SALICYLATE
AIM:
To prepare the salicylic acid from methyl salicylate by hydrolysis process.
PRINCIPLE:
The methyl salicylate is made to undergo hydrolysis by an alkale like
NaOH to give salicylic acid . The ester form of methyl salicylate is hydrolysed
to give salicylic acid and methanol. This process is termed as hydrolysis.
CHEMICALS REQUIRED :
Methyl salicylate = 4.0 ml
10% NaOH = 30.0 ml
Conc. HCl = Q.S
PROCEDURE:
Measure out exactly 4.0 ml of methyl salicylate in a clean conical flask and
add 30.0 ml of 10% NaOH solution into it.Mix well and boil the mixture on a
water bath for about 20 – 40 minutes until the pleasant odour of methyl
salicylate is suppressed. Cool the contents and acidify with sufficient quantity
of Con.HCl to precipitate out salicylic acid
Filter the precipitate,dry,weigh and calculate the percentage yield produced
, CALCULATIONS:
MOLECULAR WEIGHT OF METHYL SALICYLATE
C = 8 x 12 = 96
O = 3 x 16 = 48
H=8 x1= 8
= 152
MOLECULAR WEIGHT OF SALICYLIC ACID
C = 7 x 12 = 84
O = 3 x 12 = 48
H=6x1 = 6
=138
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
=--------%