Nitration of Methyl Benzoate

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NITRATION
OF
METHYL
BENZOATE
 
 Purpose:
The main objective of this experiment was to synthesize methyl nitrobenzoate from methyl benzoate, using the mixture of nitric and sulfuric acid by performing the process of electrophillic aromatic substitution. During this reaction, the combination of HNO3 and H2SO4 made a nitrating solution. The crystallization was done to accomplish pure product. The melting point and Thin Layer Chromatography (TLC) were performed to test the purity of the product. Using the methyl benzoate reaction product, methyl nitrobenzoate, one can determine the meta-substituted, para-substituted and orthosubstituted of the final products. Furthermore, HNMR and IR used to investigate the quality of the product. 
 
 
 Reaction
Scheme:
 
 O H3CO

H3CO

O

H2SO4/HNO3


 
 
 
 
 
 Mechanisms:

 The
electrophillic
addition
of
the
nitronium
ion
to
methyl
benzoate
made
the
 formation
of
the
nitronium
ion.
AS
shown
on
the
mechanism
is
shown
below,
the
 carbonmethoxy
group
directs
the
nitronium
ion
to
a
position
of
meta.
For
example,
 formation
of
carbonation
intermediate
yields
a
resonance
stabilized
structure
of
the
 proton.


 
 


NO2

H3CO

O

H3CO

O

H3CO

O

H3CO

O

O

N

O
NO2 H NO2 NO2 NO2

H

H3CO

O

H3CO

O

HSO4
NO2 NO2

H2SO4


 
 Procedure:

The
procedure
is
outlined
is
“the
laboratory
Manual
for
Organic
 Chemistry
2311”,
Eight
Edition
by
Jane
E.
Wissinger.
University
of
Minnesota
 Department
of
Chemistry,
PP.
74‐76.
During
the
mixture
sulfuric
acid/nitric
acid
and
 methyl
benzoate
the
stir
bar
used
to
make
a
through
mixture
of
the
solution.

 
 Reagent
and
Product:
 
 H

Substances/ MW Compounds g/mol

Quantity

Moles Used

Melting Point °C

Boiling Point °C

Density

Solubility
Water
 soluble

Hazards
Irritates
skin
 and
eyes Irritate
eyes,
 skin,
and
 respiratory
 tract CORROSIVE CORROSIVE

Methyl benzoate Meta-Methyl nitrobenzoate

136.15 181.13

0.5g 0.385
g


3.36x10-3 2.13x10-3

-12 76 – 80

199.6 279

1.094 N/A

Water soluble

Conc. Nitric acid Conc. sulfuric acid Ethanol, 95%

63.01 98.08

0.35 mL 7.89x10-3 0.35mL 6.66x10-3

-42 10

121 337

1.42g/mL 1.84 g/mL

Water soluble Water soluble
Miscible in water

46.07

2-3 mL

N/A

N/A

N/A

N/A

FLAMMABLE


 
 Calculation:
 Finding
Limiting
Reagent

 1. HNO3 (0.35 mL HNO3) (1.5027 g HNO3) (1 mol HNO3) (1 mol methyl nitrobenzoate) (181.3 g methyl nitrobenzoate)/(1 mL HNO3) (63.01 g HNO3) (1 mol HNO3) (1 mol methyl nitrobenzoate) = 2.159 g methyl

nitrobenzoate 2. H2SO4
(0.35
mL
H2SO4)
(1.841
g
H2SO4)
(1
mol
H2SO4)
(1
mol
methyl
nitrobenzoate)
(181.3
g
methyl
 nitrobenzoate)/(1
mL
H2SO4)
(98.08
g
H2SO4)
(1
mol
H2SO4)
(1
mol
methyl
nitrobenzoate)=
2.039
g
 methyl
nitrobenzoate
 3. Methyl
Benzoate
(0.554
g
methyl
benzoate)
(1
mol
methyl
benzoate)
(1
mol
methyl
nitrobenzoate)
(181.13
 g
methyl
nitrobenzoate)
(136.15
g
methyl
benzoate)/(1
mol
methyl
benzoate)
(1
mol
methyl
 nitrobenzoate)=
0.732
g
methyl
nitrobenzoate
 4. Theoretical
Yield
 (0.554
g
methyl
benzoate)
(1
mol
methyl
benzoate)
(1
mol
methyl
nitrobenzoate)
(181.13
g
methyl
 nitrobenzoate)/(136.15
g
methyl
benzoate)
(1
mol
methyl
benzoate)
(1
mol
methyl
nitrobenzoate)

 =
0.732
g
methyl
nitrobenzoate

 Percent
Yield
 For
recrystallized
product
(mass
of
recrystallized
methyl
nitrobenzoate)/(theoretical
yield)=
(0.385
g
 methyl
nitrobenzoate)/(theoretical
yield)
(0.732
g
methyl
nitrobenzoate)X
(100)=52.59%
yield

 
 
 
 Crystal
Yield:
 Theoretical
Yield

 Crude
mass
product

 Percent
yield
 Mass
of
recrystalization
 Final
percent
yield
 0.732g
 
 
 0.413g
 56.42%
 0.385g
 52.59%


TLC
Result:
 Description
of
plate
 Starting
Material
 Crude
Mass
Product
 Re‐crystallized
Product
 Melting
point:

 Expected
melting
point

 780C


Travel
of
solvent
 5.2cm
 5.2cm
 5.2cm


Travel
of
solute
 2.98cm
 2.2cm
 2.1cm


Rf
value
 0.573cm
 0.423cm
 0.404cm



 
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