PREPARTION OF ACETYL SALICYLIC ACID

PREPARTION OF ACETYL SALICYLIC ACID (ASPIRIN) FROM
SALICYLIC ACID
AIM:
Prepartion of acetyl salicylic acid from salicylic acid by acetylation process.
PRINCIPLE:
The salicylic acid is made to condense with acetic anhydride in presence of
sulphuric acid to give the acetyl salicylic acid in which the hydroxyl group of
salicylic acid is acetylated.This process is known as acetylation.
The commericial name for acetyl salicylic acid is aspirin which is an
antipyretic analysic.




CHEMICALS REQUIRED:
Salicylic acid = 3.0 g
Acetic anhydride = 5.0 ml
Conc.Sulphuric acid = 1.0 ml
PROCEDURE:
Weigh accurately 3.0 g of salicylic acid into a clean conical flask and add
5.0 ml of acetic anhydride. Mix well and add 1ml of Conc.Sulphuric acid drop
wise and heat the contents on a water bath for about 15 – 20 minutes.
Cool the contents and pour it into 100ml of fresh water taken in 250ml
beaker.The white precipitate of acetyl salicylic is formed.Filter the
precipitate,dry,weigh and calculate the percentage yield.

, CALCULATIONS:
MOLECULAR WEIGHT OF SALICYLIC ACID
C = 7 x 12 = 84
H=6x 1= 6
O = 3 x 16 =48
=136
MOLECULAR WEIGHT OF ASPIRIN
C = 9 x 12 = 117
H=8x 1= 8
O = 4 x 16 = 64
=180




THEORTICAL = MOL WT OF THE PRODUCT X WEIGHT OF

YIELD MOL WT OF THE REACTANT REACTANT TAKEN

=------g

PRACTICAL YIELD =------g

PERCENTAGE YIELD = PRACTICAL YIELD X 100

THEORITCAL YIELD

=--------%