`CH_(3) - undersetunderset(Cl)(|)C = CH - undersetunderset(O)("||")C - OCH_(3)` is named in IUPAC as :

Options

A. Methyl -3-chloro-2-butenoate
B. Methyl 4 chloro -2-pentanoate
C. Methoxy -3-chloro butanol
D. Methoxy -2-chloro butanone

Answer

To determine the IUPAC name of the given compound, we will follow these steps:

### Step 1: Identify the Functional Group
The given structure contains an ester functional group, which is characterized by the presence of the -COO- group.

**Hint:** Look for the -COO- group to identify esters.

### Step 2: Number the Carbon Chain
We will start numbering the carbon chain from the carbon of the ester group. This will help us identify the longest carbon chain and the position of the functional groups.

- Start numbering from the carbon of the ester (C=O).
- The numbering will be as follows:
1. Carbon of the ester (C=O)
2. Carbon next to it
3. Carbon with chlorine attached
4. Last carbon in the chain

**Hint:** Always start numbering from the functional group that has the highest priority.

### Step 3: Determine the Parent Chain
The longest carbon chain we have is 4 carbons long, which is called butane. However, since there is a double bond present, we will modify the name to butene.

**Hint:** Count the number of carbons in the longest chain to determine the base name.

### Step 4: Identify the Position of the Double Bond
The double bond is located between the 2nd and 3rd carbons. Therefore, we will specify the position of the double bond in the name as 2-butene.

**Hint:** The position of the double bond is indicated by the lowest numbered carbon involved in the double bond.

### Step 5: Name the Ester Component
In the case of esters, the alkyl group attached to the oxygen is named first. Here, the alkyl group is a methyl group (from -OCH₃).

**Hint:** The alkyl group from the ester is named first in the IUPAC name.

### Step 6: Modify the Parent Name for Ester
In the naming of esters, the "e" in the alkene name (butene) is replaced with "oate". Therefore, "butene" becomes "butenoate".

**Hint:** Remember to replace the "e" in the alkene name with "oate" when naming esters.

### Step 7: Identify and Name Substituents
There is a chlorine atom attached to the 3rd carbon in the chain. We will denote this as 3-chloro.

**Hint:** Substituents are named with their position number before the parent name.

### Step 8: Combine All Parts to Form the Complete Name
Now, we can combine all parts:
- Alkyl group from the ester: methyl
- Substituent: 3-chloro
- Parent name: 2-butenoate

Putting it all together, we get the complete IUPAC name: **methyl-3-chloro-2-butenoate**.

**Final Answer:** The IUPAC name of the compound is **methyl-3-chloro-2-butenoate**.