Reaction of Alcohols with Sodium
2R−OH+2Na→2R−ONa+H2↑ Demonstration of acidic nature of alcohols.
applies whenActive metals like Na, K, Al.
reactionaciditymetal
Action of Heated Copper on Tertiary Alcohols
R3COHCu573 KAlkene+H2O Tertiary alcohols undergo dehydration instead of dehydrogenation when passed over heated Cu.
applies whenVapors passed over heated Cu at 573 K.
reactiondehydrationcatalytic
Acidic Dehydration to Alkene
CH3CH2OHconc.H2SO4443 KCH2=CH2+H2O Intramolecular elimination of water from ethanol at high temperature.
applies whenHigh temperature (443 K), yields alkene.
reactiondehydrationelimination
Acidic Dehydration to Ether
2CH3CH2OHconc.H2SO4413 KC2H5OC2H5+H2O Intermolecular dehydration of primary alcohols at lower temperatures to form ethers.
applies whenLower temperature (413 K), SN2 mechanism. Only valid for unhindered 1° alcohols.
reactiondehydrationsubstitutionether
Esterification of Alcohols
ROH+R′COOHH+R′COOR+H2O Reaction of alcohols with carboxylic acids to form esters.
applies whenReversible; water must be continuously removed.
reactionesterification
ROH+HClZnCl2RCl+H2O Reaction of alcohols with HCl in presence of zinc chloride to form alkyl chlorides.
applies whenDistinguishes 1° (no room temp reaction), 2° (5 mins), and 3° (immediate turbidity).
reactionlucas-testidentification
Mild Oxidation of Primary Alcohols
RCH2OHPCC or CrO3RCHO Oxidation of primary alcohols to aldehydes using PCC or anhydrous CrO3.
applies whenPrevents over-oxidation to carboxylic acid.
reactionoxidationaldehyde
Oxidation of Secondary Alcohols
R2CHOHCrO3R2C=O Oxidation of secondary alcohols to ketones.
applies whenChromic anhydride used as oxidizing agent.
reactionoxidationketone
Pinacol-Pinacolone Rearrangement
R2C(OH)−C(OH)R2H+R3C−C(=O)R+H2O Acid-catalyzed dehydration and rearrangement of a vicinal diol to a ketone.
applies whenInvolves carbocation formation and 1,2-alkyl shift.
reactionrearrangementjee-advanced
Cleavage of Alkyl Aryl Ethers
C6H5−O−CH3+HI→C6H5OH+CH3I Alkyl-oxygen bond cleavage occurs exclusively due to strong sp2 C-O bond in phenol.
applies whenPhenol does not react further with HI.
reactionethercleavageanisole
C6H5−O−CH2−CH=CH2Δo-HO-C6H4-CH2−CH=CH2 Thermal rearrangement of an allyl phenyl ether to an o-allylphenol.
applies whenTakes place purely via heating (~200 C);-sigmatropic rearrangement.
reactionrearrangementetherjee-advanced
Ether Cleavage by Hydrogen Halides
R−O−R′+HX→R−X+R′−OH Cleavage of ethers to alkyl halide and alcohol.
applies whenReactivity order: HI > HBr > HCl. With excess HX, both R groups become alkyl halides.
reactionethercleavage
C6H5OCORAlCl3,Δo/p-HO-C6H4-COR Conversion of phenolic esters to corresponding hydroxyaryl ketones.
applies whenCatalyzed by Lewis acids like AlCl3.
reactionrearrangementphenoljee-advanced
Bromination of Phenol (Aqueous)
C6H5OH+3Br2H2O2,4,6-tribromophenol↓+3HBr Reaction with bromine water yielding tribromophenol.
applies whenForms a white precipitate.
reactionphenolhalogenation
C6H5ONa+CO2H+o-Hydroxybenzoic acid Electrophilic aromatic substitution of phenoxide with carbon dioxide to form salicylic acid.
applies whenPhenoxide is more reactive than phenol, allowing weak electrophile CO2 to attack.
reactionphenolkolbename-reaction
Nitration of Phenol (Concentrated)
C6H5OHconc. HNO3,conc.H2SO42,4,6-trinitrophenol (Picric Acid) Formation of picric acid using concentrated acids.
applies whenModern method involves intermediate sulfonation to improve poor yield.
reactionphenolnitrationpicric-acid
Nitration of Phenol (Dilute)
C6H5OH+dil. HNO3298 Ko-nitrophenol+p-nitrophenol Electrophilic substitution yielding a mixture of ortho and para nitrophenols.
applies whenLow temperature. o-isomer is steam volatile due to intramolecular H-bonding.
reactionphenolnitration
C6H5OHNa2Cr2O7,H2SO4Benzoquinone Oxidation to a conjugated diketone using chromic acid.
applies whenSlow oxidation in air also yields dark mixtures of quinones.
reactionphenoloxidation
C6H5OH(i)CHCl3, aq. NaOH(ii)H+o-Hydroxybenzaldehyde Reaction of phenol with chloroform and base yielding salicylaldehyde.
applies whenProceeds via a substituted benzal chloride intermediate.
reactionphenolreimer-tiemannname-reaction
C6H5OH+ZnΔC6H6+ZnO Cleavage of aromatic C-O bond by heating with zinc dust.
applies whenRequires heating.
reactionphenolreduction