Effects of Caffeine, Uses and Chemical Tests

Molecular Formula of Caffeine:

The molecular formula of caffeine is C8H10O2N4.

Physical and Chemical Properties of Caffeine:

Caffeine occurs as a white powder with bitter taste, it does not have any odour.

English: Chemical structure of Caffeine. Français : Structure chimique de la caféine. (Photo credit: Wikipedia)

It is a weak base and is feebly soluble in water, chloroform, alcohol and solvent ether. Its solubility in water can be increased in the presence of benzoates, bromides, citric acid and salicylates.

Chemical Tests for identification of caffeine:

1. Murexide colour reaction : Caffeine and other purine alkaloids gives the murexide colour reaction. Caffeine is taken in a petridish, to it hydrochloric acid and potassium chlorate are added. This mixture is heated to dryness. When the residue is exposed to vapours of dilute ammonia, a purple colour is obtained. If a fixed alkali is added, the purple colour is lost.

2. White precipitate is obtained when caffeine is mixed with tannic acid solution.

Uses of Caffeine:

• Central Nervous System stimulant
• It has cerebral vasoconstrictor effect
• It is used as a specific analgesic in migraine when given along with the ergotamine tartarate.