IUPAC name of `CH_(3)-underset(CH_(3))underset(|)C=CH-underset(O)underset(||)C-CH_(3)` is

Options

A. 4-methylpent-3-en-2-one
B. 2-Methylpent-3-en-2-one
C. 3-Methylpent-2-en-1-one
D. none of these.

Answer

To determine the IUPAC name of the compound `CH₃-CH₃-C=CH-C(=O)-CH₃`, we will follow these steps:

### Step 1: Identify the Functional Group
The main functional group in this compound is a ketone, which is represented by the carbonyl group (C=O).

### Step 2: Determine the Longest Carbon Chain
Count the number of carbon atoms in the longest continuous chain that includes the functional group. In this case, the longest chain has 5 carbon atoms.

### Step 3: Number the Carbon Chain
Number the carbon chain starting from the end closest to the functional group (the carbonyl group). This ensures that the functional group gets the lowest possible number.

- Starting from the right:
1. C1: CH₃
2. C2: C=CH
3. C3: C
4. C4: C(=O)
5. C5: CH₃

### Step 4: Identify Substituents
Look for any substituents attached to the main carbon chain. In this case, there is a methyl group (CH₃) attached to the fourth carbon.

### Step 5: Combine the Information
Now, we can combine the information to write the IUPAC name:
- The main chain is a pentane (5 carbon atoms).
- There is a ketone functional group at position 2 (C=O).
- There is a methyl group at position 4.

### Step 6: Write the Name
The name will be constructed as follows:
- Start with the substituent: "4-methyl"
- Then the main chain: "pent"
- Indicate the position of the double bond: "3-en"
- Finally, indicate the ketone: "2-one"

Putting it all together, the IUPAC name is **4-methyl-3-penten-2-one**.

### Final Answer
The IUPAC name of the compound is **4-methyl-3-penten-2-one**.

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