Which is the correct structure of `3-`cyclohexylmethyl betanamide?

Options

A.
B.
C.
D.

Explanation

To determine the correct structure of `3-cyclohexylmethyl butanamide`, we can follow these steps:

### Step 1: Identify the Parent Chain
The name `butanamide` indicates that the parent chain consists of four carbon atoms (butane) with an amide functional group. The structure of butanamide can be represented as:

```
O
||
H2N-C-C-C-C
```
Where the carbon chain is numbered from 1 to 4.

### Step 2: Add the Amide Group
In butanamide, the amide group (–C(=O)NH2) is attached to the first carbon. Therefore, the structure becomes:

```
O
||
H2N-C1-C2-C3-C4
```

### Step 3: Identify the Substituent
The name `3-cyclohexylmethyl` indicates that on the third carbon of the butanamide chain, there is a cyclohexyl group attached along with a methyl group.

### Step 4: Draw the Cyclohexyl Group
The cyclohexyl group is a six-membered carbon ring. We can represent it as:

```
C
/ \
C C
| |
C C
\ /
C
```

### Step 5: Attach the Cyclohexyl Group
Now, we need to attach the cyclohexyl group to the third carbon of the butanamide chain. The structure now looks like this:

```
O
||
H2N-C1-C2-C3(Cyclohexyl)-C4
```

### Step 6: Add the Methyl Group
The methyl group (–CH3) is also attached to the cyclohexyl group. So, we place a methyl group on one of the carbons of the cyclohexyl ring.

The final structure can be represented as:

```
O
||
H2N-C1-C2-C3(Cyclohexyl with a methyl group)-C4
```

### Step 7: Verify the Structure
Now, we need to check the options provided. The correct structure should have:
- A four-carbon chain (butanamide)
- A cyclohexyl group on the third carbon
- A methyl group on the cyclohexyl group

After checking the options, we find that option D matches this description.

### Final Answer
The correct structure of `3-cyclohexylmethyl butanamide` is option D.

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