JAMB Chemistry 2022 Paper

Concept:Dehydration of an alcohol is an elimination reaction in which a molecule of water is removed from adjacent carbon atoms to form an alkene.Explanation:The compound $\mathrm{CH_3CH_2CH_2CH_2OH}$ is butan-1-ol, a primary alcohol.During dehydration, the $\mathrm{-OH}$ group is lost from the first carbon atom, and a hydrogen atom is removed from the second carbon atom.A double bond forms between carbon 1 and carbon 2, while the chain length remains four carbon atoms.Only water is eliminated, so the product is an alkene and not an alkyne.The reaction is:$$\mathrm{CH_3CH_2CH_2CH_2OH} \xrightarrow[\Delta]{\mathrm{conc.\ H_2SO_4}} \mathrm{CH_2{=}CHCH_2CH_3} + \mathrm{H_2O}$$This is a terminal alkene, known as but-1-ene.Answer:But-1-ene, $\mathrm{CH_2{=}CHCH_2CH_3}$.