Properties and reactions of alcohols

Properties of alcohols Low mass alcohols are liquids and miscible in water Alcohols are neutral to litmus and do not conduct. They dissolve in some polar compounds and some non-polar compounds because they have a polar and a non-polar region Alcohols are often used as solvents

Preparation of alcohols Ethanol is made by the fermentation of sugars by yeast Industrial ethanol is made by the fermentation of lactose Ethanol has been produced by the hydration of ethene

Methane from the Maui gas field is converted to methanol

Primary, Secondary, Tertiary Like Haloalkanes alcohols can be classified as Primary, Secondary or Tertiary This is determined by the number of Carbons that the carbon bonded to the –OH group is bonded to.

Reactions of Alcohols - Combustion Alcohols burn with a clean flame to produce CO2 and H2O Reactions are balanced as for alkanes and alkenes Methanol and Ethanol can be used as transport fuels

Reactions of Alcohols - Oxidation Primary alcohols can be oxidised to aldehydes, then further oxidised to carboxylic acids This is what turns wine sour. The oxidation of ethanol to ethanoic acid.

Reactions of Alcohols - Oxidation To oxidise alcohol in the lab we use acidified potassium dichromate (H+/K2Cr2O7) Potassium is orange and turns green after the reaction. We can also use acidified Potassium Permanganate (H+/MnO4-). The purple potassium permanganate turns colourless Aldehydes have low boiling points and evaporate. To obtain carboxylic acids the aldehydes must be collected in a condensor tube and be returned to the reaction

Reactions of Alcohols - Elimination Alcohol can be dehydrated producing an alkene and water. This is called an elimination reaction