Question

Question: Reaction of tert-butyl pentyl ether $\mathbf{}\mathbf{\left[}{\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{OC}{\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{3}}\mathbf{\right]}$with HBr forms 1-bromopentane$\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{Br}\mathbf{\right)}$ and compound B. B has a molecular ion in its mass spectrum at 56 and gives peaks in its IR spectrum at 3150–3000, 3000–2850, and 1650 cm^-1. Propose a structure for B and draw a stepwise mechanism that accounts for its formation.

Short answer

Answer

Step-by-step solution

Substitution reaction

Reactions that involve the replacement or substitution of one or more atoms or groups of a compound by another atom or group are known as substitution reactions.

tert-butylpentyl ether reacts with H-Br to form 1-bromopentane; 1-bromopentane reacts with H-Br to form 2-methyl propene.

Structure determination

IR absorptions at: 3150–3000 cm^-1 = C sp³-H

1650 cm^-1 = $\mathrm{C}=\mathrm{C}$(double bond)

3000-2850 cm^-1= (=C sp² -H )

The molecular ion peak 52 indicates that the compound possesses a molecular mass of 52 amu.