Question

why is sulphuric acid not used during the reaction of alcohols with KI

Answer 1

Since H2SO4 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.

Answer 2

Hello buddy..
Harshi this side..

Just see the reaction below, as we know that KI will produce HI in presence of Sulphuric acid..

2KI  +  H2SO4     →    2KHSO4  + 2HI

Since H2SO4 is an oxidizing agent, it oxidizes HI (produced in the reaction to I2).

2HI  + H2SO4    →  I2  +  SO2  +  H2O

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.

Hope it helps you buddy..