Title of Invention	A PROCESS FOR THE PREPARATION OF AN ELECTRODE USEFUL FOR ELECTROCATALYTIC OXIDATION OF ALKENES
Abstract	This invention relates to a process for the preparation of an electrode useful for electrocatalytic oxidation of alkenes. More particularly it relates to modification of metallic anode using conducting polymers having appropriate composition which can be used for electro-oxidation of alkenes.

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This invention relates to a process for the preparation of an electrode useful for electrocatalytic oxidation of alkenes. More particularly it relates to modification of metallic anode using conducting polymers having appropriate composition which can be used for electro-oxidation of alkenes. Oxidation of alkenes to ketones, alcohols etc. using different types of catalysts such as palladium or ruthenium complexes has been known for several years (Synthesis, 7, 739, 1990). However, these type of reactions usually take place efficiently at high temperatures. Since high pressure builds up during the process, such reactions are carried out in closed high pressure reactors. This leads to hazardous conditions due to possibilities of explosion. Hence, it is desirable to carry out such reactions at normal ambient conditions, which can be feasible by electrochemical methods. The electro-oxidation of alcohols using carbon or graphite electrodes has been reported before (Electrochim. Acta, 44(15), 1999 p.2559-2569) but the currents are not very high and the yield is poor when used for alkenes such as hexene or decene. In order to increase the electrode activity it is essential to modify the same and preferably make it electrocatalytic so that high yield and selectivity are obtained for alkenes. Such modifications have not been reported before for alkene oxidation processes using metallic or other electrodes . The main object of the present invention is to provide a process for preparation of electrodes useful for electrocatalytic oxidation of alkenes so as to make the electrodes more efficient. Accordingly, the present invention provides a process for the preparation of an electrode useful for the electrocatalytic oxidation of alkenes, which comprises pre-coating an insulating substrate with a polymer by dipping the said insulated substrate in a polymer solution made in an organic solvent, coating the above said pre-coated substrate with a metallic layer by known methods, coating electrochemically the above said metal pre-coated insulating substrate with a conducting polymer using a monomer, or a mixture of the monomer and a macrocyclic compound, optionally doping the above said conducting polymer coated substrate with a doping agent in a concentration ranging between 0.001 M to 0.1 M to obtain the desired modified electrode. In an embodiment of the present invention the insulating substrate used is selected from glass plate, polyester film having smooth surface having electrical resistivity higher than 10 10 ohm-cm. In yet another embodiment the polymer used for pre-coating the insulating substrate is selected from the group consisting of polyvinyl butyral, polyvinyl acetate and styrene butadiene co-polymere having adhesion strength higher than 10 g/micron . In yet another embodiment the concentration of polymer solution used for pre-coating is in the range of 1 to 2 % wt./v. In yet another embodiment the organic solvent used for preparing polymer solution is selected from methanol, and toluene. In yet another embodiment the metallic layer used is selected from gold, platinum and chromium. In yet another embodiment the macrocyclic compound used is selected from the group consisting of phthalocyanine, porphyrin and their substituted derivatives. In yet another embodiment the doping agent used is selected from the group consisting of copper chloride, ferric chloride, cobalt chloride and similar Lewis acid compounds. - In yet another embodiment the concentration of doping agent used prereferably in the range of 0.006 M to 0.012 M. In still another embodiment the monomer used for depositing conducting polymer film is an aromatic or heterocyclic compound containing nitrogen selected from the group consisting of aniline, pyrrole, anisidene, and toluediene. The process of the present invention is described herein below with examples, which are illustrative only and should not be construed to limit the scope of the invention in any manner. EXAMPLE -1 Clean microscopic grade glass slides were dip coated in a solution (1.0 wt%) of polyvinyl butyral in methanol, dried and heated to 60 °C for few minutes to drive off the solvent. These were placed in a vacuum deposition chamber, which was evacuated to 10"6 torr and gold films (0.1 to 0.2 um thick) were deposited using thermal evaporation technique. The substrates with metallic coating were placed in an electrochemical cell as working electrode, platinum foil as counter electrode and SCE reference electrode. The electrolyte was a mixture of deionised water (100 ml) and n-methyl pyrrolidone (100 ml) with 8 ml hydrochloric acid (35%) with 4 ml aniline and 0.04 gm copper phthalocyanine . The conducting polymer deposition was carried out by applying a potential of 0.9V (Saturated standard Calomel Electorde) for 180 seconds. The modified electrodes were removed and dried at 25 °C for 2 to 3 hours. EXAMPLE -2 The clean microscopic glass plates were dip coated in a solution (1.0 wt%) of styrene-butadiene copolymer in toluene and dried at 50 ° C for 10 min. These were placed in a vacuum chamber, which was evacuated to 10 ~ 6 torr and gold films deposited by thermal evaporation technique. These were then placed in the electrochemical cell with platinum counter electrode and SCE reference electrode . The electrolyte used consisted of 100 ml water ( deionised), 100 ml n-methyl pyrrolidone, 8 ml hydrochloric acid (35%), 4 ml aniline and 0.08 gm copper phthalocyanine. The conducting polymer deposition was carried out by applying a potential of 0.9V (SCE) for 180 s. The electrodes were removed, dried at room temperature and then used for electro-oxidation reaction. EXAMPLE-3 Clean microscopic grade glass slides were dip coated in a solution (1.0 wt%) of polyvinyl butyral in methanol, dried and heated to 60 °C for few minutes to drive off the solvent. These were placed in a vacuum deposition chamber which was evacuated to 10-6 torr and gold films (0.1 to 0.2 um thick) were deposited using thermal evaporation technique. The substrates with metallic coating were placed in an electrochemical cell as working electrode, platinum foil as counter electrode and SCE reference electrode. The electrolyte was 200 ml water (deionised), 8 ml hydrochloric acid (35%), 4 ml aniline. The conducting polymer deposition was carried out by applying a potential of 0.9V (SCE) for 180 s. The modified electrodes were removed and dried at 25 C for 4our hours. These were then dipped in the methanolic solution of palladium chloride (0.006 molar) for 30 minutes and then dried at room temperature for few hours. The main advantage of the present invention is that it makes use of much cheaper material than metals / metallic complexes based on palladium, ruthenium, platinum etc. It also gives better results than the latter compounds. The anodic currents at 0.5 V (SCE) for oxidation of 0.1 M decene were found to be 5000 (aA, 20000 pA, 8000 ^A for electrodes illustrated in examples 1, 2 and 3 respectively as compared to 100 for bare unmodified metal electrodes. We claim A process for the preparation of an electrode useful for the electrocatalytic oxidation of alkenes, which comprises pre-coating an insulating substrate with a polymer by dipping the said insulated substrate in a polymer solution made in an organic solvent, coating the above said pre-coated substrate with a metallic layer by known methods, coating electrochemically the above said metal pre-coated insulating substrate with a conducting polymer using a monomer, or a mixture of the monomer and a macrocyclic compound, optionally doping the above said conducting polymer coated substrate with a doping agent in a concentration ranging between 0.001 M to 0.1 M to obtain the desired modified electrode. A process as claimed in claim 1 wherein the insulating substrate used is selected from glass plate, polyester film having smooth surface having electrical resistivity higher than 10 10 ohm-cm. A process as claimed in claims 1&2, wherein the polymer used for pre-coating the insulating substrate is selected from the group consisting of polyvinyl butyral, polyvinyl acetate and styrene butadiene co-polymere having adhesion strength higher than 10 g/micron . A process as claimed in claims 1-3, wherein the concentration of polymer solution used for pre-coating is in the range of 1 to 2 % wt./v. A process as claimed in claims 1-4, wherein the organic solvent used for preparing polymer solution is selected from methanol, and toluene. A process as claimed in claims 1-5, wherein the metallic layer used is selected from gold, platinum and chromium. A process as claimed in claims 1-6, wherein the macrocyclic compound used is selected from the group consisting of phthalocyanine, porphyrin and their substituted derivatives. A process as claimed in claims 1-7, wherein the doping agent used is selected from the group consisting of copper chloride, ferric chloride, cobalt chloride and similar Lewis acid compounds. A process as claimed in claims 1-8, wherein the concentration of doping agent used prereferably in the range of 0.006 M to 0.012 M. A process as claimed in claims 1-9, wherein the monomer used for depositing conducting polymer film is an aromatic or heterocyclic compound containing nitrogen selected fro the group consisting of aniline, pyrrole, anisidene, and toluediene. A process for the preparation of an electrode useful for electrocatalytic oxidation of alkenes, substantially as herein described with reference to examples accompanying this specification.

Documents:

152-DEL-2002-Abstract (09-10-2007).pdf

152-del-2002-abstract.pdf

152-DEL-2002-Claims (09-10-2007).pdf

152-DEL-2002-Claims-(13-06-2008).pdf

152-del-2002-claims.pdf

152-DEL-2002-Correspondence-Others (09-10-2007).pdf

152-DEL-2002-Correspondence-Others-(13-06-2008).pdf

152-del-2002-correspondence-others.pdf

152-del-2002-description (complete)-13-06-2008.pdf

152-del-2002-description (complete).pdf

152-DEL-2002-Form-1 (09-10-2007).pdf

152-del-2002-form-1.pdf

152-del-2002-form-18.pdf

152-del-2002-form-2.pdf

152-DEL-2002-Form-3 (09-10-2007).pdf

152-del-2002-form-3.pdf