4.3 ALCOHOLS AND PHENOLS

Halogenoalkane to alcohol

Reaction: Halogenoalkane + OH^- → Alcohol + Halide ion^-

Condition: Aqueous NaOH Heat under reflux

Nucleophilic substitution

OH- nucleophile (lone pair donor)

Aldehyde to Primary alcohol

Reagent: NaBH₄

Conditions: Aqueous ETHANOL Room temperature

Hydride attack +carbon → potonation

Ketone to secondary alcohol

Reagent: NaBH₄

Conditions: Aqueous ETHANOL Room temperature

Carboxylic acid to primary alcohol

Reagent LiALH₄

Conditions: Dry ether (no water ) Dilute acid

Alcohol → Halogenoalkane

Alcohol + HX → Halogenoalkane + H₂O

• HCl needs ZnCl₂ catalyst

• HBr made in situ KBr + conc H₂SO₄

Tertiary → immediate cloudy (form carbocation more easily)

Secondary → Slow cloudy

Primary → No change

Alcohol + ethanoyl chloride

Alcohol + COCL → Ester + HCl

• Steamy white fumes HCl gas

Fast, no catalyst

Alcohol + Carboxylic acid → Ester

Alcohol + Carboxylic acid ⇌ Ester + H₂O

Conc H₂SO₄ catalyst

Heat under reflux

Fruity smell

Phenol and NaOH

Phenol + NaOH → Sodium phenoxide + H₂O

Phenol and bromine water

Phenol + Br₂ → 2,4,6 tribromophenol

Orange brown bromine → Colourless

White precipitate

Room temp no catalyst

No catalyst faster than benzene

Phenols acidity

Weak acid phenol > alcohol

React with NaOH not Na₂CO₃

• Phenoxide ion stabilised by delocalisation

• Negative charge spread over benzene ring

Phenol + ethanoyl chloride

Phenol + COCL → Phenyl COCH3 + HCL

Steamy white fumes HCl

No catalyst

FeCl₃ test phenols

Purple violet colour