BRAINCAKEAlcohols
Revision notes for Alcohols in AQA Chemistry (7404). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- AlcoholsAlcohols are a homologous series of organic compounds containing the hydroxyl functional group, -OH, bonded to a saturated carbon atom.
- Naming AlcoholsAlcohols are named using IUPAC rules, with the suffix -ol replacing the final -e of the parent alkane.
- Primary, Secondary and Tertiary AlcoholsAlcohols are classified by the number of carbon atoms bonded to the carbon atom that carries the -OH group.
- Ethanol by FermentationFermentation is the conversion of sugars such as glucose into ethanol and carbon dioxide by enzymes in yeast: C6H12O6(aq) → 2CH3CH2OH(aq) + 2CO2(g)…
- Ethanol by Hydration of EtheneIndustrially, ethanol is made on a large scale by the hydration of ethene with steam: CH2=CH2(g) + H2O(g) ⇌ CH3CH2OH(g) Conditions: a concentrated…
- Biofuels and Carbon NeutralityA biofuel is a fuel produced from biomass (recently living material).
- Oxidation of AlcoholsAlcohols can be oxidised by acidified potassium dichromate(VI): potassium dichromate(VI), K2Cr2O7, with dilute sulfuric acid.
- Oxidation of Primary Alcohols to Aldehydes and Carboxylic AcidsA primary alcohol is oxidised by acidified potassium dichromate(VI) in two stages: first to an aldehyde, then to a carboxylic acid.
- Oxidation of Secondary AlcoholsSecondary alcohols are oxidised by acidified potassium dichromate(VI) to ketones.
- Distinguishing Aldehydes and KetonesAldehydes can be oxidised further to carboxylic acids, but ketones cannot.
- Dehydration of AlcoholsDehydration is an elimination reaction in which a molecule of water is removed from an alcohol to form an alkene: CH3CH2OH → CH2=CH2 + H2O…
- Mechanism of DehydrationThe acid-catalysed dehydration of an alcohol is an elimination reaction.
- Reflux and DistillationTwo heating methods are used when preparing organic liquids, for example in the oxidation of alcohols.