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

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Sulphuric acid is not used during the reaction of alcohols with KI as it produces HI which is oxidized during the reaction to I2. In the presence of sulphuric acid (H2SO4), KI produces HI:

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 conversion of alcohol to alkyl iodide cannot take place. Sulphuric acid is therefore not employed when reacting alcohols with KI. Instead, a non-oxidizing acid such as H3PO4 is used. Other names for sulfuric acid include Mattling acid and Oil of Vitriol. It is corrosive and has a strong acidic tendency. It functions as an oxidising and dehydrating agent at greater concentrations.

Uses of sulphuric acid

  • It is utilised to create fertilisers.
  • It is employed in the manufacture of iron and steel.
  • It is employed in the production of chemicals.
  • It is applied to refine petroleum.
  • It’s employed to make phosphoric acid.
  • In industries, it is used as a cleaning agent to get rid of rust on steel and iron.
  • It serves as a catalyst for the production of nylon by converting cyclohexanone oxime to caprolactam.
  • It serves as an electrolyte in lead-acid batteries.
  • Making ammonium sulphate requires it.
  • Batteries for storage include it.


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

Alcohols react with KI to form HI, which is then oxidised to form I2, hence sulfuric acid is not necessary in this reaction. Oil of Vitriol and Matting acid are the other names of sulfuric acid.

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