Effect of heat on Hydroxy acids
The α-, β-, γ-, and δ-hydroxycarboxylic acids all lose water upon heating, although the products are not the same
The α-hydroxy acids form cyclic dimeric esters (formed by the esterification of two molecules of the acid) called lactides
whereas the β- and γ-hydroxy acids undergo intramolecular esterification to give cyclic esters called lactones
These reactions take place so readily, even without heating, that in most cases the only way ton keep these kinds of hydroxy acids from forming cyclic esters is to convert them to their sodium or potassium salts
The α-Hydroxy acids lose water upon heating to yield α,β unsaturated acid
