In the presence of sulphuric acid (H2SO4), KI produces HI
is an oxidizing agent, it oxidizes HI (produced in
the reaction to I2). As a result, the reaction between alcohol and HI to produce alkyl iodide cannot occur. Therefore, sulphuric acid is not used during the reaction of alcohols with KI. Instead, a non-oxidizing acid such as H3PO4 is used.
