We explain what hydrolysis is and what this chemical reaction consists of. Also, the types of hydrolysis that exist.
What is hydrolysis?
Hydrolysis is a chemical reaction in which molecules from Water (H2O) are divided into their atoms components (hydrogen and oxygen). In turn, in the hydrolysis process, the atoms that make up the water molecules go on to form chemical links with the substance that reacts with water. Hydrolysis is a very important reaction, since water is the most widely used solvent worldwide.
The specific name of this reaction comes from the Greek words hydro ("water and lýsis (“Rupture”), from which it follows that it is a form of rupture of a given molecule of solute, when it reacts with water. In terms of organic chemistry, it is the exact opposite process of the reaction of condensation, which is the combination of two organic molecules, in which a product and a water molecule are obtained.
There are various forms of hydrolysis, depending on the substances that are made to react with water:
- Acid-base hydrolysis. In this reaction, water divides into a hydroxyl ion (OH–) and a proton (H +), which is immediately hydrated to form a hydronium ion (H3O +). Thus, pure water manifests this reaction spontaneously.
When certain substances are added to the water, the balance of the previous reaction can be changed. For example, if we add salts, depending on your solubility, its anions or cations can combine with the OH– and H3O + ions, which can cause the pH of the final solution to vary. Thus, there are four classifications for acid-base hydrolysis according to the type of salt added to the water:- Strong acid-strong base salt hydrolysis. When a salt from an acid and a base strong in water, almost no hydrolysis occurs, due to which the dissociation balance of water is not altered. The pH in this case it will be neutral. For example:
- Hydrolysis of weak acid-strong base salt. The anion of the salt (from the weak acid and the strong base) and a proton from the water combine, releasing hydroxyl ions, due to which the resulting pH will be basic. For example:
- Strong acid-weak base salt hydrolysis. The cation of the salt (coming from the strong acid and the weak base) gives up a proton to the water to form a hydronium ion (H3O +), due to which the resulting pH will be acidic. For example:
- Weak acid-weak base salt hydrolysis. The cation of the salt (coming from the weak base) combines with the water releasing a hydronium ion (H3O +) and the anion of the salt (coming from the weak acid) combines with the water releasing a hydroxyl ion (OH–). The resulting pH will depend on the amounts of hydronium and hydroxyl ions produced. If more H3O + ion is produced than OH– ion, the pH will be acidic, and if more OH– ion is produced than H3O + ion, the pH will be basic. On the other hand, if the amounts produced of both ions are equal, the resulting pH will be neutral. For example:
- Strong acid-strong base salt hydrolysis. When a salt from an acid and a base strong in water, almost no hydrolysis occurs, due to which the dissociation balance of water is not altered. The pH in this case it will be neutral. For example:
- Hydrolysis of amides and esters. In these types of organic substances, hydrolysis can occur in an acidic or basic medium. In the case of esters, they are hydrolyzed in an acidic and basic medium, generating carboxylic acids and alcohols. The process of hydrolysis of esters is also called saponification (hydrolysis of triglycerides to make soaps). On the other hand, amides generally hydrolyze in an acid medium, decomposing into amines and carboxylic acids. For example:
- Hydrolysis of polysaccharides. Polysaccharides (sugars) can be hydrolyzed and broken down (breaking their glycosidic bonds, which are bonds between monosaccharides to form polysaccharides) into simpler polysaccharides, disaccharides, or monosaccharides. In the process of hydrolysis, a hydrogen in the water molecule binds to the oxygen at the end of a sugar molecule, while the hydroxyl binds to the end of the rest. The hydrolysis of polysaccharides is a process carried out regularly by life forms.
- Enzymatic hydrolysis. It is the hydrolysis that occurs in the presence of enzymes (organic compounds that generally increase the speed of chemical reactions) called hydrolases. For example, urea amidohydrolase is an enzyme involved in the hydrolysis of urea: