The aniline acetate test is a

chemical test In chemistry, a chemical test is a qualitative property, qualitative or Quantitative property, quantitative procedure designed to identify, quantify, or characterise a chemical compound or substituent, chemical group. Purposes Chemical testing m ...

for the presence of certain

carbohydrate A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...

s, in which they are converted to

furfural Furfural is an organic compound with the formula C4H3OCHO. It is a colorless liquid, although commercial samples are often brown. It has an aldehyde group attached to the 2-position of furan. It is a product of the dehydration of sugars, as occu ...

with

hydrochloric acid Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...

, which reacts with

aniline Aniline (From , meaning ' indigo shrub', and ''-ine'' indicating a derived substance) is an organic compound with the formula . Consisting of a phenyl group () attached to an amino group (), aniline is the simplest aromatic amine. It is an in ...

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

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 Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...

dehydrates

pentose In chemistry, a pentose is a monosaccharide (simple sugar) with five carbon atoms. The chemical formula of many pentoses is , and their molecular weight is 150.13 g/mol.carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

atoms) to produce

. 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

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

s, but unlike 2-furanaldehyde it gives no color test with aniline acetate.

References

;Notes ;Bibliography * ''A Method for the identification of pure organic compounds by a systematic analytical procedure based on physical properties and chemical reactions.'' v. 1, 1911. By Samuel Parsons Mulliken. Published by J. Wiley & Sons, Inc., 1904
Google Books link
page 33. * "Modifications of the aniline acetate-furfural method for the determination of pentose."

The Analyst ''The Analyst'' (subtitled ''A Discourse Addressed to an Infidel Mathematician: Wherein It Is Examined Whether the Object, Principles, and Inferences of the Modern Analysis Are More Distinctly Conceived, or More Evidently Deduced, Than Religious ...

, 1956, 81, 598 - 601, {{doi, 10.1039/AN9568100598}

Biochemistry detection reactions Carbohydrate methods