Question

Why is orthophosphoric acid used with sodium iodide in the preparation of alkyl iodide from alcohol?

Answer 1

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The mixture of the iodide and phosphoric(V) acid produces hydrogen iodide, which reacts with the alcohol. Phosphoric(V) acid is used instead of concentrated sulfuric acid because sulfuric acid oxidizes iodide ions to iodine and produces hardly any hydrogen iodide.

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Answer 2

The mixture of the iodide and phosphoric(V) acid produces hydrogen iodide, which reacts with the alcohol. Phosphoric(V) acid is used instead of concentrated sulfuric acid because sulfuric acid oxidizes iodide ions to iodine and produces hardly any hydrogen iodide.