Title of Invention

"PROCISS FOR THE PRODUCTION OF 9, 10-DIHYDROXYANTHRACENE CARBOXYLIC ACID ESTER"

Abstract A process for the production of 9,10-dihydroxyanthracene carboxylic acid ester by the catalytic oxidation of anthracene, characterised in that anthracene is treated in the liquid phase in a carboxylic acid medium selected from lower organic mono or dicarboxylic acids and their anhydrides in the presence of an organic metal salt selected from transition metals in the oxidation states +III, IV, VI, and VII and an activating agent for the metal salt selected from bromides, iodides or chlorides at a temperature of 40 to 100°C, subject to the action of oxygen and light, the precipitate is separated off, the liquid remainder is treated with an esterification agent selected from lower organic mono or dicarboxylic acids and their anhydrides and the ester obtained from the reaction mixture is isolated.
Full Text The present invention relates to a process for the production of 9,10 dihydroxyanthracene carboxylic acid ester.
The invention relates to a process for the oxidation of anthracene in the liquid phase, in which process a 9,10-dihydroxyanthracene carboxyl ester is obtained as the main product.
The oxidation o'f anthracene to anthraguinone has been part of the state of the art for some considerable time and has been described by H.G. Franck, J.W. Stadelhofer, Industrielle Aromatenchemie, Springer Verlag 1987, among others. In general, anthraquinone is produced in this process from anthracene by catalytic gas phase oxidation in the presence of a gas containing molecular oxygen, heavy metal oxides being used as catalysts. The production of anthraquinone by gas phase oxidation causes considerable pollution of the environment as a result of vapours of anthracene and anthraquinone being released. A further disadvantage is that the gas phase oxidation has a low selectivity and undesirable by-products are formed during the reaction. The yield of anthraquinone following gas phase oxidation is 80 to 95 %, depending on the catalyst.
Apart from gas phase oxidation, liquid, phase oxidation, e.g. With dichromate or nitric acid, using solid anthracene as the starting product, is an known process. The use dichromate or nitric acid in liquid phase oxidation is combined in all cases with a time-consuming water treatment in order to avoid ecological problems.
In PL 0 295 761, a process is described in which hydrogen peroxide is used as oxidising agent. However, this process has the disadvantage that the consumption of hydrogen peroxide is such that the production of anthraquinone is no longer economic.
In the last few years, a surplus capacity of anthraquinone has been observed on the market. Processes for the production of anthraquinone by the oxidation of anthracene have consequently lost some of their importance. On the other hand, 9,10-dihydroxyanthracene, an intermediate from the oxidation of anthracene, or its esters, are of great interest. These compounds are suitable for use as starting material for the production of new high-value polymers.
Since the oxidation of 9,10-dihydroxyanthracene to anthraquinone takes place rapidly whereas that of anthracene to 9,10-dihydroxyanthracene is slow, a selective conversion of anthracene to 9,10-dihydroxyanthracene is hardly possible. Consequently, the production of 9,10-dihydroxyanthracene is possible only by the indirect route, e.g. by the reduction of anthraquinone with hydrogen. A multi-stage process, however, has frequently proved to be uneconomic once the costs of oxidation and reduction are added together.
The invention is based on the task of providing a process for the oxidation of anthracene to 9,10-dihydroxyanthracene carboxylic acid ester or its derivatives which process can be carried out in the liquid phase under mild conditions giving relatively high yields.
This task is solved by way of a process for the production of 9,10-dihydroxyanthracene carboxylic acid ester and its derivatives by the catalytic oxidation of anthracene by treating anthracene in the liquid phase in a carboxylic acid medium in the presence of an organic metal salt and an activating agent for the metal salt at a temperature of
approximately 40 °C and more, subject to the action of oxygen and light, separating off the precipitate, treating the liquid remainder with esterification agents and isolating the ester obtained from the reaction mixture.
In this process, the oxidation is carried out with the peroxy acids formed in situ during the oxidation of carboxylic acids with oxygen, the product arising in the form of a monoester or diester .of the carboxylic acid.
According to the present invention there is provided a process for the production of 9,lO-dihydroxyanthracene carboxylic acid ester by the catalytic oxidation of anthracene, characterised in that anthracene is treated in the liquid phase in a carboxylic acid medium selected from lower organic mono or dicarboxylic acids and their anhydrides in the presence of an organic metal salt selected from transition metals in the oxidation states +III, IV, VI, and VII and an activating agent for the metal salt selected from bromides, iodides or chlorides at a temperature of 40 to 100°C, subject to the action of oxygen and light, the precipitate is separated off, the liquid remainder is treated with an esterification agent selected from lower organic mono or dicarboxylic acids and their anhydrides and the ester obtained from the reaction mixture is isolated.
According to this process, a solid anthracene and a catalytic system can be suspended in a carboxylic acid medium and the anthracene can then be oxidised with a supply of oxygen and access of light to form a 9,10-dihydroxyanthracene carboxylic ester.
9,10 dihydroxyanthracene is highly unstable and, in the presence of air, is oxidised spontaneously to form anthraquinone. An interruption of the reaction at the dihydroxyanthracene intermediate stage was therefore not to be expected. The use of protective groups such as acetoxy groups was also not successful. In the past, 9,10-dihydroxyanthracene • was therefore produced exclusively by reduction. Even though approximately 20 % anthraquinone is still obtained, the success of the process according to the invention is nevertheless surprising.
A common industrial grade anthracene, such as that made available by Rutgers Chemicals AG, for example, can be used as starting material. This has a purity of approximately 96 % and contains phenanthrene (2 % by weight), carbazole ( The carboxylic acid medium can be formed by formic acid, acetic acid, glacial acetic acid, propionic acid, isopropionic acid, their mixtures, other low organic monocarboxylic acids or
dicarboxylic acids and their acid anhydrides. Adipic acid, maleic acid, and phthalic acid, for example, are suitable dicarboxylic acids. A mixture of acid and acid anhydride is particularly suitable. If necessary, the acids can be present in organic solvents. According to a particularly preferred embodiment, the carboxylic acid medium is a mixture of glacial acetic acid and acetic anhydride. The carboxylic acid medium should be as anhydrous as possible. A water content of up to approximately 1 % in the carboxylic acid medium is harmless.
The catalytic system used according to the invention contains an activated organic metal salt. The metal salts of the above-mentioned carboxylic acids forming the carboxylic acid medium are suitable organic metal salts. Metals particularly suitable for the formation of metal salt are the transition metals in the higher oxidation stage, +III, IV, V, VI and VII. Preferred salts are those of manganese, cobalt, molybdenum, nickel, zirconium and hafnium in the oxidation numbers mentioned above. Manganese and cobalt are particularly preferred.
Manganese acetate and cobalt acetate or manganese carbonate, for example, are preferred organic metal salts.
Preferably, the metal salts are used in concentrations of 0.0005 to 0.2 mole/1, preferably 0.002 to 0.05 mole/1.
The activation of the metal salts takes place by means of a suitable activating agent. Bromides, iodides or chlorides, for example, are activating agents. Bromides are particularly preferred. The activating agents in the form of the above-mentioned halides can be used as metal salts or as organic halides. Alkali metal bromide and alkaline earth metal bromide as well as ammonium bromide, for example, are suitable metal halides. Trimethyl text, butyl ammonium bromide, methane tribromide (bromoform), acetylene tetrabromide and phenyl bromide, for example, are suitable organic bromides. Sodium

bromide and ammonium bromide are particularly preferred activating agents for the metal salt.
The activating agent can be contained in the reaction mixture in a concentration of 0.001 to 0.5 mole/1, preferably 0.002 to 0.1 mole/1.
Preferably, the activated organic metal salt or a mixture of metal salts and the activating agent are used in a weight ratio of 0.8:1 to 1:0.8, preferably approximately 1:1.
The process according to the invention can be carried out batchwise or continuously in a standard stirred reactor.
According to the process of the invention, anthracene and the catalytic system are suspended in the carboxylic acid medium. This can take place at room temperature. With a supply of oxygen and access of light, the process according to the invention can be carried out within a temperature range of preferably 40 to 100 °C, preferably 55 to 85 °C. Oxygen is supplied preferably in the gaseous form, particularly preferably as essentially pure oxygen. The reaction period can be 3 to 24 hours.
The precipitate forming during the reaction can be separated off from the reaction liquor. After a 14 hour reaction at 60°C in an acetic acid/acetic anhydride medium, this precipitate comprises, for example, 70 to 72 % by weight of 9-acetoxy-10-hydroxyanthracene as the main oxidation product. In addition, anthraquinone (20 % by weight), phenanthrene (2 % by weight), 9-anthrone (4 % by weight) and smaller quantities (less than 1 % by weight) of unreacted anthracene are detected in the precipitate.
Separating off the precipitate can take place by sedimentation, centrifuging and/or filtration. The separation of the precipitate takes place preferably at room temperature.

The crude anthraquinone contained in the precipitate can be recrystallised from one of the carboxylic acids used, e.g. acetic acid. It is then present with a purity of more than 99.2 % by weight. The yield of anthraquinone, based on anthracene, is approximately 20 %.
The liquid remainder after separating off the precipitate is then concentrated either under vacuum or treated with a precipitating agent such as water. In order to convert the 9-carboxy-10-hydroxyanthracene into a 9,10-dihydroxyanthracene carboxylic acid ester resistant to oxidation, the enriched intermediate can additionally be treated with a carboxylic anhydride such as acetic anhydride. This treatment can take place in the presence of bases such as pyridine or sodium acetate. In this way, the complete conversion of 9-carboxyl-10-hydroxyanthracene to 9,10-diacetic carboxyanthracene is achieved.
In order to remove residual quantities of anthraquinone from the product, a metal such as zinc or aluminium preferably in powder form, can be added to the liquid remainder after separating off the precipitate. If a mixture of acetic acid/acetic anhydride is used as the carboxylic acid medium, the product is isolated from the reaction mixture by crystallisation in the form of yellow needles with a melting point 272 °C. The purity of the product is higher than 99.5 %. The yield of 9,10-diacetoxyanthracene is 67 %, based on anthracene.
9,10-Dihydroxyanthracene carboxylic acid esters obtainable according to the invention are 9,10-dialkyl carboxyl oxyanthracenes, 9,10-alkyl aryl carboxyl oxyanthracenes and 9,10-diaryl carboxyl oxyanthracenes, in which alkyl may represent a hydrocarbon group with 1 to 8 carbon atoms and aryl a substituted or unsubstituted aromatic hydrocarbon radical with 5 to 14 carbon atoms.
The following example serves as a further explanation of the
invention.
EXAMPLE
20 ml of acetic acid (pure), 30 ml of acetic anhydride, 2.5 g of industrial grade anthracene, 0.08 g of manganese carbonate (pure) and 0.08 g of sodium bromide are introduced into a round-bottom three-necked flask with a capacity of 150 ml equipped with a magnetic stirrer, thermometer, oxygen supply and reflux condenser. The mixture is heated to 60 °C with stirring and continuous gasification with oxygen (10 ml/min) and oxidised for 24 hours. The reaction mixture is examined by gas chromatography for its chemical composition after a 10 hour and 14 hour reaction respectively. The results of this investigation are shown in the table.
The reaction is considered completed when the proportion of unreacted anthracene is less than 1 % by weight. After cooling of the reaction mixture to room temperature, 0.8 g of crude anthraquinone are filtered off and recrystallised from 30 ml acetic acid. The anthraquinone has a purity of 99,6 %.
The filtrate concentrated under vacuum (40 kPa) with a water jet pump is treated by adding 5 ml of acetic anhydride, 7 g of pyridine and 2 g of zinc powder for 30 minutes at room temperature. Solid 9,10-diacetoxyanthracene is separated off as the reaction product and recrystallised from acetic acid. The product is isolated in the form of yellow needles with a melting point of 272 °C. The yield is 77 % of the theoretical, the overall yield of anthraquinone and 9,10-diacetoxyanthracene exceeds 95 % of the yield achievable theoretically.
The results summarised in the following table show the composition of the product after a 10 hour and 14 hour reaction using acetic acid/acetic anhydride as carboxylic acid medium.
Table
(Table Removed)



We Claim:
1. A process for the production of 9,10-dihydroxyanthracene carboxylic acid ester by the catalytic oxidation of anthracene, characterised in that anthracene is treated in the liquid phase in a carboxylic acid medium selected from lower organic mono or dicarboxylic acids and their anhydrides in the presence of an organic metal salt selected from transition metals in the oxidation states +III, IV, VI, and VII and an activating agent for the metal salt selected from bromides, iodides or chlorides at a temperature of 40 to 100°C, subject to the action of oxygen and light, the precipitate is separated off, the liquid remainder is treated with an esterification agent selected from lower organic mono or dicarboxylic" acids and their anhydrides and the ester obtained from the reaction mixture is isolated.
2. The process as claimed in claim 1, wherein a mixture of acetic
acid and acetic anhydride is used as the carboxylic acid
medium.
3. The process as claimed in claim 1 or 2, wherein an activated
organic metal salt or a mixture of metal salts and' activating
agent are used as the catalytic system.
4. The process as claimed in claims 1 to 3, wherein maganese
acetate or cobalt acetate or their mixtures are used as organic
metal salt.
5. The process as claimed in one of claims 1 to 4, wherein an
inorganic bromide such as sodium bromide or ammonium
bromide or an organic bromide such as trietyl tert-butyl
ammonium bromide is used as activating agent.
6. The process as claimed in one of claims 1 to 5, wherein the
liquid remainder is concentrated.
7. The process as claimed in claim 6, wherein the concentrated
medium is treated with a carboxylic anhydride as esterification
agent and, if necessary, a base.
8. The process as claimed in one of claims 1 to 7, wherein the
precipitate separated off is recrystallised from a carboxylic acid.
9. A process for the production of 9,10-dihydroxyanthracene
carboxylic acid ester substantially as herein described with
reference to the foregoing examples.

Documents:

1583-del-2003-abstract.pdf

1583-del-2003-claims.pdf

1583-del-2003-correspondence-others.pdf

1583-del-2003-correspondence-po.pdf

1583-del-2003-description (complete).pdf

1583-del-2003-form-1.pdf

1583-del-2003-form-19.pdf

1583-del-2003-form-2.pdf

1583-del-2003-form-3.pdf

1583-del-2003-form-5.pdf

1583-del-2003-gpa.pdf

1583-del-2003-petition-137.pdf


Patent Number 211363
Indian Patent Application Number 1583/DEL/2003
PG Journal Number 45/2007
Publication Date 09-Nov-2007
Grant Date 26-Oct-2007
Date of Filing 19-Dec-2003
Name of Patentee RUTGERS CHEMICALS AG
Applicant Address KEKULESTRASSE 30, 44579 CASTROP-RAUXEL,GERMANY.
Inventors:
# Inventor's Name Inventor's Address
1 JERZY POLACZEK PASAZ URSYNOSKI 3 M. 56, PL-02784 WARSZAWA, POLAND.
2 WOJCIECH DOMANOWSKI UL. TORUNSKA 78M. 22, PL-03226 WARSZAWA, POLAND.
3 JAN PIELICHOWSKI UL. ZAKATEK 5 M. 60, PL-30076 KRAKOW, POLAND.
4 ZOFIA MACHOWSKA UL. CZECHOWA 2 M. 192, PL-01912 WARSZAWA, POLAND.
5 EDGAR FUHRMANN FRIEDENSTRASSE 13, D-44579 CASTROP-RAUXEL, GERMANY.
6 JORG TALBIERSKY WACHTELSTRASEE 9, D-46282 DORSTEN, GERMANY.
PCT International Classification Number C07C 67/08
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 102 60 550.5 2002-12-21 Germany