WBJEE Organic Chemistry Syllabus

Organic Chemistry syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Organic Chemistry in WBJEE, not a summary of it.

1. 1

   Fundamentals of Organic Chemistry

   3 topics

   • Basic Concepts
     • Classification and IUPAC nomenclature
     • Isomerism - structural and stereoisomerism
     • Electronic effects - inductive, resonance, hyperconjugation
     • Reaction intermediates and types of reactions
   • Purification and Characterisation
     • Methods of purification of organic compounds
     • Qualitative and quantitative analysis
   • Hydrocarbons
     • Alkanes - preparation and reactions
     • Alkenes and alkynes - addition reactions
     • Aromatic hydrocarbons and benzene
2. 2

   Halogen and Oxygen Containing Compounds

   4 topics

   • Haloalkanes and Haloarenes
     • Nucleophilic substitution mechanisms
     • Elimination reactions
     • Preparation and properties
   • Alcohols, Phenols and Ethers
     • Preparation and reactions of alcohols
     • Phenols and acidic character
     • Ethers and their properties
   • Aldehydes and Ketones
     • Preparation and nucleophilic addition
     • Aldol and Cannizzaro reactions
   • Carboxylic Acids and Derivatives
     • Preparation and acidity
     • Esters, amides and acid chlorides
3. 3

   Nitrogen Compounds and Biomolecules

   3 topics

   • Amines and Nitrogen Compounds
     • Amines - classification and basicity
     • Diazonium salts and reactions
     • Cyanides and isocyanides
   • Biomolecules
     • Carbohydrates and their classification
     • Proteins and amino acids
     • Nucleic acids and vitamins
   • Polymers
     • Classification of polymers
     • Addition and condensation polymerization
     • Natural and synthetic polymers

Organic Chemistry flashcards for WBJEE

25 of 50 cards from the Organic Chemistry deck — real questions with worked answers.

1. What is catenation, and why is carbon especially capable of it?

   Catenation is the self-linking of atoms of an element into chains and rings. Carbon shows maximum catenation because of the strength of the $\ce{C-C}$ bond (about $348\ \text{kJ mol}^{-1}$) and its tetravalency, allowing long stable chains, branches and rings.

2. Define hybridisation and give the geometry and bond angle for $sp$, $sp^{2}$ and $sp^{3}$ carbon.

   Hybridisation is the intermixing of atomic orbitals of similar energy to form equivalent hybrid orbitals. $sp$: linear, $180^{\circ}$; $sp^{2}$: trigonal planar, $120^{\circ}$; $sp^{3}$: tetrahedral, $109.5^{\circ}$.

3. Distinguish between sigma ($\sigma$) and pi ($\pi$) bonds.

   A $\sigma$ bond forms by axial (head-on) overlap of orbitals and allows free rotation; it is stronger. A $\pi$ bond forms by sideways (lateral) overlap of unhybridised $p$ orbitals, restricts rotation, and is weaker than a $\sigma$ bond.

4. In IUPAC nomenclature, what is the order of seniority for choosing the principal characteristic (functional) group among $\ce{-COOH}$, $\ce{-CHO}$, $\ce{-OH}$ and $\ce{-NH2}$?

   Decreasing seniority: carboxylic acid ($\ce{-COOH}$) > aldehyde ($\ce{-CHO}$) > alcohol ($\ce{-OH}$) > amine ($\ce{-NH2}$). The most senior group gets the lowest locant and is named as the suffix.

5. Give the IUPAC name of $\ce{CH3-CH(CH3)-CH2-CHO}$.

   3-Methylbutanal. The aldehyde carbon is C-1, giving a 4-carbon chain (butanal) with a methyl substituent at C-3.

6. Define functional, chain, and position isomerism with the molecular formula on which each is illustrated.

   Chain isomerism: different carbon skeletons (e.g. $\ce{C4H10}$: butane vs isobutane). Position isomerism: same skeleton, group at different position (e.g. propan-1-ol vs propan-2-ol). Functional isomerism: different functional groups for same formula (e.g. $\ce{C2H6O}$: ethanol vs dimethyl ether).

7. What is metamerism, and give an example?

   Metamerism is isomerism due to different alkyl groups attached to the same polyvalent functional atom (e.g. $\ce{O}$, $\ce{N}$). Example for $\ce{C4H10O}$ ethers: diethyl ether ($\ce{C2H5-O-C2H5}$) and methyl propyl ether ($\ce{CH3-O-C3H7}$).

8. What is tautomerism? Illustrate with keto–enol forms.

   Tautomerism is a special functional isomerism in which isomers interconvert by migration of a proton and shift of a double bond. Example: keto form $\ce{CH3-CO-CH3}$ $\rightleftharpoons$ enol form $\ce{CH3-C(OH)=CH2}$.

9. Distinguish enantiomers from diastereomers.

   Enantiomers are non-superimposable mirror images (identical physical properties except optical rotation, which is equal and opposite). Diastereomers are stereoisomers that are not mirror images; they have different physical properties (e.g. cis/trans isomers, or stereoisomers differing at one of several chiral centres).

10. State the condition for a compound to be optically active (chiral), and define a chiral centre.

    A compound is optically active if it is chiral, i.e. has no plane of symmetry and is non-superimposable on its mirror image. A chiral (asymmetric) carbon is an $sp^{3}$ carbon bonded to four different groups.

11. What is a meso compound?

    A meso compound contains chiral centres but is optically inactive overall because it possesses an internal plane of symmetry; the rotation by one half is cancelled by the other half (internal compensation). Example: meso-tartaric acid.

12. For a molecule with $n$ dissimilar chiral centres, how many optical isomers are possible?

    A maximum of $2^{n}$ optical isomers, occurring as $2^{n-1}$ pairs of enantiomers (fewer if meso forms exist due to symmetry).

13. Define the inductive effect and compare $+I$ and $-I$ groups.

    The inductive effect is the permanent displacement of $\sigma$-bond electrons along a chain due to electronegativity differences. $-I$ groups withdraw electrons (e.g. $\ce{-NO2}$, $\ce{-COOH}$, halogens); $+I$ groups donate electrons (e.g. alkyl groups, $\ce{-O^-}$). The effect decreases rapidly with distance.

14. Define the resonance (mesomeric) effect and distinguish $+M$ from $-M$ groups.

    The resonance effect is the delocalisation of $\pi$ or lone-pair electrons through conjugated systems. $+M$ (electron-releasing) groups donate electrons into the system (e.g. $\ce{-OH}$, $\ce{-NH2}$, $\ce{-OR}$, halogens). $-M$ (electron-withdrawing) groups pull electrons out (e.g. $\ce{-NO2}$, $\ce{-CHO}$, $\ce{-COOH}$, $\ce{-CN}$).

15. What is hyperconjugation, and how does it stabilise carbocations and alkenes?

    Hyperconjugation is the delocalisation of $\sigma$ (C–H) electrons of a group adjacent to an empty $p$ orbital or $\pi$ bond (no-bond resonance). More $\alpha$-hydrogens give greater stabilisation, so stability order of carbocations is $3^{\circ} > 2^{\circ} > 1^{\circ}$ and more-substituted alkenes are more stable.

16. Define electromeric effect.

    The electromeric effect is a temporary, complete transfer of a shared $\pi$-electron pair to one atom of a multiple bond at the moment of attack by a reagent. It is reversible and operates only in the presence of an attacking reagent ($+E$ towards, $-E$ away from the reagent).

17. Compare carbocations, carbanions and free radicals by hybridisation and geometry.

    Carbocation: $sp^{2}$, planar, electron-deficient (6 electrons). Carbanion: $sp^{3}$, pyramidal, has a lone pair (8 electrons). Free radical: $sp^{2}$ (near-planar), has one unpaired electron (7 electrons).

18. Give the stability order of carbocations and of free radicals.

    Both follow: $3^{\circ} > 2^{\circ} > 1^{\circ} > \ce{CH3+}$ (or $\ce{CH3^.}$), due to increasing $+I$ and hyperconjugative stabilisation. Allylic and benzylic species are extra-stabilised by resonance.

19. Define electrophile and nucleophile with examples.

    An electrophile is an electron-pair-seeking (electron-deficient) species, e.g. $\ce{H+}$, $\ce{NO2+}$, $\ce{BF3}$, $\ce{AlCl3}$. A nucleophile is an electron-pair donor (electron-rich), e.g. $\ce{OH-}$, $\ce{CN-}$, $\ce{NH3}$, $\ce{H2O}$.

20. List the four fundamental types of organic reactions.

    Substitution, addition, elimination, and rearrangement (isomerisation) reactions.

21. Define homolytic and heterolytic bond fission and the species each produces.

    Homolytic fission: each atom takes one electron, giving free radicals ($\ce{A-B -> A^. + B^.}$); favoured by non-polar conditions/heat/light. Heterolytic fission: one atom takes both electrons, giving ions ($\ce{A-B -> A+ + B-}$); favoured by polar conditions.

22. State the principle of crystallisation as a purification method.

    Crystallisation purifies solids by dissolving the impure compound in a hot solvent in which it is sparingly soluble when cold; on cooling the pure compound crystallises out while soluble impurities remain in the mother liquor (and insoluble ones are filtered off hot).

23. On what principle does simple distillation work, and when is it used?

    Simple distillation separates a liquid from non-volatile impurities, or two liquids whose boiling points differ appreciably (roughly more than $25\text{--}30^{\circ}\text{C}$) and that boil below $150^{\circ}\text{C}$. The more volatile component vaporises first and is condensed.

24. What is fractional distillation and where is it applied?

    Fractional distillation uses a fractionating column to separate liquids whose boiling points are close. Repeated vaporisation–condensation along the column enriches the vapour in the more volatile component. Used in petroleum refining and separating air/aqueous mixtures.

25. Explain steam distillation and the condition a compound must satisfy.

    Steam distillation separates steam-volatile substances that are immiscible with and do not react with water. The mixture boils when the sum of the vapour pressures equals atmospheric pressure ($p_{\text{total}} = p_{\text{water}} + p_{\text{compound}}$), so it distils below $100^{\circ}\text{C}$. Example: purification of aniline.

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