Question

Choose the correct and major product formed in the below-given reaction from the choices listed below:

• A. 3-Pentene
• B. 2-Methyl-2-butene
• C. 1-Pentane
• D. 1-Methyl-2-butene

Answer 1

The Correct Option is B

In the given reaction, we need to determine the major product formed from a β-elimination (dehydrohalogenation) reaction, which typically follows the E2 mechanism.

The given compound is 2-Bromo-3-methylbutane. When reacted with ethanol (EtOH), a protic solvent, the elimination reaction results in the removal of the halogen (Br) and a hydrogen atom from the adjacent carbon atom, forming a double bond.

Applying Zaitsev's rule, which states that the more substituted alkene will be favored as the major product, we look for the formation of a double bond with greater substitution:

The possible alkenes are:

• 3-Pentene - Less substituted alkene.
• 2-Methyl-2-butene - More substituted alkene.
• 1-Pentene - Least substituted alkene.
• 1-Methyl-2-butene - Less substituted compared to 2-methyl-2-butene. 

Thus, according to Zaitsev's rule, 2-Methyl-2-butene will be the major product as it is the more substituted alkene.

The reaction can be represented as follows:

\(\text{2-Bromo-3-methylbutane} \xrightarrow{\text{EtOH}} 2-\text{Methyl-2-butene} + \text{HBr}\)

Therefore, the correct answer is 2-Methyl-2-butene.