Transcript No Slide Title

Methyl Benzoate
O
C OCH3
Esterification
O
H2SO4
C OH + CH 3OH
Methanol
Benzoic acid
O
C OCH3 + H2O
Methyl benzoate
H+
H
OH
OH
OH
OH
O
C6H5-C
C6H5-C
C6H5-C-O
CH3
OH
O
CH3
OH
OH
C6H5-C-OCH3
C6H5-C-OCH3
OH
O
H
H
O
OH
C6H5-C
OCH3
H
C6H5-C
H+
OCH3
Resonance Stabilized Ion
OH
OH
C
C
OH
OH
OH
C
OH
Intermediate
OH
C6H5-C-OCH3
OH
O
C6H5 COH
O
C6H5COCH3
Reflux
Reflux the mixture
for 60 minutes.
Methanol
Benzoic Acid
Sulfuric Acid
Boiling chips
Equilibrium
O
H2SO4
C OH + CH 3OH
O
C OCH 3 + H 2O
[C6H5COOCH 3][H 2O]
K=
[C6H5COOH][CH 3OH]
Measure Equilibrium Constant
O
C OH + CH 3OH
Recover benzoic
acid at equilibrium
H2SO4
O
C OCH 3 + H 2O
Isolate and purifiy
methyl benzoate
C6H5COOH CH 3OH H 2SO4
Reflux, Cool,
Extract with
CH2Cl2, H2O
CH2Cl2
C6H5COOCH 3
C6H5COOH
H2O
H 2SO4
C6H5COOCH 3
C6H5COOH
Extract with
NaHCO3
CH2Cl2
C6H5COOCH 3
H2O
+
C6H5COO Na
C6H5COOCH 3
Dry
Filter
Distill
Weigh
Methyl benzoate product
Simple Distillation
+
C6H5COO Na
HCl
C6H5COOH
Filter
Wash
Dry
Weigh
mp
Benzoic Acid Product
Calculate K
O
H2SO4
C OH + CH 3OH
O
C OCH 3 + H 2O
[C6H5COOCH 3][H 2O]
K=
[C6H5COOH][CH 3OH]
Initial benzoic acid = Ao
Initial Methanol = Mo
Recovered benzoic acid = A
O
O
H2SO4
C OH + CH 3OH
Initial:
Equ:
Ao
Ao - x
Mo
Mo - x
X = Ao
K=
C OCH 3 + H 2O
x
- A(recovered)
[x][x]
[Ao - x][Mo - x]
x
Example
O
O
H2SO4
C OH + CH 3OH
Ao = 0.100 moles
C OCH 3 + H 2O
Mo = 0.500 moles
A(Recovered) = 0.010 moles
x = 0.100 - 0.010 = 0.090 moles
[0.090][0.090]
K=
[0.100 - 0.090][0.500 - 0.090]
= 1.7