Why is the oxidation of a primary alcohol with mixture of sodium dichromate and sulphuric acid not a good method for the preparation of corresponding aldehyde ?

Options

A. The product will be the corresponding ketone
B. Any aldehyde produced will be oxidised further
C. The product will be an alkyl sulphonate , `R-SO_3H` mixture of sodium dichromate and sulphuric acid will not oxidize a primary alcohol
D. A mixture of sodium dichromate and sulphuric acid will not oxidized a primary alcohol

Answer

To answer the question of why the oxidation of a primary alcohol with a mixture of sodium dichromate and sulfuric acid is not a good method for the preparation of the corresponding aldehyde, we can break down the explanation into several steps:

### Step 1: Understanding the Reactants
- **Primary Alcohol**: A primary alcohol has the structure RCH2OH, where R is an alkyl group.
- **Oxidizing Agent**: Sodium dichromate (Na2Cr2O7) in the presence of sulfuric acid (H2SO4) is a strong oxidizing agent.

### Step 2: Reaction of Primary Alcohol with Sodium Dichromate
- When a primary alcohol (RCH2OH) is treated with sodium dichromate and sulfuric acid, the primary alcohol is oxidized. The expected first product of this oxidation is an aldehyde (RCHO).

### Step 3: Further Oxidation of Aldehyde
- However, sodium dichromate is a strong oxidizing agent. If the aldehyde (RCHO) is formed, it can be further oxidized by the same oxidizing agent to form a carboxylic acid (RCOOH).

### Step 4: Conclusion
- Therefore, while it is possible to form an aldehyde from a primary alcohol, the presence of sodium dichromate and sulfuric acid means that the aldehyde will not be isolated; it will be further oxidized to a carboxylic acid. This is why using this method is not a good approach for preparing aldehydes from primary alcohols.

### Final Answer
The correct reason is: **Any aldehyde produced will be oxidized further to a carboxylic acid.**

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