Title of Invention

"AN IMPROVED PROCESS FOR THE PREPARATION OF BIS (PICOLYL) AMINES"

Abstract

This invention relates to an improved process for the preparation of macroporous bis(picolyl) amine polymers useful for the selective removal of metal ion application. The macroporous bis (picolyl) amine polymers prepared by the process of this invention are useful in selective removal of metal ions in mixed stream of other metal ions. These type of polymers are also referred to as chelating polymers.

Full Text

This invention relates to an improved process for the preparation of bis(picolyl) amines useful for the selective removal of metal ion application. The bis(picolyl) amines having general formula 1 in the drawing accompanying this specification wherein R = (2-picolyl), (3-picolyl) prepared by the process of this invention are useful in selective removal of metal ions in mixed stream of other metal ions. The bis(picolyl) amines prepared by the process of this invention can be further reacted under suitable reaction conditions with macroporous polymer to prepare new chelating polymers useful in the selective removal of capper ions in mixed streams of other metal ions such as nickel, iron and the like. Selective removal of metal ions are useful in mining and easing environmental problems such as pollution due to metal ion contamination in a stream. In the hydrometal lurg ica'J. applications to remove copper from ores, use of chelating resins with specific copper ion selectivity is desired. The selectivity is desired in mixed stream of other metal ions to be economically viable. Although chelating resins for the selective removal of copper ions in mixed stream are known, the disadvantages are in terms of higher selectivity, choice of pH in these operations and the overall process economics. In mining operations, dilute solutions of copper are obtained when in-situ acid leaching of the ores is carried out. The pH of the solution is in the acidic range (pH 3 or less). Microbial leaching leads to pH of the solution in the range of 3 to 6. One of the important criteria for the effective use of the chelating ligand is that it should be possible to bind it onto polymer support for more efficient use. The chelating ligand should be stable during operation of incorporation onto the polymer matrix. There should also be no loss of activity or selectivity so the effective chelating capacity is retained. The known process for the synthesis of bispicolyl amines involves the use of expensive chloromethyl pyridine hydrochloride. This material is also not a very stable compound. The object of the present invention is to provide an improved process for the preparation of novel bis(picolyl) amines useful in selective removal of copper ions in mixed stream containing other metal ions in acidic pH range. Another objective of the present invention is to provide a process for the preparation of novel bis(picolyl) amines that overcomes the drawbacks cited above. Accordingly, the present invention provides an improved process for the preparation of bis (picolyl) amine, which comprises; characterised in that reacting 2-/3-picolyl amine with the 2-/3-pyridine carboxaldehyde in the ratio of 1:1 (w/w) in dry alcohol, in the presence of conventional drying agent at a temperature in the range of 25 to 35°C, for a period ranging from 60 to 90 minutes, filtering the solution to remove the drying agent, concentrating the solution by removing alcohol under reduced pressure to get the N-2/3-pyridylidene-pyridine-2/3- methanamine, dissolving the N-2/3-pyridylidene-pyridine-2/3-methanamine in a polar solvent in the presence of a reducing agent as herein described, at a temperature in the range of 25 to 150°C, filtering the mixture, removing the alcohol under reduced pressure, adding dilute hydrochloric acid to bring the pH to 4 to get the trihydrochloride, dissolving the precipitate in water, neutralising the solution using an alkali metal bicarbonate, extracting with an aliphatic chlorinated solvent and removing aliphatic chlorinated solvent under reduced pressure to get the bis (picolyl) amines. In an embodiment of the present invention, the picolyl amine used may be such as 2-picolyl amine, 3-picolyl amine. In another embodiment of this invention, the corresponding pyridine carboxaldehyde used may be such as 2-pyridine carboxaldehyde, 3-pyridine carboxaldehyde. In yet another embodiment of this invention the polar solvent used may be such as an alcohol selected from methanol, ethanol, isopropanol or a polar aprotic solvent such as tetrahydrofuran. In another feature of the invention, the drying agent used may be such as molecular sieves, magnesium sulphate, sodium sulphate, In yet another embodiment of the invention, the reducing agent used may be alkali metal borohydride selected from sodium borohydride, sodium borocyanide, lithium aluminium hydride or hydrogen under pressure in the range of 150 to 22.0 J ^si in presence of catalyst such as freshly prepared Raney nickle catalyst, pallidium cat'bon. In yet another feature of the invention , the chlorinated solvent used is selected from dichloromethane, chloroform, dichlo-roethane and the like. The invention is described with reference to the examples given below which are illustrative in nature and should not be construed to limit the scope of this invention. Example 1 1.0.8 gram of 2-picolyl amine was dissolved in 75.0 ml absolute ethanol and was stirred with 4.0 gram of anhydrous magnesium sulphate. To this stirred mixture 10.7 gram 2-pyridine carbox- aldehyde in 75.0 ml ethanol was added and stirred for one o hour at 25 C. The N-2-pyridylidene-pyridine-2-methanamine obtained was filtered off and concentrated under vacuum. The yield obtained was 19.7 gram. 19.7 gram of N-2-pyridy1idene-pyridine-2-methanamine prepared as described by the example given above, was dissolved in 100.0 ml ethanol and 25.0 ml distilled water and the solution was stirred. To this stirred solution 5.4 gram of sodium borohydride in 25.0 ml distilled water was added. The reaction o was allowed to continue at a temperature of 25 C. After 12 hours, additional 1.8 gram of sodium borohydride was added and the reaction was continued for a total period of 24 hours. The crude bis Example 2 10.8 gram of 2-picolyl amine was dissolved in 75.0 ml absolute ethanol and was stirred with 2.5 gram of molecular sieves. To this stirred mixture 10.7 gram 7-pyridine carboxaldehyde in 75.0 o ml ethanol was added and stir-red for one hour at 30 C. The N—2— pyridy1idene-pyridine-2-methanamine obtained was filtered off and concentrated under vacuum. The yield obtained was 19.7 gram. 19.7 gram of N-2-pyridy1idene-pyridine-2-methanamine prepared as described in the above example, was dissolved in 100.0 ml tetrahydrofuran and to the stirred solution 5.4 gram of sodium borohydride was added gradually over two hours. The reaction o was allowed to continue at a temperature of 30 C for a period of 24 hours. The crude bis(2-picoLy1) amine was filtered out, concentrated and extracted with chloroform. The bis(2- picolyl) amine was precipitated as the trihydrochloride by the addition of hydrochloric acid solution till the pH reached 4. The bis(2-picolyl) amine trihydrochloride was dissolved in water, neutralised with sodium bicarbonate and extracted with chloroform and concentrated by removing chloroform under reduced pressure to obtain pure bis(2-picolyl amine). The yield obtained was 11.5 gram. Example 3 5.4 gram of 3-picolyl amine was dissolved in 40.0 ml absolute ethanol and was stirred with 2.1 gram of anhydrous magnesium sulphate. To this stirred mixture 5.4 gram of 3-pyridine carboxaldehyde in 35.0 ml ethanol was added and stirred for o one hour at a temperature of 35 C. The N-3-pyridy1idene-pyridine- 3-methanamine obtained was filtered off and concentrated under vacuum. The yield was quantitative and was 9.8 gram. 9.8 gram of N-3-pyridylidene-pyridine-3-methanamine prepared as per the example described above was dissolved in 60.0 ml ethanol and 15.0 ml distilled water and to the stirred solution 2.75 gram of sodium borohydride in 12.5 ml distilled water was o added. The temperature of the reaction was maintained at 35 C. After 12 hours 1.35 gram sodium borohydride was added again and the reaction was continued for 24 hours. The crude bis(3-picolyl) amine was filtered out, concentrated and extracted with chloroform. The bis(3-picoly1) amine was precipitated as trihydrachloride by bringing the pH of the solution to 4 with dilute hydrochloric acid. The bis(3-picoly1) amine trihydrochloride was dissolved in water, neutralised with sodium bicarbonate and extracted with chloroform and concentrated by removal of chloroform under reduced pressure to get pure b is (3--picolyl ) amine. The yield obtained was 6.2 gram. Example 4 10.8 gram of 3-picolyl amine was dissolved in 75.(3 ml absolute ethanol and was stirred with 2.5 gram of molecular sieves. To this stirred mixture 10.7 gram of 3™pyridine carboxaldehyde in 75 ml ethanol was added and stirred for one hour at a temperature o of 35 C. The N-3-pyridy1idene-pyridine-3-methanamine obtained was filtered off and concentrated under vacuum. The yield obtained was 19.7 gram. 19.7 gram of N-3-pyrdylidene pyridine-3-me thanamine prepared as described by the above example was dissolved in 100.0 ml tetrahydrofuran and the solution stirred. To this solution 5.4 gram sodium borohydrids was added over two hours. The reaction was continued for 24 hours. The temperature of the reaction was o maintained at 35 C. The bis(3-picolyl) amine was filtered out, concentrated and extracted with chloroform. The bis(3-picolyl) amine was precipitated as the trihydrochloride by bringing the pH of the solution to 4 with dilute hydrochloric acid. The bis(3-picolyl) amine trihydrochloride was dissolved in water, neutralised with sodium bicarbonate and extracted with chlorofarm and concentrated by the removal of chloroform under reduced pressure to get pure bis(3-picolyl) amine. The yield obtained was 13.5 g. Example 5 1.0.8 grams of 2-picolyl amine was dissolved in 75.0 ml absolute ethanol and was stirred with 4.0 grams of anhydrous magnesium sulphate. To this stirred mixture 10.7 grams 2-pyridine carboxaldehyde in 75.0 ml ethanol was added and stirred for o one hour at 25 C. The N-2-pyridy1idene-pyridine-2-methanamine obtained was filtered off and concentrated under vacuum. The yield obtained was 19.7 grams. 19.7 grams of N-2-pyridylidene-pyridine-2-methanamine prepared as per the example described above was dissolved in 150.0 ml dry ethanol and was added to a 300 ml pressure reactor. 2.0 grams of freshly prepared Raney nickel catalyst was added and the reactor was filled with hydrogen under pressure till it reached a pressure of 150 psi. The reaction was allowed to proceed at o 100 C for three hours. The catalyst was filtered off and the crude bis solvent under vacuum. Addition of dilute hydrochloric acid precipitated the bis(2-picoly1) amine as the trihydrochloride. The precipitate was dissolved in water, neutralised with sodium bicarbonate solution, extracted with dichloromethane. The organic layer was separated and dichloromethane was removed by distillation under reduced pressure to get pure bis(2-picolyl) amine. The yield obtained was 8.0 grams. Example 6 10.8 grams of 2-picolyl amine was dissolved in 75.0 ml absolute ethanol and was stirred with 2.5 grams of molecular sieves. To this stirred mixture 10.7 grams 2-pyridine carbaxaldehyde in 75.0 ml ethanol was added and stirred for one o hour at 30 C. The IM-2-pyridy 1 idene-pyr id ine-2-methanamine obtained was filtered off and concentrated under vacuum. The yield obtained was 19.7 grams. 19.7 grams of N-2-pyridylidene-pyridine-2-methanamine prepared as per the example described above was dissolved in 150 ml dry methanol and was added to a 300.0 ml pressure reactor. 2.2 grams of freshly prepared Raney nickel catalyst was added and the reactor was filled with hydrogen under pressure till it reached a pressure of 180 psi. The reaction was allowed to o proceed at 120 C for three hours. The catalyst was filtered off and the crude bis(2-picoly1) amine was concentrated by removing the solvent under vacuum. Addition of dilute hydrochloric acid precipitated the bis(2-picoly1) amine as the trihydrochloride. The precipitate was dissolved in water, neutralised with sodium bicarbonate solution, extracted with dichlaroethane. The organic layer was separated and dichlaroethane removed by distillation under reduced pressure to get pure bis(2-picolyl) amine. The yield obtained was 7.8 grams . Example 7 5.4 grams of 3-picolyl amine was dissolved in 40.0 ml absolute ethanol and was stir-red with 2.1 grams of anhydrous magnesium sulphate. To this stirred mixture 5.4 grams of pyridine-3- carboxaldehyde in 35.0 ml ethanol was added and stirred for o one hour at a temperature of 30 C. The N--3~pyridy1idene-pyridine- 3-methanamine obtained was filtered off and concentrated under vacuum. The yield was quantitative and was 9.8 grams. 9.8 grams of N-3-pyridy1idene-pyridine-3-methanamine prepared as per example described above was dissolved in 80.0 ml dry ethanol and was added to a 300.0 ml Parr reactor. 1.2 grams of freshly prepared Raney nickel catalyst was added and the reactor was filled with hydrogen. The hydrogen pressure of the reactor o was maintained at 160 psi. The temperature was raised to 100 C and the reaction was continued for three hours. The crude bis(3-picolyl) amine was filtered off, concentrated under vacuum. The pH of the solution was brought to 4 by the addition of dilute hydrochloric acid to precipitate the bis(3-picolyl) amine trihydrochloride. This was dissolved in water and neutralised with potassium bicarbonate solution, extracted with dichloromethane followed by removal of dichloromethane by distillation under reduced pressure to pure bis(3—picoly1) amine. The yield obtained was 3.6 grams . Example 8 10.8 grams of 3-picoly1 amine was dissolved in 75.0 ml absolute ethanol and was stirred with 2.5 grams of molecular sieves. To this stirred mixture 10.7 grams of pyridine-3- carboxaldehyde in 75.0 ml ethanol was added and stirred for one o hour at a temperature of 35 C. The N--3--pyr idyl idene-pyrid ine-3- methanamine obtained was filtered off and concentrated under vacuum. The yield obtained was 19.7 grams . 19.7 grams of N-3-pyridyl idene-pyrid ine-3-methanamine prepared as per the example described above was dissolved in 150.0 ml dry methanol and was added to a 300.0 ml pressure reactor. 2.2 grams of freshly prepared Raney nickel catalyst was added and the reactor was filled with hydrogen under pressure till it reached a pressure of 180 psi. The reaction was allowed to o proceed at 120 C for three hours. The catalyst was filtered off and the crude bis(3-picoly1) amine was concentrated by removing the solvent under vacuum. Addition of dilute hydrochloric acid precipitated the bis(3-picoly1) amine as the trihydrochloride. The precipitate was dissolved in water, neutralised with sodium bicarbonate solution, extracted with dichloroethane. The organic layer was separated and dichloroethane removed by distillation under reduced pressure to get pure bis(3-picoly1) amine. The yield obtained was 7.1 grams . The process of invention as described and claimed in this invention has the following advantages : 1. The bis picolyl amine prepared by the process of the inven tion can be immobilized onto a polymer matrix in a single step operation and is stable during the process of incorporation onto the polymer matrix. Thus there is no loss of activity or selec tivity of the chelating ligand so that effective chelating capacity is not lost. 2. The product obtained has higher specific selectivity for copper ions in mixed streams of other metal such as nickel, iron and the like. 3. The yields are almost quantitative. 4. The product obtained does not require any pre-treatment for the preparation of metal chelating polymers. 5. New chelating polymers can be prepared by covalently at taching the chelating ligand such as the bis(picolyl) amines described by the process of this invention. The novel chelating polymers thus prepared can be used for repeated removal of copper ions from mixed metal ion streams. We Claim: 1. An improved process for the preparation of bis (picolyl) amines, which comprises; characterised in that reacting 2/3-picolyl amine with the 2-/3-pyridine carboxaldehyde in the ratio of 1:1 (w/w) in dry alcohol, in the presence of conventional drying agent at a temperature in the range of 25 to 35°C, for a period ranging from 60 to 90 minutes, filtering the solution to remove the drying agent, concentrating the solution by removing alcohol under reduced pressure to get the N-2/3-pyridylidene-pyridine-2/3- methanamine, dissolving the N-2/3-pyridylidene-pyridine-2/3-methanamine in a polar solvent in the presence of a reducing agent as herein described at a temperature in the range of 25 to 150°C, filtering the mixture, removing the alcohol under reduced pressure, adding dilute hydrochloric acid to bring the pH to 4 to get the trihydrochloride, dissolving the precipitate in water, neutralising the solution using an alkali metal bicarbonate, extracting with an aliphatic chlorinated solvent and removing aliphatic chlorinated solvent under reduced pressure to get the bis (picolyl) amines. 2. A process as claimed in claim 1 wherein, the polar solvent used is an alcohol selected from methanol, ethanol, isopropanol or a polar aprotic solvent such as tetrahy dro furan. 3. A process as claimed in claim 1, wherein, the drying agent used is selected from molecular sieves, magnesium sulphate, sodium sulphate. 4. A process as claimed in claim 1, wherein the reducing agent used is an alkali metal borohydride selected from sodium borohydride, sodium borocyanide, lithium aluminium hydride or hydrogen under pressure in the range of 150 to 220 psi in the presence of catalyst such as freshly prepared Raney nickle catalyst, palladium carbon. j. A process as claimed in claim 1, wherein, the chlorinated solvent used is selected from dichloromethane, chloroform, dichloroethane. 6. An improved process for the preparation of bis (picolyl) amines substantially as herein described with reference to the examples.

Documents:

786-del-1997-abstract.pdf

786-del-1997-claims.pdf

786-del-1997-correspondence-others.pdf

786-del-1997-correspondence-po.pdf

786-del-1997-description (complete).pdf

786-del-1997-drawings.pdf

786-del-1997-form-1.pdf

786-del-1997-form-19.pdf

786-del-1997-form-2.pdf