14.2 Reactions of alcohols

equation of complete combustion of ethanol

C₂H₅OH(l) + 3O₂(g) = 2CO₂(g) + 3H₂O(l)

trend of amount of heat released per mole of carbon atoms in alcohol chains

as the number of carbon atoms in the alcohol carbon chain increases, the quantity of heat released per mole also increase

what is the colour change for a solution containing dichromate (VI) ions

orange to green

equation of dichromate (VI) ions being reduced

Cr₂O₇^2- → Cr³⁺

name the chemicals within the oxidising solution of primary and secondary alcohols

acidified potassium dichromate (VI), K₂Cr₂O₇

dilute sulfuric acid, H₂SO₄

how to ensure the aldehyde is prepared rather than the carboxylic acid

distil the aldehyde out of the reaction mixture as it forms to prevent further reaction with the oxidising agent

the displayed formula equation for the oxidation of butan-1-ol

how to prepare a carboxylic acid rather than an aldehyde

heat strongly under reflux with an excess of acidified potassium dichromate (VI)

displayed equation of the oxidation of butanol

state the product of oxidising secondary alcohols

ketones

how are secondary alcohols oxidised

the secondary alcohol is heated under reflux with the oxidising mixture. orange to green

displayed equation of the oxidation of propan-2-ol

how are tertiary alcohols oxidised

no reaction

define dehydration

a reaction in which a water molecule is removed from the starting material

dehydration of alcohols

heat under reflux

conc H₂SO₄ or conc H₃PO₄

form an alkene

elimination reaction

substitution reaction of alcohols

alcohols react with hydrogen halides to form haloalkanes.

the alcohol is heated under reflux with sulfuric acid and a sodium halide to form hydrogen bromide in place

the HBr formed reacts with the alcohol to produce the haloalkane

in situ

in place

chemical equation for the reaction of sulfuric acid and a sodium halide as an alcohol is heated under reflux

NaBr(s) + H₂SO₄(aq) → NaHSO₄(aq) + HBr(aq)

displayed formula equation for the substitution reaction of propan-2-ol

chemical equation for the reaction of propan-2-ol with sulfuric acid and NaBr

CH₃CHOHCH₃ + NaBr + H₂SO₄ = CH₃CHBrCH₃ + NaHSO₄ + H₂O