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Aldehydes, Ketones and Carboxylic Acids

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.

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:

  1. Nomenclature and Structure of Carbonyl Group
  2. Common and IUPAC Names of Some Aldehydes and Ketones
  3. Structure of the Carbonyl Group
  4. Preparation of Aldehydes and Ketones
  • By oxidation of alcohols
  • By dehydrogenation of alcohols
  • From hydrocarbons
  • By ozonolysis of alkenes
  • By hydration of alkynes
  1. 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
  1. Preparation of Ketones
  • From acyl chlorides
  • From nitriles
  • From benzene or substituted benzenes
  1. Physical Properties
  2. Chemical Reactions
  • Nucleophilic addition reactions
  • Reduction
  • Oxidation
  • Reactions due to alpha-hydrogen
  1. Uses of Aldehydes and Ketones
  2. Nomenclature and Structure of Carboxyl Group
  3. Structure of Carboxyl Group
  4. 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
  1. 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
  1. Uses of Carboxylic Acids

Important concepts and Laws:

  1. Common and IUPAC Names of Some Aldehydes and Ketones
  2. Structure of the Carbonyl Group
  3. Rosenmund reduction
  4. Stephen reaction
  5. Etard reaction
  6. Gatterman-Koch reaction
  7. Friedel-Crafts acylation reaction
  8. Mechanism of nucleophilic addition reactions
  9. Clemmensen reduction
  10. Wolff-Kishner reduction
  11. Tollens’ test
  12. Fehling’s test
  13. Oxidation of methyl ketones by haloform reaction
  14. The acidity of α-hydrogens of aldehydes and ketones
  15. Aldol condensation/ Aldol reaction
  16. Cross aldol condensation
  17. Cannizzaro reaction
  1. Electrophilic substitution reaction
  2. Names and Structures of Some Carboxylic Acids
  3. Methods of Preparation of Carboxylic Acids
  4. Formation of anhydride
  5. Esterification
  6. Reactions with PCl5, PCl3 and SOCl2
  7. Mechanism of esterification of carboxylic acids
  8. 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.

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