Development and optimization of producing 3,3′, 4,4′-benzophenonetetracarboxylic dianhydride

Article abstract of DOI:10.13005/ojc/320627

This paper includes a series of experiments conducted in order to develop a laboratory method for producing 3,3′, 4,4′-benzophenonetetracarboxylic dianhydride and selection of the optimum conditions, allowing to obtain the greatest yield. 3,3′, 4,4′-benzophenonetetracarboxylic dianhydride is used for the preparation of polyimides with high thermal stability, chemical resistance as well as high strength and high Young's modulus. Benzophenonetetracarboxylic dianhydride was prepared by multistep route: Friedel-Crafts alkylation of o-xylene to obtain 3,3′, 4,4′-tetramethyl benzophenone followed by liquid phase oxidation to benzophenonetetracarboxylic acid and dehydration.

Full text of DOI:10.13005/ojc/320627

ISSN: 0970-020 X
CODEN: OJCHEG
2016, Vol. 32, No. (6):
Pg. 3063-3070
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Free Access, Peer Reviewed Research Journal
www.orientjchem.org
Development and Optimization of Producing
3,3', 4,4'-benzophenonetetracarboxylic dianhydride
ANTON SERGEYEVICHYEGOROV*, ALYONA IGOREVNA WOZNIAK,
VITALY SERGEYEVICH IVANOV, ELENA ALEKSANDROVNA AVERINA and
OLGA ANATOLEVNA ZHDANOVICH
Federal State Unitary Enterprise «State Scientific Research Institute of
Chemical Reagents and High Purity Chemical Substances» (FSUE “IREA”)
107076, Bogorodsky val, 3. Moscow. Russia.
*Corresponding author E-mail: egorov@irea.org.ru
http://dx.doi.org/10.13005/ojc/320627
(Received: October 04, 2016; Accepted: November 02, 2016)
AbSTRACT
This paper includes a series of experiments conducted in order to develop a laboratory method
for producing 3,3', 4,4'-benzophenonetetracarboxylic dianhydride and selection of the optimum
conditions, allowing to obtain the greatest yield. 3,3', 4,4'-benzophenonetetracarboxylic dianhydride
is used for the preparation of polyimides with high thermal stability, chemical resistance as well as
high strength and highYoung’s modulus.Benzophenonetetracarboxylic dianhydride was prepared by
multistep route: Friedel-Crafts alkylation of o-xylene to obtain 3,3', 4,4'- tetramethyl benzophenone
followed by liquid phase oxidation to benzophenonetetracarboxylic acid and dehydration.
Keywords: 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, dianhydrides,
polyimides, alkylation, heat resistant polymers, monomer.
INTRODUCTION
shape stability, including deformation stability when
heated.
It is necessary to improve polymers due to
the extensive use of polymeric materials in terms of
maintaining their properties during heating, increase
of the heat, thermal and radiation stability of the
polymers and polymeric materials. Heat resistance
of polymers and polymeric materials determines their
Polyimides are the class of thermally stable
polymers, generally with rigid aromatic backbone
chains. The most common method for producing
aromatic polyimide is the reaction of dianhydrides
of aromatic tetracarboxylic acids with aromatic

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YEGOROV et al., Orient. J. Chem., Vol. 32(6), 3063-3070 (2016)
The first oxidation method consists
diamines.This reaction is carried out both by a two-
stage or a single-stage method1.The most common in treatment with nitric acid of tetrasubstituted
is the two-stage method. A soluble prepolymer is benzophenone4-6.The yields of 70-75% of theoretical
obtained at the first stage, of which films, fibers, value (for acid) are achieved by this method.
coatings and other products can be formed. This
reaction consists in the acylation of diamine with
The second method consists in a liquid-
tetracarboxylic dianhydride in a polar solvent to form phase catalytic oxidation of tetraalkyl benzophenone
a polyamic acid (PAA) according to the equation with air in the acetic acid using a metal halide
shown in Figure 1.
catalysts (Co-Br, Co-Mn-Br, Co-Mn-Mo-Br) in the
medium, providing the activation of the catalyst
The second stage of the reaction consists (protonic acids and halogen- substituted aliphatic
in dehydrocyclization of polyamic acid (PAA) acids)7,8. The yields of 79-96% of theoretical value
(imidization) (see Figure 2) to form the end-product (for acid) are achieved by second method.
- the aromatic polyimide (PI) - and carried out by
thermal or chemical methods2.
The most economically feasible and
available raw materials used to obtain 3,3'4,4'-
In this paper, 3,3‘,4,4’-benzophenonetetra- tetraalkyl benzophenone are in particular o-xylene,
carboxylic dianhydride (Figure 3) has been selected formaldehyde and acetaldehyde. H2SO4 or more
as a target, which further can be used to obtain the expensive metal-containing catalysts are usually
polyimide. The dianhydride is a powder of white or used as the catalysts (see Figure 5). All sources of
slightly grayish color, which is resistant to air moisture these raw materials are widely available.
at room temperature; melting point is 225-228°C3.
There are data of the use of low
The literature contains information temperature methods of synthesis of 3,3‘,4,4’-
about methods for preparation the appropriate benzophenonetetracarboxylic dianhydride9,10
.
dianhydride by anhydridization of corresponding However, the use of such compounds as sodium
tetra-carboxylic acid, obtained by oxidation of hypochlorite9, and the need for use of a complex
3,3 ‘,4,4’-tetraalkylbenzophenone (mostly 3,3',4,4'- synthesis scheme, a large amount of initial reagents
tetramethyl benzophenone), as shown in Figure 4.
and expensive palladium and nickel compounds
Fig. 1: The scheme of obtaining polyamide acid
Fig. 2: Scheme of obtaining polyimide from polyamide acid

YEGOROV et al., Orient. J. Chem., Vol. 32(6), 3063-3070 (2016)
3065
still limits the ability of the widespread use of these
synthesis methods.
presence of H2SO4, under relatively mild conditions
(T = 10 - 50°C, P = 0.6-0.8 MPa), according to the
scheme which is similar to that shown in Figure 4.
The condensation of o-xylene may be carried out
using formaldehyde. Selection of formaldehyde or
acetaldehyde is determined by availability, as well
as fire and explosion hazard of these reagents.
According to the patent6 the process of
oxidation of 3,3', 4,4'-tetramethylbenzophenone is
carried out with nitric acid in the temperature range
from 150 to 250°C, and the dehydration to obtain
benzophenonetetracarboxylic dianhydride at a
temperature of 280 - 320°C for 10 hours. Synthesis
of the starting aromatic hydrocarbon is carried out
by condensation of o-xylene with acetaldehyde in the
In laboratory conditions, 3,3', 4,4'-
tetramethylbenzophenone is prepared by aluminum
trichloride catalyzed Friedel-Crafts reaction. The
method with alkylation of o-xylene with carbon
tetrachloride followed by treatment with alkali has
been chosen to develop a laboratory technique (see
Figure 6)11.
The selected method for the preparation is
shown in Figure 7.
Experimental part
Preparationof3,3‘,4,4’-benzophenonetetra-
carboxylic acid is carried out in four stages. A series
Fig. 3:The structural formula of 3,3 ‘, 4,4’-
benzophenonetetracarboxylic dianhydride
Fig. 4: Preparation of 3,3 ‘, 4,4’-benzophenonetetracarboxylic dianhydride
by the oxidation of 3,3', 4,4'-tetramethyl benzophenone
Fig. 5: Scheme of obtaining 3,3 ‘, 4,4’-tetramethyl benzophenone

YEGOROV et al., Orient. J. Chem., Vol. 32(6), 3063-3070 (2016)
3066
of optimization experiments were conducted for each
of successive reactions.
also purchased from Vekton and calcined before
use. Toluene, o-xylene, pyridine, heptane, diphenyl
oxide were purchased from Component-Reaktiv.
MATERIALS
Analytical techniques
Carbon tetrachloride, aluminum chloride,
sodium hydroxide, potassium permanganate were
purchased from Vekton. Magnesium sulfate was
The resulting products and their purity
were identified by NMR spectroscopy, elemental
analysis and mass spectroscopy.NMR spectra were
Fig. 6: Preparation of 3,3 ‘, 4,4’-tetramethyl-benzophenone by
Friedel-Crafts alkylation followed by treatment with alkali [11]
Fig. 7:The selected method for the preparation of 3,3 ‘, 4,4’-benzophenonetetracarboxylic acid
Fig. 8: Preparation of 3,3', 4,4'-diphenyl dimethyl dichloromethane
Fig. 9: Preparation of 3,3 ‘, 4,4’-tetramethyl benzophenone

YEGOROV et al., Orient. J. Chem., Vol. 32(6), 3063-3070 (2016)
3067
recorded on Bruker Avance III HD with an operating
frequency of 300 MHz. DMSO-d6 was used as the
solvent and tetramethylsilane as internal standard.
Elemental analysis was recorded on CHNS-analyzer
(EuroVector, Euro EA 3000 model). Mass spectra
were obtained using chromatography-spectrometry
system “Chromatec Kristall 5000.2” with mass-
spectrometer detector ISQ Thermo Scientific.
Table 1:The effect of the temperature conditions and the ratio of raw
materials to yield of 3,3‘,4,4’-tetramethyl diphenyl dichloromethane
No
Temperature mode
of adding o-xylene
solution (initial and
final temperature), °C
Aluminum chloride
The molar ratio
of the reactantso-
xylene: aluminum
chloride
Yield, %
Weight, g
Quantity, mol
1
2
3
4
-5 – 0
19
12
8
0,135
0,09
0,06
0,045
0,135
0,09
1:1,5
1:1
1:0,67
1:0,5
1:1,5
1:1
1:0,67
1:0,5
1:1,5
1:1
1:0,67
1:0,5
1:1,5
1:1
60,0
62,0
85,0
57,0
54,0
75,0
90,0
64,0
47,0
49,0
51,0
42,0
30,0
37,0
45,0
34,0
6
0 – 5
19
12
8
0,06
6
0,045
0,135
0,09
5 – 10
10 – 15
19
12
8
0,06
6
0,045
0,135
0,09
0,06
0,045
19
12
8
1:0,67
1:0,5
6
Fig. 10: Preparation of 3,3 ‘, 4,4’- benzophenonetetracarboxylic acid
Fig. 11: Preparation of 3,3‘,4,4’-benzophenone tetracarboxylic dianhydride

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YEGOROV et al., Orient. J. Chem., Vol. 32(6), 3063-3070 (2016)
Preparation of 3,3',4,4'-tetramethyldiphenyldich ratio of o-xylene: aluminum chloride 1: 0.67 at
loromethane
0 - 5°C.
A three-necked round bottom flask
equipped with magnetic stirrer, a reflux condenser, Preparation of 3, 3‘, 4, 4’-tetramethyl
a thermometer and a dropping funnel was filled with benzophenone
anhydrous aluminum chloride and 22 ml (35 g, 0.23
A round bottom flask, equipped with
mol) of carbon tetrachloride, then reaction mixture magnetic stirrer and reflux condenser was filled with
was cooled with vigorous stirring and a solution of 10 200 ml of sodium hydroxide solution and 20 g (0.07
g (0,09 mol) of o-xylene and 6 ml (9.5 g, 0.06 mol) of mol) of 3,3',4,4'-tetra methyldiphenyldichloromethane.
carbon tetrachloride was added dropwise in such a The reaction mixture was heated while stirring. The
way that the temperature of reaction mixture did not reaction mixture was cooled to room temperature
rise above a certain value.Upon complete addition 20 and extracted from the aqueous phase with toluene
ml of distilled water was added to the reaction mixture (3 × 50ml), the extracts were combined, washed with
through the dropping funnel, the organic layer was distilled water (3 × 50 ml) and dried with anhydrous
separated, washed with distilled water (2 × 20 ml) magnesium sulfate. The solvent was distilled off
and dried with anhydrous magnesium sulfate.Then, under vacuum to obtain the product as a white
carbon tetrachloride was distilled under vacuum and powder, which was used in the next step without
the product was obtained as colorless oil, which was further purification. The test results are shown in
used in the next stage without further purification. Table 2.
The results are shown in Table 1.
Elemental analysis.Calculated,%:C 85.67;
1H NMR spectrum (DMSO - d6) (d, ppm): H 7,61. Found,%: C 85,72; H 7,54.
7.07-7.25 (m, 6H, HAr), 2.43 (s, 12H, CH3).
1H NMR spectrum (DMSO - d6) (d, ppm):
Table 1 shows that the preparation of 3,3', 7.29-7.51 (m, 6H, HAr), 2.38 (s, 12H, CH3).
4,4'- tetramethylphenyldichloromethane by alkylation
of carbon tetrachloride in the presence of anhydrous
Table 2 shows that the hydrolysis of 3,3‘,
aluminum chloride should be conducted at a molar 4,4’-tetramethyldiphenyl dichloromethane has been
carried out with 10% sodium hydroxide solution for
1 hour.
Table 2:The influence of the concentration of hydrolyzing
agent, and reaction time on the yield of 3,3 ‘, 4,4’-tetramethyl
benzophenone
No Dwell time,
hour
The concentration of
sodium hydroxide solution, %
Yield,
%
1
2
3
4
0,5
1
2
5
10
2
5
10
2
5
10
2
5
10
40,0
63,0
75,0
65,0
90,0
93,0
79,0
87,0
93,0
81,0
87,0
93,0
2
3

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YEGOROV et al., Orient. J. Chem., Vol. 32(6), 3063-3070 (2016)
Preparation of 3,3‘,4,4’-benzophenone
tetracarboxylic acid
Mass spectrum m / z (Irel,%):322 [M - H4O2]
(32,7), 278 [M - CH4O4]
A four-necked round bottom flask equipped
with mechanical stirrer, a reflux condenser, Preparation of 3,3‘,4,4’-benzophenone
thermometer and funnel for loading bulk solids tetracarboxylic dianhydride
was filled with 10.7 g (0.045 mol) of 3,3‘,4,4’-
A two-necked round bottom flask equipped
tetramethylbenzophenone, 64 ml of solvent and with magnetic stirrer, thermometer and Dean-Stark
320 ml of water. Then started stirring and heating, trap with reflux condenser was filled with 5.8 g (0.016
the reaction mixture was adjusted to 85°C. At this mol) of 3,3‘, 4,4’-benzophenonetetracarboxylic acid,
temperature, potassium permanganate (5 - 7 g) 15ml of solvent (forming an azeotrope with water,
was added through the funnel portionwise. Before separating from the water and not reacting with
adding a further portion of potassium permanganate, either an acid or anhydride) was added. Reaction
a sample (2 ml) should be taken from the reactor via mixture was heated while stirring to boiling, and
a Pasteur pipette, and visually observed the moment water was removed from the reaction mixture as
by color change of the mixture from violet to muddy an azeotrope mixture. The process was continued
brown, when all added potassium permanganate until the formation of clear, light brown solution in
reacted, and only then the following portion should the reaction flask and the separation of ~ 0.6 ml
be added.Oxidation is considered to be finished, if a of water. The solution in the reactor was cooled to
new portion of potassium permanganate introduced 50°C and 24 ml of 1,4-dioxane was added. It was
was not oxidized for 1 hour. During the experiment, cooled to room temperature. The precipitated
it was found that 60 g (0.38 mol) of potassium crystals were filtered, washed with 10 ml of boiling
permanganate was necessary to fully oxidize the 1,4-dioxane and dried in vacuo.
3,3‘,4,4’-tetramethyl benzophenone.
According to the results it has
To convert the excess of potassium been found that anhydridization of 3,3‘,4,4’-
permanganate to manganese oxide (IV) 20 ml of benzophenonetetracarboxylic acid requires high
ethanol was added to the reaction mixture and stirred temperatures and therefore high boiling solvent.The
at room temperature until disappearance of the reaction should be conducted in the diphenyl ether
purple color.Manganese oxide (IV) formed during the at a temperature of 230°C for 2 hours for the best
reaction was filtered off and washed with hot water results.
(6 × 50 ml). Basic filtrate and washing water were
combined and water and solvent were evaporated on
Elemental analysis.Calculated,%:C 63.37;
a rotary evaporator so that the 1/3 of the initial volume H 1.88. Found,%: C 63,26; H 1,85.
of the solution was remained. The resultant filtrate
was poured into a glass, cooled to 10°C and under
1H NMR spectrum (DMSO - d6) (d, ppm):
stirring concentrated hydrochloric acid was added 8.96 (2H, dd), 8.35 (2H, d), 8.19 (2H, d).
until acidic reaction on universal indicator.The acidic
solution was left overnight at room temperature.The
crystals precipitated was filtered and recrystallized
from 10% of hydrochloric acid solution. A pyridine
RESULTS AND DISCUSSIONS
As a result of studies it has been found an
solvent should be used for preparation of 3,3 ‘, 4,4’- optimum ratio of o-xylene and aluminum chloride
benzophenonetetracarboxylic acid.
in the preparation of 3,3',4,4'- tetramethyldiphenyl
dichloromethane by alkylation with carbon
Elemental analysis.Calculated,%:C 56.99; tetrachloride is 1:0.67 of o-xylene:aluminum chloride
H 2,81. Found,%: C 57,04; H 2,76.
at 0-5°C. The yield of 3,3 ‘, 4,4’-tetramethyldiphenyl
dichloromethane under these conditions attains the
1H NMR spectrum (DMSO - d6) (d, ppm): value 90%.
11.31 (s, 4H, COOH), 8.59 (d, 2H, HAr, J = 7.69 Hz),
8.29 (d, 2H, HAr, J = 7.53 Hz), 8.07 (c, 2H, HAr).
Optimal conditions for obtaining
3,3‘,4,4’-tetramethylbenzophenone with a yield of

YEGOROV et al., Orient. J. Chem., Vol. 32(6), 3063-3070 (2016)
93% were determined, the reaction time was 1 hour, CONCLUSION
3070
the concentration of sodium hydroxide solution was
10%.
A laborator y procedure for the
preparation of intermediate products and 3,3',4,4'-
benzophenontetracarboxylic dianhydride has been
developed and optimized. The conditions which
allow to achieve yields of more than 70 and up to
95% were chosen at each stage. The available and
the least expensive reagents were used in method
obtained. The resulting target dianhydride can be
used to obtain thermally stable polyimides.
From the series of experiments for obtaining
3,3',4,4'-benzophenonetetracarboxylic acid by
oxidation of 3,3',4,4'-tetramethylbenzophenone with
potassium permanganate follows that to carry out
this process with a maximum yield a molar ratio of
3,3',4,4'-tetramethylbenzophenone to potassium
permanganate should be 1:8.4.The maximum yield
obtained has been achieved at this ratio and reached
70%.
ACKNOWLEDGEMENTS
Preparationof3,3‘,4,4’-benzophenonetetra-
carboxylic acid by anhydridization should be
performed using diphenyl ether as a solvent.
Maximum yield of dianhydride reaches 70%.
Applied researches were carried out with
state financial support represented by the Ministry
of Education of Russia under the Agreement on
granting subsidies No. 14.625.21.0035 of October
27, 2015. (Unique identifier of Applied Scientific
Researches (project) RFMEFI62515X0035)
Alltheproductsobtainedattheintermediate
and final stages of the developed method have the
purity of not less than 90%.
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