Db3

Column Chromatography

Oxidation of Alcohols

Isolation of Eugenol

Racemic

All Chemical Tests

ALDEHYDE

There are three common tests for aldehydes. The first is the Tollens test, the second is the Schiffs test and the third is a test using Brady's Reagent (2,4-dinitrophenylhydrazine). The Brady's test test for the carbonyl group, so it can give a positive test for ketones as well.

Tollens Test

A 1 molar solution of silver nitrate is mixed with sodium hydroxide solution, in equal volumes. A brown precipitate is formed. Add ammonia, drop by drop, until the precipitate just dissolves. A few drops of the aldehyde are added to approximately 3cm3of the reagent in a test tube, and warm carefully in a water bath. A silver mirror is formed around the inside of the tube.

Schiffs Test

Place 2ml of Schiff's reagent in a test tube and add 2 drops of the aldehyde. Shake the tube gently, and observe the colour that is developed. Aldehydes react with Schiff's reagent to form a complex which has a wine-purple colour.

Brady's Reagent

Add a solution of 1 or 2 drops of Aldehyde in 2ml of 95% ethanol, to 3ml of Brady's Reagent. Shake vigorously and allow the solution to stand for about 20 minutes. An orange preciptate formed is a positive test