Edexcel Chemistry A Level: Reaction Conditions

Thermal cracking

High temperatures (up to 1000°C) and high pressure (70 atm)

Catalytic cracking

Zeolite or aluminium oxide catalyst, 600°C

Reforming

Heat with a platinum catalyst

Formation of alcohols from halogenoalkanes

Aqueous potassium hydroxide, heat under reflux

Formation of nitriles from halogenoalkanes

Ethanolic KCN, heat

Formation of primary amines from halogenoalkanes

Excess, ethanolic ammonia, at pressure in a sealed container

Formation of alkenes from halogenoalkanes

Ethanolic, hot potassium hydroxide, heat

Hydrolysis of halogenoalkanes

Add ethanol and acidified silver nitrate to a test tube

Hydrogenation of alkenes

Heat (150°C), nickel catalyst

Hydration of alkenes

Steam, phosphoric acid catalyst, heat

Oxidation of alkenes to diols

Potassium manganate (VII) in acid conditions (colour change from purple to colourless)

Chlorination of alcohol

Add phosphorus pentachloride (PCl₅)

Chlorination of tertiary alcohols

Shake alcohol with concentrated HCl at room temperature

Bromination of alcohol

Warm a mixture of 50% concentrated sulfuric acid and KBr with alcohol

Iodination

Heat a mixture of red phosphorus and iodine with the alcohol under reflux

Dehydration of alcohols to alkenes

Heat with concentrated phosphoric acid

Oxidation of primary alcohols to form aldehydes

Potassium dichromate (VI) in dilute sulfuric acid, use excess alcohol not oxidising agent (colour change from orange to green)

Oxidation of primary alcohols to form carboxylic acids

Potassium dichromate (VI) in dilute sulfuric acid, use excess oxidising agent not alcohol (colour change from orange to green), heat under reflux

Oxidation of secondary alcohols to form ketones

Potassium dichromate (VI) in dilute sulfuric acid, (colour change from orange to green)

Benedict’s/Fehling’s Test

Add Fehling’s solution, colour change from blue to brick-red ppt if an aldehyde is present, place test tube in beaker of hot water

Reduction of carbonyls/carboxylic acids to alcohols

LiAlH₄ dissolved in dry ether, room temperature

Tollens’ reagent

Colourless to silver mirror if aldehyde present (a carboxylic acid forms due to oxidation), place test tube in a beaker of hot water

Reaction of carbonyls with iodine

Alkaline (NaOH often used) solution of iodine. Mixture is warmed and cooled. Yellow precipitate of CHI₃ forms.

Carbonyls with hydrogen cyanide

HCN in an aqueous alkaline solution containing KCN

Carbonyls with 2,4-DNPH

A brighly coloured orange precipitate forms

Hydrolysis of nitriles

Acidic or alkaline, heat under reflux

Halogenation of carboxylic acid

Anhydrous conditions, PCl₅, no heating

Esterification (carboxylic acid + alcohol)

concentrated sulfuric acid, heat under reflux

Acyl chlorides + water

Cold water, no heating (vigorous reaction)

Esterification (Acyl chlorides + alcohol)

Room temperature, no catalyst, vigorous reaction

Preparation of amides from acyl chlorides

Concentrated ammonia

Preparation of N-substituted amides

Primary amines

Hydrolysis of esters

In acidic solution (sulfuric acid acts as a catalyst) or alkaline solution then add dilute acid

Reduction of nitriles to aliphatic amines

LiAlH₄ in dry ether OR nitrile vapour and H₂ passed over nickel catalyst

Preparation of aromatic amines

Tin, concentration sulfuric acid, heat under reflux

Hydrolysis of proteins

concentrated HCl, heat

Hydrogenation of benzene

Nickel catalyst, 300 degrees celsius, 30 atm

Halogenation of benzene

Halogen carrier, room temperature

Nitration of benzene

Conc. nitric and sulfuric acids, warm at 55 degrees celsius

Friedel-Crafts reactions

halogen carrier as catalyst, anhydrous conditions, heat under reflux

Bromination of phenol

Room temperature, bromine water