What is the Difference Between Acetylation and Acylation

The key difference between acetylation and acylation is that acetylation involves the introduction of an acetyl group to an organic compound, whereas acylation involves the introduction of an acyl group to an organic compound.

Acetylation and acylation are important organic synthesis reactions. Acetylation is an organic esterification reaction, while acylation is an electrophilic aromatic substitution.

CONTENTS

1. Overview and Key Difference
2. What is Acetylation  
3. What is Acylation
4. Acetylation vs Acylation in Tabular Form
5. Summary – Acetylation vs Acylation 

What is Acetylation?

Acetylation is an important organic chemical process that involves the introduction of an acetyl group to a molecule. In this process, “Ac” denotes an acetyl group, and it has the chemical formula –C(O)CH3 in which an oxygen atom is bonded to the carbon atom via a double bond, and a methyl group is attached to the carbon atom. This is a replacement reaction. It is also known as a substitution reaction because, in this reaction, the acetyl group replaces a functional group that is already present in the molecule.

Most often, acetyl groups can replace reactive hydrogen atoms present in molecules. For example, hydrogen in –OH groups is reactive hydrogen. It is also possible to substitute this hydrogen atom with an acetyl group. This replacement causes the formation of an ester. That is because this replacement forms a –O-C(O)-O bond.

Figure 01: Acetylation of Salicylic Acid to form Aspirin

Acetylation commonly takes place in proteins. This process is known as protein acetylation. Here, the N-terminal acetylation takes place via replacing a hydrogen atom of the –NH2 group of the protein with an acetyl group. It is an enzymatic reaction because enzymes catalyze it.

What is Acylation?

Acylation is a chemical process that involves the addition of an acyl group to a chemical compound. In this process, we name the compound that provides the acyl group as the acylating agent. An acyl group has the chemical formula R-C(=O)- where R is either an aryl or an alkyl group. According to the final product of acylation, there are two major acylation processes as O acylation and N acylation.

Figure 02: Acylation of Benzene in the Presence of Ethanoyl Chloride

O acylation is a type of acylation process in which the final product contains an oxygen atom connecting the acyl group to the reactant compound. In other words, there is an oxygen atom between the acyl group and the reactant compound’s moiety. O acylation is a type of nucleophilic acyl substitution reaction.

N acylation is a type of acylation in which the final product contains a nitrogen atom, connecting the acyl group to the reactant compound. In other words, there is a nitrogen atom between the acyl group and the reactant compound’s moiety.

What is the Difference Between Acetylation and Acylation?

Acetylation and acylation are important organic synthesis reactions. The key difference between acetylation and acylation is that acetylation involves the introduction of an acetyl group to an organic compound, whereas acylation involves the introduction of an acyl group to an organic compound. Moreover, acetylation is an organic esterification reaction, but acylation is an electrophilic aromatic substitution.

The below infographic presents the differences between acetylation and acylation in tabular form for side by side comparison.

Summary – Acetylation vs Acylation

In brief, acetylation and acylation are important organic synthesis reactions. However, the key difference between acetylation and acylation is that acetylation involves the introduction of an acetyl group to an organic compound, whereas acylation involves the introduction of an acyl group to an organic compound.