Aniline acetate test


The aniline acetate test is a chemical test for the presence of certain carbohydrates, in which they are converted to furfural with hydrochloric acid, which reacts with aniline acetate to produce a bright pink color. Pentoses give a strong reaction, and hexoses give a much weaker reaction.

Procedure and mechanism

A dry sample is dissolved in a small volume of hydrochloric acid and briefly heated. A piece of paper, previously impregnated with aniline acetate, is exposed to the vapor from the sample solution. A bright pink color on the paper is positive for the presence of pentoses.
Hydrochloric acid dehydrates pentoses to produce furfural. The reaction of furfural and aniline produces a bright pink color. Hexoses, which are sugars which contain six carbons, are not dehydrated to furfural, and so they do not produce a pink color.

Interferences

3-Furanaldehyde responds to the usual tests for aldehydes, but unlike 2-furanaldehyde it gives no color test with aniline acetate.