Give structural formula of 2-methylbutanal .

Explanation

To derive the structural formula of 2-methylbutanal, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Base Chain**:
The name "butanal" indicates that the base chain consists of four carbon atoms (but-). Since it is an aldehyde, the carbon chain will end with a carbonyl group (C=O) at the first carbon.

**Hint**: The prefix "but-" indicates a four-carbon chain.

2. **Draw the Carbon Chain**:
Start by drawing a straight chain of four carbon atoms. This can be represented as:
```
C1 - C2 - C3 - C4
```

**Hint**: Remember to label the carbon atoms for reference.

3. **Add the Aldehyde Group**:
The aldehyde group (–CHO) is attached to the first carbon. Therefore, we place the carbonyl group (C=O) and a hydrogen atom (H) on the first carbon.

```
O
||
C1 - C2 - C3 - C4
|
H
```

**Hint**: Aldehydes always have the carbonyl group at the end of the carbon chain.

4. **Add the Methyl Group**:
The name "2-methyl" indicates that there is a methyl group (–CH3) attached to the second carbon. So, we add a methyl group to the second carbon.

```
O
||
C1 - C2 - C3 - C4
| |
H CH3
```

**Hint**: The "2-methyl" means the methyl group is on the second carbon of the chain.

5. **Complete the Valencies**:
Now, we need to add hydrogen atoms to each carbon to satisfy their tetravalency (four bonds).
- C1 has 1 H (due to the aldehyde).
- C2 will have 1 H (since it has one methyl group).
- C3 will have 2 H.
- C4 will have 3 H.

The final structure will look like this:
```
O
||
H - C1 - C2 - C3 - C4
| | |
H CH3 H
```

**Hint**: Each carbon atom should have four bonds in total.

6. **Write the Complete Structural Formula**:
The complete structural formula of 2-methylbutanal can be written as:
```
CH3-CH(CH3)-CH2-CHO
```

**Hint**: Ensure that the aldehyde group is always at the end of the carbon chain.

### Final Answer:
The structural formula of 2-methylbutanal is:
```
CH3-CH(CH3)-CH2-CHO
```