Dehydration of carboxylic acids using P2O5

Why isn’t concentrated $\ce{H2SO4}$ used for the dehydration of carboxylic acids to anhydrides? What is special about $\ce{P2O5}$?




Intermolecular forces are the reason. Carboxilic acids have capability of forming a dimer by hydrogen bonding. That enables a very stable arrangement. The hydrogen bonding stabilise the molecule, enabling the organic chain to form additional bonds by dispersion forces.Also dehydration of carboxylic acids with phosphorus pentoxide (P2O5) yields acid anhydrides,because it strong dehydrated anhydride ;P2O5 itself reacts with water molecules to form phosphoric acid. That enables it to remove free water molecules by a simple hydrolysis reaction,![enter image description here](https://i.stack.imgur.com/jWcG4.jpg)


 2

$\ce{P2O5}$ is a solid. Hence, it is easy to separate from reaction products. Moreover, $\ce{P2O5}$ is a stronger dehydrating agent than $\ce{H2SO4}$ 


 1