When an unsymmetrical aliphatic ether such as methoxyethane () is treated with cold, dilute hydroiod — Alcohols Phenols and Ethers Chemistry Question

💡 Solution & Explanation

In cold/dilute conditions with primary or secondary alkyl groups, the cleavage follows an $S_N2$ pathway. The bulky iodide nucleophile ($I^-$) prefers to attack the least sterically hindered carbon atom adjacent to the oxonium oxygen. Thus, it attacks the methyl group, cleaving the $C-O$ bond to form methyl iodide and leaving the larger fragment as ethanol.