Question

Given the following single-step reaction, draw the curved-arrow mechanism.

Answer 1

Concepts and reason

Nucleophilic substitution reactions involve the replacement of a weak nucleophile by a stronger one. This type of reactions can take place via two mechanisms. Biomolecular nucleophilic substitution reactions $\left( {{{\rm{S}}_{\rm{N}}}2} \right)$ and unimolecular nucleophilic substitution reactions $\left( {{{\rm{S}}_{\rm{N}}}1} \right)$ .

Fundamentals

Biomolecular nucleophilic substitution $\left( {{{\rm{S}}_{\rm{N}}}2} \right)$ is a second order reaction which involves only one step whereas, unimolecular nucleophilic substitution is a first order reaction having two steps.

Methoxy $\left( {{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{ - }}{{\rm{O}}^ - }} \right)$ group will attack the carbon atom attached to bromine because the electron density of methoxy group is very high. Therefore, it works as a nucleophile.

Bromine leaves the carbon atom and replaced by methoxy group.

Ans:

Curved arrow representation of the reaction is as follows: