Question

Predict a dihalide which gives ethene by treating with Zn dust under suitable conditions.

• A. 2,4-dibromo-3-methylpentane
• B. 1,2-dibromoethane
• C. 1,4-dibromomethylpentane
• D. 1,3-dibromo-2-methylbutane

Answer 1

The correct option is B 1,2-dibromoethane

Zn dust brings dehalogenation of vicinal dihalide to give alkene.
among the given option only 1,2-dibromoethane is vicinal dihalide thus it will undergo dehalogenation.
$\underset{\underset{Br}{|}}{C{H}_2}-\underset{\underset{Br}{|}}{C{H}_2}\stackrel{Zn}{⟶}C{H}_2=C{H}_2$
All others are not vicinal dihalide thus they donot undergo dehalogenation.
Hence correct option is b.