The IUPAC name of `CH_3 COCH(CH_3)_2` is

Options

A. isopropylmethyl ketone
B. 2-methylbutan-3-one
C. 4-methylisopropyl ketone
D. 3-methylbutan-2-one.

Explanation

To determine the IUPAC name of the compound `CH3COCH(CH3)2`, we can follow these steps:

### Step 1: Identify the Structure
The given compound can be represented structurally as follows:
- The central carbon is connected to a carbonyl group (C=O), indicating that it is a ketone.
- There are two methyl groups (CH3) attached to the central carbon.

### Step 2: Determine the Functional Group
Since the compound contains a carbonyl group (C=O) between two carbon atoms, it is classified as a ketone. The principal functional group here is the ketone.

### Step 3: Number the Carbon Chain
We need to number the carbon chain to give the lowest possible number to the functional group:
1. Start numbering from the end nearest to the carbonyl group.
2. The numbering would be as follows:
- Carbon 1: CH3 (methyl group)
- Carbon 2: C=O (carbonyl group)
- Carbon 3: CH (with two methyl groups attached)
- Carbon 4: CH3 (methyl group)

### Step 4: Identify the Parent Chain
The longest continuous carbon chain that includes the carbonyl group has four carbon atoms. Therefore, the parent chain is butane.

### Step 5: Identify and Name the Substituents
We have two methyl groups attached to the third carbon:
- The substituent is a methyl group (CH3).
- Since there are two methyl groups, we will use "dimethyl" in the name.

### Step 6: Combine the Information
Now we can combine all the information to write the IUPAC name:
- The substituent (dimethyl) is on the third carbon.
- The parent chain is butane.
- The functional group is a ketone, which will be indicated by the suffix "-one".

Thus, the IUPAC name of the compound is **3,3-dimethylbutan-2-one**.

### Final Answer
The IUPAC name of `CH3COCH(CH3)2` is **3,3-dimethylbutan-2-one**.

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