But-2-ene `underset(2.Zn,H_(2)O)overset(1.O_(3))(to)Punderset(Delta)overset(OH^(Ө))(to)Qunderset(H_(2))overset(Pd//C)(to)R`
R is :

Options

A.
B.
C.
D.

Answer

To solve the problem step-by-step, let's break down the reactions involved in the transformation of but-2-ene to product R.

### Step 1: Identify the starting compound
The starting compound is but-2-ene, which has the following structure:

```
CH3
|
CH3-C=C-CH3
```

### Step 2: Ozonolysis Reaction
The first step involves ozonolysis, where but-2-ene reacts with ozone (O3) followed by zinc (Zn) and water (H2O). This reaction cleaves the double bond and forms carbonyl compounds.

- The ozonolysis of but-2-ene results in two molecules of acetaldehyde (CH3CHO):

```
CH3
|
CH3-C=C-CH3 + O3 → CH3CHO + CH3CHO
```

### Step 3: Aldol Condensation
Next, the product from the ozonolysis (acetaldehyde) undergoes aldol condensation in the presence of a base (OH⁻) and heat. In this reaction, two molecules of acetaldehyde react to form a β-hydroxy aldehyde.

- The aldol condensation of acetaldehyde leads to the formation of 3-hydroxybutanal:

```
CH3CHO + CH3CHO + OH⁻ → CH3-CH(OH)-CH2-CHO
```

### Step 4: Dehydration
The β-hydroxy aldehyde (3-hydroxybutanal) can undergo dehydration (loss of water) to form an α,β-unsaturated aldehyde (crotonaldehyde):

```
CH3-CH(OH)-CH2-CHO → CH3-CH=CH-CHO + H2O
```

### Step 5: Hydrogenation
Finally, the α,β-unsaturated aldehyde (crotonaldehyde) is subjected to hydrogenation in the presence of palladium on carbon (Pd/C) and hydrogen gas (H2). This reaction reduces the double bond and converts the aldehyde group to an alcohol.

- The hydrogenation of crotonaldehyde results in butanal:

```
CH3-CH=CH-CHO + H2 → CH3-CH2-CH2-CHO
```

### Conclusion
The final product R is butanal (CH3-CH2-CH2-CHO).

### Final Answer
R is butanal.

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