Since sulfuric acid is an oxidizing agent,if it will use in the reaction,it will convert KI  to corresponding HI and oxidize the HI.Hence sulfuric acid does not used during the reaction of alcohols with KI.

H2SO4 can't be used along with KI in the conversion of an alcohol to an alkyl iodine as it converts KI  to corresponding HI and then oxidizes HI to I2.

Thank you

Hi garima ,

Sulphuric acid is a oxidizing agent ..when react  in this reaction it oxides HI ...so the reaction between alcohol and HI to produce alkyl iodide cannot occur.

Because of this , sulphuric acid is not used in this reaction mixture. A non oxidising acids are only used...

Thanks.