The typical reactions of aldehyde is

Options

A. Electrophilic addition
B. Nucleophilic substitution
C. Nucleophilic addition
D. Nucleophilic elimination

Explanation

To answer the question regarding the typical reactions of aldehydes, we can break it down into several key points:

### Step-by-Step Solution:

1. **Understanding the Structure of Aldehydes**:
- Aldehydes have the general formula RCHO, where R is a hydrocarbon group and the carbonyl group (C=O) is at the end of the carbon chain.

2. **Nucleophilic Addition Reactions**:
- One of the most typical reactions of aldehydes is nucleophilic addition. In this reaction, a nucleophile attacks the electrophilic carbon atom of the carbonyl group.
- Common nucleophiles include hydride ions (from reducing agents like NaBH4 or LiAlH4) and alcohols.

3. **Formation of Alcohols**:
- When aldehydes undergo nucleophilic addition with hydride ions, they are reduced to primary alcohols. For example:
\[ RCHO + H_2 \rightarrow RCH_2OH \]

4. **Condensation Reactions**:
- Aldehydes can also undergo condensation reactions with alcohols to form hemiacetals and acetals. This is particularly important in carbohydrate chemistry.

5. **Oxidation Reactions**:
- Aldehydes can be oxidized to carboxylic acids. This reaction can be performed using various oxidizing agents such as KMnO4 or CrO3.

6. **Reactions with Grignard Reagents**:
- Aldehydes react with Grignard reagents (RMgX) to form secondary alcohols after hydrolysis. The reaction can be represented as:
\[ RCHO + RMgX \rightarrow RCH(OMgX)R' \rightarrow RCH(OH)R' \]

7. **Addition of Cyanide**:
- Aldehydes can react with cyanide ions (CN-) to form cyanohydrins. This is another example of nucleophilic addition:
\[ RCHO + CN^- \rightarrow RCH(OH)CN \]

### Summary of Typical Reactions:
- Nucleophilic addition (with hydrides, alcohols, etc.)
- Formation of alcohols
- Condensation reactions (with alcohols)
- Oxidation to carboxylic acids
- Reactions with Grignard reagents to form alcohols
- Addition of cyanide to form cyanohydrins