Butanal undergoes aldol condensation to give

Options

A. `CH_3CH_2 CH_2 underset(OH) underset(|)CHCH_2 CH_2 CH_2CHO`
B. `CH_3 CH_2CH_2 underset(OH) underset(|)CH underset(OH) underset(|) CH CH_2 CHO`
C. `CH_3 CH_2 CH_2 underset(OH) underset(| ) CH underset(CH_2-CH_3) underset(| ) CHCHO`
D. `CH_3CH_2CH_2 underset(OH) underset(| )CH underset(OH ) underset(| ) CH CH_2 CH_2 CH_3`

Explanation

To determine the product of the aldol condensation of butanal, we will follow these steps:

### Step 1: Identify the structure of butanal
Butanal is an aldehyde with the molecular formula C4H8O. Its structure is:
```
CH3-CH2-CH2-CHO
```

### Step 2: Understand the aldol condensation process
Aldol condensation involves two molecules of an aldehyde or ketone reacting in the presence of a base. The base abstracts an alpha hydrogen from one molecule, forming an enolate ion, which then attacks the carbonyl carbon of another molecule.

### Step 3: Identify the alpha hydrogen
In butanal, the alpha carbon (the carbon adjacent to the carbonyl group) has hydrogens that can be abstracted. The alpha hydrogens in butanal are on the second carbon (C2) of the chain.

### Step 4: Form the enolate ion
When a base (like NaOH or KOH) is added, it abstracts one of the alpha hydrogens from butanal, forming the enolate ion:
```
CH3-CH2-CH2-C(-)O
```
This enolate ion is now a nucleophile.

### Step 5: Nucleophilic attack
The enolate ion attacks the carbonyl carbon of another butanal molecule:
```
CH3-CH2-CH2-C(=O)-H
```
This results in a beta-hydroxy aldehyde.

### Step 6: Form the aldol product
The product of this reaction is 3-hydroxybutanal:
```
CH3-CH2-CH(OH)-CH2-CHO
```

### Step 7: Dehydration to form the final product
The beta-hydroxy aldehyde can undergo dehydration (loss of water) to form an α,β-unsaturated aldehyde. The dehydration results in the formation of crotonaldehyde (but-2-enal):
```
CH3-CH=CH-CHO
```

### Final Product
Thus, the final product of the aldol condensation of butanal is crotonaldehyde (but-2-enal).

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