3.5 Alcohols

Alcohols have many scientific, medicinal and industrial uses. Ethanol is one such alcohol and it is produced using different methods, which are considered in this section. Ethanol can be used as a biofuel.

Nomenclature

Students should be able to apply IUPAC rules for nomenclature to alcohols, aldehydes, ketones and carboxylic acids limited to chains with up to 6 carbon atoms.

Alcohols are classified as primary, secondary and tertiary.

  • Ethanol production - Hydration of ethene Alcohols are produced industrially by hydration of alkenes in the presence of an acid catalyst. Ethanol is produced by the reaction of ethene and steam using a phosphoric acid catalyst. Fermentation Ethanol is also produced industrially by fermentation of glucose. The conditions for this process. Ethanol produced industrially by fermentation is separated by fractional distillation and can then be used as a
  • Oxidation of alcohols - Primary alcohols can be oxidised to aldehydes which can be further oxidised to carboxylic acids. Secondary alcohols can be oxidised to ketones. Tertiary alcohols are not easily oxidised. Acidified potassium dichromate(VI) is a suitable oxidising agent. Students should be able to: • write equations for these oxidation reactions (equations showing [O] as oxidant are acceptable) • explain how the method used to oxidise
  • Elimination mechanism of alcohols - Alkenes can be formed from alcohols by acid-catalysed elimination reactions (mechanism not required). Alkenes produced by this method can be used to produce addition polymers without using monomers derived from crude oil. Assessment and practical opportunities Students could carry out the preparation of cyclohexene from cyclohexanol, including purification using a separating funnel and by distillation. Required practical Distillation of a product from a reaction.
  • Ethanol - Structure Like alkenes and alkanes, ethanol is another type of organic (carbon-based) compound. Ethanol is a two-carbon length alcohol. All alcohol molecules possess at least one C-OH group, which is known as the functional group (gives the compound its properties). Ethanol has the structural molecular formula, CH3CH2OH However, this often abbreviated to C2H5OH Combustion of ethanol Ethanol combustion (burning) produces carbon