Preparation of Ketones: Structure, Reactions, Examples and Videos

Do you know a very small number of ketone production is possible on a large scale in industries? However, there are a wide variety of synthesis methods for the preparation of ketones. It is easy to synthesize ketones and they are almost ideal chemical intermediates because of the ease of preparation, high reactivity, and relative stability.

Browse more Topics under Aldehydes Ketones Carboxylic Acids

Ketones form the foundation for many building blocks. It can be used as paints, lacquers, textiles, solvents (manufacturing explosives), etc. It is also useful for tanning, preservation and in applications of hydraulic fluids. Let us understand the important preparation of ketones, an industrially important member of the carbonyl compound.

Structure of Ketones

It is a class of carbonyl compounds in which carbon atom and oxygen atom forms a covalent bond. The rest of the two bonds join with the carbon atom or other radicals of hydrocarbons (aryl or alkyl group).

Reactions of Ketones

Ketones are reactive compounds. However, they are less reactive in comparison to aldehydes even though ketones are closely related to aldehydes. The similarity in nature is due to a carbonyl group which forms the basis of chemical reactivity for both the compounds (aldehydes and ketones).

Ketones can undergo a wide range of chemical reactions. This is because of the highly polar nature of the ketones that results in uneven electronic distributions thereby forming a partial positive charge on the carbon atom. Hence, this increases the susceptibility of nucleophiles. The common reactions of ketones include oxidation-reduction reaction, nucleophilic addition reaction, etc. The polarity of the carbonyl group affects the physical properties of ketones.

Preparation of ketone is possible from secondary alcohols. Secondary alcohols can readily undergo oxidation to form ketonic compounds (R₂CHOH → R₂CO). Ketones do not undergo further oxidation like aldehydes. Therefore, the reaction can cease in the ketone stage of the reaction.

The secondary alcohol oxidation is possible by different oxidizing agents such as pyridinium chlorochromate (PCC), chromic acid (H₂CrO₄), manganese dioxide (MnO₂), potassium permanganate (KMnO₄), etc. We have already studied this method during the preparation of aldehydes and ketones. However, there are other methods for preparation of ketones as well. Let us go through those reactions one by one.

Preparation of Ketones from Acyl Chlorides

Ketone formation is possible by the treatment of acid chloride with di-alkyl cadmium [(R)₂ Cd]. Cadmium chloride reacts with the Grignard reagent to form Dialkylcadmium. However, ketone formation is not possible by Rosenmund’s Reaction.

Preparation of Ketones

Ketone Formation from Nitriles

Nitrile undergoes treatment with nitrile with Grignard reagent and further undergoes hydrolysis to form ketones.

Preparation of Ketones

Preparation of Aromatic Ketones

Preparation of Ketone from Benzene and Substituted Benzenes

Aromatic ketone formation is possible from benzene or substituted benzenes. The most suitable preparation technique for an aromatic aldehyde is Friedel-Crafts acylation reaction. In this reaction benzene or substituted benzenes undergoes treatment with an acid chloride or acid anhydride to form ketones. The reaction occurs in the presence of a catalyst such as Lewis acid such as anhydrous AlCl₃ (anhydrous aluminium chloride). Refer to the example below for the reaction.

Preparation of Ketones