Synthesis of Coumarins

Procedure for the synthesis of coumarin prepared by Sowmya B U

1. Synthesis of
7-Hydroxy-4-Methyl Coumarin
Prepared By
SOWMYA B U
ⅡM.Sc. ⅣSemester
Department of Studies and Research in Organic Chemistry
Tumkur University, Tumakuru

2. To synthesize 7-Hydroxy-4-Methyl Coumarinby the reaction of
Resorcinol and Ethyl acetoacetatein presence of conc. H
2SO
4.
CoumarinsaremadeoffusedBenzeneandPyronering.Theseare
presentinsignificantamountinplantsandmorethan1300
Coumarinshavebeenisolatedfromnaturalsources.
Coumarinspossessremarkableandbroadmedicinalapplicationslike
antimicrobial,antitumourandanticoagulantsetc.Coumarincanbe
synthesizedbyseveralroutesincludingPechmann,Perkin,
KnoevenagelandReformatskyreactions.ThePechmann
condensationreactionofaphenolwithaβ-ketoesterinpresenceofan
acidcondensingagentisavaluablesyntheticmethod.
Principle
Aim

3. Resorcinol
Ethyl acetoacetate
Conc. H
2SO
4
NaOH
Conical flask
Beaker
Dropper
Glass rod
Thermometer
Filter paper
Filter funnel
Watch glass
Chemicals required; Apparatus required;

4. Procedure
Cool 7 ml of conc. H
2SO
4in 50 ml conical flask in an ice bath until
the temperature reaches below 5°C.
When temperature falls below 5°C add solution of 1 g of resorcinol
in 1.75 g (≈ 2 ml) of ethyl acetoacetatedropwisewith constant
stirring.
Maintain the temperature below 10°C during the addition (30
minutes).
Keep the reaction mixture at lab temperature for 24 hr and then
pour the reaction mixture on to the crushed ice.

5. Collect the precipitate and wash it with cold water
Dissolve the precipitate in 1N NaOHfilter and add 1N H
2SO
4with
vigorous stirring till the solution is acidic to litmus.
Filter the crude 7-hydroxy-4-methyl coumarin, wash with cold
water and dry.
Report the yield of crude product.
Recrystallisation: Recrystallisethe product from ethanol.

6. Reaction
Calculation
Amount Molecular
Weight
Moles Equivalents
Resorcinol1 g 110.1 g 0.009 1
Ethylaceto-
acetate
1.756 g
(or) 1.72 ml
130.14 g
(d =1.02
g/cm
3
)
0.0135 1.5

7. Percentage yield
Theoretical yield:
110 g of Resorcinol forms 176 g of 7-Hydroxy-4-Methyl Coumarin
1 g of Resorcinol forms ‘x’ g of 7-Hydroxy-4-Methyl Coumarin
x = 1×176/110
x = 1.6 g
Practical yield= …………g
Percentage yield = (Practical yield/Theoretical yield)×100
= ……………%

8. Mechanism

9. Importance of Coumarins
Coumarins
Anticancer
Antineurodegenerative
Antibacterial
Antifungal
Antiviral
Fluorescent
sensors
Anti inflammatory
Anti diabetic
Anticoagulant
Antioxidant

10. Structure and Name of
the compound
Theoretical
yield
Practical
yield
Percentage
yield
Theoretical
melting
point
Report
Thank You