Difference Between Hydrolysis and Condensation

Hydrolysis vs Condensation
 

Condensation and hydrolysis are two types of chemical reactions, which are involved in bond formation and bond breakage. Condensation is the reverse of hydrolysis. These two types of reactions are commonly found within biological systems, and we also use these reactions to obtain many commercially important products.

Condensation

Condensation reactions are a type of chemical reaction where small molecules get together to form a large single molecule. The reaction takes place within two functional groups in the molecules. Other characteristic feature of a condensation reaction is that a small molecule is lost during the reaction. This molecule can be water, hydrogen chloride, acetic acid, etc. If the lost molecule is water, those types of condensation reactions are known as dehydration reactions. Since the reactant molecules are smaller and the product molecule is very large, the density of products will be always higher than the reactions in condensation reactions. Condensation reactions take place in several ways. For example, we can widely divide these into two types as intermolecular condensation reactions and intra-molecular condensation reactions. If the two functional groups are residing in the same molecule, they are known as intra-molecular condensations. For example, glucose has a linear structure as follows.

In a solution, majority of the molecules are in a cyclic structure. When a cyclic structure is forming, the -OH on carbon 5 is converted into the ether linkage, to close the ring with carbon 1. This forms a six member hemiacetal ring structure. During this intra-molecular condensation reaction, a water molecule is repelled, and an ether linkage is formed. Intermolecular reactions produce many useful and common products. During this, the reaction takes place between the functional groups of two separate molecules. For example, when forming a macromolecule like protein, amino acids are condensed. A water molecule is released, and an amide linkage is formed which is known as a peptide bond. When two amino acids are bound together, a dipeptide is formed, and when many amino acids are joined it is called a polypeptide. DNA and RNA are also two macromolecules formed as a result of condensation reactions between nucleotides. Condensation reactions produce very large molecules and sometimes the molecules are not so large. For example: in the esterification reaction between an alcohol and a carboxylic acid, a small ester molecule if formed. Condensation is important in polymer formation. Polymers are large molecules, which has the same structural unit repeating over and over. The repeating units are called monomers. These monomers are bonded to each other with covalent bonds to form a polymer.

Hydrolysis

This is a reaction where a chemical bond is broken using a water molecule. During this reaction, a water molecule splits up into a proton and a hydroxide ion. And then these two ions are added to the two parts of the molecule where the bond is broken. For example, following is an ester. The ester bond is between –CO and –O.

In the hydrolysis, the proton from the water adds to the –O side, and the hydroxide ion adds to the –CO side. Therefore, as a result of the hydrolysis, an alcohol and a carboxylic acid will form which were the reactants when forming the ester.