The IUPAC name of `CH_3 - underset(OH)underset(|) CH- underset(C_2H_5) underset(|) CH - CH_2 - OH` is

Options

A. 3-Ethylbutane-2, 4-diol
B. 2-Ethylbutane-1,3-diol
C. 3-Ethylbutane-1,3-diol
D. 2-Ethyl-1-methylpropane-1,3-diol

Explanation

To determine the IUPAC name of the compound `CH_3 - OH - CH - C_2H_5 - CH - CH_2 - OH`, we will follow a systematic approach:

### Step-by-Step Solution:

1. **Identify the Longest Carbon Chain**:
- The first step in naming the compound is to identify the longest continuous carbon chain. In this case, we have a total of 4 carbon atoms in the main chain.
- The longest carbon chain can be represented as:
```
CH3 - CH - CH2 - CH2
```

2. **Identify Substituents and Functional Groups**:
- In addition to the main chain, we notice that there are two hydroxyl (–OH) groups and one ethyl (–C2H5) group as a substituent.
- The functional group –OH indicates that this compound is an alcohol.

3. **Number the Carbon Atoms**:
- We need to number the carbon atoms in such a way that the functional groups receive the lowest possible numbers.
- If we number from left to right, we get:
```
1 2 3 4
CH3 - CH - CH2 - CH2
```
- Here, the –OH groups are on carbons 1 and 3.

4. **Assign the Correct Locants**:
- The hydroxyl groups are on carbon 1 and carbon 3, and the ethyl group is on carbon 2.
- Therefore, we have:
- 2 hydroxyl groups (–OH) at positions 1 and 3.
- 1 ethyl group at position 2.

5. **Construct the Name**:
- The base name for a 4-carbon alcohol is "butane".
- Since there are two hydroxyl groups, we use the prefix "di" to indicate two –OH groups, resulting in "butane-1,3-diol".
- We also need to include the ethyl substituent at position 2, which gives us "ethyl".
- The final IUPAC name is: **2-ethylbutane-1,3-diol**.

### Final Answer:
The IUPAC name of the compound is **2-ethylbutane-1,3-diol**.