The aniline acetate test is a

chemical test In chemistry, a chemical test is a qualitative or quantitative procedure designed to identify, quantify, or characterise a chemical compound or chemical group. Purposes Chemical testing might have a variety of purposes, such as to: * Determine ...

for the presence of certain

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ...

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 occur ...

with

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dig ...

, which reacts with

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile start ...

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, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dig ...

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 with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...

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 () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...

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

Chemical tests