Classification Tests On Organic Compounds

I. Abstract

The experiment: Classification tests on Organic Compounds, allows the students to be familiarized with different classification tests used for identifying the different classes of organic compounds; examine unknown compounds using appropriate tests; and identify functional group of an organic compound based on the tests performed.

Several organic compounds with different functional groups were tested to identify the functional groups present in the compound. n-heptane, pentene, benzene, heptanol, sec-butanol, phenol, acetyl chloride, buteraldehyde, benzaldehyde, 2-butanone, propanoic acid, sucrose, diethyl ether, butyl bromide, acetonitrile, L-alanine, n-amyl acetate, benzene sulfonyl chloride and aniline were used as test compounds. Observations were noted, such as changes in color and product formation.

Iodine test, bromine test, Baeyer Test, Chloroform and aluminum chloride, fuming sulfuric acid, acetyl chloride, chromic acid, iodoform, Lucas’ test, Anilide formation, ester formation, hydrolysis, hydroxamic acid, Benedict’s test, Chromic test, 2,4-Dinitrophenylhydrazine, Fehling’s solution, Schiff’s reagent, Tollen’s test, bromine water, cerric ammonium nitrate, ferric chloride, esterification, sodium bicarbonate, silver nitrate, Barfoed’s test, Borax Test, Bial test, Osazones, Seliwanoff’s test, Molisch test, Beilstein test, hydroxamic test, sodium hydroxide hydrolysis, complex copper formation, ninhydrin test, nitrous acid, alkaline hydrolysis and, Zinc and ammonium chloride hydrolysis were used for the test for presence of functional groups.

II. Introduction

Preliminary tests previously learned are not enough to identify organic compounds. Functional groups present in organic compounds must be identified.

Acetyl chloride test can be used for alcohols, amines and phenols. A positive result for alcohol is the formation of a separate layer, and is usually accompanied by heat. For amines, solid amides were formed.

Alkaline hydrolysis is used for amides, a positive result is reflected by appearance of blue color on fiter paper; and esters, where ester’s odor vanishes during the reaction.

Anilide formation is used for acid anhydrides and acyl halides, a positive result is indicated by the formation of a solid precipitate.

Potassium Permanganate test is used for alkenes and alkynes, wherein a positive result is indicated by he formation of a brown precipitate or a reddish brown suspension.

Barfoed’s test is used for sugars and carbohydrates. A positive result is indicated by a red precipitate.

Benedict’s test is used for aldehydes, wherein a positive result is indicated by formation of yellow to orange precipitates; and carbohydrates, positive result indicated by formation of red, brown, or yellow precipitate.

Bial’s test is for sugars. A positive result is indicated by green, brown, and reddish brown-colored solution.

Borax test is for carbohydrates. A positive result is indicated bythe formation of a pink solution.

Bromine solution is for alkenes and alkynes, aldehydes, ketones, amines, and phenols. A positive result is indicated by decolorization of the solution formed, and evolution of a gas.

Bromine water is for phenols and aromatic amines. A positive result is indicated by a formation of a white precipitate.

Ceric ammonium nitrate is fro alcohols and phenols. A positive result is indicated by formation of black precipitates.

Chloroform and aluminum chloride is for aromatic hydrocarbons, of which a positive result is indicated by formation of green, blue, orange to red, or purple-colored solution.

Chromic anhydride is for alcohols and phenols, of which a positive result is indicated by blue green colored solution.

Copper complex formation is for amino acids. A positive result is indicated by blue-colored solution.

2-4 Dinitrophenylhydrazine is for aldehydes and ketones. A positive result is indicated by formation of a insoluble solid.

Ester Formation is for acid anhydrides, acyl halides and carboxylic acids. A positive result is indicated by a fruity smell.

Fehling’s solution is for aldehydes and carbohydrates. A positive result is indicated by brick red, yellow, or yellowish green precipitate.

Ferric Chloride Test is for phenols. A positive result is indicated by blue, green, purple, red-brown, or intense red complexes.

Ferrox test if for oxyen containing compounds.

Fuming Sulfuric acid is for the detection of aromatic rings. A positive result is indicated by complete dissolution of the compound with evolution of heat.

Hydrolysis is for acid anhydride and acyl halide. A positive result is indicated by evolution of heat.

Hydroxamic acid test was used for acid anhydride, acid halide, and esters. A positive result is indicated by formation of magenta or burgundy colored solution.

Iodine test is for ethers. A positive result is indicated by light brown colored solution.

Iodoform test gives a yellow precipitate for acetaldehydes, ketones, alcohols, and aldehydes.

Osazones forms osazone precipitate for carbohydrates. Schiff’s reagent produces a wine-purple colored solution for aldehydes.

Seliwanoff test produces a dark red colored solution for sugars.

Silver Nitrate produces a white precipitate for alkyl halides, formation of silver carboxylic salt for acyl halides or carboxylic acids, and formation of solid silver sulfonic salt for sulfonyl chloride.

A positive result for Sodium bicarbonate test is indicated by formation of bubbles.

Sodium hydroxide treatment produces oily layer for amines.

Tollen’s test produces a metallic silver on the surface of the liquid for aldehydes.

Zinc and ammonium chloride reduction has a positive result by s formstion of gray precipitate for aromatic nitro compounds.

To verify results from several tests, a proper