Soaps are formed from the reaction of glycerides with sodium hydroxide. The product of the reaction is glycerol and salts of fatty acids. Fatty acids in the soap emulsify the oils in dirt, enabling the removal of oily dirt with water.
Partial glycerides are esters of glycerol with fatty acids, where not all the hydroxyl groups are esterified. Since some of their hydroxyl groups are free their molecules are polar. Partial glycerides may be monoglycerides (two hydroxyl groups free) or diglycerides (one hydroxyl group free). Short chain partial glycerides are more strongly polar than long chain partial glycerides, and have excellent solvent properties for many hard-to-solubilize drugs, making them valuable as excipients in improving the formulation of certain pharmaceuticals.