Title of Invention

"AN ELECTROCHEMICAL PROCESS FOR THE PREPARATION OF ORTHO CHLOROBENZYLAMINE"

Abstract

An electrochemical process for preparation of ortho chlorobenzylamine by reducing ortho chloro benzonitrile electrochemically in a divided cell consist of deposited cathodes like Nickel black, Cobalt black or iron black over graphite, at a cathode current density of 2-10 A/dm2, in 30-70% aqueous ethanol containing 0.5-5% o-Chlorobenzonitrile in 5-15% sulphuric acid as catholyte and lead placed inside porous pot as anode with 5-15% sulphuric acid as anolyte at a temperature of 35-40°C, separating o-Chlorobenzylamine by conventional extraction method using diethyl ether.

Full Text

The present invention particularly relates to an electrochemical process for the preparation of o- Chlorobenzylamine (OCBA) from o-Chlorobenzonitrile (OCBN). o-Chlorobenzylamine is used as analgesic, antihypertensive, antitumor active, blood stream disorder disease remedy, anticoagulant, antifolate agent, anticholestermic agent, microbicide, for angina treatment, haemorrhagic stroke treatment and to improve cognitic function. Hitherto o-Chlorobenzylamine has been prepared by reduction of o-Chlorobenzamide using Lithium aluminium hydride (yield 59 % - Ref.: JACS 1959, 81, 3728), (ii) amination of o-Chlorobenzylchloride using hexamethylene tetramine as a reagent (yield 44% - Ref.: CA 110, 23511). These methods involve the use of either costly reagent or reagents, which generate pollution problem. The present electrochemical method avoids these problems. More over high pressure generating equipment are not necessary in electrochemical method, which is required in conventional catalytic methods. As the o-Chlorobenzylamine has the industrial importance it has been attempted to prepare o-Chlorobenzylamine by electrochemical method. The best condition arrived at for the preparation of o-Chlorobenzylamine from o-Chlorobenzonitrile has been described in this patent. Till now no one has attempted to prepare o-Chlorobenzylamine from o-Chlorobenzonitrile by electrochemical method. The novelty of this patent lie in the electro reduction of nitrile group to amino group using the catalytic cathode - namely deposited nickel black. The main objective of this invention is to develop an electrochemical method for the preparation of o-Chlorobenzylamine from o-Chlorobenzonitrile employing nickel black over graphite as cathode. Accordingly the present invention relates to an electrochemical process for the preparation of o-Chlorobenzylamine by reducing o-Chlorobenzonitrile in a divided cell consists of deposited cathodes like Nickel black, Cobalt black or iron black over graphite, at a cathode current density of 2-10 A/dm2, in 30-70 % aqueous ethanol containing 0.5 - 5% o-Chlorobenzonitrile in 5-15% sulphuric acid as catholyte and a lead placed inside porous pot as anode with 5-15% sulphuric acid as anolyte at a temperature of 35-40°C. The deposition procedure of Nickel black, cobalt black & iron black is reported in the literature. [ V.Krishnan, A.Muthukumaran, K.Raghupathy and H.V.K.Udupa, J.Chem. Tech. Bio-Tech, 29 (1979) 163 & V.Krishnan and A.Muthukumaran, J.of Appl. Electrochem, 9. (1979) 657]. In the present approach a simple technique which involves a combination of insitu electrochemical generation of pure hydrogen and its adsorption on a deposited nickel black cathode acting as the catalyst is adopted. In an electrochemical method, the pure hydrogen is made available insitu and hence the cathode acting as a catalyst is always fresh and active. o-Chlorobenzonitrile (0.5 - 5%) dissolved in 30 - 70% aqueous ethanol containing sulphuric acid (5-15% ) is used as catholyte. Deposited nickel black, cobalt black or iron black over graphite plate was used as a cathode. Lead plate kept inside a ceramic porous pot on either side of the cathode was used as anode. The catholyte was agitated by a glass stirrer and the temperature of the catholyte was maintained around 35-40°C, current density ranging from 2 to 10 A / dm2 were employed during electrolysis. As the yield of the o-Chlorobenzylamine was found to be low for theoretical current (4 Faraday /mole) the electrolysis was continued upto twice the theoretical current. After the electrolysis the reaction solution was distilled to remove ethanol and then the aqueous portion was extracted with an organic solvent to remove the unreacted nitrile. After removal of the nitrile the aqueous portion was basified with sodium hydroxide to liberate the free base which was extracted with an organic solvent diethyl ether. The organic layer was dried over sodium sulphate and then distilled to get the amine. The novelty of the process is in the electro reduction of the nitrile group using the catalytic cathodes like deposited nickel black, cobalt black and iron black. This electrochemical method has the following advantages • Always electrode is fresh and active in this method • No poisoning of electrode • Cheap raw materials (when compared to lithium aluminium hydride and hexamethylenetetramine) are used in this route. • Hazardous reagents are avoided • Reduction can be carried out at room temperature and at normal pressure. The following examples are given by way of illustration of the present invention and should not be construed to limit the scope of the invention. Example: 1 Cathode : Nickel black over graphite (Area: 0.8 dm2) Anode : Lead (Area: 0.2 dm2) Anolyte : 10 % aqueous sulphuric acid -100 ml Catholyte : 50 % aqueous ethanol containing 10 % sulphuric acid and 1 % o-Chlorobenzonitrile - 500 ml Diaphragm : Ceramic porous pots Temperature : 40° C Current density : 5 A/ dm2 Quantity of electricity : Theoretical current (4 faraday) Cell voltage : 5.0 V Current efficiency : 48 % Yield of o-Chlorobenzylamine 48% Example : 2 Cathode Anode Anolyte Catholyte Diaphragm Temperature Current density Quantity of electricity Cell voltage Current efficiency Yield of o-Chlorobenzylamine Example : 3 Cathode Anode Anolyte Catholyte Diaphragm TemperatureNickel black over graphite (Area: 0.8 dm2) Lead (Area: 0.2 dm2) 10 % aqueous sulphuric acid -100 ml 50 % aqueous ethanol containing 10 % sulphuric acid and 1 % o-Chlorobenzonitrile - 500 ml Ceramic porous pots 40° C 5 A / dm2 twice the theoretical current (8 faraday) 5.0V 42% 83% Nickel black over graphite (Area: 0.8 dm2) Lead (Area: 0.2 dm2) 10 % aqueous sulphuric acid -100 ml 50 % aqueous ethanol containing 10 % sulphuric acid and 1 % o-Chlorobenzonitrile - 500 ml Ceramic porous pots 40° C Current density Quantity of electricity Cell voltage Current efficiency Yield of o-Chlorobenzylamine Example 4: Cathode Anode Anolyte Catholyte Diaphragm Temperature Current density Quantity of electricity Cell voltage Current efficiency Yield of o-Chlorobenzylamine3 A / dm2 twice the theoretical current ( 8 faraday) 3.5V 37% 62% Cobalt black over graphite (Area: 0.8 dm2) Lead (Area: 0.2 dm2) 10 % aqueous sulphuric acid -100 ml 50 % aqueous ethanol containing 10 % sulphuric acid and 1 % o-Chlorobenzonitrile - 500 ml Ceramic porous pots 40° C 5 A / dm2 Theoretical current (4 faraday) 5.0V 18. 5 % 18.5% Example 5: Cathode Anode Anolyte Catholyte Diaphragm Temperature Current density Quantity of electricity Cell voltage Current efficiency Yield of o-Chlorobenzylamine Iron black over graphite (Area: 0.8 dm ) Lead (Area: 0.2 dm2) 10 % Sulphuric acid -100 ml 50 % aqueous ethanol containing 10 % sulphuric acid and 1 % o-Chlorobenzonitrile - 500 ml Ceramic porous pots 40° C 5 A / dm2 Theoretical current (4 faraday) 5.0V 20% 20% We c laim: 1. An electrochemical process for preparation of ortho chlorobenzylamine which comprises reducing ortho chloro benzonitrile electrochemically in a divided cell consist of deposited cathodes like Nickel black, Cobalt black or iron black over graphite, at a cathode current density of 2-10 A/dm2, in 30-70% aqueous ethanol containing 0.5-5% o-Chlorobenzonitrile in 5-15% sulphuric acid as catholyte and lead placed inside porous pot as anode with 5-15% sulphuric acid as anolyte at a temperature of 35-40°C, separating o-Chlorobenzylamine by conventional extraction method using diethyl ether. 2. A process as claimed in claims 1 to 3 wherein the operating current density is 5 A/dm2. 3. An electrochemical process for the preparation of ortho chlorobenzylamine substantially as herein described with reference to the examples.

Documents:

282-del-2001-abstract.pdf

282-del-2001-claims.pdf

282-del-2001-correspondence-others.pdf

282-del-2001-correspondence-po.pdf

282-del-2001-description (complete).pdf

282-del-2001-form-1.pdf

282-del-2001-form-18.pdf

282-del-2001-form-2.pdf