Question

Which of the following, is the product of the reaction between $AlCl_3$ and $CH_3OCH_3$?

• A. Cl - $\underset{Cl}{\overset{Cl}{|}}Al^-$ - $O^+\begin{matrix}CH_3 \\CH_3\end{matrix}$
• B. Cl - $\underset{Cl}{\overset{Cl}{|}}Al^+$ - $O^-\begin{matrix}CH_3 \\CH_3\end{matrix}$
• C. Cl - $\underset{Cl}{\overset{Cl}{|}}Al^+$ - $O^+\begin{matrix}CH_3 \\CH_3\end{matrix}$
• D. Cl - $\underset{Cl}{\overset{Cl}{|}}Al^-$ - $CH_3OCH_3$

Answer 1

Answer: (A)

Cl - $\underset{Cl}{\overset{Cl}{|}}Al^-$ - $O^+\begin{matrix}CH_3 \\CH_3\end{matrix}$

Answer 2

$AlCl_3$ acts as a Lewis acid due to the incomplete octet on the aluminum atom. $CH_3OCH_3$ (dimethyl ether) acts as a Lewis base, with the oxygen atom donating a lone pair of electrons. The reaction forms a coordinate covalent bond between the oxygen atom of dimethyl ether and the aluminum atom of $AlCl_3$. This results in a formal positive charge on the oxygen atom and a formal negative charge on the aluminum atom. The structure of the adduct formed is: Cl | Cl-Al⁻ - O⁺ | /
Cl CH3 CH3