Question

How will you carry out the following conversion?

1-bromobutane to but-1-ene

Answer 1

1-bromobutane is converted to but-1-ene by heating it with alcoholic potassium hydroxide (alc. KOH). This causes a dehydrohalogenation reaction, where a hydrogen atom and the bromine atom are eliminated from adjacent carbon atoms, resulting in the formation of a double bond. As a result, but-1-ene is formed through an elimination (E₂) reaction.

\[\ce{\underset{1-bromobutane}{CH3-CH2-CH2-CH2-Br} ->[KOH (alc{.})][]\underset{but-1-ene}{CH2=CH-CH2-CH3} + HBr}\]