SYNTHESIS OF CINNAMIC ACID FROM BENZALDEHYDE

SYNTHESIS OF CINNAMIC ACID FROM BENZALDEHYDE

AIM:

To prepare cinnamic acid from benzaldehyde

PRINCIPLE:

Cinnamic acid is prepared by using perkin condensation reaction. Cinnamic acid is
prepared by the condensation of benzaldehyde and acetic anhydride in the presence of
sodium acetate as catalyst followed by hydrolysis.The perkin condensation is useful
organic reaction which provide a way to add two carbon atoms to the side chain to the
aromatic ring. Only Non- enolizable aldehyde and ketones can be used.




CHEMICALS REQUIRED:

Benzaldehyde = 5.0 ml

Acetic anhydride = 7.5ml

Sodium acetate = 2.5 g

10% NaOH = Q.S

Conc.HCl = Q.S

PROCEDURE:

Place 5.0 ml of benzaldehyde, 7.5ml of acetic anhydride and 2.5gm of sodium acetate in
round bottom flask.Fit with reflux condenser heat the contents for 1 hour at 70 – 80 c
temperature.After the complete of reaction cool the reaction mixture and add 40.0 ml of
water to it then make the solution alkaline by adding 10 % NaOH solution followed by
acedify the contents with conc.HCl until no more carbon dioxide is liberated.

The cinnamic acid will settle down.Filter the crude sample dry,weigh and calculate the
percentage yield is produced.

, CALCULATIONS:

MOLECULAR WEIGHT OF BENZALDEHYDE

C= 7 x 12 = 84

H= 6 x 1 = 6

O= 1 x 16 = 16

=106

MOLECULAR WEIGHT OF CINNAMIC ACID

C= 9 x 12 = 108

H= 8 x 1 = 6

O = 2 x 16 = 32

=148

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

=--------%