hydrolysis n : a chemical reaction in which water reacts with a compound to produce other compounds; involves the splitting of a bond and the addition of the hydrogen cation and the hydroxide anion from the water

English

Noun

1. A chemical process of decomposition involving the splitting of a bond and the addition of the hydrogen cation and the hydroxide anion of water.

Related terms

• hydrolyze

Translations

Hydrolysis is a chemical reaction or process in which a chemical compound is broken down by reaction with water. It is the type of reaction that is used to break down certain polymers, especially those made by step-growth polymerization. Such polymer degradation is usually catalysed by either acid or alkali, attack often increasing with strength or pH.

Types

In organic chemistry, hydrolysis can be considered as the reverse or opposite of condensation, a reaction in which two molecular fragments are joined for each water molecule produced. As hydrolysis may be a reversible reaction, condensation and hydrolysis can take place at the same time, with the position of equilibrium determining the amount of each product.

In inorganic chemistry, the word is often applied to solutions of salts and the reactions by which they are converted to new ionic species or to precipitates (oxides, hydroxides, or salts). The addition of a molecule of water to a chemical compound, without forming any other products is usually known as hydration, rather than hydrolysis.

In biochemistry, hydrolysis is considered the reverse or opposite of dehydration synthesis. In hydrolysis, a water molecule (H2O), is added, whereas in dehydration synthesis, a molecule of water is removed.

In electrochemistry, hydrolysis can also refer to the electrolysis of water. In hydrolysis, a voltage is applied across an aqueous medium, which produces a current and breaks the water into its constituents, hydrogen and oxygen.

In polymer chemistry, hydrolysis of polymers can occur during high-temperature processing such as injection moulding leading to chain degradation and loss of product integrity. Polymers most at risk include PET, polycarbonate, nylon and other polymers made by step-growth polymerization. Such materials must be dried prior to moulding.

Hydrolysis of amide links

In other hydrolysis reactions, such as hydrolysis of an amide link into a carboxylic acid and an amine product or ammonia, only the carboxylic acid product has a hydroxyl group derived from the water. The amine product (or ammonia) gains the remaining hydrogen ion. A more specific case of the hydrolysis of an amide link is hydrolyzing the peptide links of amino acids.

Many polyamide polymers such as nylon 6,6 are attacked and hydrolysed by strong acids. Such attack leads to depolymerization and nylon products fail by fracturing when exposed to even small amounts of acid. The reaction is essentially the reverse of the synthesis from monomers:

• Dehydration synthesis
• Polymer degradation
• Solvolysis

References

External links

• Molecular Structure
• Hydrolyzed Collagen (Gelatin)