Question

One mole of glycerol is treated with an excess of $HI$ to obtain isopropyl iodide. The number of moles of $HI$ consumed by one mole of glycerol in this reaction is:

Answer 1

When glycerol is heated with 3 moles of $HI$, the allyl iodide formed first is reduced to propene. Propene in presence of excess of $HI$ forms iso-propyl iodide.

From the reaction, it can be seen that five moles of $HI$ are consumed by one mole of glycerol to finally form isopropyl iodide.

So correct answer is 5.