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

CBSE Class 12 Chemistry Notes Chapter 12: The important organic molecules aldehydes, ketones, and carboxylic acids are covered in Chapter 12 of CBSE Class 12 Chemistry. Ketones have the carbonyl group (C=O) joined to two alkyl groups, whereas aldehydes have the carbonyl group (C=O) bonded to a hydrogen atom. A carboxyl group (-COOH) is present in carboxylic acids.

CBSE Class 12 Chemistry Notes Chapter 12 Overview

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CBSE Class 12 Chemistry Notes Chapter 12 PDF

CBSE Class 12 Chemistry Notes Chapter 12 PDF

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

Haloform reaction - When sodium hypohalite is added to aldehydes and ketones with at least one methyl group [3-α hydrogen] attached to the carbonyl carbon atom, it oxidises the compounds to sodium salts of the corresponding carboxylic acids, which have one carbon atom less than the carbonyl compound. Haloform is produced by converting the methyl group.

Nature of Carbonyl Group

Nomenclature

Preparation of Aldehydes and Ketones

i) By alcohols oxidising Typically, primary and secondary alcohols are oxidised to produce aldehydes and ketones, respectively.

By ozonolysis of alkenes

Preparation of Aldehydes

Preparation of Ketones

Physical Properties of Aldehydes and Ketones

1.It is a gas at room temperature, methanal (HCHO). and formalin is the name given to its 40% aqueous solution. It works as a reducing agent to remove colour from vat dyes and silver mirrors. 2. The liquid ethanol (CH3CHO) is volatile. At room temperature, other aldehydes and ketones are either liquid or solid. 3. Because of the strong dipole-dipole interactions, aldehydes and ketones have higher boiling points than ethers and hydrocarbons with similar molecular masses. 4. The boiling points of aldehydes and ketones are lower than those of alcohols with comparable molecular masses because there are no hydrogen bonds between the molecules. 5. Because a hydrogen bond forms with water, the lower members of aldehydes and ketones are miscible with it. However, as the alkyl chain lengthens, the solubility diminishes. 6. Acetophenone is a hypnotic (drug that induces sleep), so it is marketed as hypnone in medicine.

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Chemical Reactions of Aldehydes and Ketones

Fehling solution is made up of a 1:1 mixture of Fehling solutions A and B. Aqueous copper sulphate is Fehling solution A, while alkaline sodium potassium tartrate, sometimes known as Rochelle salt, is Fehling solution B.

(c) Benedict's resolution It also produces red ppt. of CU2O in aldehydes, with the exception of benzaldehyde.

Schiff's reagent - This is an aqueous solution of magenta or pink-colored rosaniline hydrochloride that has been decolored by passing SO2. Ketones do not react with this reagent to produce a pink hue, but aldehydes do.

Carboxylic Acids

Carboxylic acids are organic compounds that contain a carboxyl group (-COOH), which is made up of a carbonyl group (C=O) attached to a hydroxyl group (OH). The general formula is R-COOH, where "R" is an alkyl or aryl group.

Methods of Preparation of Monocarboxylic Acids

Using Grignard reagents (v) Grignard reagents react with carbon dioxide (dry ice) to produce carboxylic acid salts, which are then acidified with mineral acid to produce matching carboxylic acids.

Physical Properties of Carboxylic Acids

Benefits of CBSE Class 12 Chemistry Notes Chapter 12

Concise and Organized Content : The notes provide well-structured summaries of key concepts, helping students quickly grasp important topics like nomenclature, structure, and reactions of aldehydes, ketones, and carboxylic acids.

Simplified Explanations : Complex chemical reactions, mechanisms, and properties are explained in a simplified manner, making it easier for students to understand and retain information.

Exam-Focused : These notes highlight important topics frequently asked in exams, such as nucleophilic addition reactions, preparation methods, and industrial applications, helping students focus on exam-relevant material.

Time-Saving : By providing concise summaries of lengthy textbook content, the notes save time during revision and help students cover the entire chapter quickly before exams.

Clarifies Doubts : The notes clear common doubts related to reaction mechanisms, functional groups, and the behavior of these compounds, enabling better concept clarity.