Question

What is the use of reaction of diethyl ether with excess hi?

Answer 1

Mechanism: Strong acid (HI) protonates the ether oxygen, which turns it into a better leaving group (Step 1, arrows A and B). Next, the iodide ion attacks the carbon in an SN2 reaction (Step 2, arrows C and D) to give the alcohol and methyl iodide.

Answer 2

If the ether is on a primary carbon this may occur through an SN2 pathway. Notes: Common acids for this purpose are HI and other hydrogen halides, as well as H2SO4 in the presence of H2O. In the case where the ether being cleaved is secondary and has a stereocenter, there will be inversion of configuration.