Hydrolysis
Hydrolysis is a chemical process defined as "cleavage by water," where water molecules react with a compound to break it down into two separate components. This reaction involves the addition of a hydrogen ion (H) to one part of the molecule and a hydroxyl group (−OH) to another, effectively splitting the functional group. Hydrolysis is crucial across various chemical fields, affecting both organic and inorganic compounds, including esters, amides, and phosphates. For example, when a carboxylic ester undergoes hydrolysis, it yields a carboxylic acid and an alcohol.
A significant aspect of hydrolysis is its role in biological systems, including the extraction of energy from adenosine triphosphate (ATP) during respiration. In this context, hydrolysis breaks the high-energy bond in ATP, producing adenosine diphosphate (ADP) and inorganic phosphate, which is vital for cellular energy transfer. This process is not only essential for metabolic functions but also plays a role in chemical synthesis, often involving protecting groups to manage reactive sites in molecules. Through these various applications, hydrolysis proves to be a fundamental and versatile reaction in both chemistry and biochemistry.
Hydrolysis
FIELDS OF STUDY: Organic Chemistry; Inorganic Chemistry; Biochemistry
ABSTRACT
The process of hydrolysis is defined and its importance in all chemistry-related fields is elaborated. Hydrolysis is a fundamental and necessary process for living systems, and it is perhaps the single most common chemical reaction process known.
Understanding Hydrolysis
Hydrolysis means "cleavage by water" (literally, "dissolution" or "disintegration" by water), and in any hydrolysis reaction, a functional group is cleaved into two separate components by the addition of H to one component and −OH, or a hydroxyl group, to the other component. Overall, the result is the addition of a molecule of HO−H, or H2O (water), across the principal bond of a functional group. A carboxylic ester, for example, is an acid derivative having the functional group characterized by a carbonyl group (C=O) in which the C atom is bonded to another carbon atom of an alkyl group and to the oxygen atom of an alkoxy group. The addition of HO−H across the bond between the carbonyl carbon atom and the alkoxy oxygen atom produces a carboxylic acid and an alcohol.
Hydrolysis occurs with many types of compounds, including esters, amides, acid anhydrides, ethers, alkyl halides, nitriles, phosphates, carbohydrates, acetals, epoxides, and lactones. The term applies generally to the process rather than to any specific types of compounds. The common feature is that the molecule or part of a molecule undergoing hydrolysis is split apart with the overall addition of a molecule of water to the two separated components. A great many compounds have a cyclic structure in which a functional group on one part of the molecule has formed a bond to a different functional group on another part of the same molecule. In such cases, hydrolysis of the connection separates the two functional groups from each other, but it does not produce two separate molecules.
The same principle applies to both inorganic compounds and organic compounds. Metal halides, for example, undergo a hydrolysis reaction with water molecules to form the corresponding metal hydroxides and hydrogen halides. The inorganic compound phosphoric acid also forms compounds such as esters that are analogous to their carboxylic acid counterparts. These play a significant role in biochemistry in the formation of DNA, RNA, and the many phosphate ester polymers, such as phosphatidylcholine and adenosine triphosphate (ATP), and the phospholipids that comprise cell membranes.
In chemical synthesis, it is a valuable and common practice to use a protecting group through a series of chemical reactions when there is more than one reactive site in a molecule. The protecting group is bonded to a functional group such as a carbonyl group to prevent it from undergoing undesired reactions. When the desired reactions are completed, the protecting group is removed, typically by a hydrolysis reaction.
Hydrolysis in Respiration
A key feature of the respiration process is the transfer of hydrolysis to extract energy from ATP. When energy is required, the anhydride bond between the second and third units of the triphosphate component of ATP is hydrolyzed (that is, undergoes hydrolysis) to produce adenosine diphosphate (ADP) and inorganic phosphate (PO43−), often symbolized in biochemical notation as Pi. This bond is referred to as a "high-energy" bond, and its hydrolysis and reformation is the means by which energy is extracted and stored in biochemical systems.
PRINCIPAL TERMS
- ester: a class of compounds characterized by a carbonyl group bonded to an alkoxy group, formed by the condensation of an acid and an alcohol.
- hydrogen ion: a hydrogen atom that has lost its one electron, represented by the symbol H+.
- hydroxyl group: a primary functional group consisting of an oxygen atom covalently bonded to a single hydrogen atom.
- monomer: a molecule capable of bonding to other molecules to form a polymer.
- polymer: a large molecule formed by the concatenation of many individual smaller molecules, known as monomers.
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