Aspirin Preparation

Chemical Structure

·   Generic name :- aspirin

·   Chemical name :- Acetyl salicylic acid.

·    Pharmacological use:- analgesic ,antipyretic , anti-rheumatic

    and  anti-inflammatory .

 Synonyms: Acetylsalicylic acid ; Acetophen ; Acetosal ; Acetylin ; Acetyl–SAL

Method:

It is prepared from salicylic acid, acetic anhydride and glacial acetic acid.

Principle:

 Chemicals Required.

(i) Salicylic acid : 6 g

(ii) Acetic anhydride : 10 ml ;

(iii) Glacial acetic acid : 10 ml.

Procedure.

1.    Prepare an admixture of 10 ml each of acetic anhydride and glacial acetic acid in a 100ml clean and dry beaker.

2.    Now, add this mixture carefully to 6 g salicylic acid previously weighed and placed in a 100ml round bottom flask ; and fit the same with a reflux condenser.

3.    Boil the reaction mixture on an electric heating mantle for a duration of 35–45 minutes.

4.    Pour the hot resulting mixture directly into 100 ml cold water, contained in a 500ml beaker in one lot ; and stir the contents vigorously with a clean glass rod when the shining tiny crystals of aspirin separate out.

5.    Filter off the crude aspirin in a Büchner funnel fitted with an air-suction device and wash the residue with sufficient cold water, drain well and finally remove the excess of water by pressing it between the folds of filter paper and spread it in the air to allow it dry completely. However, it may also be dried expeditiously by drying it in an electric oven maintained at 100°C for about an hour.

6.    The yield of crude aspirin (mp133.5–135°C) is approximately 7.5 g.

 Recrystallizatoin. Recrystallize the crude product from a mixture of acetic acid and water (1 : 1).

The yield of pure colourless aspirin (mp 13.4°C) is 7.25 g.

Aspirin is obtained as monoclinic tablets or needlelike

crystals, mp 135°C

         

Results :-

Name of preparation	Test	Specification
Acetyl salicylic acid  (aspirin)	Description	Crystalline powder
	Colour	White
	Odour	Weak odour of acetic acid
	Weight	(9.4) gm =0.05mole + (0.05- 0.1)
	Melting point
	Solubility	1.    Easy dissolved in – alcohol, other organic solvent and alkaline solution. 2.    2. Difficult to dissolve in – water

               Report  

Name of preparation	Test	Specification
aspirin	Description
	Colour
	Odour
	Weight
	Melting point
	Solubility