Write the structural formula of : 3-hydroxy-2-methylpentanal .

Explanation

To write the structural formula of 3-hydroxy-2-methylpentanal, we will follow these steps:

### Step 1: Determine the Base Chain
The name "pentanal" indicates that we have a five-carbon chain (pent-). The suffix "-al" indicates the presence of an aldehyde functional group at the end of the chain.

**Hint:** Remember that "pent" refers to a five-carbon chain.

### Step 2: Draw the Five-Carbon Chain
We will draw a straight chain of five carbon atoms:
```
C1 - C2 - C3 - C4 - C5
```

**Hint:** Number the carbon atoms from 1 to 5, starting from the end where the aldehyde group will be attached.

### Step 3: Add the Aldehyde Group
The aldehyde group (–CHO) is attached to the first carbon (C1). This is represented as:
```
O
||
C1 - C2 - C3 - C4 - C5
|
H
```

**Hint:** The aldehyde group is always at the terminal carbon of the chain.

### Step 4: Identify and Add the Hydroxy Group
The name specifies a hydroxy group (–OH) at the third carbon (C3). We will add this group:
```
O
||
C1 - C2 - C3 - C4 - C5
| |
H OH
```

**Hint:** The hydroxy group is an alcohol functional group and is indicated by "hydroxy" in the name.

### Step 5: Identify and Add the Methyl Group
The name also specifies a methyl group (–CH3) at the second carbon (C2). We will add this group:
```
O
||
C1 - C2 - C3 - C4 - C5
| | |
H OH CH3
```

**Hint:** The methyl group is a simple alkyl group derived from methane.

### Step 6: Complete the Structure with Hydrogen Atoms
Now, we need to add hydrogen atoms to each carbon to satisfy the tetravalency of carbon:
```
O
||
H-C1 - C2 - C3 - C4 - C5
| | |
H OH CH3
|
H
```
Now, we can fill in the remaining hydrogen atoms:
```
O
||
H-C1 - C2 - C3 - C4 - C5
| | |
H OH H
|
H
```
The complete structural formula of 3-hydroxy-2-methylpentanal is:
```
O
||
H-C1 - C2 - C3 - C4 - C5
| | |
H OH H
|
H
```

### Final Structural Formula
The final structural formula can be represented as:
```
O
||
CH3-CH-CH(OH)-CH2-CHO
```

### Summary
The structural formula of 3-hydroxy-2-methylpentanal includes a five-carbon chain with an aldehyde group at one end, a hydroxy group on the third carbon, and a methyl group on the second carbon.