Organic Chemistry Formulas

Organic Chemistry514 Qs

Hydrocarbons (Alkanes, Alkenes, Alkynes)

Markovnikov & anti-Markovnikov additions, ozonolysis, Wurtz reaction, Friedel-Crafts alkylation/acylation, and acidic nature of alkynes.

Organic Chemistry527 Qs

Haloalkanes & Haloarenes

SN1 and SN2 nucleophilic substitutions, E1 and E2 eliminations, Saytzeff rule, and Grignard reagent synthesis.

Organic Chemistry594 Qs

Alcohols, Phenols & Ethers

Lucas test, Reimer-Tiemann reaction, Kolbe reaction, Williamson ether synthesis, and acidic strength of phenols.

Organic Chemistry395 Qs

Aldehydes, Ketones & Carboxylic Acids

Nucleophilic addition, Aldol condensation, Cannizzaro reaction, Tollens/Fehling test, Hell-Volhard-Zelinsky (HVZ) reaction.

9 Formulas

Organic Chemistry585 Qs

Amines & Diazonium Salts

Basicity of amines in gas/aqueous phase, Hoffmann bromamide degradation, Gabriel phthalimide synthesis, and Sandmeyer reaction.

7 Formulas

Organic Chemistry572 Qs

Biomolecules & Polymers

Carbohydrates (glucose, fructose, mutarotation), amino acids, peptide bonds, isoelectric point, and nucleic acids (DNA/RNA).

Formulas Reference (Organic Chemistry)

7 Chapters match

Organic ChemistryTop Priority (3-4 Qs in JEE)377 PYQs

General Organic Chemistry (GOC)

Inductive effect, resonance & mesomeric effect, hyperconjugation, aromaticity (Hückel's 4n+2 rule), and carbocation stability.

Hückel's Rule of Aromaticity

4n + 2 \; \pi\text{-electrons} \; (n = 0, 1, 2, \dots) \implies \text{Aromatic}

Requires cyclic, planar, fully conjugated ring system with (4n + 2) π-electrons.

4n π-electrons in cyclic planar conjugated ring = Anti-aromatic (least stable).

Carbocation & Carbanion Stability Order

\text{Carbocation: } 3^\circ > 2^\circ > 1^\circ > \text{CH}_3^+, \quad \text{Carbanion: } \text{CH}_3^- > 1^\circ > 2^\circ > 3^\circ

Carbocations are stabilized by +I, +M, and hyperconjugation (α-hydrogens).

Stability of carbocation increases with number of α-hydrogens for hyperconjugation.

Electronic Effects Order (+M / -M & +I / -I)

+M: \; -O^- > -NH_2 > -OH > -OR; \quad -M: \; -NO_2 > -CN > -CHO > -COOH

Relative strength of resonance and inductive donor/acceptor substituents.

Mesomeric effect M operates at ortho/para positions, NOT meta positions.

Acidic Strength Comparison

\text{Acidic Strength } \propto K_a \propto \frac{1}{pK_a} \propto \text{Stability of Conjugate Base (Anion)}

Anion stability is increased by -I and -M electron-withdrawing groups.

Ortho-substituted benzoic acids are stronger acids regardless of whether the group is +I or -I (ortho effect).

Hyperconjugation & Heat of Hydrogenation

\text{Alkene Stability} \propto \text{No. of } \alpha\text{-H atoms} \propto \frac{1}{\Delta H_{\text{hydrogenation}}}

σ(C-H) to empty p or π* orbital overlap stabilizes alkenes and free radicals. More stable alkenes release less heat upon hydrogenation.

Trans-alkene is generally more stable than cis-alkene due to lower steric hindrance.

Tautomerism & Keto-Enol Equilibrium

\% \text{ Enol Content} \propto \text{Aromatic Enol Driving Force} > \text{Intramolecular H-Bonding (Chelation)}

Spontaneous interconversion between constitutional isomers differing in position of hydrogen atom and double bond.

Phenol enol content is ~100% due to aromatic resonance; acetylacetone (CH₃COCH₂COCH₃) enol content is ~76% in gas phase due to 6-membered quasi-ring H-bonding.

Stereochemistry & Specific Optical Rotation

[\alpha]_\lambda^T = \frac{\alpha_{\text{observed}}}{l \text{ (dm)} \times c \text{ (g/mL)}}, \quad \% ee = \frac{|d - l|}{d + l} \times 100\%, \quad \text{Stereoisomers} = 2^n

Optical rotation of chiral molecules in polarimeter tube of length l and concentration c, and enantiomeric excess (% ee).

Meso compounds contain chiral carbons with an internal plane of symmetry (C_s) or inversion center (C_i) and are optically inactive by internal compensation.

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Hydrocarbons (Alkanes, Alkenes, Alkynes)

Markovnikov & anti-Markovnikov additions, ozonolysis, Wurtz reaction, Friedel-Crafts alkylation/acylation, and acidic nature of alkynes.

Markovnikov & Anti-Markovnikov Addition

R-\text{CH}=\text{CH}_2 + \text{HX} \longrightarrow R-\text{CH(X)}-\text{CH}_3 \quad (\text{Markovnikov})

Electrophile H⁺ adds to form the more stable carbocation intermediate.

In presence of peroxide (R₂O₂), HBr adds anti-Markovnikov via free radical mechanism.

Ozonolysis of Alkenes

R_1 R_2 \text{C}=\text{C} R_3 R_4 \xrightarrow{\text{1. } O_3, \; \text{2. } Zn / H_2O} R_1 R_2 \text{C}=\text{O} + R_3 R_4 \text{C}=\text{O}

Cleaves carbon-carbon double bonds to form carbonyl compounds.

Reductive ozonolysis uses Zn/H₂O or (CH₃)₂S to prevent oxidation of aldehydes to carboxylic acids.

Wurtz Reaction & Corey-House Synthesis

2 \text{ R-X} + 2 \text{Na} \xrightarrow{\text{dry ether}} \text{R-R} + 2 \text{NaX}

Coupling of alkyl halides to produce symmetrical alkanes.

Methane (CH₄) cannot be prepared by the Wurtz reaction.

Friedel-Crafts Alkylation & Acylation

\text{C}_6\text{H}_6 + \text{R-Cl} \xrightarrow{\text{anh. AlCl}_3} \text{C}_6\text{H}_5\text{R}, \quad \text{C}_6\text{H}_6 + \text{RCOCl} \xrightarrow{\text{anh. AlCl}_3} \text{C}_6\text{H}_5\text{COR}

Electrophilic aromatic substitution on benzene ring.

Acylation avoids carbocation rearrangement and polyalkylation.

Acidic Nature of Terminal Alkynes

\text{R-C}\equiv\text{CH} + \text{NaNH}_2 \longrightarrow \text{R-C}\equiv\text{C}^- \text{Na}^+ + \text{NH}_3

Terminal alkyne hydrogen is acidic due to 50% s-character of sp hybridized carbon.

Gives red precipitate with ammoniacal Cu₂Cl₂ and white precipitate with Tollen's reagent.

Stereoselective Reduction of Alkynes (cis vs trans)

\text{R-C}\equiv\text{C-R}' \xrightarrow{\text{H}_2 / \text{Pd-CaCO}_3 \text{ (Lindlar)}} \text{cis-alkene}, \quad \text{R-C}\equiv\text{C-R}' \xrightarrow{\text{Na / liq. } \text{NH}_3 \text{ (Birch)}} \text{trans-alkene}

Syn-addition catalytic hydrogenation versus anti-addition dissolving metal reduction to control alkene geometry.

Birch reduction of benzene gives non-conjugated 1,4-cyclohexadiene.

Hydration of Alkenes: OMDM vs Hydroboration-Oxidation

\text{OMDM: } \text{R-CH=CH}_2 \xrightarrow{\text{1. Hg(OAc)}_2/\text{H}_2\text{O}, \; \text{2. NaBH}_4} \text{Markovnikov (no rearr.)}, \quad \text{HBO: } \xrightarrow{\text{1. B}_2\text{H}_6, \; \text{2. H}_2\text{O}_2/\text{OH}^-} \text{Anti-Markovnikov (syn)}

Two non-rearranging pathways for regioselective water addition across carbon-carbon double bonds.

OMDM avoids carbocation ring expansions and hydride/methyl shifts.

Hückel's Rule of Aromaticity & Anti-Aromaticity

\text{Aromatic: Planar, cyclic, conjugated, } (4n + 2)\pi e^-, \quad \text{Anti-Aromatic: Planar, cyclic, conjugated, } 4n\pi e^-

Stability criteria based on cyclic π-electron delocalization. Anti-aromatic compounds are destabilized relative to open-chain analogs.

Cyclooctatetraene (8 π electrons) adopts a non-planar tub conformation to avoid anti-aromaticity, behaving as non-aromatic.

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Haloalkanes & Haloarenes

SN1 and SN2 nucleophilic substitutions, E1 and E2 eliminations, Saytzeff rule, and Grignard reagent synthesis.

SN1 vs SN2 Nucleophilic Substitution

\text{S}_\text{N}1: \; \text{Rate} = k[\text{R-X}] \; (3^\circ > 2^\circ > 1^\circ), \quad \text{S}_\text{N}2: \; \text{Rate} = k[\text{R-X}][\text{Nu}^-] \; (\text{CH}_3\text{X} > 1^\circ > 2^\circ > 3^\circ)

Two-step unimolecular vs one-step concerted bimolecular substitution.

Polar protic solvents favor SN1; polar aprotic solvents (DMSO, DMF, acetone) favor SN2.

Saytzeff vs Hofmann Elimination Rule

\text{Saytzeff: More substituted alkene (more } \alpha\text{-H)}, \quad \text{Hofmann: Less substituted alkene (bulky base like } t\text{-BuO}^-)

Regioselectivity in dehydrohalogenation reactions.

Alcoholic KOH promotes E2 elimination.

Grignard Reagent Preparation & Reactions

\text{R-X} + \text{Mg} \xrightarrow{\text{dry ether}} \text{R-MgX} \xrightarrow{\text{H}_2\text{O}} \text{R-H} + \text{Mg(OH)X}

Organomagnesium halide organometallic reagent acts as powerful carbanion nucleophile and strong base.

Reacts with active hydrogen compounds (water, alcohol, amine) instantly to give alkane.

Halogen Exchange: Finkelstein & Swarts Reactions

\text{Finkelstein: } \text{R-Cl}/\text{Br} + \text{NaI} \xrightarrow{\text{acetone}} \text{R-I} + \text{NaCl}\downarrow, \quad \text{Swarts: } \text{R-Cl}/\text{Br} + \text{AgF}/\text{SbF}_3 \to \text{R-F} + \text{AgX}\downarrow

Specific pathways for synthesizing alkyl iodides (precipitation drives equilibrium) and alkyl fluorides (using heavy metal fluorides).

Swarts fluorinating agents: AgF, Hg₂F₂, CoF₃, SbF₃.

Nucleophilic Aromatic Substitution (S_NAr & Benzyne)

\text{S}_\text{N}\text{Ar Rate: } \text{Ar-F} \gg \text{Ar-Cl} > \text{Ar-Br} > \text{Ar-I} \; (\text{with } -\text{NO}_2 \text{ at } o/p), \quad \text{Benzyne: } \text{Ph-Cl} + \text{NaNH}_2 \xrightarrow{\text{liq } \text{NH}_3} [\text{C}_6\text{H}_4] \to \text{Ph-NH}_2

S_NAr proceeds via Meisenheimer complex (rate-determining addition). Strong base on unactivated haloarene proceeds via benzyne intermediate.

Benzyne mechanism leads to cine substitution (50:50 mixture of substituted products).

Haloform Reaction Mechanism & Specificity

\text{R-CO-CH}_3 + 3\text{X}_2 + 4\text{OH}^- \to \text{R-COO}^- + \text{CHX}_3\downarrow + 3\text{X}^- + 3\text{H}_2\text{O} \quad (\text{CHI}_3 \text{ Yellow ppt})

Characteristic test for methyl ketones (CH₃-C=O) and secondary alcohols oxidizable to them (CH₃-CH(OH)-R), plus ethanol and acetaldehyde.

Tertiary alcohols and methanol DO NOT give the haloform test.

Elimination Reaction Spectrum (E1, E2, E1cB)

\text{E1: Carbocation intermediate}, \quad \text{E2: Anti-periplanar concerted TS}, \quad \text{E1cB: Carbanion intermediate (poor leaving group like F)}

Mechanistic comparison of β-eliminations. E1cB occurs when strong electron-withdrawing groups stabilize conjugate carbanion base with poor leaving group.

E2 dehydrohalogenation requires strictly anti-coplanar alignment of β-hydrogen and α-halogen.

Coupling Reactions: Wurtz, Fittig & Ullmann Synthesis

\text{Wurtz: } 2\text{R-X} + 2\text{Na} \to \text{R-R}, \quad \text{Fittig: } 2\text{Ar-X} + 2\text{Na} \to \text{Ar-Ar}, \quad \text{Ullmann: } 2\text{Ar-I} + \text{Cu} \xrightarrow{\Delta} \text{Ar-Ar}

Reductive coupling reactions forming symmetric carbon-carbon bonds. Ullmann reaction specifically synthesizes biaryls using copper powder.

Ullmann reaction works best with ortho-halonitrobenzenes.

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Alcohols, Phenols & Ethers

Lucas test, Reimer-Tiemann reaction, Kolbe reaction, Williamson ether synthesis, and acidic strength of phenols.

Lucas Test for Alcohol Distinction

\text{R-OH} + \text{conc. HCl} \xrightarrow{\text{anh. ZnCl}_2} \text{R-Cl} \downarrow \; (\text{Turbidity})

Differentiates 1°, 2°, 3° alcohols via SN1 rate.

3° alcohol turbidity appears immediately; 1° alcohol shows no turbidity at room temperature.

Reimer-Tiemann & Kolbe Reactions of Phenol

\text{Ph-OH} \xrightarrow{\text{CHCl}_3 + \text{NaOH}} \text{Salicylaldehyde}, \quad \text{Ph-OH} \xrightarrow{\text{CO}_2 + \text{NaOH}} \text{Salicylic Acid}

Electrophilic aromatic substitutions on highly activated phenoxide ring.

Reimer-Tiemann intermediate is electrophilic dichlorocarbene (:CCl₂).

Williamson's Ether Synthesis

\text{R-O}^- \text{Na}^+ + \text{R'-X} \longrightarrow \text{R-O-R'} + \text{NaX} \quad (\text{R' must be } 1^\circ)

SN2 displacement by alkoxide ion on alkyl halide.

If R' is 3°, elimination (alkene) occurs exclusively instead of ether formation.

Pinacol-Pinacolone Rearrangement

\text{R}_2\text{C(OH)-C(OH)R}_2 \xrightarrow{\text{H}^+, \Delta} \text{R}_3\text{C-CO-R} + \text{H}_2\text{O}

Acid-catalyzed dehydration of vicinal diols accompanied by 1,2-migratory shift to form a stable ketone.

Migratory aptitude order: p-anisyl > p-tolyl > phenyl > 3° alkyl > 2° alkyl > 1° alkyl > H.

Cleavage of Ethers with Hydrogen Halides (HI)

\text{R-O-R'} + \text{HI} \longrightarrow \begin{cases} \text{SN2: } \text{R-I (smaller)} + \text{R'OH (larger)} & (1^\circ / 2^\circ) \\ \text{SN1: } \text{R-I (from } 3^\circ / \text{benzyl)} + \text{R'OH} & (3^\circ) \end{cases}

Nucleophilic attack on protonated ether oxonium ion. Excess HI yields two moles of alkyl iodides.

Anisole (Ph-O-CH₃) with HI produces Phenol (Ph-OH) and Methyl Iodide (CH₃I) because the Ph-O bond has partial double bond character.

Victor Meyer & Catalytic Dehydrogenation Tests

\text{Victor Meyer: } 1^\circ \to \text{Blood Red}, \; 2^\circ \to \text{Blue}, \; 3^\circ \to \text{Colorless}; \quad \text{Cu / 573 K: } 1^\circ \to \text{Aldehyde}, \; 2^\circ \to \text{Ketone}, \; 3^\circ \to \text{Alkene}

Colorimetric identification of primary, secondary, and tertiary alcohols.

3° alcohol undergoes catalytic elimination (dehydration) with heated Cu yielding an alkene instead of dehydrogenation.

Acidic Strength of Substituted Phenols & Intramolecular H-Bonding

\text{Acidity: } \text{Picric Acid} > p\text{-Nitrophenol} > o\text{-Nitrophenol} > m\text{-Nitrophenol} > \text{Phenol} > \text{Cresols}

Electron-withdrawing groups (-M, -I) disperse phenoxide negative charge and drastically increase acidity.

o-Nitrophenol is steam volatile due to intramolecular H-bonding (chelation); p-nitrophenol has higher boiling point due to intermolecular H-bonding.

Fries & Claisen Rearrangements

\text{Fries: } \text{Ar-OCO-R} \xrightarrow{\text{anh. AlCl}_3} o/p\text{-acylphenol}, \quad \text{Claisen: } \text{Ar-O-CH}_2\text{CH=CH}_2 \xrightarrow{\Delta} o\text{-allylphenol}

Thermal and Lewis-acid catalyzed rearrangements of phenyl esters and allyl aryl ethers into ortho- and para-substituted phenols.

In Fries rearrangement, low temperature (below 60°C) favors para-isomer; high temperature (above 160°C) favors ortho-isomer.

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Aldehydes, Ketones & Carboxylic Acids

Nucleophilic addition, Aldol condensation, Cannizzaro reaction, Tollens/Fehling test, Hell-Volhard-Zelinsky (HVZ) reaction.

Aldol Condensation & Cannizzaro Reaction

2 \text{ RCH}_2\text{CHO} \xrightarrow{\text{dil. NaOH}} \text{RCH}_2\text{CH(OH)CH(R)CHO} \xrightarrow{\Delta} \alpha,\beta\text{-unsaturated aldehyde}

Cross-aldol occurs between two different carbonyl compounds with α-hydrogen.

Cannizzaro reaction: 2 HCHO + conc. NaOH -> CH₃OH + HCOONa (disproportionation).

Haloform (Iodoform) Test

\text{R-COCH}_3 \xrightarrow{I_2 + NaOH} \text{R-COONa} + \text{CHI}_3 \downarrow \; (\text{Yellow ppt})

Positive test given by compounds containing CH₃-CO- group or CH₃-CH(OH)- group.

Ethanol gives positive iodoform test, but methanol does not.

Tollens' & Fehling's Distinction Tests

\text{R-CHO} + 2[\text{Ag(NH}_3)_2]^+ + 3\text{OH}^- \longrightarrow \text{R-COO}^- + 2\text{Ag} \downarrow + 4\text{NH}_3 + 2\text{H}_2\text{O}

Aldehydes reduce Tollens' reagent to give silver mirror; ketones do not.

Fehling's solution oxidizes aliphatic aldehydes to give red cuprous oxide Cu₂O precipitate.

Hell-Volhard-Zelinsky (HVZ) Reaction

\text{R-CH}_2\text{-COOH} \xrightarrow{\text{1. } X_2 / \text{Red P}, \; \text{2. } H_2O} \text{R-CH(X)-COOH} \quad (X = Cl, Br)

Halogenation specifically at the α-position of carboxylic acids containing α-hydrogen.

Formic acid (HCOOH) and benzoic acid cannot undergo HVZ reaction (no α-hydrogen).

Clemmensen & Wolff-Kishner Reductions to Hydrocarbons

\text{Clemmensen: } \text{C=O} \xrightarrow{\text{Zn-Hg / conc. HCl}} \text{CH}_2, \quad \text{Wolff-Kishner: } \text{C=O} \xrightarrow{\text{NH}_2\text{NH}_2 / \text{KOH, glycol, } \Delta} \text{CH}_2 + \text{N}_2\uparrow

Total reduction of carbonyl group to methylene (>C=O → >CH₂). Clemmensen for base-sensitive substrates; Wolff-Kishner for acid-sensitive substrates.

Clemmensen cannot be used if molecule contains -OH (undergoes substitution to -Cl) or C=C double bonds.

Rosenmund & DIBAL-H Selective Reductions to Aldehydes

\text{Rosenmund: } \text{R-COCl} + \text{H}_2 \xrightarrow{\text{Pd-BaSO}_4 / \text{quinoline}} \text{R-CHO}, \quad \text{DIBAL-H: } \text{R-COOR}' \xrightarrow{-78^\circ\text{C}} \text{R-CHO}

Controlled partial reduction of acyl chlorides, esters, and nitriles avoiding over-reduction to primary alcohols.

DIBAL-H at -78°C selectively reduces esters and nitriles to aldehydes without affecting isolated C=C double bonds.

Decarboxylation of \beta-Keto Acids & Blanc's Rule for Di-acids

\text{R-CO-CH}_2\text{-COOH} \xrightarrow{\Delta} \text{R-CO-CH}_3 + \text{CO}_2\uparrow \quad (\text{6-membered cyclic TS})

β-dicarboxylic and β-keto acids lose carbon dioxide easily upon gentle heating. Di-acids with 4-5 carbon chains form cyclic anhydrides; 6-7 carbon chains form cyclic ketones.

Oxalic and Malonic acids eliminate CO₂; Succinic and Glutaric acids eliminate H₂O to form cyclic anhydrides.

Perkin & Benzoin Condensation

\text{Perkin: } \text{ArCHO} + (\text{RCH}_2\text{CO})_2\text{O} \xrightarrow{\text{RCH}_2\text{COO}^- / \Delta} \text{ArCH=CRCOOH} \quad (\alpha,\beta\text{-unsaturated acid})

Perkin condensation: aromatic aldehyde + acid anhydride → α,β-unsaturated carboxylic acid (base = sodium salt of the acid). Benzoin condensation: 2 PhCHO → PhCH(OH)COPh (α-hydroxy ketone) catalysed by KCN (CN⁻ acts as nucleophile).

Perkin product undergoes decarboxylation to give cinnamic acid analogs. Benzoin condensation is reversed by NaOH (benzoin oxidation → benzil) and reduced by Raney Ni to give diol.

Nucleophilic Addition Reactivity Order of Carbonyls

\text{Reactivity: } \text{HCHO} > \text{CH}_3\text{CHO} > \text{PhCHO} > \text{CH}_3\text{COCH}_3 > \text{PhCOCH}_3 > \text{PhCOPh}

Carbonyl electrophilicity is governed by steric bulk (alkyl/aryl groups hinder nucleophile approach) and electronic effects (electron-donating groups reduce carbonyl δ⁺ character).

Aldehyde > Ketone always. Benzaldehyde is less reactive than acetaldehyde due to resonance delocalization of carbonyl π-electrons into benzene ring. Ketones can undergo nucleophilic addition only under acidic or basic catalysis.

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Amines & Diazonium Salts

Basicity of amines in gas/aqueous phase, Hoffmann bromamide degradation, Gabriel phthalimide synthesis, and Sandmeyer reaction.

Hoffmann Bromamide Degradation

\text{R-CONH}_2 + \text{Br}_2 + 4\text{NaOH} \longrightarrow \text{R-NH}_2 + \text{Na}_2\text{CO}_3 + 2\text{NaBr} + 2\text{H}_2\text{O}

Step-down conversion of primary amide to primary amine with ONE LESS carbon atom.

Intermediate is isocyanate (R-N=C=O).

Basicity Order of Amines in Water

(\text{CH}_3)_2\text{NH} > \text{CH}_3\text{NH}_2 > (\text{CH}_3)_3\text{N} > \text{NH}_3 \quad (2^\circ > 1^\circ > 3^\circ > \text{NH}_3)

Combined result of inductive (+I), steric hindrance, and hydration stabilization.

In gaseous phase with no hydration: 3° > 2° > 1° > NH₃.

Diazotization & Sandmeyer Reaction

\text{Ar-NH}_2 \xrightarrow{\text{NaNO}_2 + \text{HCl, } 0-5^\circ\text{C}} \text{Ar-N}_2^+ \text{Cl}^- \xrightarrow{\text{Cu}_2\text{X}_2} \text{Ar-X} + \text{N}_2 \uparrow

Conversion of primary aromatic amine into benzene diazonium chloride and aryl halides.

Temperature must be strictly between 0°C and 5°C to prevent decomposition of diazonium salt.

Carbylamine (Isocyanide) Test

\text{R-NH}_2 + \text{CHCl}_3 + 3\text{KOH} \xrightarrow{\Delta} \text{R-NC} \; (\text{Foul smell}) + 3\text{KCl} + 3\text{H}_2\text{O}

Specific test given ONLY by primary (1°) aliphatic and aromatic amines.

Secondary and tertiary amines do NOT give carbylamine test.

Gabriel Phthalimide Synthesis

\text{Phthalimide} \xrightarrow{\text{KOH}} \text{K-Phthalimide} \xrightarrow{\text{R-X}} N\text{-alkyl phthalimide} \xrightarrow{\text{NaOH (aq)}} \text{R-NH}_2 \; (1^\circ \text{ Aliphatic Amine})

Clean synthetic preparation of pure 1° aliphatic amines free from 2° and 3° amine impurities.

Aromatic 1° amines (like Aniline) CANNOT be prepared by this method because aryl halides do not undergo SN2 displacement.

Hinsberg Test for Amine Classification

1^\circ: \text{Soluble in KOH}; \quad 2^\circ: \text{Insoluble in KOH}; \quad 3^\circ: \text{Does not react with } \text{PhSO}_2\text{Cl}

Benzene sulfonyl chloride (Hinsberg reagent) distinction between 1°, 2°, and 3° amines based on active hydrogen.

The sulfonamide from 1° amine contains an acidic N-H proton which dissolves in alkaline KOH.

Azo Dye Coupling Reactions

\text{Ph-N}_2^+ \text{Cl}^- + \text{Ph-OH} \xrightarrow{pH \; 9-10} p\text{-Hydroxyazobenzene (Orange Dye)}, \quad \text{Ph-N}_2^+ \text{Cl}^- + \text{Ph-NH}_2 \xrightarrow{pH \; 4-5} p\text{-Aminoazobenzene (Yellow Dye)}

Electrophilic aromatic substitution of diazonium ion on highly activated aromatic rings.

Coupling with phenol requires mildly basic pH (9-10) to form phenoxide; coupling with aniline requires mildly acidic pH (4-5).

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Biomolecules & Polymers

Carbohydrates (glucose, fructose, mutarotation), amino acids, peptide bonds, isoelectric point, and nucleic acids (DNA/RNA).