Elimination of bromine from 2–bromobutane results in the formation of –

Options

A. predominantly 2–butene
B. equimolar mixture of 1 and 2–butene
C. predominantly 2–butyne
D. predominantly 1–butene

Answer

To solve the problem of what product is formed from the elimination of bromine from 2-bromobutane, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of 2-Bromobutane**:
- 2-bromobutane is a four-carbon alkane with a bromine atom attached to the second carbon. The structure can be represented as:
```
CH3-CH(Br)-CH2-CH3
```

2. **Understand the Elimination Reaction**:
- The elimination of bromine (Br) from 2-bromobutane typically occurs through a reaction called dehydrohalogenation, which involves the removal of a hydrogen atom and a bromine atom from adjacent carbon atoms.

3. **Determine the Possible Products**:
- When bromine is eliminated, a double bond is formed between the carbon atoms. There are two possible products:
- If bromine is removed from the second carbon and a hydrogen from the third carbon, the product will be:
```
CH3-CH=CH-CH3 (2-butene)
```
- If bromine is removed from the second carbon and a hydrogen from the first carbon, the product will be:
```
CH2=CH-CH2-CH3 (1-butene)
```

4. **Identify the Major Product**:
- According to Zaitsev's rule, the more substituted alkene is favored in elimination reactions. In this case, 2-butene (which has a double bond between the second and third carbons) is more substituted than 1-butene (which has a double bond between the first and second carbons).
- Therefore, the major product of the elimination reaction will be:
```
2-butene
```

5. **Conclusion**:
- The elimination of bromine from 2-bromobutane predominantly results in the formation of 2-butene.

### Final Answer:
The product formed from the elimination of bromine from 2-bromobutane is **2-butene**.

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