Title of Invention

PROCESS FOR THE PREPARATION OF DIPHENIC ACID FROM PHENANTHRENE

Abstract The present invention provides a process for the preparation of diphenic acid from phenanthrene which comprises heating phenanthrene and glacial acetic acid, adding drop-wise a pre-determined amount of 30% hydrogen peroxide, heating the resulting mixture after completion of drop wise addition of hydrogen peroxide, distilling the resulting mixture under reduced pressure to make the volume half, cooling the mixture till diphenic acid crystalises out, filtering the cooled mixture and boiling the residue after adding 10% solution of sodium carbonate and activated charcoal, filtering and discarding the residue; acidifying the filtrate with hydrogen chloride; cooling the resultant mixture till more diphenic acid crystallises out; repeating filtration till pure diphenic acid is obtained.
Full Text PROCESS FOR THE PREPARATION OF DIPHENIC ACID
Field of the invention
The present invention relates to a process of synthesis of diphenic acid. More
particularly, the present invention relates to a process of synthesis of diphenic acid
from phenanthrene. The invention finds its usage in production of high temperature
heat resistant resins, engineering plastics, liquid crystalline polymers,
Pharmaceuticals, agro-chemical industries etc. This method produces an acceptable
poly-(amide-imide) resin with adequate thermal stability having good impact
resistance, tensile strength or elongation properties and can be drawn as long fibres.
Diphenic acid residues act as chain terminators on reaction with the aromatic diamine.
Background of the invention
Next to naphthalene, phenanthrene is the second largest component of high
temperature coal tar. It is concentrated in anthracene oil fraction (300-360°C) of coal
tar distillation. It constitutes 30-40% of the crude anthracene cake obtaineed from
anthracene oil by cooling and cetrifuging. After recrystalisation of anthracene residue,
phenanthrene is recovered from the filtrate by solvent extraction and/or fractional
distillation. Phenanthrene and its derivatives, particularly 9:10-Phenanthraquinone,
2,2'-biphenyldicarboxylic acid (Diphenic acid) and 4,4'-biphenyldicarboxylic acid are
in growing demand in the world market (annual growth rate 15%) due to their
excellent performance in many newly developed applications, such as production of
high temperature heat resistant resins, engineering plastics, liquid crystalline
polymers, pharmaceuticals and agro-chemical industries etc.
Reference is made to US Patent 4,352,922 wherein basic chemistry of
phenanthrene-derived poly-(amide-imide) resins is described. Although this method
produces an acceptable poly-(amide-imide) resin with adequate thermal stability, the
resin does not have very good impact resistance, tensile strength or elongation
properties and cannot be drawn as long fibres. It is thought that the deficiencies in the
physical properties of the resin are due to the low molecular weight of the
phenanthrene / formaldehyde reaction product and the presence therein of many
oligomers of phenanthrene having terminal moieties linked to the chain at either the 9
or 10 position. On oxidation, such a reaction product will give rise to diphenic acid
residues which will act as chain terminators on reaction with the aromatic diamine. R.
Behrend, Zeit. Phys. Chem., 1892, 9, p. 405; 10, p. 265 describes oxidation of
phenanthrene by reacting alcoholic solution of phenanthrene with chromic acid, first
to phenanthre-4uinone, and then to diphenic acid but the yield and purity are poor.
Reference made to US Patent 4,373,089 wherein phenanthrene is converted to its 9, 10 diol derivative via 9, 10 phenanthraquinone. The phenanthrene is oxidised by a mild oxidising agent, such as potassium dichromate, to produce the phenanthraquinone which is reduced to the 9, 10 phenanthrene diol by a mild reducing agent, such as sulphur dioxide. Sulphur dioxide is a convenient reducing agent because it is possible to bubble it through a solution of the phenanthraquinone to produce the 9, 10, diol derivative. The derivative can be protected from reoxidation by a blanket of an inert gas such as nitrogen. According to a second aspect of the present invention, there is provided a polyimide resin comprising the condensation product of a reaction between an aromatic diamine and a polycarboxylated product formed by reacting the 9, 10-diol derivative of a phenanthrene with formaldehyde and oxidising the reaction product to produce keto groups bridging the diphenic acid moieties produced. According to a third aspect of the present invention, there are provided intermediates in the formation of a polyimide resin comprising firstly the reaction product of a 9, 10-diol derivative of a phenanthrene with formaldehyde in the presence of an acid catalyst, and secondly the reaction product which has been oxidised to produce keto groups bridging the diphenic acid moieties produced.
Prior art search for production of diphenic acid was done based on literature survey and patent databases and did not yield any relevant references. Objects of the invention
The main object of the invention is to provide a process of synthesis of diphenic acid from phenanthrene which obviates the drawbacks as detailed above.
Another object of the invention is to obtain 99% pure diphenic acid.
Yet another object of the invention is to provide a process for the preparation of diphenic acid which is simple and eco-friendly.
It is another object of the invention to provide a process for the synthesis of diphenic acid which is economical. Summary of the invention
Accordingly the present invention provides a process for the preparation of diphenic acid from phenanthrene which comprises;
(i) heating phenanthrene and glacial acetic acid in the ratio of 1: 10 to 1: 12 (w/w) in a reactor at a temperature in the range of 75 to 85°C,
(ii) adding drop-wise of 30% hydrogen peroxide in an amount in the range of 100 to 300 ml, for a time period in the range of 30 to 60 minutes,

(iii) heating the resulting mixture after completion of drop wise addition of hydrogen peroxide,
(iv) distilling the resulting mixture under reduced pressure to make the volume half,
(v) cooling the mixture till diphenic acid crystalises out,
(vi) filtering the cooled mixture and boiling the residue after adding 10% solution of sodium carbonate and activated charcoal,
(vii) filtering and discarding the residue;
(viii) acidifying the filtrate with hydrogen chloride;
(ix) cooling the resultant mixture till more diphenic acid crystallises out;
(x) repeating filtration till pure diphenic acid is obtained.
In one embodiment of the invention, the heating in step (i) above is done in a reactor at a temperature in the range of 75 to 85°C.
In another embodiment of the invention, 30% hydrogen peroxide is added drop wise in an amount in the range of 100 to 300 ml, for a time period in the range of 30 to 60 minutes.
In yet another embodiment of the invention, the heating in step (iii) is done for a time period in the range of 3 to 7 hours.
In yet another embodiment of the invention, the residue in step (vi) is boiled at 100°C after adding 10% solution of sodium carbonate and activated charcoal for decolouration.
In a further embodiment of the invention, the acid is added to maintain the pH of the mixture in the range of 3 to 4.5.
In another embodiment of the invention, the amounts of phenanthrene and glacial acetic acid added are in the ratio of 1: 10 to 1: 12 (w/w).
In a further embodiment of the invention, the purity of diphenic acid produced is 99%. Detailed description of the invention
Phenanthrene and glacial acetic acid are added together in a reactor and heated up within 75 - 85°C. To the resulting mixture, 100-300 ml of 30% hydrogen peroxide solution is added drop wise, which takes between 30-60 minutes. After completion of addition of hydrogen peroxide solution, the temperature of 75-85°C is further maintained for a time period ranging between 3 to 4 hours. The resulting mixture is subjected to distillation, under reduced pressure, to make the volume half and the

We claim:
1. A process for the preparation of diphenic acid from phenanthrene which comprises
(i) heating phenanthrene and glacial acetic acid in the ratio of 1: 10 to 1: 12 (w/w) in
a reactor at a temperature in the range of 75 to 85°C, (ii) adding drop-wise of 30% hydrogen peroxide in an amount in the range of 100 to
300 ml, for a time period in the range of 30 to 60 minutes, (iii) heating the resulting mixture after completion of drop wise addition of
hydrogen peroxide, (iv) distilling the resulting mixture under reduced pressure to make the volume
half, (v) cooling the mixture till diphenic acid crystalises out, (vi) filtering the cooled mixture and boiling the residue after adding 10% solution
of sodium carbonate and activated charcoal, (vii) filtering and discarding the residue; (viii) acidifying the filtrate with hydrogen chloride; (ix) cooling the resultant mixture till more diphenic acid crystallises out; (x) repeating filtration till pure diphenic acid is obtained.
2. A process as claimed in claim 1, wherein the heating in step (iii) is done for a time period in the range of 3 to 7 hours.
3. A process as claimed in claim 1, wherein the residue in step (vi) is boiled at 100°C after adding 10% solution of sodium carbonate and activated charcoal for decolouration.
4. A process as claimed in claim 1, wherein the acid is added to maintain the pH of the mixture in the range of 3 to 4.5.
5. A process as claimed in claim 1, wherein the purity of diphenic acid produced is 99%.
6. A process for the preparation of diphenic acid from phenanthrene substantially as herein describe with reference to examples accompanying this specification.






mass is allowed to cool. On cooling, considerable amount of diphenic acid crystalises
out.
The cooled mixture is filtered and the residue is boiled at 100°C after addition
of 10% solution of sodium carbonate and activated charcoal ( for decolouration) and
subjected to filtration after which the residue is discarded and the filtrate is acidified
with hydrogen chloride to maintain the pH at 4.5 and cooled where diphenic acid
crystallises out. This process is repeated several times till pure diphenic acid is
obtained having melting point at 228 - 229°C.
The phenanthrene and glacial acetic acid added are preferably in a ratio of 1:
10 (w/w). It is observed that the purity of diphenic acid produced is about 99%.
The novelty of the present invention resides in slow and controlled oxidation
of phenanthrene (drop wise addition of the oxidising agent at a specific temperature
range and a specific time range, which was unknown in the prior art). This method
produces an acceptable poly-(amide-imide) resin with adequate thermal stability
having good impact resistance, tensile strength or elongation properties and which can
be drawn as long fibres. Diphenic acid residues act as chain terminators on reaction
with the aromatic diamine. The method of the invention can be used in many newly
developed field of applications e.g. production of heat resistant resins, engineering
plastics, liquid crystalline polymers, Pharmaceuticals, agro-chemical industries etc.
from phenanthrene, which was otherwise unutilised due to cost factors. The present
process was proved to enhance the yield of diphenic acid drastically.
The following examples are given by way of illustration and should not be
construed to limit the scope of the present invention.
Example-
25 grams of Phenanthrene and 253 grams glacial acetic acid are added
together in a reactor and heated up to 85°C. To the resulting mixture, 100 ml of 30%
hydrogen peroxide solution is added drop wise, which normally takes 40 minutes.
After completion of addition of hydrogen peroxide solution, the temperature of 85°C
is further maintained for a time period of 6 hours. The resulting mixture is subjected
to distillation, under reduced pressure, to make the volume half and the mass is
allowed to cool. On cooling, considerable amount of diphenic acid crystalises out.
The cooled mixture is filtered and the residue is boiled at 100°C after addition of 10%
solution of sodium carbonate and activated charcoal (for decolouration) and subjected
to filtration after which the residue is discarded and the filtrate is acidified with
hydrogen chloride to maintain the pH at 4.5 and cooled where diphenic acid
crystallises out. This process is repeated several times till pure diphenic acid is
obtained having melting point at 228°C. Yield obtained was 11 grams.
Example-2
25 grams Phenanthrene and 253 grams glacial acetic acid are added together in
a reactor and heated up to 85°C. To the resulting mixture, 200 ml of 30% hydrogen
peroxide solution is added drop wise, which normally takes 40 minutes. After
completion of addition of hydrogen peroxide solution, the temperature of 85°C is
further maintained for a time period 6 hours. The resulting mixture is subjected to
distillation, under reduced pressure, to make the volume half and the mass is allowed
to cool. On cooling, considerable amount of diphenic acid crystalises out. The cooled
mixture is filtered and the residue is boiled at 100°C after addition of 10% solution of
sodium carbonate and activated charcoal (for decolouration) and subjected to filtration
after which the residue is discarded and the filtrate is acidified with hydrogen chloride
to maintain the pH at 4.5 and cooled where diphenic acid crystallises out. This process
is repeated several times till pure diphenic acid is obtained having melting point at
229°C. The yield obtained was 17 grams.
ExampIe-3
25 grams Phenanthrene and 253,grams of glacial acetic acid are added
together in a reactor and heated up to 85°C. To the resulting mixture, 88 ml of 30%
hydrogen peroxide solution is added drop wise, which normally takes 30 minutes.
After completion of addition of hydrogen peroxide solution, the temperature of 80°C
is further maintained for a time period of 3.5 hours. The resulting mixture is subjected
to distillation, under reduced pressure, to make the volume half and the mass is
allowed to cool. On cooling, considerable amount of diphenic acid crystalises out.
The cooled mixture is filtered and the residue is boiled at 100°C after addition of 10%
solution of sodium carbonate and activated charcoal (for decolouration) and subjected
to filtration after which the residue is discarded and the filtrate is acidified with
hydrogen chloride to maintain the pH at 4.5 and cooled where diphenic acid
crystallises out. This process is repeated several times till pure diphenic acid is
obtained having melting point at 229°C. The yield is 12 gms.
The main advantages of the present invention are:
1. The process is very simple and eco-friendly.
2. The yield of the product is very high in comparison to prior art.
3. No side reactions are involved in the process.



We claim:
1. A process for the preparation of diphenic acid from phenanthrene which comprises
(i) heating phenanthrene and glacial acetic acid in the ratio of 1: 10 to 1: 12 (w/w) in
a reactor at a temperature in the range of 75 to 85°C, (ii) adding drop-wise of 30% hydrogen peroxide in an amount in the range of 100 to
300 ml, for a time period in the range of 30 to 60 minutes, (iii) heating the resulting mixture after completion of drop wise addition of
hydrogen peroxide, (iv) distilling the resulting mixture under reduced pressure to make the volume
half, (v) cooling the mixture till diphenic acid crystalises out, (vi) filtering the cooled mixture and boiling the residue after adding 10% solution
of sodium carbonate and activated charcoal, (vii) filtering and discarding the residue; (viii) acidifying the filtrate with hydrogen chloride; (ix) cooling the resultant mixture till more diphenic acid crystallises out; (x) repeating filtration till pure diphenic acid is obtained.
2. A process as claimed in claim 1, wherein the heating in step (iii) is done for a time period in the range of 3 to 7 hours.
3. A process as claimed in claim 1, wherein the residue in step (vi) is boiled at 100°C after adding 10% solution of sodium carbonate and activated charcoal for decolouration.
4. A process as claimed in claim 1, wherein the acid is added to maintain the pH of the mixture in the range of 3 to 4.5.
5. A process as claimed in claim 1, wherein the purity of diphenic acid produced is 99%.
6. A process for the preparation of diphenic acid from phenanthrene substantially as herein describe with reference to examples accompanying this specification.



Documents:

2133-DELNP-2004-Abstract(25.02.2009).pdf

2133-DELNP-2004-Abstract-(08-05-2009).pdf

2133-delnp-2004-abstract.pdf

2133-DELNP-2004-Claims (25.02.2009).pdf

2133-DELNP-2004-Claims-(08-05-2009).pdf

2133-delnp-2004-claims.pdf

2133-DELNP-2004-Correspondence-Others (25.02.2009).pdf

2133-DELNP-2004-Correspondence-Others-(24-03-2009).pdf

2133-delnp-2004-correspondence-others.pdf

2133-DELNP-2004-Description (Complete) (25.02.2009).pdf

2133-DELNP-2004-Description (Complete)-(08-05-2009).pdf

2133-delnp-2004-description (complete).pdf

2133-DELNP-2004-Form-1 (25.02.2009).pdf

2133-delnp-2004-form-1.pdf

2133-delnp-2004-form-18.pdf

2133-DELNP-2004-Form-2 (25.02.2009).pdf

2133-delnp-2004-form-2.pdf

2133-DELNP-2004-Form-3 (25.02.2009).pdf

2133-delnp-2004-form-3.pdf

2133-delnp-2004-form-5.pdf

2133-DELNP-2004-Petition-137-(24-03-2009).pdf


Patent Number 234412
Indian Patent Application Number 2133/DELNP/2004
PG Journal Number 25/2009
Publication Date 19-Jun-2009
Grant Date 27-May-2009
Date of Filing 22-Jul-2004
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110001,INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 KUMARES CHANDRA BIT CENTRAL FUEL RESEARCH INSTITUTE, P.O.F.R.I.-828108, DHANBAD,JHARKHAND, INDIA.
2 SANJAY KUMAR THAKUR CENTRAL FUEL RESEARCH INSTITUTE, P.O.F.R.I.-828108, DHANBAD,JHARKHAND, INDIA.
3 KAMLESH KUMAR MISHRA CENTRAL FUEL RESEARCH INSTITUTE, P.O.F.R.I.-828108, DHANBAD,JHARKHAND, INDIA.
4 SUKURU RAMAKRISHNA RAO CENTRAL FUEL RESEARCH INSTITUTE, P.O.F.R.I.-828108, DHANBAD,JHARKHAND, INDIA.
5 KAUSHAL KISHORE TIWARI CENTRAL FUEL RESEARCH INSTITUTE, P.O.F.R.I.-828108, DHANBAD,JHARKHAND, INDIA.
PCT International Classification Number C07C
PCT International Application Number PCT/IB02/05612
PCT International Filing date 2002-12-23
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 IB02/05612 2002-12-23 EUROPEAN UNION