Question

What is Molisch's test?

Answer 1

Molisch's test

• Molisch’s test is a chemical test that is used to check for the presence of carbohydrates in a given sample.
• This test is named after Austrian botanist Hans Molisch.
• Molisch’s test involves the addition of Molisch’s reagent {a solution of α-naphthol in ethanol $({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH})$} to the sample and the subsequent addition of a few drops of concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$ (sulphuric acid ) to the mixture.
• Tetrose and triose sugars don’t give Molisch’s test.
• The principle of Molisch's test is the dehydration of sulphuric acid into furfural.

Positive Molisch's Test

• The formation of a purplish-red ring at the point of contact between sulphuric acid ${\mathrm{H}}_2{\mathrm{SO}}_4$ and the analyte + Molisch’s reagent mixture confirms the presence of carbohydrates in the sample.