A hydroxyl acid on heating gives a 5 - membered lactone. The acid is

Options

A. `CH_2OHCH_2CH_2COOH`
B. `CH_3CHOHCH_2COOH`
C. `CH_3CH_2CHOHCOOH`
D. `CH_3CHOHCHOHCOOH`

Answer

To determine which hydroxyl acid gives a 5-membered lactone upon heating, we can follow these steps:

### Step 1: Understand the structure of a 5-membered lactone
A 5-membered lactone is a cyclic ester formed from a hydroxyl acid. It consists of a ring of five atoms, including one oxygen atom and four carbon atoms. The general structure can be represented as follows:

```
O
/ \
C C
| |
C C
```

### Step 2: Identify the components of the hydroxyl acid
A hydroxyl acid contains both a hydroxyl group (-OH) and a carboxylic acid group (-COOH). For the formation of a 5-membered lactone, the hydroxyl group must be positioned such that it can react with the carboxylic acid group upon heating.

### Step 3: Analyze the given compounds
We need to analyze the four given hydroxyl acids to determine which one can form a 5-membered lactone. The key points to consider are:
- The presence of a -COOH group.
- The presence of a -OH group.
- The carbon chain length must allow for the formation of a 5-membered ring.

### Step 4: Draw the structures of the compounds
1. **Compound 1**: CH2(OH)CH2COOH
2. **Compound 2**: CH3CH(OH)CH2COOH
3. **Compound 3**: CH3CH2CH(OH)COOH
4. **Compound 4**: CH3CH2C(OH)COOH

### Step 5: Determine which compound can form a 5-membered lactone
- For **Compound 1**: The structure allows for the -OH group to react with the -COOH group to form a 5-membered ring.
- For **Compound 2**: The -OH is not positioned to effectively react with the -COOH group to form a 5-membered lactone.
- For **Compound 3**: Similar to Compound 2, the positioning does not favor lactone formation.
- For **Compound 4**: The structure does not allow for a 5-membered lactone formation.

### Step 6: Conclusion
The only compound that can form a 5-membered lactone upon heating is **Compound 1** (CH2(OH)CH2COOH).

Thus, the answer is:
**The hydroxyl acid that gives a 5-membered lactone upon heating is Compound 1.**