|Title of Invention||
AN IMPROVED PROCESS FOR THE PREPRATION OF PURE HIGH QUALITY 3,3',4,4'-TETRAMINOBIPHENYL
|Abstract||The present invention relates to a process for the preparation of pure high quality 3,3', 4,4'-tetraminobiphenyl (TAB) involving a three step process (1) oxidation of 3,3',-dichloro4,4'-diaminobiphenyl (DCB) with 50% aq. H2O2, (2) ammonolysis of the resulting 3,3'-dinitro4,4'-dinitrobiphenyl (DCDNB) and (3) the reduction of 3,3'-diamino-4,4'-dinitrobiphenyl (DADNB) with stannous chloride and concentrated hydrochloric acid.|
|Full Text||IMPROVED PROCESS FOR THE PREPARATION OF PURE HIGH QUALITY 3, 3', 4, 4'TETRAMINOBIPHENYL
Field of the present invention
The present invention relates to a process for the preparation of pure high quality 3, 3', 4, 4'-tetraminobiphenyl (TAB) of formula 1 in high yields.
Background and prior art references of the present Application
3,3', 4,4'-Tetraminobiphenyl (TAB) is a valuable intermediate and final product in various areas. For example, TAB is used as monomer in the preparation of polybenzimidazole (PBI) polymers, which are characterized by excellent thermal and mechanical stability. These PBI polymers are widely used as proton-conducting materials for fuel cell applications (compare U.S. Pat. Nos. 2,895,948, 3,174,947, 5,317,078 and 6,187,231). TAB is also used as an antioxidant and as an agent for stabilizing epoxide resins.
In the prior art, TAB has been prepared by three known methods. One such known method is ammonolysis of 3,3'-dichlorobenzidine (DAB) in the presence of mainly Cu catalysts (both copper salts and elemental Cu) using aqueous NH3. For example, French Patent Specification No. 1,475,631 describes such an ammonolysis of DCB, in the presence of a Cul salt and/or of Cu2O and CaCl2 at an elevated temperature preferably 150 - 210°C and under an elevated inert gas pressure. The crude TAB thus obtained is purified via its salt formation with a strong acid (yield of TAB is about 70% of theory). Subsequently, various attempts were made to obtain TAB in highly pure form and in high yields from crude TAB as described below.
The U.S. Pat. No. 3,865,876 describes the improvement on the result of the method described in the above mentioned French Patent Specifications by using essentially only CuCl as a catalyst for the ammonolysis of DCB. The yield of TAB of theory having purity of about 75-82% is between about 85 and 87 %. This product has a Cu content of about 3 - 6% by weight. The process of U.S.Pat. No. 3,943,175 (CuCl / Cu powder can also be used as catalyst, in addition to CuCl describes the purification of TAB (converting it into its sulfate by means of sulfuric acid, isolation of the sulfate and liberation there
from of TAB by means of a base). The TAB thus liberated is dissolved and reprecipitated from an aqueous solution advantageously with the addition of activated charcoal and diatomaceous earth. However, the Cu content present in TAB is about 0.6 to 0.9 % and the yield at most 45.7 % of theory, relative to DCB employed.
The German Patent (Ger. Offen. DE 3, 111, 470) discloses the purification of crude TAB (obtained by ammonolysis process) by boiling it with H2O containing activated carbon and sodium dithionate (yield of TAB is 75.9 % with 10 ppm Cu) Three more patents (U.S.Pat. No. 4, 433,168, 5,235,105 and Eur. Pat. Appl. EP 522,577) describe the purification of crude TAB (obtained from ammonolysis of DCB with copper catalyst) by crystallizing it in water in presence of 0-5 % by weight of activated carbon and about 1- 2 % by weight of a water-soluble reducing agent (alkali metal dithionate or alkali metal sulfite) at temperature of 100-140 °C under N2 atmosphere (yield of TAB: 88.2 % of theory with only 10 ppm Cu). In the second method for producing TAB, which has generated substantial interest, the starting material is benzidine which is acetylated with acetic anhydride, to form N, N-diacetylbenzidine. The latter compound is then nitrated with cone. HNO3 to form 3,3'-dinitro-N, N-diacetylbenzidine which is base hydrolysed to form 3.3'-dinitrobenzidine. This is then reduced by any of various means to form TAB [H.Vogel and C.S.Marvel, J. Poly. Sci. Part Al, 1531(1963)]
The third method describes the production of TAB from biphenyl which comprises the following six steps: (1) acetylating the biphenyl in the presence of an appropriate Friedel -Crafts catalyst to obtain 4,4'-diacetylbiphenyl (DAcB); (2) oximating the DAcB to form DAcB dioxime; (3) subjecting the dioxime to a double Beckmann rearrangement to obtain N, N-diacetylbenzidine. (DiAcBz); (4) nitrating the DiAcBz to obtain 3,3'-dinitro-N,N '-diacetylbenzidine (DNAcBz) ; (5) removing the acetyl groups of the DNAcBz by basic hydrolysis to form 3,3'-dinitrobenzidine (DNB) and (6) reducing the nitro groups of DNB to form TAB (U.S.Pat. No. 5,041,666). All the foregoing methods suffer from the following disadvantages associated with them:
1. They utilize benzidine as one of the raw materials, which is a known carcinogen.
2. Direct ammonolysis of DCB catalyzed by copper salts requires high temperatures
(200°- 300 °C) at a pressure of 900-1000 psig of making the process more hazardous
from Safety point of view. Our own experience with direct ammonolysis of DCB by following the Patented procedures is very disappointing to obtain TAB as tarry materials always accompany it.
3. In the direct ammonolysis, copper forms stable complexes probably with TAB in situ
so that liberating TAB from the complex becomes tedious.
4. In the direct ammonolysis, copper forms stable complexes probably with the
corresponding triaminobiphenyl and little amount of copper, so that separation of these
impurities from TAB becomes tedious.
5. In the dioximation method, many of steps are involved starting from expensive
biphenyl with low yield.
All the above methods make use of relatively expensive starting materials and the
reaction conditions are harash to carry out. Thus, any method for producing TAB utilizing
a cheaper raw material, which is both safer and easier to handle, would be very desirable.
Objects of the present invention
The main object of the present invention is to provide an improved process for the
preparation of pure high quality 3,3,'4,4'-tetramino biphenyl (TAB), which avoids the
drawbacks as detailed above.
Another object of the present invention is to demonstrate the use of heterogeneous Ti-
superoxide as a catalyst for the oxidation of DCB to obtain 3,3'-dichloro-4, 4'-
dinitrobiphenyl (DCDNB). DCDNB which smoothly underwent ammonolysis affording
3,3'-dichloro-4,4'dinitrobiphenyl (DADNB), followed by the reduction of nitro groups of
DADNB yielded TAB in high yields.
It is therefore an object of the present invention to provide an improved process for the
synthesis of TAB, which is substantially free of one or more of the disadvantages prior
Yet another object is to provide a novel process for the synthesis of TAB of greater purity
than heretofore possible.
Summary of the present invention
Present application relates to a process for the preparation of pure high quality 3,3',
4,4'-tetraminobiphenyl (TAB) in high yields.
More particularly, it relates to a process for preparation of 3,3', 4,4' tetraminobiphenyl
(TAB) involving a three step process (1) oxidation of 3,3',-dichloro 4,4'-
diaminobiphenyl (DCB) with 50% aq. H2O2, (2) ammonolysis of the resulting 3,3'-
dinitro 4,4'-dinitrobiphenyl (DCDNB) and (3) the reduction of 3,3'-diamino-4,4'-dinitrobiphenyl (DADNB)with stannous chloride and concentrated hydrochloric acid. Detailed description of the present invention
Accordingly the present invention provide improved process for the preparation of pure, high quality 3,3', 4,4'-Tetraminobiphenyl (TAB) of formula 1
(Formula 1 Removed)
from 3, 3'- Dichloro benzidine (DCB) of formula 2
(Formula 2 Removed)
which comprises oxidizing DCB by an oxidising agent in presence of a Titanium super oxide catalyst, in presence of a solvent to obtain 3,3'dichloro 4,4'dinitro biphenyl (DCDNB) of formula (3).
(Formula 3 Removed)
Ammonolysing DCDNB using aq. ammonia in presence of a solvent to obtain 3,3',diamino 4,4' dinitro biphenyl (DADNB) of formula (4)
reducing DADNB using a reducing agent and basifying the resultant mixture with an
alkali to obtain 3,3',4,4' tetraminobiphenyl (TAB)
Figure (2) shows reaction sequence of above described process
In one of the embodiments, the present invention the titanium super oxide used as the
heterogeneous catalyst, is prepared as per procedure given in the publication [Angew.
Chem. Int. Ed. Engl. 2001,40,405-408]
In another embodiment, the oxidant may be preferably H2O2 having the strength of 30 to
In yet another embodiment, the solvent used may be selected from a range of organic
solvents such as but are not limited to, acetonitrile, acetone methanol, acetic acid and
In yet another embodiment, ammonolysis may be carried out at temperature ranging from
In yet another embodiment, preferred temperature for ammonolysis is 100 °C
In yet another embodiment, ammonolysis may be carried out at a pressure of 100-500
In yet another embodiment, ammonolysis is preferably carried out at 100 psig.
In yet another embodiment, reducing agents is selected from a group consisting of
SnC12/conc. HC1 mixture.
In yet another embodiment, reduction is carried out at in the temperature ranging between
The process of the present invention is described herein with reference to examples,
which are illustrative only and should not be construted to limit the scope of the present
invention in any manner. In order to fully illustrate the nature of the present invention and
the manner of practicing the same, the following examples are presented:
Preparation of Ti-superoxide catalyst (1)
To a solution of Ti (O'Pr)4, (5.0 g, 0.0175 moles) in anhydrous MeOH (50mL) placed in a
two-necked round bottomed flask equipped with addition funnel, nitrogen inlet and reflux
condenser, 50% H2O2, (5.98 g, 0.175 moles) was added slowly over a period of 40
minutes under stirring at room temperature. The yellow-colored precipitate formed at
once was filtered through a sintered funnel, washed with anhydrous methanol and dried
under reduced pressure (3 mm Hg) at room temperature (25 °C) for 1 h, Yield: 3.94 g (98
%). EPR spectra were recorded on a Bruker EMX spectrometer operating at 9.76 GHz,
298 K and g values were determined with reference to standard marker: α, α'-diphenyl-β-
picryl hydrazyl (DPPH, g = 2.0036). Thermogravimetric and differential thermal analysis
(TG/DTA) was performed on TG/DTA 22, TG/DTA 32 system (Seiko Instruments Inc.)
in the range of 30 - 400 °C with a temperature program 10°C /min.
Preparation of 3,3'-dicbloro-4,4'- dinitrobiphenyl (DCDNB) by oxidative procedure
In a two-necked round-bottomed flask equipped with nitrogen gas bubbler, addition
funnel, water condenser and stirring magnetic bar were placed 3,3'-dichlorobenzidiene (5
g, 0.019 moles), Ti-superoxide catalyst (1), (2.5 g, 50 wt %) and anhydrous methanol (30
ml). 50 % aq. H2O2, (10.74 g, 0.158 moles) was added slowly under stirring for a period
of 20 min. Reaction was found to be exothermic and a yellow to reddish brown color
change was observed during the addition of H2O2. The progress of the reaction was
monitored by TLC [in ethyl acetate] and after completion, catalyst 1 was filtered out and
methanol evaporated under reduced pressure. The crude product weighed 4.2 g, (66.28 %)
was analyzed by gas chromatography for its purity.
Preparation of 3, 3'- diamino 4, 4'- dinitrobiphenyl (DADNB) by ammonolysis
A mixture of 3,3'-dichloro-4, 4'-dinitrobiphenyl (5 g, 0.0197 mol) and excess ammonia
solution (100 ml), in methanol (100 ml) was charged into an autoclave and the whole
mixture was heated at 100 °C for 3h. After the reaction was complete, methanol was
removed by distillation and the amino product was precipitated. It was then filtered and
washed with H2O and dried. Yield 3.82 g (86.99%) m.p. 226 °C.
Preparation of 3,3'-4,4'- tetraminobiphenyl (TAB) by reduction of nitro groups
A mixture of 3,3'-dinitrobenzidine (2 g, 0.007 mol) and stannous chloride (6.4 g, 0.034
mol) was stirred at 0 °C in ethanol (125 ml) and con. HC1 (30 %) was added drop-wise
over 30 min. The reaction mixture was refluxed for 10-12 h. The salt of the tetramine was
precipitated out, which was basified with cold 10 % NaOH solution and the solid filtered
out, washed with water dried under vacuum to give TAB in 80 % yield (1.159 g).
The advantages of the present invention are:
1. In all three steps of reactions, the isolation of the products can be done by simple
2. The ammonolysis of DCB can be done without the use of any metal catalyst and
under milder reaction temperature (100°C) and autogenic pressure (250 psig).
3. The product TAB can be produced without any contamination of copper and its
salts, thus enhancing the purity of TAB.
4. No by- products (diamine complexes of TAB with copper salts) are produced in
the reaction mixture.
5. Quantitative conversions are obtained in all the three steps of oxidation,
ammonolysis, and reduction.
1. An improved process for the preparation of pure, high quality 3,3',4,4'-Tetraminobiphenyl (TAB) of formula 1, said process comprises the
oxidizing 3,3'dichloro benzidine of formula 2 by an oxidizing agent such as herein described in presence of Titanum super oxide catalyst and a solvent to obtain 3,3'dichloro4,4'dinitro biphenyl of formula3;
b. ammonolysing 3,3'dichloro4,4'dinitro biphenyl of formula 3 using
ammonia solution in presence of a organic solvent such as herein
described at temperature ranging between 50-200°C and pressure
ranging between 100-500psig to obtain 3,3',diamino4,4'dinitro
biphenyl of formula 4 ;
c. reducing 3,3',diamino4,4'dinitro biphenyl of formula 4 using a
reducing agent which are selected from SnC12/conc. HCL mixture at a
temperature ranging between 50-60°C, and
d. basifying the resultant mixture with an alkali to obtain 3,3',4,4'
tetraminobiphenyl of formula 1.
2. A process as claimed in claim 1, wherein the titanium super oxide used is as the heterogeneous catalyst.
3. A process as claimed in claim 1, wherein the oxidant is preferably H2O2 having the strength of 30 to 50% v/v.
4. A process as claimed in claim 1, wherein the solvent is organic solvent comprising of acetonitrile, acetone, methanol, acetic acid, and water.
5. A process as claimed in claim 1, wherein ammonolysis is preferably carried out at 100°C.
6. A process as claimed in claim 1, wherein ammonolysis is preferably carried out at l00 psig.
7. An improved process for the preparation of pure, high quality 3,3', 4,4'-Tetraminobiphenyl substantially as herein describe with reference to examples accompanying this specification.
|Indian Patent Application Number||401/DELNP/2004|
|PG Journal Number||06/2011|
|Date of Filing||20-Feb-2004|
|Name of Patentee||COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH|
|Applicant Address||RAFI MARG, NEW DELHI-110001, INDIA|
|PCT International Classification Number||C08G 73/00|
|PCT International Application Number||PCT/IN03/00403|
|PCT International Filing date||2003-12-29|