When 3-methylbutan-2-ol reacts with PCl5 in the presence of anhydrous AlCl3, the hydroxyl group -OH in the alcohol is replaced by a chlorine atom, resulting in the formation of 3-methylbutan-2-chloride.The balanced equation for the reaction is:C5H11OH + PCl5 C5H11Cl + POCl3 + HClThe type of reaction is a nucleophilic substitution reaction, specifically, it is an S_N2 reaction where the hydroxyl group is replaced by a chlorine atom.