dichromate.