Aldehydes, Ketones and Carboxylic Acids

Edited By Team Careers360 | Updated on Jan 12, 2022 05:21 PM IST

Introduction:
The carbonyl group, which is found in aldehydes, ketones, and carboxylic acids, is a carbon-oxygen double bond.
The carbonyl group is connected to a single hydrogen atom as well as a single alkyl or aryl group in aldehydes. Ketones, on the other hand, have their carbonyl group connected to two alkyls, aryl groups, or both.

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The carbonyl group in aldehydes is connected to carbon and hydrogen, whereas the carbonyl group in ketones is bonded to two carbon atoms. Carboxylic acids and their derivatives (e.g. esters, anhydrides) are carbonyl compounds in which the carbonyl group is connected to oxygen, whereas amides and acyl halides are carbonyl compounds in which the carbonyl group is bonded to nitrogen or halogens.

Aldehydes, ketones, and carboxylic acids are found in abundance in both plants and animals. They serve a crucial function in life's metabolic processes. Vanillin (from vanilla beans), salicylaldehyde (from meadowsweet), and cinnamaldehyde (from cinnamon) are examples of compounds that lend aroma and flavour to nature.

They're used to flavour a variety of foods and medications. Some of these families are made to be used as solvents (for example, acetone) and to prepare products such as adhesives, paints, resins, fragrances, plastics, and fabrics.

These organic compounds are very important both in the industry and in the synthesis of other organic compounds. Therefore, their study forms an important part of organic chemistry.

List of topics according to NCERT and JEE Main/NEET syllabus:

Nomenclature and Structure of Carbonyl Group
Common and IUPAC Names of Some Aldehydes and Ketones
Structure of the Carbonyl Group
Preparation of Aldehydes and Ketones

By oxidation of alcohols
By dehydrogenation of alcohols
From hydrocarbons
By ozonolysis of alkenes
By hydration of alkynes

Preparation of Aldehydes

From acyl chloride (acid chloride)
From nitriles and esters
From hydrocarbons
By oxidation of methylbenzene
By side-chain chlorination followed by hydrolysis
By Gatterman – Koch reaction

Preparation of Ketones

From acyl chlorides
From nitriles
From benzene or substituted benzenes

Physical Properties
Chemical Reactions

Nucleophilic addition reactions
Reduction
Oxidation
Reactions due to alpha-hydrogen

Uses of Aldehydes and Ketones
Nomenclature and Structure of Carboxyl Group
Structure of Carboxyl Group
Methods of Preparation of Carboxylic Acids

From primary alcohols and aldehydes
From alkylbenzenes
From nitriles and amides
From Grignard reagents
From acyl halides and anhydrides
From esters

Chemical Reactions

Reactions Involving Cleavage of O–H Bond
Reactions Involving Cleavage of C–OH Bond
Reactions Involving –COOH Group
Substitution Reactions in the Hydrocarbon Part

Uses of Carboxylic Acids

Important concepts and Laws:

Common and IUPAC Names of Some Aldehydes and Ketones
Structure of the Carbonyl Group
Rosenmund reduction
Stephen reaction
Etard reaction
Gatterman-Koch reaction
Friedel-Crafts acylation reaction
Mechanism of nucleophilic addition reactions
Clemmensen reduction
Wolff-Kishner reduction
Tollens’ test
Fehling’s test
Oxidation of methyl ketones by haloform reaction
The acidity of α-hydrogens of aldehydes and ketones
Aldol condensation/ Aldol reaction
Cross aldol condensation
Cannizzaro reaction

Electrophilic substitution reaction
Names and Structures of Some Carboxylic Acids
Methods of Preparation of Carboxylic Acids
Formation of anhydride
Esterification
Reactions with PCl5, PCl3 and SOCl2
Mechanism of esterification of carboxylic acids
Hell-Volhard-Zelinsky reaction

Importance of Aldehydes, ketones and carboxylic acids class 12:

In Organic Chemistry, aldehydes and ketones form an important topic to cover. Aldehydes, Ketones, and Carboxylic Acids are compounds containing a carbon-oxygen double bond named carbonyl group. In Aldehydes, the carbonyl group is attached to a single hydrogen atom and a single alkyl or aryl group. Ketones, on the other hand, has its carbonyl group linked to either two alkyls or aryl groups or both the groups.

These organic compounds are very important both in the industry and in the synthesis of other organic compounds. Therefore, their study forms an important part of organic chemistry.

Although, in the JEE Examination, there are just two to three questions from Aldehydes, Ketones and Carboxylic acids.

However, it is still very important.

According to JEE syllabus, this topic contains the reactions involving the preparation of aldehydes and ketones and their chemical and physical properties. All the reactions of aldehydes and ketones are of utmost importance.

NCERT Solutions Subject wise link:

NCERT Exemplar Solutions Subject wise link:

Frequently Asked Questions (FAQs)

1. Do carboxylic acids react with aldehydes?

The carbonyl groups in aldehydes and ketones can be oxidized to form the next “oxidation level” compound-carboxylic acid. Adding water to an aldehyde or ketone produces a product called a hydrate or gem diol (two OH groups on one carbon). The reaction is catalyzed by acids and bases.

2. Are ketones and aldehydes carboxylic acid derivatives?

The difference between carboxylic acid derivatives and aldehydes and ketones is that there is a group containing a negatively charged heteroatom (usually oxygen, nitrogen or sulfur), which is directly connected to the carbonyl carbon atom. You can think of carboxylic acid derivatives as bilateral.

3. Which is a more acidic aldehyde or ketone?

Compared with the alkyl groups of ketones, aldehydes are more acidic (lower pKa) than ketones due to the lower electron-donating effect of protons.

4. What is the purpose of aldol condensation?

Aldol condensations are important in organic synthesis because they provide a good way to form carbon-carbon bonds. For example, the Robinson annulation reaction sequence features an aldol condensation; the Wieland-Miescher ketone product is an important starting material for many organic syntheses.