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The hydrolysis of substance is its decomposition by water thanks to ions H+ and OH- coming from the dissociation of water. For example, the hydrolysis of the Saccharose gives Glucose and Fructose, or, the hydrolysis of Ester will give an alcohol and an acid.
The hydrolysis is less known than its opposite reaction: the Esterification which is much more interesting from an industrial point of view (production of ester) whereas the hydrolysis produces only Acide S and alcohol S.
For organic substances such as the Protein S, a hydrolysis is equivalent to the cut of the peptide connections between the various amino-acids which constitute them. The amino-acids are cut by the enzymes.
There is R1-COO-R2 + H2O ↔ R2-OH (alcohol) + R1-COOH (acid) .
As example, during the cooking of a meat, collagen can be transformed into gelatin only when it is cooked in an moist environment (presence of water).
Substances hydrolysables
Many molecules can be hydrolized. Among the functions hydrolysables, we find the Ester S, the Acétal S (present in polysaccharides) and the Amide S (present in proteins)
Convertion rate of hydrolysis
The hydrolysis of ester by water is a slow and limited reaction. Indeed, it is formed products which are acids and alcohols, which themselves react together in the reactional medium to form in their turn of ester and water. The convertion rate of ester hydrolysis during the introduction of the reagents into stoechiometric quantities is about 33% when it forms a primary education alcohol, 40% for a secondary and 95% for a tertiary sector. A water excess logically moves this balance towards the formation of alcohol.
Basic hydrolysis
The basic hydrolysis is, as its name indicates it, a reaction of hydrolysis. But, contrary to traditional hydrolysis, water is generally replaced by soda or any other solution containing of the ions hydroxide (like potassium hydroxide for example), from where the name of basic hydrolysis because the reaction of hydrolysis proceeds in basic medium. The general equation of a basic reaction of hydrolysis is the following one:
R-COO- R' (aq) + HO- (aq) ↔ R-COO- (aq) + R'-OH (aq)
ester + carboxylate HO- ↔ ion + alcohol
The carboxylate ion (contrary to the carboxylic acid formed during traditional hydrolysis) is without effect on alcohol so that the reaction reverses esterification does not take place. Consequently a basic transformation of hydrolysis is total contrary to traditional hydrolysis. Basic hydrolysis is fast hot.
See also: Saponification, To manufacture soap
An application of the basic hydrolysis is the soap formation. Indeed, the reactions of saponification at the origin of the soaps are not other than reactions of basic hydrolysis starting from greasy substances (which are triesters of glycerol). The soaps are obtained by precipitation of the carboxylate ion obtained during saponification using sodium or of potassium. The soaps are the carboxylate ones of sodium or potassium.
Simple: Hydrolysis
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