Which of the following are used to convert RCHO into `RCH_(2)OH` ?

Options

A. `H_(2)//Pd`
B. `LiAlH_(4)`
C. `NaBH_(4)`
D. Reaction with RMgX followed by hydrolysis

Explanation

To convert an aldehyde (RCHO) into a primary alcohol (RCH₂OH), we can use several reducing agents. Let's analyze the options provided in the question step-by-step.

### Step 1: Understanding the Reaction
- Aldehydes (RCHO) can be reduced to primary alcohols (RCH₂OH) through various reducing agents. The process involves the addition of hydrogen (H) across the carbonyl (C=O) bond of the aldehyde.

### Step 2: Evaluating Each Option
1. **Option A: H₂ / Pd (Palladium)**
- This is a catalytic hydrogenation reaction. The presence of palladium as a catalyst facilitates the addition of hydrogen to the carbonyl carbon of the aldehyde, converting it to a primary alcohol (RCH₂OH).
- **Conclusion**: This option works.

2. **Option B: Lithium Aluminium Hydride (LiAlH₄)**
- LiAlH₄ is a strong reducing agent that can effectively reduce aldehydes to primary alcohols. It donates hydride ions (H⁻) to the carbonyl carbon, resulting in the formation of RCH₂OH.
- **Conclusion**: This option works.

3. **Option C: Sodium Borohydride (NaBH₄)**
- NaBH₄ is a milder reducing agent compared to LiAlH₄ but is still capable of reducing aldehydes to primary alcohols. It also provides hydride ions (H⁻) for the reduction process.
- **Conclusion**: This option works.

4. **Option D: Reaction with MgX followed by Hydrolysis**
- This reaction involves the formation of a Grignard reagent (RMgX) and subsequent hydrolysis. The product of this reaction is a secondary alcohol rather than a primary alcohol. The Grignard reagent reacts with the carbonyl carbon, leading to a secondary alcohol upon hydrolysis.
- **Conclusion**: This option does not work for producing primary alcohols.

### Final Answer
The reagents that can convert RCHO into RCH₂OH are:
- **A: H₂ / Pd**
- **B: Lithium Aluminium Hydride**
- **C: Sodium Borohydride**

Thus, the correct options are A, B, and C.