# Dehydration of alcohol

I have seen $\ce{P4O_{10}}$ and $\ce{HSO3Cl}$ being used to dehydrate carboxylic acids giving an anhydride and a ketene respectively.

Can we use them to dehydrate $\ce{-OH}$ (of aliphatic alcohol) group from an organic compound? I have never seen anyone do that. If we can, then please specify the appropriate conditions for the reaction to be carried out.

• $\ce{P4O10/P2O5}$ with some heating dehydrates alcohols. Apr 7 '17 at 14:54
• Look up Eaton's reagent Apr 7 '17 at 15:02

As you've noted, $\ce{P4O10}$ (or $\ce{P2O5}$ ) is a powerful dehydrating agent. According to the Chemical Book, it can actually dehydrate concentrated sulfuric acid to $\ce{SO3}$. So, it's not surprising that it can indeed dehydrate aliphatic alcohols. Using ethanol as an example, ethene can be produced by refluxing ethanol over $\ce{P4O10}$:
$$\ce{C2H5OH ->[P4O10] C2H4 + H2O}$$