The IUPAC name of `CH_3 - CH_2 underset(C_2H_5)underset(|)(C ) - overset(O)overset(||)C - OCH_3` is :

Options

A. Methyl 2-ethylbutanoate
B. 1-methoxy-2-ethylbutanone
C. 3-Methoxycarbonylpentane
D. 1-methoxy-2-ethylbutanal

Explanation

To determine the IUPAC name of the compound `CH_3 - CH_2 - C(C_2H_5) - C(=O) - OCH_3`, we will follow these steps:

### Step 1: Identify the Functional Group
The given compound has an ester functional group, which is characterized by the structure RCOOR', where R and R' are alkyl groups. In this case, we can see that there is a carbonyl group (C=O) followed by an oxygen atom connected to a methyl group (OCH3).

### Step 2: Determine the Parent Carbon Chain
Next, we need to identify the longest continuous carbon chain that includes the carbonyl carbon. In this compound, the longest chain consists of four carbon atoms:
1. CH3 (1st carbon)
2. CH2 (2nd carbon)
3. C (3rd carbon with an ethyl substituent)
4. C(=O) (4th carbon, part of the carbonyl)

### Step 3: Identify Substituents
The substituent on the second carbon of the main chain is an ethyl group (C2H5).

### Step 4: Number the Carbon Chain
We will number the carbon chain starting from the end nearest to the carbonyl group to give the substituents the lowest possible numbers:
1. Carbon 1: CH3
2. Carbon 2: CH2 with an ethyl group (C2H5)
3. Carbon 3: C (part of the carbonyl)
4. Carbon 4: C(=O)

### Step 5: Combine the Information
Now we can combine the information to name the compound:
- The substituent ethyl is on the second carbon, so we denote it as "2-ethyl".
- The parent chain has four carbon atoms, which corresponds to "butane".
- Since it is an ester, we add the suffix "-oate".

### Step 6: Finalize the Name
Putting it all together, the IUPAC name of the compound is:
**Methyl 2-ethylbutanoate**

### Summary
The IUPAC name of the compound `CH_3 - CH_2 - C(C_2H_5) - C(=O) - OCH_3` is **Methyl 2-ethylbutanoate**.

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