Write the structural formula of 4-hydroxybutan-2-one.

Explanation

To write the structural formula of 4-hydroxybutan-2-one, we can follow these steps:

### Step 1: Identify the Carbon Chain
The name "butan" indicates that we have a four-carbon chain. We will start by drawing a straight chain of four carbon atoms.

**Hint:** Remember that "but" in butan refers to a four-carbon chain.

### Step 2: Number the Carbon Atoms
We need to number the carbon atoms in the chain. We will number them from left to right for clarity:
1. C1
2. C2
3. C3
4. C4

**Hint:** Number the carbon chain starting from the end closest to the functional groups.

### Step 3: Identify the Ketone Group
The "2-one" in the name indicates that there is a ketone group (C=O) at the second carbon (C2). We will place a double bond oxygen (C=O) at this position.

**Hint:** A ketone group is characterized by a carbon atom double-bonded to an oxygen atom.

### Step 4: Identify the Hydroxyl Group
The "4-hydroxy" part of the name indicates that there is a hydroxyl group (–OH) at the fourth carbon (C4). We will add an –OH group to this carbon.

**Hint:** Hydroxyl groups are represented as –OH and are characteristic of alcohols.

### Step 5: Complete the Valencies with Hydrogen Atoms
Now, we need to add hydrogen atoms to each carbon to satisfy their tetravalency (four bonds):
- C1 will have 3 hydrogens (CH3).
- C2 will have 1 hydrogen (since it is bonded to the ketone and C1).
- C3 will have 2 hydrogens (CH2).
- C4 will have 1 hydrogen and the hydroxyl group (–OH).

So, the complete structure will look like this:
- C1: CH3
- C2: C(=O)H
- C3: CH2
- C4: CH2OH

### Final Structural Formula
Putting it all together, the structural formula of 4-hydroxybutan-2-one is:

```
CH3
|
C(=O)
|
CH2
|
CH2OH
```

### Summary
The structural formula of 4-hydroxybutan-2-one is represented with a four-carbon chain, a ketone group at the second carbon, and a hydroxyl group at the fourth carbon.

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