Hydrolysis definition, hydrolysis vs dehydration synthesis and mechanism

Hydrolysis definition

Hydrolysis is a chemical reaction in which water is used to break a bond in a molecule, typically resulting in the formation of one or more new molecules. The term "hydrolysis" comes from the Greek words "hydro-" (water) and "-lysis" (to break). In the process of hydrolysis, water is split into its two components, hydrogen (H+) and hydroxide (OH-), and one of these components acts as a nucleophile, or an electron pair donor, attacking the bond to be broken. The other component acts as an electron pair acceptor and forms a new bond with the other atom in the broken bond.

There are two types of hydrolysis reactions:

Neutral hydrolysis: It is the hydrolysis of ester and amides where the water acts as a nucleophile and the acid acts as an electrophile. It results in the formation of carboxylic acids and alcohols or amines, respectively.

Acidic hydrolysis: It is the hydrolysis of acid derivatives such as acid chlorides, anhydrides, and esters where the water acts as an acid, and the acid derivative acts as a nucleophile. It results in the formation of carboxylic acids and alcohols or amines, respectively.

Overall, hydrolysis reactions are a way to break down molecules by adding water, and are often used in biochemistry and food chemistry to break down complex molecules into simpler components that can be more easily metabolized or digested.

⇒Hydrolysis vs dehydration synthesis

Hydrolysis and dehydration synthesis are two chemical reactions that involve water, but they have opposite effects.

Hydrolysis is a chemical reaction in which water is used to break a bond in a molecule, typically resulting in the formation of one or more new molecules. The term "hydrolysis" comes from the Greek words "hydro-" (water) and "-lysis" (to break). In the process of hydrolysis, water is split into its two components, hydrogen (H+) and hydroxide (OH-), and one of these components acts as a nucleophile, or an electron pair donor, attacking the bond to be broken. The other component acts as an electron pair acceptor and forms a new bond with the other atom in the broken bond.

Dehydration synthesis, also known as condensation reaction, is a chemical reaction in which two molecules combine to form a larger molecule, while releasing a small molecule, typically water. The term "dehydration" comes from the Greek words "de-" (removal of) and "hydration" (water). In the process of dehydration synthesis, the hydroxyl group of one molecule reacts with the hydrogen atom of another molecule to form a covalent bond and a molecule of water is released.

In summary, hydrolysis breaks down molecules by adding water, while dehydration synthesis builds up molecules by removing water.

⇒Hydrolysis reaction mechanism

The mechanism of hydrolysis reactions can be divided into two main types: neutral hydrolysis and acidic hydrolysis.

Neutral hydrolysis:

Neutral hydrolysis is the hydrolysis of ester and amides where the water acts as a nucleophile and the acid acts as an electrophile. The mechanism of neutral hydrolysis can be described as follows:

• The nucleophile, the hydroxide ion (OH-), attacks the electrophilic carbon atom of the ester or amide bond.
• This creates a tetrahedral intermediate, with a partial positive charge on the leaving group, typically a hydrogen atom.
• The leaving group is then replaced by a water molecule, forming the carboxylic acid or amine and an alcohol or a carboxylate ion.

Acidic hydrolysis:

Acidic hydrolysis is the hydrolysis of acid derivatives such as acid chlorides, anhydrides, and esters where the water acts as an acid and the acid derivative acts as a nucleophile. The mechanism of acidic hydrolysis can be described as follows:

• A protonated water molecule acts as an acid and donates a proton (H+) to the acid derivative.
• This creates a tetrahedral intermediate, with a partial positive charge on the leaving group, typically a halogen or a carbonyl.
• The leaving group is then replaced by a water molecule, forming the carboxylic acid and an alcohol or halide or carbonyl.

It's important to note that the type of hydrolysis that occurs depends on the specific molecule and reaction conditions and the rate of the reaction can be influenced by the presence of catalysts or by changing the pH of the reaction.

The overall hydrolysis reaction is exothermic, releasing energy in the form of heat.

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