Properties and reactions of Carboxylic acids
Properties of Carboxylics acids Carboxylic acids contain a carbonyl group =O and a hydroxyl group –OH Low mass carboxylic acids are oily liquids. They have a strong smell and mix with water High mass carboxylic acids are waxy solids. They do not smell and do not mix with water Carboxylics acids boil at higher temperatures than alcohols or alkanes with the same number of carbons
Formation of Carboxylic acids Carboxylic acids are made by the oxidation of primary alcohols. Oxidation is the addition of an oxygen atom. To oxidise alcohols Oxidising agents such as acidified potassium dichromate (H + /K 2 Cr 2 O 7 ) or acidified potassium permanganate (H + /K 2 MnO 4 ) can be used. Some bacteria can oxidise alcohol
Vinegar is ethanoic acid (acetic acid) It is made by fermenting sugars to make ethanol then a bacteria oxidising the ethanol to ethanoic acid.
Reactions of Carboxylic acids Carboxylic acids are weak acids. Weak acids dissociate to form H + ions and anions poorly. They react with bases, carbonates and reactive metals slowly. The RCOO - ions are named using –anoate ion instead of -anoic acid Eg. Ethanoic acid dissociates to form CH 3 COO - and H + ions
Carboxylic acids react with alcohols to form esters and water