What is the correct IUPAC name for
`CH_3-underset(C_2H_5)underset(|)"CH"-CH_2-Br ?`

Options

A. 1-Bromo-2-ethylpropane
B. 1-Bromo-2-ethyl-2-methylethane
C. 1-Bromo-2-methylbutane
D. 2-Methyl-1-bromobutane

Answer

To determine the correct IUPAC name for the compound `CH_3-CH(CH_2Br)-CH_2-CH_3`, we will follow the steps outlined below:

### Step 1: Write the Compound in Expanded Form
The given compound can be expanded to show all the carbon atoms and their connections:
- The structure can be represented as:
```
CH3-CH(CH2Br)-CH2-CH3
```
This indicates that there is a bromine (Br) substituent on one of the carbon atoms.

### Step 2: Identify the Longest Carbon Chain
Next, we need to identify the longest continuous carbon chain in the molecule:
- The longest chain consists of 4 carbon atoms, which is a butane chain.

### Step 3: Number the Carbon Chain
We will number the carbon chain to give the substituents the lowest possible numbers:
- Starting from the end nearest to the bromine substituent:
```
1 2 3 4
CH3 - CH - CH2 - CH3
|
Br
```
- Here, the bromine is on carbon 2.

### Step 4: Identify and Name the Substituents
Now, we identify the substituents on the main chain:
- There is one bromine substituent (bromo) on carbon 2.
- There are two methyl groups (CH3) on carbon 2 as well.

### Step 5: Combine the Names
According to IUPAC naming conventions, we list the substituents in alphabetical order:
- The substituents are "bromo" and "methyl".
- The correct order is "1-bromo" and "2-methyl".

### Step 6: Write the Full IUPAC Name
Putting it all together, the IUPAC name of the compound is:
- **1-bromo-2-methylbutane**

### Final Answer
The correct IUPAC name for the compound is **1-bromo-2-methylbutane**.

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