`CH_(3)CHO + LiAlH_(4) to CH_(3)CH_(2)OH` Nucleophite added in this reaction is

Options

A. `AlH_(4)^(-)`
B. `Li^(+)`
C. `H_(-)^(+)`
D. `H^(-)`

Answer

To determine the nucleophile added in the reaction between acetaldehyde (CH₃CHO) and lithium aluminum hydride (LiAlH₄), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
The reactants in this reaction are acetaldehyde (CH₃CHO) and lithium aluminum hydride (LiAlH₄).

2. **Understand the Role of LiAlH₄**:
Lithium aluminum hydride is a strong reducing agent. It is used to reduce carbonyl compounds (like aldehydes and ketones) to their corresponding alcohols.

3. **Dissociation of LiAlH₄**:
In solution, lithium aluminum hydride dissociates to produce hydride ions (H⁻) and lithium ions (Li⁺). The relevant part for nucleophilic attack is the hydride ion (H⁻).

4. **Nucleophilic Attack**:
The hydride ion (H⁻) acts as a nucleophile. It attacks the carbonyl carbon of the aldehyde (C=O) in acetaldehyde. This leads to the formation of an alkoxide intermediate.

5. **Formation of the Alkoxide Intermediate**:
When the H⁻ nucleophile attacks the carbonyl carbon, the double bond between carbon and oxygen shifts, resulting in the formation of an alkoxide ion (O⁻) attached to the carbon.

6. **Protonation of the Alkoxide**:
Upon hydrolysis (usually by adding water or an acid), the alkoxide ion is protonated, leading to the formation of the final alcohol product, which is ethanol (CH₃CH₂OH).

7. **Conclusion**:
The nucleophile added in this reaction is the hydride ion (H⁻).

### Final Answer:
The nucleophile added in this reaction is **H⁻**.

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