Elementary plant Biochemistry and Biotechnology (2+1)

Reaction with acids

• Heating a solution of hexoses in a strong non-oxidising acidic conditions, hydroxyl methyl furfural is formed. The hydroxymethyl furfural from hexose is usually oxidized further to other products When phenolic compounds such as resorcinol, α-naphthol or anthrone are added, mixture of coloured compounds are formed. The molisch test used for detecting carbohydrate in solution is based on this principle. When conc. H2SO4 is added slowly to a carbohydrate solution containingα -naphthol, a pink color is produced at the junction.The heat generated during the reaction hydrolyse and dehydrate it to produce furfural or hydroxymethyl furfural which then react with α -naphthol to produce the pink color.