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General Organic Chemistry (GOC) revision notes

Every idea in the General Organic Chemistry (GOC) chapter for JEE Main, with the usual mistakes and the fast methods. Topic 1 is open to everyone; sign in free to read all 30 and download the PDF.

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How we count: 7× asked means 7 past JEE Main questions in the PrepWiser bank needed that concept, and "last" is the latest year one appeared. ★ marks ideas asked 8 or more times.

Bonding, classification and IUPAC names

Hybridisation, bond counts, unsaturation
5× asked, last 2025
DoU=2C+2+N−H−X2,σ=atoms−1+rings\text{DoU} = \frac{2C + 2 + N - H - X}{2},\qquad \sigma = \text{atoms} - 1 + \text{rings}
4 single bonds: sp³; one double: sp²; a triple or two doubles: sp. Each ring or π bond is 1 DoU; a triple bond is 2.
C₁sp²C₂sp²C₃sp³Csp³Csp³C₄spC₅spC₆sp³sp³: 4sp²: 2sp: 2DoU = (16 + 2 − 12)/2 = 3; σ 19, π 3
3,3-Dimethylhex-1-en-4-yne (CX8HX12\ce{C8H12}): hybridisation read off each carbon’s π bonds; the two CH₃ branches are sp³ too
  • Not the parent chain only. Branch carbons count too. 3,3-Dimethylhex-1-en-4-yne: C3, C6 and both CHX3\ce{CH3} are sp³ (4), C1–C2 sp² (2), C4–C5 sp (2). A nitrile C is sp; a C=O carbon is sp².
Classification and homologous series
6× asked, last 2025
acyclic ∣ alicyclic ∣ aromatic ∣ heterocyclic;homologues differ by −CHX2−\text{acyclic}\ \mid\ \text{alicyclic}\ \mid\ \text{aromatic}\ \mid\ \text{heterocyclic};\qquad \text{homologues differ by } \ce{-CH2-}
Cyclohexene, COT: alicyclic; tropolone: non-benzenoid aromatic. Homologues: same functional group (1° vs 2° amines do not).
Functional-group priority
4× asked, last 2026
−COOH>−SOX3H>anhydride>−COOR>−COX>−CONHX2>−CN>−CHO>>C=O>−OH>−NHX2>C=C, C≡C\begin{gathered}\ce{-COOH} > \ce{-SO3H} > \text{anhydride} > \ce{-COOR} > \ce{-COX} > \ce{-CONH2} > \ce{-CN}\\ > \ce{-CHO} > \ce{>C=O} > \ce{-OH} > \ce{-NH2} > \ce{C=C},\ \ce{C#C}\end{gathered}
Top group = suffix, nearest C1. −R\ce{-R}, −X\ce{-X}, −NOX2\ce{-NO2}, −OR\ce{-OR} are always prefixes (alkyl, halo, nitro, alkoxy).
O H C 7 C 6 C 5 C 4 C 3 C 2 O C 1
ketone outranks –OH: C=O takes the suffix and the lower locant (2), OH is the prefix (7)
  • Not ketone above aldehyde or amine above alcohol. −CHO>>C=O>−OH>−NHX2\ce{-CHO} > \ce{>C=O} > \ce{-OH} > \ce{-NH2}. So HO(CHX2)X5COCHX3\ce{HO(CH2)5COCH3} is 7-hydroxyheptan-2-one, never 2-oxoheptan-7-ol.
Parent chain, locants and prefixes
9× asked, last 2025
chain: principal group→most multiple bonds→longest→most brancheslocants: suffix→multiple bonds→all prefixes together\begin{gathered}\text{chain: principal group} \to \text{most multiple bonds} \to \text{longest} \to \text{most branches}\\ \text{locants: suffix} \to \text{multiple bonds} \to \text{all prefixes together}\end{gathered}
Lowest locant set at the first point of difference. Prefixes alphabetical (di-, tri- ignored); '-en-' is written before '-yn-'.
C 1 C 2 C 3 C 4 C 5 C 6 C 7 C 8
2,5,6-trimethyloctane: {2,5,6}, not {3,4,7} from the other end
C 1 C 2 C 3 C 4 C 5 C 6 C 7
3-ethyl-5-methylheptane: prefixes alphabetical
  • Not the first branch from one end. Compare whole sets: {2,5,6} beats {3,4,7}, so the octane is 2,5,6-trimethyloctane. A CX2HX5\ce{C2H5} at a chain end extends the chain (3-ethyl-5-methylheptane).
  • Quick method. When the locant sets are equal, the first-cited prefix takes the lower number: 1-bromo-3-chlorobenzene, not 3-bromo-1-chloro.
Polyfunctional chains and esters
6× asked, last 2026
OHC−CH(CHX3)−CH=CH−CH(CHX3)−COOH: 2,5-dimethyl-6-oxohex-3-enoic acid\ce{OHC-CH(CH3)-CH=CH-CH(CH3)-COOH}:\ \text{2,5-dimethyl-6-oxohex-3-enoic acid}
The C of −COOH\ce{-COOH}, −CHO\ce{-CHO}, −CN\ce{-CN}, −COOR\ce{-COOR} is chain C1. Ester: alkyl (on O) alkanoate, two words.
O H C 1 O C 2 C 3 C 4 C 5 C 6 O
–COOH carbon is C1; the CHO at the far end becomes 6-oxo
  • Not '-al' for an outranked CHO. If it ends the chain it is oxo (6-oxohex-3-enoic acid), if it hangs off it is formyl: 2-formyl-4-hydroxyhept-6-enoic acid. Ketone + aldehyde: 4-methyl-6-nitro-3-oxohept-4-enal.
Rings, benzene derivatives, common names
7× asked, last 2025
benzene-1,2-, 1,3-, 1,4-diol: catechol, resorcinol, quinol;CHX3CHClX2: ethylidene chloride=1,1-dichloroethane\text{benzene-1,2-, 1,3-, 1,4-diol: catechol, resorcinol, quinol};\qquad \ce{CH3CHCl2}:\ \text{ethylidene chloride} = \text{1,1-dichloroethane}
Principal-group ring C is C1; '-carboxylic acid', '-carbaldehyde'. Greek α = C next to the group (γ-aminobutyric: 4-amino).
O H O H
catechol (1,2)
O H O H
resorcinol (1,3)
O H O H
quinol (1,4)

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Practise General Organic Chemistry (GOC)

24 more concepts in 6 topics

Structural and geometrical isomerism, Optical isomerism, Electronic effects, Reactive intermediates and reaction types, Aromaticity and physical properties and Acidity and basicity. Read the first part free. Sign in free with Google to read the rest and download the PDF.

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Structural and geometrical isomerism

  • Types of structural isomerism11×
  • Counting substitution products6×
  • Keto–enol tautomerism3×
  • Geometrical isomerism11×

Optical isomerism

  • Chirality and chiral centres15×
  • Stereoisomer counts, meso, R/S, D/L13×

Electronic effects

  • Inductive effect5×
  • Resonance (mesomeric) effect8×
  • Canonical forms: rules and stability5×
  • Resonance, bond length and dipole4×
  • Hyperconjugation6×
  • Electromeric effect3×
  • Substituent effects on a benzene ring9×

Reactive intermediates and reaction types

  • Bond fission, intermediates, reaction types6×
  • Carbocation and free-radical stability14×
  • Carbocation rearrangements3×
  • Carbanion stability6×
  • Electrophiles and nucleophiles4×

Aromaticity and physical properties

  • Hückel's rule for rings and ions15×
  • Boiling point, melting point, density7×

Acidity and basicity

  • Acid strength from the conjugate base8×
  • C–H acidity6×
  • Substituted phenols and the ortho effect5×
  • Basicity of nitrogen compounds7×

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