(Solved): a) Dialkyl ether undergoes \( \mathrm{S}_{\mathrm{N}} 2 \) reaction to form two equivalents of the ...

a) Dialkyl ether undergoes \( \mathrm{S}_{\mathrm{N}} 2 \) reaction to form two equivalents of the alkyl bromide as shown in the reaction below: Propose a stepwise mechanism with curved arrows for the substitution reaction. (5 marks) b) Compound \( \mathbf{V} \) is reacted with strong nucleophile as shown below. This reaction proceeds via \( \mathrm{S}_{\mathrm{N}} 2 \) reaction mechanism to give \( \mathbf{W} \) as the final product. i) Show the mechanism of the substitution reaction to produce \( \mathbf{W} \). (2 marks) ii) If \( \mathrm{NaSH} \) was substituted with \( \mathrm{Na}\left(\mathrm{OCH}_{3}\right)_{3} \), suggest ii-a) the new type of mechanism ii-b) structure of the new products. ii-c) trend on the reaction rates if doubled the concentration of \( \mathbf{V} \). (4 marks)