JEE Organic Chemistry Cheatsheet

Cheatsheet Content

Nomenclature IUPAC Rules: Longest carbon chain (parent chain). Numbering starts from the end closer to the functional group/substituent. Alphabetical order for multiple substituents. Prefixes: di-, tri-, tetra- for identical groups. Common Functional Groups: Alkane: -ane Alkene: -ene Alkyne: -yne Alcohol: -ol (or hydroxy-) Aldehyde: -al (or formyl-) Ketone: -one (or oxo-) Carboxylic Acid: -oic acid (or carboxy-) Ester: -oate Amine: -amine (or amino-) Ether: alkoxyalkane Isomerism Structural Isomerism: Same molecular formula, different structural formula. Chain Isomerism Position Isomerism Functional Group Isomerism Metamerism Tautomerism (e.g., keto-enol) Stereoisomerism: Same molecular formula, same structural formula, different spatial arrangement. Geometrical Isomerism (cis-trans): Restricted rotation around C=C bond or in cyclic compounds. Optical Isomerism: Chiral center (asymmetric carbon), non-superimposable mirror images (enantiomers). Chiral carbon: $sp^3$ carbon bonded to four different groups. Racemic mixture: Equimolar mixture of enantiomers, optically inactive. Meso compound: Chiral centers present but optically inactive due to internal plane of symmetry. Specific Rotation: $[\alpha]_D^T = \frac{\alpha}{l \times c}$ General Organic Chemistry (GOC) Electronic Effects Inductive Effect (-I / +I): Permanent shift of $\sigma$-electrons along a carbon chain. -I groups: $-NO_2, -CN, -COOH, -F, -Cl, -Br, -I, -OH, -OR, -C_6H_5$ +I groups: Alkyl groups (e.g., $-CH_3, -CH_2CH_3$), $-COO^-$ Resonance Effect (+R / -R or Mesomeric Effect): Delocalization of $\pi$-electrons or lone pair electrons. +R groups (electron donating): $-NH_2, -OH, -OR, -Cl, -Br, -I, -C_6H_5$ (through lone pair/ $\pi$-bond) -R groups (electron withdrawing): $-NO_2, -CN, -CHO, -COR, -COOH, -COOR$ (through $\pi$-bond) Hyperconjugation (No bond resonance): Delocalization of $\sigma$-electrons of C-H bond with adjacent $\pi$-system or empty p-orbital. Stabilizes carbocations, free radicals, and alkenes. Acidity & Basicity Acidity: Stability of conjugate base. Electron withdrawing groups (-I, -R) increase acidity. Electron donating groups (+I, +R) decrease acidity. Hybridization: $sp > sp^2 > sp^3$ (for C-H bond acidity). Basicity: Availability of lone pair of electrons. Electron donating groups (+I, +R) increase basicity. Electron withdrawing groups (-I, -R) decrease basicity. Aromatic amines are less basic than aliphatic amines. Reaction Intermediates Carbocation: $sp^2$ hybridized, trigonal planar, electron deficient. Stability: $3^\circ > 2^\circ > 1^\circ > CH_3^+$. Stabilized by +I, +R, hyperconjugation. Carbanion: $sp^3$ hybridized, pyramidal, electron rich. Stability: $CH_3^- > 1^\circ > 2^\circ > 3^\circ$. Stabilized by -I, -R. Free Radical: $sp^2$ hybridized, planar, odd electron. Stability: $3^\circ > 2^\circ > 1^\circ > CH_3^\cdot$. Stabilized by +I, +R, hyperconjugation. Hydrocarbons Alkanes Preparation: Wurtz reaction, Decarboxylation, Hydrogenation of alkenes/alkynes, Kolbe's electrolysis. Reactions: Free radical substitution (Halogenation), Combustion, Pyrolysis. Alkenes Preparation: Dehydration of alcohols, Dehydrohalogenation of alkyl halides (Saytzeff's rule), Hydrogenation of alkynes (Lindlar's catalyst for cis-alkene, Na/Li in $\text{liq. NH}_3$ for trans-alkene). Reactions: Electrophilic addition (Markovnikov's rule, Anti-Markovnikov's with HBr/peroxide), Hydrogenation, Halogenation, Hydrohalogenation, Hydration, Ozonolysis, Baeyer's test (cold dil. $KMnO_4$). Alkynes Preparation: Dehydrohalogenation of gem/vicinal dihalides, From calcium carbide. Reactions: Acidity of terminal alkynes, Electrophilic addition (HX, $H_2O$), Hydrogenation, Ozonolysis, Polymerization. Aromatic Compounds (Benzene) Aromaticity: Hückel's Rule ($4n+2$ $\pi$-electrons), Planar, Cyclic, Complete delocalization. Electrophilic Aromatic Substitution (EAS): Nitration: $HNO_3/H_2SO_4$ Halogenation: $X_2/FeX_3$ Sulfonation: $H_2SO_4$ (fuming) Friedel-Crafts Alkylation: $R-Cl/AlCl_3$ Friedel-Crafts Acylation: $RCOCl/AlCl_3$ Directing Groups: Ortho-para directing & Activating: $-OH, -OR, -NH_2, -NR_2, -R, -X$ (halogens are deactivating but o,p-directing) Meta directing & Deactivating: $-NO_2, -CN, -CHO, -COR, -COOH, -COOR, -SO_3H$ Halogen Derivatives Nomenclature: Haloalkanes, Haloarenes. Preparation: From alcohols ($SOCl_2, PCl_3, PCl_5, HX$), From hydrocarbons (free radical halogenation, EAS), Halogen exchange (Finkelstein, Swartz). Reactions: Nucleophilic Substitution ($S_N1, S_N2$): $S_N1$: $3^\circ > 2^\circ > 1^\circ$, Carbocation intermediate, Racemization, Polar protic solvents. $S_N2$: $1^\circ > 2^\circ > 3^\circ$, Concerted, Inversion of configuration, Polar aprotic solvents. Elimination (E1, E2): Dehydrohalogenation (alcoholic KOH - Saytzeff's rule). Reaction with Metals: Wurtz reaction, Grignard reagent, Ullmann reaction. Alcohols, Phenols, Ethers Alcohols Preparation: From alkyl halides, Reduction of aldehydes/ketones/carboxylic acids/esters, Grignard reagent, Hydroboration-oxidation of alkenes, Oxymercuration-demercuration. Reactions: Dehydration (Saytzeff's rule), Oxidation ($PCC, K_2Cr_2O_7, KMnO_4$), Esterification, Reaction with HX (Lucas test), Reaction with $SOCl_2$. Phenols Preparation: From diazonium salts, From cumene, Dow's process. Reactions: Acidic nature, Electrophilic substitution (Nitration, Halogenation, Sulfonation, Kolbe's reaction, Reimer-Tiemann reaction), Reaction with $Zn$ dust. Ethers Preparation: Williamson synthesis. Reactions: Cleavage with HI/HBr (least hindered alkyl group forms halide), Electrophilic substitution (EAS). Aldehydes, Ketones, Carboxylic Acids Aldehydes & Ketones Preparation: Oxidation of alcohols ($1^\circ \rightarrow$ aldehyde, $2^\circ \rightarrow$ ketone), Ozonolysis of alkenes, Hydration of alkynes, Rosenmund reduction, Stephen reduction, Etard reaction, Gattermann-Koch reaction, Friedel-Crafts acylation. Reactions: Nucleophilic Addition: To HCN, $NaHSO_3$, alcohols (hemiacetal/acetal), Grignard reagent. Reduction: To alcohols, Clemmensen reduction, Wolff-Kishner reduction. Oxidation: Tollen's test, Fehling's test (aldehydes only). Reactions involving $\alpha$-Hydrogen: Aldol condensation, Cannizzaro reaction (no $\alpha$-H), Haloform reaction. Carboxylic Acids Preparation: Oxidation of $1^\circ$ alcohols/aldehydes, From nitriles/amides, Grignard reagent with $CO_2$, Hydrolysis of esters. Reactions: Acidic nature, Esterification, Formation of acid halides, anhydrides, amides. Reduction to alcohols ($LiAlH_4$), Hell-Volhard-Zelinsky (HVZ) reaction. Nitrogen Containing Compounds Amines Preparation: Reduction of nitro compounds, nitriles, amides. Ammonolysis of alkyl halides, Gabriel phthalimide synthesis, Hoffmann bromamide degradation. Reactions: Basic nature, Alkylation, Acylation, Carbylamine reaction ($1^\circ$ amines only), Reaction with nitrous acid ($HNO_2$). Hinsberg test ($1^\circ, 2^\circ, 3^\circ$ amine distinction). Diazonium Salts Preparation: Diazotization (reaction of $1^\circ$ aromatic amine with $NaNO_2/HCl$ at $0-5^\circ C$). Reactions: Sandmeyer reaction ($CuCl/HCl, CuBr/HBr, CuCN/KCN$), Gattermann reaction ($Cu/HCl, Cu/HBr$), Balz-Schiemann reaction ($HBF_4$), Coupling reactions (azo dye formation). Biomolecules Carbohydrates Classification: Monosaccharides (glucose, fructose), Disaccharides (sucrose, maltose, lactose), Polysaccharides (starch, cellulose). Glucose: Open-chain and cyclic (pyranose) structures. Mutarotation. Reducing sugar. Sucrose: Non-reducing sugar, hydrolysis yields glucose + fructose. Proteins Amino Acids: Zwitterionic form, Isoelectric point. Peptide Bond: Formed between -COOH and $-NH_2$ groups. Structure: Primary, Secondary ($\alpha$-helix, $\beta$-pleated sheet), Tertiary, Quaternary. Denaturation: Loss of biological activity due to change in structure. Vitamins Fat-soluble: A, D, E, K. Water-soluble: B-complex, C. Nucleic Acids DNA, RNA: Nucleotides (sugar, phosphate, nitrogenous base). Bases: Adenine, Guanine, Cytosine, Thymine (DNA), Uracil (RNA). Double Helix: Complementary base pairing (A-T, G-C). Polymers Classification: Natural, Synthetic. Addition, Condensation. Homo, Co-polymers. Addition Polymers: Polyethylene, Polypropylene, PVC, Teflon, Polyacrylonitrile, Buna-S, Buna-N. Condensation Polymers: Nylon 6,6, Nylon 6, Polyester (Dacron), Bakelite, Melamine-formaldehyde resin. Biodegradable Polymers: PHBV, Nylon 2-Nylon 6. Chemistry in Everyday Life Drugs: Analgesics, Antipyretics, Antiseptics, Disinfectants, Antibiotics, Antacids, Antihistamines, Tranquilizers. Food Additives: Artificial sweeteners, Food preservatives, Antioxidants. Soaps & Detergents: Soaps (sodium/potassium salts of fatty acids), Synthetic detergents (anionic, cationic, non-ionic).