Structure of the compound whose `IUPAC` name is `3-`ethyl`-2-`hydroxy`-4-`methylhex`-3-`en`-5-`ynoic acid is

Options

A.
B.
C.
D.

Explanation

To determine the structure of the compound with the IUPAC name `3-ethyl-2-hydroxy-4-methylhex-3-en-5-ynoic acid`, we will follow a systematic approach based on the nomenclature provided.

### Step-by-Step Solution:

1. **Identify the Parent Chain:**
- The root name is "hex," which indicates that the main chain has 6 carbon atoms. Therefore, we will start by drawing a straight chain of 6 carbon atoms.

**Hint:** Count the number of carbon atoms in the root name to determine the length of the main chain.

2. **Number the Carbon Atoms:**
- We will number the carbon chain from the end closest to the highest priority functional group, which is the carboxylic acid (-COOH) group. This will be at carbon 1.

**Hint:** Always number the carbon chain from the end nearest to the functional group with the highest priority.

3. **Add the Carboxylic Acid Group:**
- At carbon 1, we will attach the carboxylic acid group (-COOH).

**Hint:** The carboxylic acid group is always at the first carbon when present in the compound.

4. **Add the Hydroxy Group:**
- The name indicates a hydroxy group (-OH) at carbon 2. We will place an -OH group on the second carbon.

**Hint:** Hydroxy groups are indicated by the prefix "hydroxy" in the name; place them on the specified carbon.

5. **Add the Methyl Group:**
- The name specifies a methyl group (-CH3) at carbon 4. We will attach a methyl group to the fourth carbon.

**Hint:** Methyl groups are indicated by the prefix "methyl" in the name; place them on the specified carbon.

6. **Add the Ethyl Group:**
- The name specifies an ethyl group (-C2H5) at carbon 3. We will attach the ethyl group to the third carbon.

**Hint:** Ethyl groups are indicated by the prefix "ethyl" in the name; place them on the specified carbon.

7. **Add the Double and Triple Bonds:**
- The name indicates a double bond between carbons 3 and 4 (hex-3-en) and a triple bond between carbons 5 and 6 (5-ynoic). We will add a double bond between carbon 3 and carbon 4, and a triple bond between carbon 5 and carbon 6.

**Hint:** Pay attention to the suffixes "en" and "yn" to determine the positions of double and triple bonds.

8. **Final Structure:**
- Now, we can combine all the components to draw the complete structure. The final structure will have:
- 6 carbon atoms in a chain.
- A carboxylic acid group at carbon 1.
- A hydroxy group at carbon 2.
- An ethyl group at carbon 3.
- A methyl group at carbon 4.
- A double bond between carbons 3 and 4.
- A triple bond between carbons 5 and 6.

### Final Structure:
The structure can be represented as follows:

```
OH
|
CH3-CH-CH=CH-C≡C-COOH
| |
CH2 CH3
```