MECAHNISMS - Conditions & Reagents

alkene → halogenoalkane

electrophilic addition

conditions = room temp.

reagents = HBr/HCl

halogenoalkane →alkene

elimination (dehydration)

conditions = heat under reflux, dissolved in ethanol

reagents = conc. KOH (aq) or NaOH

alkene → dihalogenoalkane

electrophilic addition

conditions = room temp.

reagents = Br₂ or Cl₂

alkane → halogenoalkane

free radical substitution

conditions = under UV light

reagents = Br₂ or Cl₂

dihalogenoalkane → diol

nucleophilic substitution

conditions = heat under reflux, dissolved in ethanol

reagents = KOH (aq) or NaOH

why are halogenoalkanes normally dissolved in ethanol solution?

they’re insoluble so this makes them soluble

alkene → alcohol

electrophilic addition

conditions = 60atm, 600K

reagents = conc. H₃PO₄ or conc. H₂SO₄

reaction name for alkene to alcohol

hydrolysis

alcohol → alkene

elimination (dehydration)

conditions = 170°C

reagents = conc. H₃PO₄ or conc. H₂SO₄

what is another method of producing alkene from alcohol?

pass alcohol vapour over heated Al₃O₂ catalyst at 600°C

alcohol → aldehyde

oxidation

conditions = distillation

reagents = acidified potassium dichromate

when making aldehyde from alcohol, what type of alcohol is it?

primary alcohol

colour change that occurs during oxidation

orange to green

how is potassium dichromate acidified?

using HCl/sulfuric acid

aldehyde → carboxylic acid

oxidation

conditions = heat under reflux

reagents = acidified potassium dichromate

when making carboxylic acid from alcohol, what type of alcohol is it?

primary alcohol

aldehyde → alcohol

nucleophilic addition

conditions = reflux

reagents = NaBH₄ in aq solution and dilute H₂SO₄

reaction name for aldehyde to alcohol

reduction

alcohol → ketone

oxidation

conditions = heat gently under reflux

reagents = acidified potassium dichromate

when making ketone from alcohol, what type of alcohol is it?

secondary alcohol

ketone → alcohol

nucleophilic addition

conditions = reflux

reagents = NaBH₄ in aq solution and dilute H₂SO₄

aldehyde/ketone → hydroxynitrile

nucleophilic addition

conditions = room temp. and room pressure

reagents = KCN and dilute H₂SO₄

alcohol → ester

mechanism = nucleophilic add. elim but esterification is the reaction occurring.

conditions = heat

reagents = carboxylic acid + H₂SO₄

halogenoalkane → alcohol

nucleophilic substitution

conditions = reflux gently, halogenoalkane dissolved in ethanol

reagents = aq NaOH

halogenoalkane → nitrile

nucleophilic substitution

conditions = reflux gently, dissolved in ethanol

reagents = aq KCN

halogenoalkane → 1° amine

nucleophilic substitution

conditions = sealed under pressure, dissolved in ethanol

reagents = conc. NH₃ in excess

nitrile → 1° amine

reduction

conditions = in dry ether

reagents = LiAlH₄

another way to reduce nitrile to 1° amine

conditions = H₂ with nickel catalyst

1° amine → 2° amine/3° amine/quaternary salts

nucleophilic substitution

conditions = sealed in container and heated

reagents = with halogenoalkane in excess

what can you add when produce 2/3° amine from 1° amine to make NH₄X?

NH₃

carboxylic acid → esters

esterification

conditions = heat

reagents = alcohol and H₂SO₄

acyl chloride/acid anhydride → esters

nucleophilic addition elimination

conditions = room temp.

reagents = alcohol

acyl chloride/acid anhydride → carboxylic acid

nucleophilic addition elimination

conditions = room temp.

reagents = water

acyl chloride/acid anhydride → 1° amide

nucleophilic addition elimination

conditions = room temp.

reagents = NH₃

acyl chloride/acid anhydride → 2° amide

nucleophilic addition elimination

conditions = room temp.

reagents = 1° amine

what do you add in excess to produce 1° amine and why?

excess NH₃ because amine will less likely react with halogenoalkane.

what do you need in excess to produce quaternary ammonium salt and why?

excess halogenoalkane because it ensures each ammonia reacts with 4 halogenoalkane molecules.

quaternary ammonium salt uses?

cationic surfactants/detergents