Which of the following is incorrect common names ?

Options

A. Sec-butyl alcohol.
B. Neopentyl amine
C. Isopentyl alcohol
D. Ethyl methyl ketone

Explanation

To determine which of the following common names is incorrect, we can follow these steps:

### Step 1: Analyze the Given Names
We have several common names to analyze:
1. Secondary butyl alcohol
2. Neopentyl amine
3. Isopentyl alcohol
4. Ethyl methyl ketone

### Step 2: Draw the Structures
Let's draw the structures for each of the names provided.

#### 1. Secondary Butyl Alcohol
- The common name "secondary butyl alcohol" suggests that the alcohol group (OH) is on the second carbon of a butane chain.
- The structure would be:
```
CH3
|
CH3-CH-CH2-OH
|
CH3
```
- This structure corresponds to 2-butanol, which is indeed a secondary alcohol.

#### 2. Neopentyl Amine
- Neopentyl amine has a structure that consists of a central carbon bonded to four other carbons, with an amine group (NH2) attached.
- The structure would be:
```
CH3
|
CH3-C-CH2-CH3
|
NH2
```
- This structure is correct for neopentyl amine.

#### 3. Isopentyl Alcohol
- Isopentyl alcohol, also known as isoamyl alcohol, has the structure where the alcohol group is on the second carbon of a pentane chain.
- The structure would be:
```
CH3
|
CH3-CH-CH2-CH3
|
OH
```
- This structure is correct for isopentyl alcohol.

#### 4. Ethyl Methyl Ketone
- Ethyl methyl ketone is a common name for butan-2-one, which has a ketone group (C=O) on the second carbon of a butane chain.
- The structure would be:
```
CH3
|
CH3-C-CH2-CH3
||
O
```
- This structure is correct for ethyl methyl ketone.

### Step 3: Identify the Incorrect Name
From our analysis:
- The structure drawn for **secondary butyl alcohol** does not correspond to the name given. The correct IUPAC name for the structure drawn is 2-methyl-propan-1-ol, not secondary butyl alcohol.

### Conclusion
The incorrect common name is **secondary butyl alcohol**.

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