Alcohols

Alcohol production: electrophilic addition of steam to alkene

Reagents: H₂O (g)

Condition: H₃PO₄ catalyst

Alcohol production: alkenes oxidised by cold dilute acidified KMnO₄ → diol

colour change: purple → colourless

Alcohol production: substitution of haloalkane

Reagents: NaOH (aq)

Conditions: heat

C₂H₅Br + NaOH (aq) → C₂H₅OH + NaBr

Alcohol production: reduction of aldehyde or ketone

Reagents: [H]: NaBH₄ or LiAlH₄

Conditions:

aldehyde → primary alcohols

ketone → secondary alcohols

Alcohol production: reducation of carboxylic acid

Reagents: [H]: LiAlH₄

Conditions:

Alcohol production: hydrolysis of an ester

Reagents: dilute acid / dilute alkali

Conditions: heat

Combustion of alcohol

→ products: CO₂ and H₂O

HX substitute in alcohol to form halogenoalkanes

Reagents: HX

Conditions: KX with H₂SO₄ or H₃PO₄ to make HX

PCl₃ substitute in alcohol to form halogenoalkanes

Reagents: PCl₃

Conditions: heat

3C₂H₅OH + PCl₃ → 3C₂H₅Cl + H₃PO₃

PCl₅ substitute in alcohol to form halogenoalkanes

Reagents: PCl₅

Conditions: room temp

C₂H₅OH + PCl₅ → C₂H₅Cl + POCl₃ + HCl

SOCl₂ substitute in alcohol to form halogenoalkanes

Reagents: SOCl₂

Conditions: no conditions

C₂H₅OH + SOCl₂ → C₂H₅Cl+ HCl + SO₂

alcohol reacts with Na (s)

ethanol + Na (s) → sodium ethanoate + H₂

→ redox reaction

Oxidation of alcohols

K₂Cr₂O₇: orange → green

KMnO₄: purple → colourless

=> cannot oxidise tertiary alcohol

Distillation of alcohol

primary alcohol → aldehyde

secondary alcohol → ketone

Reflux of alcohol

primary alcohol → aldehyde → carboxylic acid

dehydration of alcohol → alkene

Reagents: Alcohol

Conditions: Al₂O₃ catalyst and heat

ethanol → ethene + water

formation of esters from alcohol

Reagents: carboxylic acids

Conditions: catalyst (conc. H₂SO₄) or Al₂O₃ , heated

carboxylic acid + alcohol → ester + water

K₂Cr₂O₇ used to test for alcohols

primary and secondary alcohols: colour change from purple → green

tertiary alcohols: no colour change, green

Test of alkaline I₂ (aq)

the aciditiy of alcohols compared to water

• alcohols have alkyl group while water have no

• alkyl makes the O atom more e- dense

→ alcohol is more likely to accept the H⁺ proton

→ alcohol is less acidic than water, it behaves as a base