CBSE Class 12 Chemistry Notes Chapter 12 Aldehydes, Ketones and Carboxylic Acid

Aldehydes, Ketones and Carboxylic Acid, belong to the class of carbonyl compounds that contain carbon-oxygen double bonds. These organic compounds, combined with other functional groups, have been used for a wide range of applications.

• The carbon-oxygen bonds in the carbonyl group are sp2 hybridized.
• Aldehydes are volatile and flammable compounds where the central carbonyl group is doubly bonded to oxygen and single-bonded to any alkyl group and a hydrogen atom.
• It is considered more reactive than ketone as it contains an extra hydrogen atom.
• Ketone is an organic compound where the carbonyl group is bonded with two aryl or alkyl groups with the structure R-(C=O)-R’.
• Carboxylic acid is either an aliphatic or aromatic compound with a carbonyl group attached to a hydroxyl group.
• Aldehydes, Ketones and Carboxylic Acid, are used for many industrial purposes, which include the production of plastics, polymers and rubber respectively. 

According to the CBSE Syllabus 2023-24, the Aldehydes, Ketones and Carboxylic Acid chapter has been renumbered as NCERT Class 12 Chemistry Chapter 8. Aldehydes, Ketones and Carboxylic Acid Notes are given in this article for preparation for the CBSE Class 12 Chemistry Examination. The chapter helps an individual score eight marks in the board exam.

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Aldehydes, Ketones and Carboxylic Acids Notes

Nomenclature of Aldehydes, Ketones and Carboxylic Acids

The nomenclature of aldehydes, ketones and carboxylic acid are as follows:

Nomenclature of Aldehydes

• The naming of acyclic and aliphatic aldehydes starts with the longest carbon chain, along with the suffix al.
• When the compound is added into a ring, then the "carbaldehyde" suffix is used, such as cyclohexanecarbaldehyde.
• The structure of aldehyde is in the form R−CH=O, where R denotes the alkyl or aryl group.

Nomenclature of Aldehydes

Nomenclature of Ketones

• The naming of ketone depends upon the parent alkane name with the suffix “anone” suffix attached to it.
• It is generally written by first writing the name of the alkyl group attached to the carbonyl carbon and then lastly, “ketone” as the third word of the name.
• The structure of ketone is in the form R-(C=O)-R’ where R and R’ are various types of carbon substituents.

Nomenclature of Carboxylic Acid

• The naming of the carboxylic group involves the addition of an "oic acid" suffix to their parent chain.
• In case other substituent groups are attached, carboxylic acid naming starts from the parent chain's first position, such as 3-chloropropanoic acid.

Nomenclature of Carboxylic Acids

Properties of Aldehydes, Ketones and Carboxylic Acid

The properties of aldehydes, ketones and carboxylic acid are as follows:

Properties of Aldehydes

• Aldehydes are highly soluble in water which include compounds such as formaldehyde and acetaldehyde.
• The boiling point is directly proportional to the molecular weight, and hence, the boiling point of aldehydes is higher in comparison to other compounds.
• They have a pungent odour, which is quite volatile in nature.
• Aldehydes undergo oligomerization or polymerization reactions.

Properties of Ketone

The properties of ketones are divided into physical and chemical properties which are as follows:

Physical Properties of Ketones

• Ketone is a type of compound that is either solid or liquid at room temperature.
• It has a higher boiling point in comparison to other hydrocarbons.
• Ketone forms a bond angle of 120 degrees.
• They are polar in nature and have high dipole moments.

Chemical Properties of Ketones

• Nucleophilic Reaction: Ketones undergo a nucleophilic substitution reaction where nucleophiles will attack the carbonyl compound to form different compounds.
• Grignard Reagents: When a grignard reagent reacts with a ketone, the carbonyl group triple bond is reduced to a single bond to form alcohols.

Grignard Reagents

Properties of Carboxylic Acid

The properties of carboxylic acid are divided into physical and chemical properties which are as follows:

Physical Properties of Carboxylic Acid

• Carboxylic acids are polar compounds that are colourless and corrosive liquids.
• Due to its acidic character, the compound has a pungent smell.
• They are polar in nature and practically insoluble in cold water.
• The boiling point of carboxylic acid is high in comparison to alcohol and alkanes.

Chemical Properties of Carboxylic Acid

• Hydrogenation Reaction: In hydrogenation, carboxylic acid is reduced to alcohol on treatment with hydrogen.
• Hell Volhard Zelinsky Reaction: The reaction involves the halogenation of carboxylic acid in the absence of a catalyst.

Hell Volhard Zelinsky Reaction

• Schmidt Reaction: Schmidt reaction involves the reaction of a carbonyl compound with azides to form amines.

Schmidt reaction

Preparation of Aldehydes, Ketones and Carboxylic Acid

The preparation of aldehydes, ketones and carboxylic acid are as follows:

Preparation of Aldehydes

• Rosenmund Reaction: In this reaction, aldehydes are produced after reducing acid chlorides in the presence of a palladium catalyst.

Rosenmund Reaction

• Stephen Reaction: In the Stephen reaction, aldehydes are produced after a reaction between nitriles and esters.

Stephen Reaction

• Etard Reaction: Etard reaction involves partial oxidation of an aromatic ring using chromyl chloride to form aldehydes. 

Etard Reaction

Preparation of Ketones

• Friedel-Crafts Acylation Reaction: Friedel-Crafts Acylation Reaction involves the preparation of ketones using nitriles or benzene compounds.

Friedel-Crafts Acylation Reaction

• Grignard Reaction: Grignard reaction involves the reaction between acid chloride and dialkyl cadmium.

Grignard Reaction

Preparation of Carboxylic Acids

• From alcohol: Carboxylic acids are prepared by using primary alcohol in the presence of strong oxidizing agents.

Preparation of Carboxylic Acid from Alcohol

• From Alkyl Benzene: The process involves the oxidation of alkyl benzene with alkaline potassium permanganate and acidic potassium dichromate to form carboxylic acid.

Preparation of Carboxylic Acid from Alkyl Benzene

• Hydrolysis: The process involves hydrolysis of alkaline or acidic ester to the compound.

Hydrolysis

• Grignard Reaction: The reaction involves the preparation of carboxylic acids using nitriles and amides.

Preparation of Carboxylic acid from Grignard Reaction

Uses of Aldehydes, Ketones and Carboxylic Acids

The uses of aldehydes, ketones and carboxylic acids are as follows:

Uses of Aldehydes

• Aldehydes are used in the manufacturing of acetic acid.
• Formaldehyde, an important example of the compound, is used as a disinfectant.
• It is used in the preparation of glues and polymeric products.
• Benzaldehyde is used in the manufacturing of rubber accelerators. 
• Aliphatic aldehyde is a type of compound that is used in the preparation of perfumes.

Uses of Ketones

• Ketone, like acetone, is used in the preparation of industrial solvent.

• The compound is also used in curation of skin acne.
• It is also used as nail paint thinner and remover.
• Cyclohexanone is a type of ketone that is used in the production of nylon.

Uses of Carboxylic Acids

• Carboxylic acid is a carbonyl compound used to prepare vinegar and food preservatives.
• Methanoic acid is used in the dyeing, rubber and textile industries.
• Ethanoic acid is used in the production of solvents.
• Benzonic acid is used in the creation of different perfumes.

There are Some important List Of Top Chemistry Questions On Aldehydes, Ketones And Carboxylic Acids Asked In CBSE CLASS XII