Class 12 Organic Chemistry

Organic Chemistry is one of the branches of Chemistry that studies the structure, properties, composition, reactions and preparation of compounds containing carbon. These contain not just hydrocarbons but compounds with other elements like oxygen, nitrogen, phosphorus, halogens, sulfur and silicon. Initially, Organic Chemistry was limited to compounds produced by living organisms but it has now been stretched to human-made substances like plastics. Ranging from pharmaceuticals, food, explosives, petrochemicals to paints and cosmetics, application of such compounds is enormous. Class 12 Organic Chemistry includes 7 units contributing to nearly 28 marks in the CBSE class 12 Chemistry paper.

NCERT Class 12 Organic Chemistry Chapters

Below is a list of units for Organic Chemistry as per the NCERT Chemistry Part II book:

• Unit VIII Haloalkanes and Haloarenes
• Unit IX Alcohols, Phenols and Ethers
• Unit X Aldehydes, Ketones and Carboxylic Acids
• Unit XI Organic Compounds containing Nitrogen (Amines)
• Unit XII Biomolecules
• Unit XIII Polymers
• Unit XIV Chemistry in Everyday Life

To know the latest CBSE structure and syllabus 2023, read our blog on Chemistry syllabus for class 12. You can see the mark distribution as per the important units and topics of the subject which has been asked in last year examination.

Important Concepts of Class 12 Organic Chemistry

Classification of Organic Compounds

Organic Compounds in class 12 Organic Chemistry have been broadly classified as follows:

• Acyclic Compounds (Open-chain): Also known as aliphatic compounds, these consists of straight or branched chain compounds. E.g. Ethane, Isobutane, Acetic acid.
• Alicyclic Compounds (Closed-chain): These are aliphatic cyclic compounds consisting of carbon atoms attached in the form of a ring (homocyclic).  
• Aromatic Compounds: E.g. Benzene, Aniline and Naphthalene, Furan, Thiophene, etc.
• Functional Groups: An atom or group of atoms combined in a specific manner that determines the chemical properties of an organic compound.

Organic Chemistry: Haloalkanes and Haloarenes

Classification of Haloalkanes and Haloarenes

• On the Basis of Number of Halogen Atoms: Compounds may be classified as mono, di, or polyhalogen compounds depending on whether they contain 1, 2 or more halogen atoms in their structures.

• Compounds Containing sp3 C—X Bond (X= F, Cl, Br, I): Alkyl halides or haloalkanes (R—X), Allylic halides and Benzylic halides.

• Compounds Containing sp2 C—X Bond: Vinylic halides and Aryl halides.

Methods of Preparation

• From Alcohol: Alkyl chloride is prepared by either passing dry hydrogen chloride gas through a solution of alcohol or by simply heating a solution of alcohol in concentrated aqueous acid.
• From Hydrocarbons: By free radical halogenation (chlorination or bromination) of Alkanes, electrophilic substitution of arenes with chlorine and bromine and Sandmeyer’s reaction.
• From Alkenes: Addition of hydrogen halides and halogens
• Halogen Exchange: Finkelstein reaction (Reaction of alkyl chloride/bromide) with NaI in dry acetone to give out Alkyl iodides.

Chemical Reactions

• Reaction of Haloalkanes: Nucleophilic substitution, Elimination reactions and Reaction with metals.
• Reactions of Haloarenes: Nucleophilic substitution, Electrophilic substitution reactions and Reaction with metals (Wurtz-Fittig reaction and Fittig reaction)

In class 12 Organic Chemistry, you will study several polyhalogen compounds like chloroform, iodoform, dichloromethane, carbon tetrachloride, Freon and DDT (Dichlorodiphenyltrichloroethane) have many industrial applications. However, some of these cannot be decomposed easily resulting in depletion of the ozone layer and increasing environmental hazards.

Organic Chemistry: Alcohols, Phenols and Ethers

Classification of Alcohols, Phenols and Ethers

• Mono, Di, Tri or Polyhydric Compounds

Monohydric alcohols in class 12 Organic Chemistry can be further classified into:

Compounds containing C sp3—OH Bond: Primary, secondary and tertiary alcohols, Allylic alcohols and Benzylic alcohols

Compounds containing Csp2—OH Bond: Vinylic alcohol and Phenols

Ethers are classified as simple or symmetrical and mixed or unsymmetrical.

Methods of Preparation

Preparation of Alcohols from

• Alkenes: By acid catalysed hydration and hydroboration–oxidation
• Carbonyl Compounds: By reduction of aldehydes and ketones and reduction of carboxylic acids and esters
• Grignard Reagents

Preparation of Phenols from

• Haloarenes
• Benzenesulphonic Acid
• Diazonium Salts
• Cumene (Isopropylbenzene)

Preparation of Ethers by

• Dehydration of Alcohols
• Williamson Synthesis

Chemical Reactions

• Reactions involving Cleavage of O—H Bond: Acidity of Alcohols and Phenols and Esterification 
• Reactions involving Cleavage of C—O Bond in Alcohols: Reaction with hydrogen halides, Reaction with phosphorus trihalides,  Dehydration Oxidation
• Reactions of Phenols: Electrophilic aromatic substitution, Kolbe’s reaction, Reimer-Tiemann reaction,  Reaction of phenol with zinc dust, Oxidation
• Cleavage of C–O Bond in Ethers
• Electrophilic Substitution: Halogenation, Friedel-Crafts reaction and Nitration

Organic Chemistry: Aldehydes, Ketones and Carboxylic Acid

Methods of Preparation

Preparation of Aldehydes and Ketones by

• Oxidation of Alcohols
• Dehydrogenation of Alcohols
• Hydrocarbon: Ozonolysis of Alkenes and Hydration of Alkynes

Preparation of Aldehydes from

• Acyl Chloride (acid chloride)
• Nitriles and Esters: Stephen Reaction
• Hydrocarbons: Oxidation of Methylbenzene, Estard Reaction, Side-chain chlorination followed by hydrolysis and Gatterman – Koch reaction

Preparation of Ketones from

• Acyl Chlorides
• Nitriles
• Benzene or Substituted Benzenes: Friedel-Crafts acylation Reaction

Preparation of Carboxylic Acids from

• Primary Alcohols and Aldehydes
• Alkylbenzenes
• Nitriles and Amides
• Grignard Reagents
• Acyl halides and Anhydrides
• Esters

Chemical Reaction

• Nucleophilic addition reactions
• Reduction to alcohols and hydrocarbons (Clemmensen reduction and Wolff-Kishner reduction)
• Oxidation: Tollens’ test, Fehling’s test and Oxidation of methyl ketones by haloform reaction
• Reaction due to α-hydrogen: Acidity of α-hydrogen of aldehydes and ketones, Aldol condensation, Cross aldol condensation
• Other reactions: Cannizzaro reaction, Electrophilic substitution reaction
• Reactions Involving Cleavage of O–H Bond: Acidity
• Reactions Involving Cleavage of C–OH Bond: Formation of Anhydride, Esterification, Reactions with PCl5, PCl3 and SOCl2 and Reaction with Ammonia
• Reactions Involving –COOH Group: Reduction and Decarboxylation (Kolbe electrolysis)
• Substitution Reactions in the Hydrocarbon Part: Halogenation (Hell-Volhard-Zelinsky reaction), Ring substitution (Friedel-Crafts reaction)

Reference Books for Organic Chemistry

Many times students are unable to understand the bulky concepts of organic chemistry class 12trh from the formal language used in the NCERT books. In such a case, candidates need to refer to the right book to understand these concepts well. Here is a list of popular reference books for chemistry: 

Book	Buy Here
Modern ABC of Chemistry Class-12 Part I & Part II	Buy Here
All In One Physics CBSE Class 12	Buy Here
Xam Idea Chemistry for CBSE Class 12	Buy Here
10 Years CBSE Champion Chapterwise-Topicwise – Chemistry-Class- 12	Buy Here
Oswaal NCERT Exemplar (Problems – solutions) Class 12 Chemistry Book	Buy Here
thinkBoard: Class – 12 Board Companion Chemistry	Buy Here

FAQs

With a detailed syllabus for class 12 Organic Chemistry, we hope you’ll prepare well for the upcoming CBSE Chemistry exam 2023. Organic Chemistry is, directly and indirectly, involved in various facets of everyday living. Whether it is developing new medicines, plastics, fuels or food, Organic Chemistry majors enjoy a diverse range of lucrative career opportunities. Is chemistry your subject of interest and you are planning to study abroad after 12th? Then, our experts at Leverage Edu can help you identify the right university that will provide you the foundation to fulfil your dream of making an amazing career out of the study of molecules, elements, compounds and chemical reactions.