When 3-bromo-2,2-dimethyl butane is treated with alcoholic potassiumn hydroxide the number of possible alkene isomers formed is

Answer

To determine the number of possible alkene isomers formed when 3-bromo-2,2-dimethylbutane is treated with alcoholic potassium hydroxide, we can follow these steps:

### Step 1: Identify the structure of 3-bromo-2,2-dimethylbutane
3-bromo-2,2-dimethylbutane has the following structure:

```
Br
|
CH3-C-CH-CH3
|
CH3
```

In this structure, the bromine (Br) is attached to the third carbon of the butane chain, and there are two methyl (CH3) groups attached to the second carbon.

### Step 2: Understand the elimination reaction
When 3-bromo-2,2-dimethylbutane is treated with alcoholic potassium hydroxide (KOH), an elimination reaction occurs. This reaction typically leads to the formation of alkenes by removing the bromine atom and a hydrogen atom from adjacent carbons.

### Step 3: Identify the possible elimination sites
The bromine is on the third carbon, and we can eliminate a hydrogen from either the second carbon or the fourth carbon. This gives us two potential elimination pathways:

1. **Elimination from C2 and C3**: This will form an alkene with a double bond between C2 and C3.
2. **Elimination from C3 and C4**: This will form an alkene with a double bond between C3 and C4.

### Step 4: Draw the possible alkenes
1. **From C2 and C3**:
The resulting alkene will be 2,2-dimethyl-2-butene.

Structure:
```
CH3
|
CH3-C=CH-CH3
```

2. **From C3 and C4**:
The resulting alkene will be 3,3-dimethyl-1-butene.

Structure:
```
CH3-CH2-C=CH2
|
CH3
```

### Step 5: Count the isomers
Now, we need to check if there are any geometric (cis/trans) isomers for the alkenes formed:

1. **2,2-dimethyl-2-butene**: This compound does not have geometric isomers because the double bond is between two identical groups (the two methyl groups).

2. **3,3-dimethyl-1-butene**: This compound also does not have geometric isomers because it has a terminal double bond.

### Conclusion
Thus, the total number of possible alkene isomers formed is **2**.