The two most powerful tools in Organic Chemistry are the alkylation reaction and acylation reaction. However, here we will be dealing with the topic of “Acylation Reaction.” There are various numbers of organic chemical structures and elements since the carbon can form links to itself by forming chains and also rings. The entire molecules can also be added to each other or other elements, and such is the case with the acylation reaction.

Mechanism of Acylation Reaction

The mechanism of this Acylation Reaction is the electrophilic aromatic substitution. In Organic Chemistry, acylation is the process or mechanism of adding an acyl group (RCO-) to a particular compound. This compound that provides the acyl group is called the acylating agent.

Since these form strong electrophiles when added with some metal catalysts, acyl halides are widely used as acylating agents. Consider, for example, the Friedel-Crafts acylation reaction uses the acetyl chloride, CH3COCl, as the acylating agents and the compound called aluminium chloride, AlCl3 as the catalyst for adding ethanol or the acetyl group to the benzene. The following reaction shows the mechanism.


An acyl group is the alkyl group that is attached to the carbon-oxygen double bond as shown in the below figure. If the letter “R” represents the alkyl group, the acyl group will have the formula RCO-. The process of Acylation is to substitute an acyl group into the reaction. The most widely used acyl group is the CH3CO-. It is called the ethanoyl group.


The Acyl halides and the anhydrides of the carboxylic acids are commonly used as the acylating agents for acylating amines forming amides or also acylate alcohols which form the esters. The alcohols and amines are nucleophiles; this mechanism is a kind of nucleophilic acyl substitution reaction. Succinic acid is commonly used in various types of acylation reactions. Acylation occurs when two or more salts of succinic acid add to form a single compound.

The acylation process is used in preventing the rearrangement reactions which occur in the process of alkylation. For achieving this, the acylation reaction is usually performed, later the carbonyl group is removed by the Clemmensen reduction reaction or some similar process.

Acylation Reaction – Example

A Simple kind of Acylation reaction Example is given below-

The Acetic acid or the CH3COOH, vinegar which is 5 per cent of the acetic acid in water are present in the form of their chloride, this is the acetyl chloride, having chemical structure CH3-COCl.

The process of Acylating the benzene with such substance in presence of the catalyst aluminium chloride gives this reaction. It is as shown below.

C6H6 + CH3-COCl + catalyst ? C6H5-CO-CH3 + HCl

The above sequence of reaction explains that one molecule of benzene and one molecule of acetyl chloride in presence of some aluminium chloride catalyst is said to produce one molecule of the methyl phenyl ketone and one molecule of the hydrogen chloride gas. The Ketones are of great importance as compounds offering a variety of reaction paths for the additional synthesis process.

Friedel Craft’s Reactions

Friedel-Crafts Alkylation

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