Hydrolysis Definition and Examples

Understand Hydrolysis in Chemistry

Human protein phosphatase removes a phosphate group from its substrate by hydrolysing phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl group.
Human protein phosphatase removes a phosphate group from its substrate by hydrolysing phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl group. Laguna Design / Getty Images

Hydrolysis Definition

Hydrolysis is a type of decomposition reaction where one reactant is water. Typically, water is used to break chemical bonds in the other reactant. The term comes from the Greek prefix hydro- (meaning water) with lysis (meaning to break apart). Hydrolysis may be considered the reverse of a condensation reaction, in which two molecules combine with each other, producing water as one of the products.



The general formula of a hydrolysis reaction is:

AB + H2O → AH + BOH

Organic hydrolysis reactions involve the reaction of water and a ester. This reaction follows the general formula:

RCO-OR' + H20 → RCO-OH + R'-OH

The dash denotes the covalent bond that is broken during the reaction.

The first commercial application of hydrolysis was making soap. The saponification reaction occurs when a triglyceride (fat) is hydrolyzed with water and a base (usually sodium hydroxide, NaOH, or potassium hydroxide, KOH). The reaction produces glycerol. Fatty acids react with the base to produce salts, which are used as soap.

Hydrolysis Examples

Dissolving a salt of a weak acid or base in water is an example of a hydrolysis reaction. Strong acids may also be hydrolyzed. For example, dissolving sulfuric acid in water yields hydronium and bisulfate.

Hydrolysis of a sugar has its own name: saccharification. For example, the sugar sucrose may undergo hydrolysis to break into its component sugars, glucose and fructose.

Acid-base catalyzed hydrolysis is another type of hydrolysis reaction. An example is the hydrolysis of amides.

In biological systems, hydrolysis tends to be catalyzed by enzymes. A good example is the hydrolysis of the energy molecule ATP. Catalyzed hydrolysis is also used for digestion of proteins, carbohydrates, and lipids.