Title of Invention	A PROCESS FOR THE PREPARATION OF HIGH QUALITY AMINE OXIDES FROM SECONDARY AND TERTIARY ALIPHATIC AMINES
Abstract	The present invention relates to a process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines. The amines are useful in the preparation of hair conditioners and shampoos, toothpaste, laundry detergent powder, fabric softeners, toilet soap bars and cosmetics, surfactants as well as in other applications as synthetic intermediates and excellent spin trapping reagents. The process steps are: reacting a tertiary or secondary aliphatic amine with hydrogen peroxide as an oxidant in presence of a recyclable heterogeneous layered double hydroxide exchanged with one of the anions of transition metal oxides as a catalyst in water miscible organic solvent at a temperature ranging between 10-25°C for a period of 1-6 hours under continuous stirring and separating the product by simple filtration and subsequently evaporation of solvents by known methods.

Title of Invention

A PROCESS FOR THE PREPARATION OF HIGH QUALITY AMINE OXIDES FROM SECONDARY AND TERTIARY ALIPHATIC AMINES

Abstract

The present invention relates to a process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines. The amines are useful in the preparation of hair conditioners and shampoos, toothpaste, laundry detergent powder, fabric softeners, toilet soap bars and cosmetics, surfactants as well as in other applications as synthetic intermediates and excellent spin trapping reagents. The process steps are: reacting a tertiary or secondary aliphatic amine with hydrogen peroxide as an oxidant in presence of a recyclable heterogeneous layered double hydroxide exchanged with one of the anions of transition metal oxides as a catalyst in water miscible organic solvent at a temperature ranging between 10-25°C for a period of 1-6 hours under continuous stirring and separating the product by simple filtration and subsequently evaporation of solvents by known methods.

Full Text	Field of the invention: The present invention relates to a process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines. More particularly, the present invention relates to an improved process for the preparation of amine oxides from secondary and tertiary aliphatic amines useful in the preparation of hair conditioners and shampoos, toothpaste, laundry detergent powder, fabric softeners, toilet soap bars and cosmetics, surfactants as well 'as in other applications as synthetic intermediates and excellent spin trapping reagents. Background of the invention: N-oxides hold a key position in the chemistry of heterocycles as well as in biomedical area. Tertiary amine oxides are widely used in treatment of fabrics and preparation of hair conditioners and shampoos, toothpaste, laundry detergent powder, « fabric softeners, toilet soap bars and cosmetics as well as in other applications. They were also used as stoichiometric oxidants in metal catalysed hydroxylation and epoxidation reactions of olefins. On the other hand, oxides derived from secondary amines, called nitrones are highly valuable synthetic intermediates and excellent spin trapping reagents In particular nitrones are excellent 1,3 dipoles and have been utilized for the synthesis of various nitrogen containing biologically active compounds e.g. alkaloids and lactams. Conventionally tertiary amine oxides are prepared by oxidation of respective tertiary amines with strong oxidising agent like aqueous hydrogen peroxide in a solvent such as water, lower alcohol, acetone or acetic acid. A dilute or preferably concentrated (30-90% by weight) hydrogen peroxide solution is added in stoichiometric or greater amount to an aqueous solution containing the tertiary amine to obtain amine oxide, (US Pat No. 3,215, 741). The drawback associated with this process is the formation of a gel resembling a thick paste long before completion of the reaction, which retards further reaction. The yields are only 30-40% by weight of amine oxide. Several other methods such as incorporation of catalyst and/chelating agent have been developed in order to increase the quality and yields of the product In case of secondary amines, the classical methods involve the condensation of N-monosubstituted hydroxylamines with carbonyl compounds or the direct oxidation of N,N-disubstituted hydroxylamines. Subsequently, direct oxidation of secondary amines using several oxidising systems such as R2C(µ-O2), Na2WO4-H2O2, SeO2, TPAP-NMO and UHP-M (M=Mo, W), MTO-H2O2 have been developed to prepare nitrones under homogenous conditions. The drawback in all the above cases is the difficulty in recovering the homogeneous catalyst/reagents from the reaction mixture. Reference is made to U.S. patent 3,283,007 wherein the oxidation of tertiary amines using diethelene triamine penta/tetra acetic acid as chelating agent and sometimes contaminated with heavy metals is recommended to improve the yield. The hydrogen peroxide solution employed has concentration of at least 30-75% by weight. The disadvantages of this process are high reaction temperatures ranging between 40-100°C, longer reaction periods, and lower yields of amine oxides. Reference is made to US patent 3,424,780, wherein high yields of tertiary amine oxides are achieved by carrying the oxidation of tertiary amine with 30-70% by weight of aqueous hydrogen peroxide using 0.01 to 2% weight of carbondioxide, in presence of a chelating agent, tetra acetylene diamine, a salt thereof, polyphosphates, stannates, a hydroxy carboxylic acid salts or the salt of poly carboxylic acid. The reaction is carried « out at a temperature ranging from 40 to 80°C. The disadvantages of this process are high reaction temperature, longer reaction periods and that the amine oxide formed is intensively coloured when carbon dioxide atmosphere is used to speed up the reaction and this method necessitates injecting a gas which requires handling facilities. Another disadvantage is that the presence of more than 30% by weight of hydrogen peroxide is not environmentally friendly. Reference is made to another US patent 4,889,954 wherein the tertiary amines are reacted in high yields to give the corresponding amine oxides with a low content of nitrosamine, the oxidation of tertiary amine being carried out in the presence of a dialkyl carboxylic acid ester as catalyst and if appropriate, ascorbic acid as a co-catalyst using 45- 70% by weight of hydrogen peroxide. The drawbacks in the above process are the requirement of frequent addition of water to avoid gel formation, high reaction temperatures, longer reaction periods and difficulty in separation of the catalyst from the reaction mixture. Reference is made to another US patent 4,565,891 wherein dctacyano molybdate or iron salts are used as catalysts and molecular oxygen for oxidation of tertiary amines at high pressures and temperatures. The main drawback of this process is the need of very high temperature of 90-130°C and very low yields of amine oxide reporting 11- 52% of conversion. Reference is made to a US patent 5,130,488 wherein the solid amine oxide can be prepared by reacting a tertiary amine with hydrogen peroxide using carbon dioxide in presence of acetate and cooling to precipitate the product. This process is superior to previously known methods of preparing amine oxides. However, its use can sometimes lead to cleavage of the solvents, plating on the walls of the vessel used for the precipitation, contamination of the product with residual peroxide, and or discoloration of the product. Reference is made to a publication by Walter W. Zajac et al., J. Org. Chem., 53, 5856, 1988 wherein the oxidation of secondary and tertiary amines using 2-sulfonyloxyxaziridines (Davis Reagents) were reported. The drawback of the above process is that the reagent is used in stoichiometric amounts. Reference is made to a publication by Shun-Ichi Murahashi et al., J. Org. Chem., 55, 1736, 1990 wherein sodium tungstate is used as catalyst for the oxidation of secondary amines. The drawback is the difficulty in recovery of the catalyst from homogeneous conditions. Reference is also made to publication by Murraay et al., J. Org. Chem., 61, 8099, 1996 wherein methyltrioxorhenium was used as a catalyst in oxidation of secondary amines. The drawback is the difficulty in recovery of the catalyst. Objects of the invention. The main object of the present invention is to provide an eco-friendly and simple process for N-oxidation of secondary and tertiary amines using layered double hydroxides exchanged with anion of transition metal oxides as a catalyst, which is cheaper, non-corrosive and recyclable catalyst utilizing only lower percentage of hydrogen peroxide at room temperatures to give high yields of product. Another object of the present invention is the use of non-corrosive and low cost heterogenerous catalyst i.e, layered double hydroxides exchanged with tungstate, molybdate, vanadate and their polyanions. Summary of the Invention Accordingly, the present invention provides a process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines which comprises; reacting a tertiary or secondary aliphatic amine with hydrogen peroxide as an oxidant in presence of a recyclable heterogeneous layered double hydroxide exchanged with one of the anions of transition metal oxides as a catalyst in water miscible organic solvent at a temperature ranging between 10-25°C for a period of 1-6 hours under continuous stirring and separating the product by simple filtration and subsequently evaporation of solvents by known methods. In embodiment of the present invention, the heterogeneous catalyst used is the layered double hydroxides exchanged with transition metal oxides selected from a group consisting of tungstate, molybdate, vanadate and their polyanions i.e. polyoxometalates having formula I: [MII(I-x)MIII x(OH)2] [Mn-]x/2zH2O, which is derived from LDH having formula II [Mn(i.x)MUI x(OH)2][An-] x/2. zH2O where M is a transition metal oxides selected from the group consisting of W, Mo, V and An- is interstitial anion, selected from nitrate and chloride and M11 is a divalent cation selected from the group consisting of Mg2+, Mn2+, Fe2+, V2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+ and M is a trivalent ion selected from the group consisting of Al , Cr , V , Mn , Fe and Co , x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4. In another embodiment of the present invention, the tertiary amines used have the general formula R1R2NR3 wherein R1, R2 and R3, which may be the same or different, and are the straight-chain or branched-chain groups selected from alkyl, alkenyl and aralkyls having C1-C24 carbons selected from N, N- dimethyl decyl amine, N, N-dimethyl dodecyl amine, N, N-dimethylbenzylamine, triethylamine, tributylamine and cyclic amines selected from imidazolines pyrididines, N-substituted piperazines, N-substituted piperadines or N-substituted morpholines, e.g., N-methylmorpholine. In another embodiment of the present invention, the secondary amines used have the general formula R!R2NH wherein R1 and R2 may be the same or different and are the straight-chain or branched- chain groups selected from alkyl, alkenyl and aralkyls having C1-C24 carbons, selected from dibutyl amine, dibenzyl amine, dibenzyl amine, N-benzyl phenethylamine, N-phenyl benzylamine and cyclic amines selected from piperidine, 1,2,3,4, tetrahydro isoquinoline. In another embodiment of the present invention aqueous hydrogen peroxide is added slowly in a controlled manner for a period ranging between 0-120 min. In yet another embodiment of the present invention, the catalyst introduced in the system is 6-12 % by weight of anion of transition metal oxides selected from tungstate, molybdate, vanadate and their polyanions as polyoxometalates. In still another embodiment of the present invention, water miscible organic solvent used is selected from group consisting of methonol, ethanol, isopropanol, 1-propanol, 1-butanol, 2-butanol and isobutyl alcohol In still another embodiment of the present invention, the amount of hydrogen peroxide used is 2 to 6 moles per mole of amine Detailed Description of the Invention: The catalyst of the invention comprises a recyclable heterogeneous catalyst, i.e. layered double hydroxides exchanged with tungstate, molybdate, vanadate and their polyanions i.e. polyoxometalates that catalyses oxidation of secondary and tertiary amines The advantages such as low cost of the catalyst, reusability for several times and its ability to oxidise the amines at I0-25°C, below or at room temperature in a shorter period make the present invention as a promising candidate for a clean and efficient industrial route to amine oxide preparation. The novelty of the invention lies in the use of heterogeneous catalyst for the first time for the Noxidation of secondary^ and tertiary amines. The anion of transition metal oxides intercalated in the layered double hydroxide effectively catalyses the oxidation of amines to amine oxides. The catalyst was removed by simple filtration and the solid catalyst obtained thus is recycled for several times without any addition of fresh catalyst. The consistent activity for several cycles, mild reaction conditions, shorter reaction times makes the process economical and possible for commercial realisation. According to the invention, amine oxides are prepared by reacting tertiary and secondary amines with hydrogen peroxide as an oxidant in presence of a recyclable heterogeneous catalyst comprising layered double hydroxides exchanged with anion of transition metal oxides selected from tungstate, molybdate, vanadate, and their polyanions. in an organic solvent at a temperature in the range between 10-25°C for a period of 1-6 hours under continuous stirring. The product is separated by simple filtration and the solvents evaporated by known methods. The heterogeneous catalyst used are layered double hydroxides exchanged with transition metal oxides selected from a group consisting of tungstate, molybdate, vanadate and their polyanions i.e. polyoxometalates having formula I [M o-x>M x(OH)2][Mn-]x/2.zH2O, which is derived from LDH having formula II [MII(1-x)MIIIx(OH)2][An-]x2.zH2O where M is a transition metal oxides selected from the group consisting of W, Mo, V and An- is interstitial anion, selected from nitrate and chloride and Mu is a divalent cation selected from the group consisting of Mg2+ ,Mn2+, Fe2+, V2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+ and MIII is a trivalent ion selected from the group consisting of Al3+, Cr3+, V3+, Mn3+, Fe3+ and Co3+, x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4. The tertiary amines used have the general formula R1R2NR3 wherein R1, R2 and RJ, which may be the same or different, and are the straight-chain or branched-chain groups selected from alkyl, alkenyi and aralkyls having C1-C24 carbons selected from N,N-dimethyl decyl amine, N,N-dimethyl dodecyl amine, N,N-dimethylbenzylamine, triethylamine, tributylamine and cyclic amines selected from imidazolines pyrididines, N-substituted piperazines, N-substituted piperadines or N-substituted morpholines, e.g., N-methylmorpholine. The secondary amines used have the general formula R'R2NH wherein R' and R2 may be the same or different and are the straight-chain or branched-chain groups selected from alkyl, alkenyi and aralkyls having G-C24 carbons, selected from dibutyl amine, A dibenzyi amine, N-benzyl phenethylamine, N-phenyl benzylamine and cyclic amines selected from piperidine, 1,2,3,4, tetrahydro isoquinoline. Aqueous hydrogen peroxide is added slowly in a controlled manner for a period ranging between 0-120 min. The catalyst introduced in the system is generally 6-12% by weight of anion of transition metal oxides selected from tungstate, molybdate, vanadate and their polyanions as polyoxometaiates The water miscible organic solvents are selected from group consisting of methonol, ethanoi. isopropanol, 1-propanol, 1-butanoi. 2-butanol and isobutyl alcohol. The amount of hydrogen peroxide used may be in the range of 2 to 6 moles per mole of amine The catalytic cycle in the oxidation of amines to amine oxides involves the easy formation of peroxotungstate, HOOWO3VHOOWO0 on interaction of tungstate with hydrogen peroxide. These peroxy species will act as an active species for the oxidation of secondary/tertiary amines as described by Murahashi et.ai. for the Na2WO4 cataiyseci oxidation of secondary amines by hydrogen peroxide The secondarv amine undergoes nucleophilic reaction with peroxotungstate species to give hydroxylamine. Further oxidation of hydroxylamine followed by dehydration gives nitrone. In case of tertiary amines, the oxygen transfer occurs from peroxotungstate species to tertiary amine in a single step to form tertiary amine oxide. The species HOWO3VHOWCV thus formed is readily oxidized with another molecule of H2O2 to give peroxo tungstate HOOWO3" /HOOWCV, thus completing the catalytic cycle. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. Example 1 Preparation of the various catalysts /. Preparation of Mg-AI hydrotalcite (LDH) chloride: Mg-AJ-CI hydrotalcite (3:1) is prepared as follows: About 200ml of decarbonated and deionised water was taken into a 1 litre four necked round bottomed flask and stirred at 25 °C with a magnetic stirrer under a nitrogen flow. The mixture (Al3'=0.05mol/1), (Mg2 = 0.15mol/l) of decarbonated solution of AICI3.9H2O (12.07g), MgCl2.6H20 (30 49g) (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland) and aqueous solution of sodium hydroxide (16g, 0.2mol/l) were added continuously drop-wise from a burette, the pH of the reaction mixture being kept at 10.00-10.2 during the reaction. The precipitate obtained was filtered, washed with deionised and decarbonated water and dried at 70 °C for 15h. a) Preparation of Mg-AI hydrotalcite (LDH) tungstate (Catalyst A): To reach anion exchange of degree of 12%, 1 g of Mg-Al-CI hydrotalcite was stirred in 100ml of aqueous solution of I.87mM (0 616g) sodium tungstate (obtained from M/s Fluka, a Sigma Aldrich Company, Switzerland), at 293K. for 24h. The solid catalyst was filtered, washed with deionised and decarbonated water and lyophilized to dryness. b) Preparation of Mg-AI hydrotalcite (LDH) moiybdate (Catalyst B): To reach anion exchange of degree of 12%. 1 g of Mg-Al-CI hydrotalcite was stirred in 100ml of aqueous solution of 1.87mM (0 452g) sodium moiybdate (obtained from M/s. Fluka, a Sigma Aldrich Company. Switzerland), at 293K for 24h The solid catalyst was filtered, washed with deionised and decarbonated water and lyophiiized to dryness c) Preparation of Mg-AI hydrotalcite (LDH) vanadate (Catalyst C): To reach anion exchange of degree of 12%. i g of Mg-Al-Ci hydrotalcite is stirred in 100 mi of aqueous solution of 1.87mM (0 456g) sodium vanadate (obtained from M/s Fluka, a Sigma Aldrich Company, Switzerland), at 293K for 24h. The solid catalyst was filtered, washed with deionised and decarbonated water and lyophilized to dryness 2. Preparation of Mg-AI hydrotalcite (LDH) nitrate: Magnesium nitrate hexahydrate (30.8g, 0.12mol) and aluminium nitrate nonahydrate (I5.0g, 0.04mol) were dissolved in 100ml of deionised and decarbonated water. The pH of the solution was adjusted to 10 by adding 2M NaOH. The resulting suspension was stirred for 2h at room temperature. The precipitate hydrotaicite was collected by filtration under N2 atmosphere and dried overnight at 80 °C. a) Preparation ofMg-Al hydrotaicite (LDH) tungstate (Catalyst D): To reach anion exchange of degree of 12%, 1 g of Mg-Al-NC«3 hydrotaicite was stirred in 100ml of aqueous 1.87mM (0.616g) sodium tungstate (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland), at 293K for 24h. The solid catalyst was filtered, washed with of deionised and decarbonated water and lyophilized to dryness. 3. Preparation of Mg-Al hydrotaicite (LDH) carbonate: Mg-Al-C03 hydrotaicite (3:1) is prepared as follows: An aqueous solution (0.280 1) containing Mg(NO3)2.6H2O (0.2808 mol) and A1(N03)3.9H20 (0.093 mol) (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland) was added slowly to a second solution (0.280 1) containing NaOH (0.6562 mol) and Na2C03 (0.3368 mol) in a 10 1 round bottomed flask under vigorous stirring. The addition took nearly 3h. Then the slurry was heated to 338 K for 16h. The precipitate formed was filtered off and washed with hot distilled water until the pH of the filtrate was 7. The precipitate was dried in an oven at 353Kforl5h. a) Preparation of Mg-Al hydrotaicite (LDH) tungstate (Catalyst E): To reach anion exchange of degree of 12%, 1 g of Mg-Al- C03 calcined (at 723 K for 6h in a flow of air) hydrotaicite was stirred in 100ml of aqueous solution of 1.87mM (0.616g) sodium tungstate (obtained from M/s. Fluka, a Sigma Aldrich Company. Switzerland), a* 293K for 24h. The solid catalyst was filtered, washed with deionised and decarbonated water and lyophilized to dryness J.Preparation of Ni-Al hydrotaicite (LDH) chloride: Ni-Al hydrotaicite chloride (3:1) was prepared as follows: About 200ml of decarbonated and deionised water was taken into a 1 litre four necked round bottomed flask and stirred at 25 °C with a magnetic stirrer under nitrogen flow A mixture (Al3 = 0.05mol/l), (Ni2+ = 0.15mol/l) of decarbonated solution of A1C13.9H20 (12 07g), NiCl2 6H2O (35 65g) (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland) and aqueous solution of sodium hydroxide (16g, 0.2mol/l) were added continuously drop-wise from a burette, the pH of the reaction mixture being kept at 10 00-10 2 during the reaction. The precipitate obtained was filtered, washed with deionised and decarbonated water and dried at 70 °C for 15h. a) Preparation of Ni-Al hydrotaicite (LDH) tungstate (Catalyst F): To reach anion exchange of degree of 12%, 1 g of Ni-Al hydrotalcite chloride was stirred in 100ml of aqueous 1.87mM (0.616g) sodium tungstate (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland), at room temperature for 24h. The solid catalyst was filtered, washed with deionised and decarbonated water and lyophilized to dryness. 5. Preparation of Ni-Al hydrotalcite (LDH) nitrate: Nickel nitrate hexahydrate (34.8g, 0.12mol) and aluminium nitrate nonahydrate (15.0g, 0.04mol) were dissolved in 100ml of deionised and decarbonated water. The pH of the solution was adjusted to 10 by adding 2M NaOH. The resulting suspension was stirred for 2h at room temperature. The precipitate hydrotalcite was collected by filtration under N2 atmosphere and dried overnight at 80 °C. a) Preparation of Ni-Al hydrotalcite (LDH) tungstate (Catalyst G): To reach anion exchange of degree of 12%, 1 g of Ni-Al-NC>3 hydrotalcite was « stirred in 100ml of aqueous 1.87mM (0.616g) sodium tungustate (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland), at 293K for 24h. The solid catalyst was filtered, washed with of deionised and decarbonated water and lyophilized to dryness. Example 2 Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with Mg/Al (3:1) layered double hydroxides using aqueous hydrogen peroxide The four-necked flask was charged with 0.22ml (2mmol) of N-methylmorpholine, 200mg of catalyst A and 50ml of methanol. To the mixture was added dropwise 6.6ml (6 mmol) of a 30% by weight of aqueous solution of hydrogen peroxide for period of 2.0 hours in 2 to 3 portions at 25°C under continuous stirring. Continued the reaction for another 0 5hour After the completion of the reaction (followed by TLC), the catalyst was filtered off and washed with methanol. To the filtrate a small amount of manganese dioxide was added to decompose the unrcccted hydrogen peroxide. The treated reaction mixture was filtered to remove the solid MnOz and concentrated under reduced pressure to obtain the product. The product thus obtained was purified by column chromatography to afford the corresponding amine oxide. N-methylmorpholine N-oxide of 98% yield was obtained. This product is commercially available from Fluka, Aldrich, Lancaster and Merck companies. Example 3 Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with Mg/Al (3:1) layered double hydroxides using aqueous hydrogen peroxide: recvcle-I The oxidation reaction of N-methylmorpholine by using catalyst A which had been used in example 2 was performed in an identical procedure as in example 2, without further addition of fresh catalyst. N-methylmorpholine N-oxide of 98% yield was obtained. Example 4 Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with MsAl (3:1) layered double hydroxides using aqueous hydrogen peroxide: recvcle-II The oxidation reaction of N-methylmorpholine by using catalyst A which had been used in example 3 was performed in an identical procedure as in Example 2. without further addition of fresh catalyst. N-methylmorpholine N-oxide of 96% yield was obtained. Example 5 Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with MgAl (3:1) layered double hydroxides using aqueous hydrogen peroxide: recycle-Ill The oxidation reaction of N-methylmorpholine by using catalyst A which had been used in example 4 was performed in an identical procedure as in example 2, without further addition of fresh catalyst. N-methylmorpholine N-oxide of 97% yield was obtained. Example 6 Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with Ms Al (3:1) layered double hydroxides using aqueous hydrogen peroxide: recvcle-II' The oxidation reaction of N-methylmorpholine by using catalyst A which had been used in example 5 was performed in an identical procedure as in example 2. without further addition of fresh catalyst. N-methylmorpholine N-oxide of 96% yield was obtained Example 7 Oxidation of N-methvlmorpholme catalysed by tungstate exchanged with MgAl (3:1) layered double hydroxides using aqueous hydrogen peroxide: recvcle-V The oxidation reaction of N-methylmorpholine by using catalyst A which had been used in reaction 6 in an identical procedure as in example 2, without further addition of fresh catalyst. N-methylmorpholine N-oxide of 96% yield was obtained. Example 8 Oxidation oftriethvl amine catalyzed bv tunestate exchaneed with Me/Al (3.1) layered double hydroxides usine aqueous hvdroeen peroxide. The oxidation reaction of triethyl amine by using catalyst A was performed in an identical procedure as in example 2. The time taken fro the completion of reaction was 3 hours. Triethyl amine N-oxide of 98% yield was obtained. Example 9 Oxidation oftriethvl amine catalysed bv tunestate exchaneed with Me/Al (3.1) layered double hydroxides usine aqueous hvdroeen peroxide. The oxidation reaction of tributyl amine was performed by using catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. Tributyl amine N-Oxide of 95% yield was obtained. Example 10 Oxidation of N. N-dibutvl benzvlamine catalyzed bv tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide. The oxidation reaction of N, N-dibutyl benzyl amine was performed by using catalyst A in an identical procedure as in example 3. The time taken for the completion of reaction was 3 hours. N, N-dibutyl benzyl amine N-oxide of 96% yield was obtained. Example 11 Oxidation ofN-benzvl piperidine catalysed bv tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide. The oxidation reaction of N-benzyl piperidine was performed by using catalyst A, in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-benzyl piperidine N-oxide of 98% yield was obtained. Example 12 Oxidation ofN. N-dimethvldecvlamine catalyzed bv tunestate exchaneed with Me. Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide. The oxidation reaction of N,N-diemthyldecylamine was performed by using catalyst A in an identical procedure as in example 2. N, N-dimethyldecylamine N-oxide of 98% yield was obtained. This product is commercially available from Lonza Inc., With trade name Barlox IOS (Specification: 30 weight percent decyldimethyl tertiary amine oxide) Example 13 Oxidation of N..N-dimethvloctvlamine catalysed bv tumstate exchanged with Me/Al (3:1) layered double hydroxides using aqueous hydrogen peroxide. The oxidation reaction of N, N-dimethylctylamine was performed by using catalyst A in an identical procedure as in example 3. N, N-diemthyloctylamine N-oxide of 98% yield was obtained. Example 14 Oxidation of N.N-dimethvl benzvlatnine catatvused bv tumstate exchanged with Ms Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide The oxidation reaction of N,N-dimethyl benzylamine was performed by using catalyst A in an identical procedure as in Example 2. The time taken for the completion of reaction was 3 hours. N,N-diemthyl benzylamine amine N-oxide of 95% yield was obtained. Example 15 Oxidation of NJV-dimethvl benzylamine catalysed bv tunestate exchanged with Me Al (3:1) layered double hydroxides using aqueous hydrogen peroxide The oxidation reaction of N, N-dimethylcyclohexylamine by using catalyst A was performed in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N, N-dimethylcyclohexylaminne N-oxide of 97% yield was obtained. Example 16 Oxidation of N.N-dimethvl benzylamine catalvused bv tunestate exchanged with Me Al (3:1) layered double hydroxides using aqueous hydrogen peroxide The oxidation reaction of N-methylamorpholine was performed using catalyst B in an identical procedure as in Example 2 N-methylmorpholine N-oxide of 90% yield was obtained. Example 17 Oxidation of NJV-dimethvl benzylamine catalyzed bv tunestate exchanged with Me Al (3:1) layered double hydroxides usine aqueous hydrogen peroxide The oxidation reaction of N-methylmorpholine by using catalyst C was performed in an identical procedure as in example 2. N-methylmorpholine N-oxide of 40% yield was obtained. Example 18 Oxidation of NJV-dimethvl benzvlamine catalysed bv tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide The oxidation reaction of N-methylmorpholine by using catalyst D was performed in an identical procedure as in example 2. N-methylmorpholine N-oxide of 96% yield was obtained. Example 19 Oxidation of N.N-dimethyl benzvlamine catalvused by tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide The oxidation reaction of N-methylmorpholine by using catalyst E was performed in an identical procedure as in example 2. N-methylmorpholine N-oxide of 95% yield was obtained. Example 20 Oxidation of NJSf-dimethvl benzvlamine catalysed bv tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide The oxidation reaction of N-methylmorpholine was performed using catalyst F in an identical procedure as in example 2. N-methylmorpholine N-oxide of 98% yield was obtained. Example 21 Oxidation of N-methvlmorDholine catalysed bv tunestate exchaneed with NUAl (3:1) layered double hydroxides usine aqueous hvdroeen peroxide. The oxidation reaction of N-methylmorpholine was performed using catalyst G in an identical procedure as in example 2, N-methylmorpholine N-oxide of 96% yield was obtained. Example 22 Oxidaiton ofdibutvl amine catalysed bv tunestate exchaneed with MeAl (3:1) layered double hydroxides usine aqueous hvdroeen peroxide. The oxidation reaction of dibutyl amine was performed by using catalyst D in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-butylidene-butylamine N-oxide of 96% yield was obtained. Example 23 Oxidation of dibutvl amine catalysed bv tunastate exchanged with Me/Al (3:1) layered double hydroxides usine aqueous hvdrosen peroxide. The oxidation reaction of dibutyl amine was performed by using catalyst E in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-butylidene-butylamine N-oxide of 95% yield was obtained Example 24 Oxidation ofdibuytyl amine catalyzed by tungstate exchanged with Ni/Al (3:1) layered double hydroxides using aqueous hydrogen peroxide. The oxidation reaction of dibutyl amine was performed by using catalyst F in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-butylidene-butylamine N-oxide of 96% yield was obtained. Example 25. Oxidation of dibutvl amine catalysed bv tunastate exchanee with Ni/Al (3:1) layered double hydroxides usine aqueous hvdrosen peroxide. The oxidation reaction of dibutyl amine was performed by using catalyst G in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours N-butylidene-butylamine N-oxide of 95% yield was obtained. Example 26 Oxidation ofdihvtvl amine catalysed bv tunestate exchaneed with Me/Al (3:1) layered double hydroxides usine aqueous hvdrosen peroxide. The oxidation reaction of dibutyl amine was performed by using cataly6st A in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours N-butylidene-butylamine N-oxide of 97% yield was obtained. Example 27 Oxidation of dihenzyl amine catalyzed by tungstate exchanged with Mg, M (3:1) layered double hydroxides using aqueous hydrogen peroxide. The oxidation reaction of dibenzyl amine was performed by using of catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 5 hours N-benzylidenebenzylamine N-oxide of 60% yield was obtained. Example 28 Oxidation MN-benzvl phenethvlamine catalyzed bv tunestate exchanged with Me/Al (3:1) layered double hydroxides wins aqueous hydrogen peroxide. The oxidation reaction of N-benzyl phenethylamine was performed by using catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 6 ho9urs. N (1-methyl benzylidine) phenylamine N-oxide of 90% yield was obtained. Example 29 Oxidation of N-phenyl benzylamine amine catalyzed by tunestate exchaneed with MeAl (3:1) layered double hydroxides usine aqueous hvdroeen peroxide. The reaction oxidation reaction of N-phenyl benzylamine was performed by using catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 4 hours. N-bezylidine phenylamine N-oxide of 93% yield was obtained Example 30 Oxidation piperidine catSalysed by tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide The oxidation reaction of piper dines by using catalyst A was performed in an identical procedure as in example 2. The time taken for completion of reaction was 3 hours. 2,3,4,5 tetrahydro pyridine N-oxide of 92% yield was obtained. Example 31 Oxidation of 1,2,3,4-tetrahvdroisoauinoline catalyzed bv tunestate exchaneed with Me. Al (3:1) layered double hydroxides usine aaueous hvdroeen peroxide. The oxidation reaction of 1,2,3,4-tetrahydroisoquinoline performed by using catalyst A in an identical procedure as in example 2. The time taken for completion of reaction was 5 hours 3,4 dihydroisoquinoline N-oxide of 93% yield was obtained. Example 32 Oxidation of drisopropyl amine catalyzed bv tunestate dexchaneed with Met Al (3:1) layered double hydroxides usine aaueous hvdroeen peroxide. The reaction oxidation reaction of diisopropyl amine was performed by using catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-(l-methylethylindine) -1-methylethylamine N-oxide of 92% yield was obtained. The main advantages of the present invention are: 1. The present process is eco-friendly and very simple. 2. The catalyst is cheap, non-corrosive, recyclable for several times and heterogeneous in nature. 3. The reaction conditions are very mild, being the reaction temperature ranges between 10-25°C. 4. The hydrogen peroxide used is 30% by weight, which is more environmentally friendly. 5. The process is economical. 6. The process is accomplished in a short time to afford high productivity. 7. The amount of effluents formed in this process is minimized because the catalyst and solvent are recovered/recycled and reused. 8. The process provides high quality of the product without resulting in gel formation during the course of reaction. Table 1 Reusability of the catalyst in the oxidation of N-methylmorpholine catalyzed by tungstate exchanged with Mg/Al (3:1) layered double hydroxides (catalyst A) using aqueous hydrogen peroxidea (Table Removed) aIsolated yields Table 2. Oxidation of tertiary amines catalyzed by anion of transition metal oxides exchanged layered double hydroxides using aqueous hydrogen peroxide8 (Table Removed) aReaction conditions as exemplified in example 2 bIsolated yields Table 3: Oxidation of secondary amines catalyzed by anion of transition metal oxides exchanged layered double hydroxides using aqueous hydrogen peroxidea (Table Removed) +Reaction conditions as exemplified in example 2 bIsolated yields Claim: 1. A process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines which comprises; reacting a tertiary or secondary aliphatic amine with hydrogen peroxide as an oxidant in presence of a recyclable heterogeneous layered double hydroxide exchanged with one of the anions of transition metal oxides as a catalyst in water miscible organic solvent at a temperature ranging between 10-25°C for a period of 1-6 hours under continuous stirring and separating the product by simple filtration and subsequently evaporation of solvents by known methods. 2. A process as claimed in claims 1 wherein the heterogeneous catalyst used is layered double hydroxide with transition metal oxides selected from a group consisting of tungstate, molybdate, vanadate and their polyanions as polyoxometalates having formula I : [MII(1-x)M111 x(OH)2][M"-]^. zH2O, which is derived from LDH having formula II [MII(1-x)M111 X(OH)2][AN-] X/2. ZH2O where Mn- is an anion of transition metal oxide selected from nitrate, chloride and M11 is a divalent cation selected from the group consisting of Mg2+, Mn2+, Fe2+, V2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+ and M1II is a trivalent ion selected from the group consisting of Al3+, Cr3+, V3+, Mn3+, Fe3+ and Co3+, x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4. 3. A process as claimed in claim 1 & 2 wherein the tertiary amines, having the general formula R1R2NR3 wherein R1, R2 and R3 are the same or different and are the straight-chain or branched- chain groups selected from alkyl, alkenyl and aralkyls having C1-C24 carbons selected from dimethyl decyl amine, dimethyl docyl amine, dimethylbenzylamine, cyclic amines from imidazolines pyrididines, N-substituted piperazinesm, or N-substituted morpholines such as N-methylmorpholine. 4. A process as claimed in claims 1-3 wherein the secondary amines used in the system are having general formula R1R2NH wherein R1 and R2 are the same or different and are the straight-chain or branched chain groups selected from alkyl, alkenyl and aralkyls having C1- C24 carbons selected from dibutyl amine, dibenzyl amine, N-benzyl phenethylamine, N-phenyl benzylamine, cyclic amines selected from piperidine, 1,2,3,4 tetrahydro isoquinoline. 5. A process as claimed in claims 1-4 wherein 10 - 50% by weight of aqueous hydrogen peroxide is added slowly in a controlled manner during the period specified. 6. A process as claimed in claims 1-5 wherein the catalyst introduced in the system is 6-12 weight % anion of transition metal oxides selected from tungstate, molybdate, vanadate and their polynions as polyoxometalates. 7. A process as claimed in claims 1 -6 wherein the water miscible organic solvent used for the reactions is selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and isobutyl alcohol. 8. A process as claimed in claims 1-7 wherein the amount of hydrogen peroxide used ranges between 2 to 6 moles per mole of secondary or tertiary amine. 9. A process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines substantially as herein described with reference to the examples.

Full Text

Field of the invention:
The present invention relates to a process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines. More particularly, the present invention relates to an improved process for the preparation of amine oxides from secondary and tertiary aliphatic amines useful in the preparation of hair conditioners and shampoos, toothpaste, laundry detergent powder, fabric softeners, toilet soap bars and cosmetics, surfactants as well 'as in other applications as synthetic intermediates and excellent spin trapping reagents. Background of the invention:
N-oxides hold a key position in the chemistry of heterocycles as well as in
biomedical area. Tertiary amine oxides are widely used in treatment of fabrics and
preparation of hair conditioners and shampoos, toothpaste, laundry detergent powder,
« fabric softeners, toilet soap bars and cosmetics as well as in other applications. They were
also used as stoichiometric oxidants in metal catalysed hydroxylation and epoxidation
reactions of olefins. On the other hand, oxides derived from secondary amines, called
nitrones are highly valuable synthetic intermediates and excellent spin trapping reagents
In particular nitrones are excellent 1,3 dipoles and have been utilized for the synthesis of
various nitrogen containing biologically active compounds e.g. alkaloids and lactams.
Conventionally tertiary amine oxides are prepared by oxidation of respective tertiary amines with strong oxidising agent like aqueous hydrogen peroxide in a solvent such as water, lower alcohol, acetone or acetic acid. A dilute or preferably concentrated (30-90% by weight) hydrogen peroxide solution is added in stoichiometric or greater amount to an aqueous solution containing the tertiary amine to obtain amine oxide, (US Pat No. 3,215, 741). The drawback associated with this process is the formation of a gel resembling a thick paste long before completion of the reaction, which retards further reaction. The yields are only 30-40% by weight of amine oxide. Several other methods such as incorporation of catalyst and/chelating agent have been developed in order to increase the quality and yields of the product
In case of secondary amines, the classical methods involve the condensation of N-monosubstituted hydroxylamines with carbonyl compounds or the direct oxidation of N,N-disubstituted hydroxylamines. Subsequently, direct oxidation of secondary amines using several oxidising systems such as R2C(µ-O2), Na2WO4-H2O2, SeO2, TPAP-NMO and UHP-M (M=Mo, W), MTO-H2O2 have been developed to prepare nitrones under
homogenous conditions. The drawback in all the above cases is the difficulty in recovering the homogeneous catalyst/reagents from the reaction mixture.
Reference is made to U.S. patent 3,283,007 wherein the oxidation of tertiary amines using diethelene triamine penta/tetra acetic acid as chelating agent and sometimes contaminated with heavy metals is recommended to improve the yield. The hydrogen peroxide solution employed has concentration of at least 30-75% by weight. The disadvantages of this process are high reaction temperatures ranging between 40-100°C, longer reaction periods, and lower yields of amine oxides.
Reference is made to US patent 3,424,780, wherein high yields of tertiary amine
oxides are achieved by carrying the oxidation of tertiary amine with 30-70% by weight of
aqueous hydrogen peroxide using 0.01 to 2% weight of carbondioxide, in presence of a
chelating agent, tetra acetylene diamine, a salt thereof, polyphosphates, stannates, a
hydroxy carboxylic acid salts or the salt of poly carboxylic acid. The reaction is carried
« out at a temperature ranging from 40 to 80°C. The disadvantages of this process are high
reaction temperature, longer reaction periods and that the amine oxide formed is
intensively coloured when carbon dioxide atmosphere is used to speed up the reaction and
this method necessitates injecting a gas which requires handling facilities. Another
disadvantage is that the presence of more than 30% by weight of hydrogen peroxide is not
environmentally friendly.
Reference is made to another US patent 4,889,954 wherein the tertiary amines are
reacted in high yields to give the corresponding amine oxides with a low content of
nitrosamine, the oxidation of tertiary amine being carried out in the presence of a dialkyl
carboxylic acid ester as catalyst and if appropriate, ascorbic acid as a co-catalyst using 45-
70% by weight of hydrogen peroxide. The drawbacks in the above process are the
requirement of frequent addition of water to avoid gel formation, high reaction
temperatures, longer reaction periods and difficulty in separation of the catalyst from the
reaction mixture.
Reference is made to another US patent 4,565,891 wherein dctacyano molybdate
or iron salts are used as catalysts and molecular oxygen for oxidation of tertiary amines at
high pressures and temperatures. The main drawback of this process is the need of very
high temperature of 90-130°C and very low yields of amine oxide reporting 11- 52% of
conversion.
Reference is made to a US patent 5,130,488 wherein the solid amine oxide can be
prepared by reacting a tertiary amine with hydrogen peroxide using carbon dioxide in
presence of acetate and cooling to precipitate the product. This process is superior to previously known methods of preparing amine oxides. However, its use can sometimes lead to cleavage of the solvents, plating on the walls of the vessel used for the precipitation, contamination of the product with residual peroxide, and or discoloration of the product.
Reference is made to a publication by Walter W. Zajac et al., J. Org. Chem., 53, 5856, 1988 wherein the oxidation of secondary and tertiary amines using 2-sulfonyloxyxaziridines (Davis Reagents) were reported. The drawback of the above process is that the reagent is used in stoichiometric amounts.
Reference is made to a publication by Shun-Ichi Murahashi et al., J. Org. Chem., 55, 1736, 1990 wherein sodium tungstate is used as catalyst for the oxidation of secondary amines. The drawback is the difficulty in recovery of the catalyst from homogeneous conditions.
Reference is also made to publication by Murraay et al., J. Org. Chem., 61, 8099, 1996 wherein methyltrioxorhenium was used as a catalyst in oxidation of secondary amines. The drawback is the difficulty in recovery of the catalyst.
Objects of the invention.
The main object of the present invention is to provide an eco-friendly and simple process for N-oxidation of secondary and tertiary amines using layered double hydroxides exchanged with anion of transition metal oxides as a catalyst, which is cheaper, non-corrosive and recyclable catalyst utilizing only lower percentage of hydrogen peroxide at room temperatures to give high yields of product.
Another object of the present invention is the use of non-corrosive and low cost heterogenerous catalyst i.e, layered double hydroxides exchanged with tungstate, molybdate, vanadate and their polyanions.
Summary of the Invention
Accordingly, the present invention provides a process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines which comprises; reacting a tertiary or secondary aliphatic amine with hydrogen peroxide as an oxidant in presence of a recyclable heterogeneous layered double hydroxide exchanged with one of the anions of transition metal

oxides as a catalyst in water miscible organic solvent at a temperature ranging between 10-25°C for a period of 1-6 hours under continuous stirring and separating the product by simple filtration and subsequently evaporation of solvents by known methods.
In embodiment of the present invention, the heterogeneous catalyst used is the layered double hydroxides exchanged with transition metal oxides selected from a group consisting of tungstate, molybdate, vanadate and their polyanions i.e. polyoxometalates having formula I: [MII(I-x)MIII x(OH)2] [Mn-]x/2zH2O, which is derived from LDH having formula II [Mn(i.x)MUI x(OH)2][An-] x/2. zH2O where M is a transition metal oxides selected from the group consisting of W, Mo, V and An- is interstitial anion, selected from nitrate and chloride and M11 is a divalent cation selected from the group consisting of Mg2+, Mn2+, Fe2+, V2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+ and M is a trivalent ion selected from the group consisting of Al , Cr , V , Mn , Fe and Co , x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4.
In another embodiment of the present invention, the tertiary amines used have the general formula R1R2NR3 wherein R1, R2 and R3, which may be the same or different, and are the straight-chain or branched-chain groups selected from alkyl, alkenyl and aralkyls having C1-C24 carbons selected from N, N- dimethyl decyl amine, N, N-dimethyl dodecyl amine, N, N-dimethylbenzylamine, triethylamine, tributylamine and cyclic amines selected from imidazolines pyrididines, N-substituted piperazines, N-substituted piperadines or N-substituted morpholines, e.g., N-methylmorpholine.
In another embodiment of the present invention, the secondary amines used have the general formula R!R2NH wherein R1 and R2 may be the same or different and are the straight-chain or branched- chain groups selected from alkyl, alkenyl and aralkyls having C1-C24 carbons, selected from dibutyl amine, dibenzyl amine, dibenzyl amine, N-benzyl phenethylamine, N-phenyl benzylamine and cyclic amines selected from piperidine, 1,2,3,4, tetrahydro isoquinoline.
In another embodiment of the present invention aqueous hydrogen peroxide is added slowly in a controlled manner for a period ranging between 0-120 min.
In yet another embodiment of the present invention, the catalyst introduced in the system is 6-12 % by weight of anion of transition metal oxides selected from tungstate, molybdate, vanadate and their polyanions as polyoxometalates.
In still another embodiment of the present invention, water miscible organic solvent used is selected from group consisting of methonol, ethanol, isopropanol, 1-propanol, 1-butanol, 2-butanol and isobutyl alcohol
In still another embodiment of the present invention, the amount of hydrogen peroxide used is 2 to 6 moles per mole of amine Detailed Description of the Invention:
The catalyst of the invention comprises a recyclable heterogeneous catalyst, i.e. layered double hydroxides exchanged with tungstate, molybdate, vanadate and their polyanions i.e. polyoxometalates that catalyses oxidation of secondary and tertiary amines The advantages such as low cost of the catalyst, reusability for several times and its ability to oxidise the amines at I0-25°C, below or at room temperature in a shorter period make the present invention as a promising candidate for a clean and efficient industrial route to amine oxide preparation.
The novelty of the invention lies in the use of heterogeneous catalyst for the first time for the Noxidation of secondary^ and tertiary amines. The anion of transition metal oxides intercalated in the layered double hydroxide effectively catalyses the oxidation of amines to amine oxides. The catalyst was removed by simple filtration and the solid catalyst obtained thus is recycled for several times without any addition of fresh catalyst. The consistent activity for several cycles, mild reaction conditions, shorter reaction times makes the process economical and possible for commercial realisation.
According to the invention, amine oxides are prepared by reacting tertiary and secondary amines with hydrogen peroxide as an oxidant in presence of a recyclable heterogeneous catalyst comprising layered double hydroxides exchanged with anion of transition metal oxides selected from tungstate, molybdate, vanadate, and their polyanions. in an organic solvent at a temperature in the range between 10-25°C for a period of 1-6 hours under continuous stirring. The product is separated by simple filtration and the solvents evaporated by known methods.
The heterogeneous catalyst used are layered double hydroxides exchanged with transition metal oxides selected from a group consisting of tungstate, molybdate, vanadate and their polyanions i.e. polyoxometalates having formula I [M o-x>M x(OH)2][Mn-]x/2.zH2O, which is derived from LDH having formula II [MII(1-x)MIIIx(OH)2][An-]x2.zH2O where M is a transition metal oxides selected from the group consisting of W, Mo, V and An- is interstitial anion, selected from nitrate and chloride and Mu is a divalent cation selected from the group consisting of Mg2+ ,Mn2+, Fe2+, V2+, Co2+, Ni2+, Cu2+, Zn2+ and
Ca2+ and MIII is a trivalent ion selected from the group consisting of Al3+, Cr3+, V3+, Mn3+, Fe3+ and Co3+, x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4.
The tertiary amines used have the general formula R1R2NR3 wherein R1, R2 and RJ, which may be the same or different, and are the straight-chain or branched-chain groups selected from alkyl, alkenyi and aralkyls having C1-C24 carbons selected from N,N-dimethyl decyl amine, N,N-dimethyl dodecyl amine, N,N-dimethylbenzylamine, triethylamine, tributylamine and cyclic amines selected from imidazolines pyrididines, N-substituted piperazines, N-substituted piperadines or N-substituted morpholines, e.g., N-methylmorpholine.
The secondary amines used have the general formula R'R2NH wherein R' and R2 may be the same or different and are the straight-chain or branched-chain groups selected from alkyl, alkenyi and aralkyls having G-C24 carbons, selected from dibutyl amine,
A
dibenzyi amine, N-benzyl phenethylamine, N-phenyl benzylamine and cyclic amines selected from piperidine, 1,2,3,4, tetrahydro isoquinoline.
Aqueous hydrogen peroxide is added slowly in a controlled manner for a period ranging between 0-120 min. The catalyst introduced in the system is generally 6-12% by weight of anion of transition metal oxides selected from tungstate, molybdate, vanadate and their polyanions as polyoxometaiates The water miscible organic solvents are selected from group consisting of methonol, ethanoi. isopropanol, 1-propanol, 1-butanoi. 2-butanol and isobutyl alcohol. The amount of hydrogen peroxide used may be in the range of 2 to 6 moles per mole of amine
The catalytic cycle in the oxidation of amines to amine oxides involves the easy formation of peroxotungstate, HOOWO3VHOOWO0 on interaction of tungstate with hydrogen peroxide. These peroxy species will act as an active species for the oxidation of secondary/tertiary amines as described by Murahashi et.ai. for the Na2WO4 cataiyseci oxidation of secondary amines by hydrogen peroxide The secondarv amine undergoes nucleophilic reaction with peroxotungstate species to give hydroxylamine. Further oxidation of hydroxylamine followed by dehydration gives nitrone. In case of tertiary amines, the oxygen transfer occurs from peroxotungstate species to tertiary amine in a single step to form tertiary amine oxide. The species HOWO3VHOWCV thus formed is readily oxidized with another molecule of H2O2 to give peroxo tungstate HOOWO3" /HOOWCV, thus completing the catalytic cycle.
The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. Example 1
Preparation of the various catalysts /. Preparation of Mg-AI hydrotalcite (LDH) chloride:
Mg-AJ-CI hydrotalcite (3:1) is prepared as follows: About 200ml of decarbonated and deionised water was taken into a 1 litre four necked round bottomed flask and stirred at 25 °C with a magnetic stirrer under a nitrogen flow. The mixture (Al3'=0.05mol/1), (Mg2 = 0.15mol/l) of decarbonated solution of AICI3.9H2O (12.07g), MgCl2.6H20 (30 49g) (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland) and aqueous solution of sodium hydroxide (16g, 0.2mol/l) were added continuously drop-wise from a burette, the pH of the reaction mixture being kept at 10.00-10.2 during the reaction. The precipitate obtained was filtered, washed with deionised and decarbonated water and dried at 70 °C for 15h.
a) Preparation of Mg-AI hydrotalcite (LDH) tungstate (Catalyst A):
To reach anion exchange of degree of 12%, 1 g of Mg-Al-CI hydrotalcite was stirred in 100ml of aqueous solution of I.87mM (0 616g) sodium tungstate (obtained from M/s Fluka, a Sigma Aldrich Company, Switzerland), at 293K. for 24h. The solid catalyst was filtered, washed with deionised and decarbonated water and lyophilized to dryness.
b) Preparation of Mg-AI hydrotalcite (LDH) moiybdate (Catalyst B):
To reach anion exchange of degree of 12%. 1 g of Mg-Al-CI hydrotalcite was stirred in 100ml of aqueous solution of 1.87mM (0 452g) sodium moiybdate (obtained from M/s. Fluka, a Sigma Aldrich Company. Switzerland), at 293K for 24h The solid catalyst was filtered, washed with deionised and decarbonated water and lyophiiized to dryness c) Preparation of Mg-AI hydrotalcite (LDH) vanadate (Catalyst C):
To reach anion exchange of degree of 12%. i g of Mg-Al-Ci hydrotalcite is stirred in 100 mi of aqueous solution of 1.87mM (0 456g) sodium vanadate (obtained from M/s Fluka, a Sigma Aldrich Company, Switzerland), at 293K for 24h. The solid catalyst was filtered, washed with deionised and decarbonated water and lyophilized to dryness 2. Preparation of Mg-AI hydrotalcite (LDH) nitrate:
Magnesium nitrate hexahydrate (30.8g, 0.12mol) and aluminium nitrate nonahydrate (I5.0g, 0.04mol) were dissolved in 100ml of deionised and decarbonated water. The pH of the solution was adjusted to 10 by adding 2M NaOH. The resulting
suspension was stirred for 2h at room temperature. The precipitate hydrotaicite was collected by filtration under N2 atmosphere and dried overnight at 80 °C. a) Preparation ofMg-Al hydrotaicite (LDH) tungstate (Catalyst D):
To reach anion exchange of degree of 12%, 1 g of Mg-Al-NC«3 hydrotaicite was stirred in 100ml of aqueous 1.87mM (0.616g) sodium tungstate (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland), at 293K for 24h. The solid catalyst was filtered, washed with of deionised and decarbonated water and lyophilized to dryness. 3. Preparation of Mg-Al hydrotaicite (LDH) carbonate:
Mg-Al-C03 hydrotaicite (3:1) is prepared as follows: An aqueous solution (0.280 1) containing Mg(NO3)2.6H2O (0.2808 mol) and A1(N03)3.9H20 (0.093 mol) (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland) was added slowly to a second solution (0.280 1) containing NaOH (0.6562 mol) and Na2C03 (0.3368 mol) in a 10 1 round bottomed flask under vigorous stirring. The addition took nearly 3h. Then the slurry was heated to 338 K for 16h. The precipitate formed was filtered off and washed with hot distilled water until the pH of the filtrate was 7. The precipitate was dried in an oven at 353Kforl5h. a) Preparation of Mg-Al hydrotaicite (LDH) tungstate (Catalyst E):
To reach anion exchange of degree of 12%, 1 g of Mg-Al- C03 calcined (at 723 K for 6h in a flow of air) hydrotaicite was stirred in 100ml of aqueous solution of 1.87mM (0.616g) sodium tungstate (obtained from M/s. Fluka, a Sigma Aldrich Company. Switzerland), a* 293K for 24h. The solid catalyst was filtered, washed with deionised and decarbonated water and lyophilized to dryness J.Preparation of Ni-Al hydrotaicite (LDH) chloride:
Ni-Al hydrotaicite chloride (3:1) was prepared as follows: About 200ml of decarbonated and deionised water was taken into a 1 litre four necked round bottomed flask and stirred at 25 °C with a magnetic stirrer under nitrogen flow A mixture (Al3 = 0.05mol/l), (Ni2+ = 0.15mol/l) of decarbonated solution of A1C13.9H20 (12 07g), NiCl2 6H2O (35 65g) (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland) and aqueous solution of sodium hydroxide (16g, 0.2mol/l) were added continuously drop-wise from a burette, the pH of the reaction mixture being kept at 10 00-10 2 during the reaction. The precipitate obtained was filtered, washed with deionised and decarbonated water and dried at 70 °C for 15h. a) Preparation of Ni-Al hydrotaicite (LDH) tungstate (Catalyst F):
To reach anion exchange of degree of 12%, 1 g of Ni-Al hydrotalcite chloride was stirred in 100ml of aqueous 1.87mM (0.616g) sodium tungstate (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland), at room temperature for 24h. The solid catalyst was filtered, washed with deionised and decarbonated water and lyophilized to dryness. 5. Preparation of Ni-Al hydrotalcite (LDH) nitrate:
Nickel nitrate hexahydrate (34.8g, 0.12mol) and aluminium nitrate nonahydrate (15.0g, 0.04mol) were dissolved in 100ml of deionised and decarbonated water. The pH of the solution was adjusted to 10 by adding 2M NaOH. The resulting suspension was stirred for 2h at room temperature. The precipitate hydrotalcite was collected by filtration under N2 atmosphere and dried overnight at 80 °C. a) Preparation of Ni-Al hydrotalcite (LDH) tungstate (Catalyst G):
To reach anion exchange of degree of 12%, 1 g of Ni-Al-NC>3 hydrotalcite was
«
stirred in 100ml of aqueous 1.87mM (0.616g) sodium tungustate (obtained from M/s. Fluka, a Sigma Aldrich Company, Switzerland), at 293K for 24h. The solid catalyst was filtered, washed with of deionised and decarbonated water and lyophilized to dryness. Example 2
Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with Mg/Al (3:1) layered double hydroxides using aqueous hydrogen peroxide
The four-necked flask was charged with 0.22ml (2mmol) of N-methylmorpholine, 200mg of catalyst A and 50ml of methanol. To the mixture was added dropwise 6.6ml (6 mmol) of a 30% by weight of aqueous solution of hydrogen peroxide for period of 2.0 hours in 2 to 3 portions at 25°C under continuous stirring. Continued the reaction for another 0 5hour After the completion of the reaction (followed by TLC), the catalyst was filtered off and washed with methanol. To the filtrate a small amount of manganese dioxide was added to decompose the unrcccted hydrogen peroxide. The treated reaction mixture was filtered to remove the solid MnOz and concentrated under reduced pressure to obtain the product. The product thus obtained was purified by column chromatography to afford the corresponding amine oxide. N-methylmorpholine N-oxide of 98% yield was obtained. This product is commercially available from Fluka, Aldrich, Lancaster and Merck companies.
Example 3
Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with Mg/Al (3:1)
layered double hydroxides using aqueous hydrogen peroxide: recvcle-I
The oxidation reaction of N-methylmorpholine by using catalyst A which had been
used in example 2 was performed in an identical procedure as in example 2, without
further addition of fresh catalyst. N-methylmorpholine N-oxide of 98% yield was
obtained.
Example 4
Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with MsAl (3:1)
layered double hydroxides using aqueous hydrogen peroxide: recvcle-II
The oxidation reaction of N-methylmorpholine by using catalyst A which had been
used in example 3 was performed in an identical procedure as in Example 2. without
further addition of fresh catalyst. N-methylmorpholine N-oxide of 96% yield was
obtained.
Example 5
Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with MgAl (3:1)
layered double hydroxides using aqueous hydrogen peroxide: recycle-Ill
The oxidation reaction of N-methylmorpholine by using catalyst A which had been used in example 4 was performed in an identical procedure as in example 2, without further addition of fresh catalyst. N-methylmorpholine N-oxide of 97% yield was obtained. Example 6
Oxidation of N-methvlmorpholine catalysed by tungstate exchanged with Ms Al (3:1) layered double hydroxides using aqueous hydrogen peroxide: recvcle-II'
The oxidation reaction of N-methylmorpholine by using catalyst A which had been used in example 5 was performed in an identical procedure as in example 2. without further addition of fresh catalyst. N-methylmorpholine N-oxide of 96% yield was obtained Example 7
Oxidation of N-methvlmorpholme catalysed by tungstate exchanged with MgAl (3:1) layered double hydroxides using aqueous hydrogen peroxide: recvcle-V
The oxidation reaction of N-methylmorpholine by using catalyst A which had been used in reaction 6 in an identical procedure as in example 2, without further addition of fresh catalyst. N-methylmorpholine N-oxide of 96% yield was obtained.

Example 8
Oxidation oftriethvl amine catalyzed bv tunestate exchaneed with Me/Al (3.1) layered double hydroxides usine aqueous hvdroeen peroxide.
The oxidation reaction of triethyl amine by using catalyst A was performed in an identical procedure as in example 2. The time taken fro the completion of reaction was 3 hours. Triethyl amine N-oxide of 98% yield was obtained.
Example 9
Oxidation oftriethvl amine catalysed bv tunestate exchaneed with Me/Al (3.1) layered double hydroxides usine aqueous hvdroeen peroxide.
The oxidation reaction of tributyl amine was performed by using catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. Tributyl amine N-Oxide of 95% yield was obtained.
Example 10
Oxidation of N. N-dibutvl benzvlamine catalyzed bv tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide.
The oxidation reaction of N, N-dibutyl benzyl amine was performed by using catalyst A in an identical procedure as in example 3. The time taken for the completion of reaction was 3 hours. N, N-dibutyl benzyl amine N-oxide of 96% yield was obtained.
Example 11
Oxidation ofN-benzvl piperidine catalysed bv tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide.
The oxidation reaction of N-benzyl piperidine was performed by using catalyst A, in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-benzyl piperidine N-oxide of 98% yield was obtained.
Example 12
Oxidation ofN. N-dimethvldecvlamine catalyzed bv tunestate exchaneed with Me. Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide.
The oxidation reaction of N,N-diemthyldecylamine was performed by using catalyst A in an identical procedure as in example 2. N, N-dimethyldecylamine N-oxide of 98% yield was obtained. This product is commercially available from Lonza Inc., With trade name Barlox IOS (Specification: 30 weight percent decyldimethyl tertiary amine oxide)
Example 13
Oxidation of N..N-dimethvloctvlamine catalysed bv tumstate exchanged with Me/Al (3:1) layered double hydroxides using aqueous hydrogen peroxide.
The oxidation reaction of N, N-dimethylctylamine was performed by using catalyst A in an identical procedure as in example 3. N, N-diemthyloctylamine N-oxide of 98% yield was obtained.
Example 14
Oxidation of N.N-dimethvl benzvlatnine catatvused bv tumstate exchanged with Ms Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide
The oxidation reaction of N,N-dimethyl benzylamine was performed by using catalyst A in an identical procedure as in Example 2. The time taken for the completion of reaction was 3 hours. N,N-diemthyl benzylamine amine N-oxide of 95% yield was obtained.
Example 15
Oxidation of NJV-dimethvl benzylamine catalysed bv tunestate exchanged with Me Al (3:1) layered double hydroxides using aqueous hydrogen peroxide
The oxidation reaction of N, N-dimethylcyclohexylamine by using catalyst A was performed in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N, N-dimethylcyclohexylaminne N-oxide of 97% yield was obtained.
Example 16
Oxidation of N.N-dimethvl benzylamine catalvused bv tunestate exchanged with Me Al (3:1) layered double hydroxides using aqueous hydrogen peroxide
The oxidation reaction of N-methylamorpholine was performed using catalyst B in an identical procedure as in Example 2 N-methylmorpholine N-oxide of 90% yield was obtained.
Example 17
Oxidation of NJV-dimethvl benzylamine catalyzed bv tunestate exchanged with Me Al (3:1) layered double hydroxides usine aqueous hydrogen peroxide
The oxidation reaction of N-methylmorpholine by using catalyst C was performed in an identical procedure as in example 2. N-methylmorpholine N-oxide of 40% yield was obtained.
Example 18
Oxidation of NJV-dimethvl benzvlamine catalysed bv tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide
The oxidation reaction of N-methylmorpholine by using catalyst D was performed in an identical procedure as in example 2. N-methylmorpholine N-oxide of 96% yield was obtained.
Example 19
Oxidation of N.N-dimethyl benzvlamine catalvused by tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide
The oxidation reaction of N-methylmorpholine by using catalyst E was performed in an identical procedure as in example 2. N-methylmorpholine N-oxide of 95% yield was obtained.
Example 20
Oxidation of NJSf-dimethvl benzvlamine catalysed bv tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide
The oxidation reaction of N-methylmorpholine was performed using catalyst F in an identical procedure as in example 2. N-methylmorpholine N-oxide of 98% yield was obtained.
Example 21
Oxidation of N-methvlmorDholine catalysed bv tunestate exchaneed with NUAl (3:1) layered double hydroxides usine aqueous hvdroeen peroxide.
The oxidation reaction of N-methylmorpholine was performed using catalyst G in an identical procedure as in example 2, N-methylmorpholine N-oxide of 96% yield was obtained.
Example 22
Oxidaiton ofdibutvl amine catalysed bv tunestate exchaneed with MeAl (3:1) layered double hydroxides usine aqueous hvdroeen peroxide.
The oxidation reaction of dibutyl amine was performed by using catalyst D in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-butylidene-butylamine N-oxide of 96% yield was obtained.

Example 23
Oxidation of dibutvl amine catalysed bv tunastate exchanged with Me/Al (3:1) layered double hydroxides usine aqueous hvdrosen peroxide.
The oxidation reaction of dibutyl amine was performed by using catalyst E in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-butylidene-butylamine N-oxide of 95% yield was obtained
Example 24
Oxidation ofdibuytyl amine catalyzed by tungstate exchanged with Ni/Al (3:1) layered double hydroxides using aqueous hydrogen peroxide.
The oxidation reaction of dibutyl amine was performed by using catalyst F in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-butylidene-butylamine N-oxide of 96% yield was obtained.
Example 25.
Oxidation of dibutvl amine catalysed bv tunastate exchanee with Ni/Al (3:1) layered double hydroxides usine aqueous hvdrosen peroxide.
The oxidation reaction of dibutyl amine was performed by using catalyst G in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours N-butylidene-butylamine N-oxide of 95% yield was obtained.
Example 26
Oxidation ofdihvtvl amine catalysed bv tunestate exchaneed with Me/Al (3:1) layered double hydroxides usine aqueous hvdrosen peroxide.
The oxidation reaction of dibutyl amine was performed by using cataly6st A in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours N-butylidene-butylamine N-oxide of 97% yield was obtained.
Example 27
Oxidation of dihenzyl amine catalyzed by tungstate exchanged with Mg, M (3:1) layered double hydroxides using aqueous hydrogen peroxide.
The oxidation reaction of dibenzyl amine was performed by using of catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 5 hours N-benzylidenebenzylamine N-oxide of 60% yield was obtained.
Example 28
Oxidation MN-benzvl phenethvlamine catalyzed bv tunestate exchanged with Me/Al (3:1) layered double hydroxides wins aqueous hydrogen peroxide.
The oxidation reaction of N-benzyl phenethylamine was performed by using catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 6 ho9urs. N (1-methyl benzylidine) phenylamine N-oxide of 90% yield was obtained.
Example 29
Oxidation of N-phenyl benzylamine amine catalyzed by tunestate exchaneed with MeAl (3:1) layered double hydroxides usine aqueous hvdroeen peroxide.
The reaction oxidation reaction of N-phenyl benzylamine was performed by using catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 4 hours. N-bezylidine phenylamine N-oxide of 93% yield was obtained
Example 30
Oxidation piperidine catSalysed by tunestate exchaneed with Me Al (3:1) layered double hydroxides usine aqueous hvdroeen peroxide
The oxidation reaction of piper dines by using catalyst A was performed in an identical procedure as in example 2. The time taken for completion of reaction was 3 hours. 2,3,4,5 tetrahydro pyridine N-oxide of 92% yield was obtained.
Example 31
Oxidation of 1,2,3,4-tetrahvdroisoauinoline catalyzed bv tunestate exchaneed with Me. Al (3:1) layered double hydroxides usine aaueous hvdroeen peroxide.
The oxidation reaction of 1,2,3,4-tetrahydroisoquinoline performed by using catalyst A in an identical procedure as in example 2. The time taken for completion of reaction was 5 hours 3,4 dihydroisoquinoline N-oxide of 93% yield was obtained.
Example 32
Oxidation of drisopropyl amine catalyzed bv tunestate dexchaneed with Met Al (3:1) layered double hydroxides usine aaueous hvdroeen peroxide.
The reaction oxidation reaction of diisopropyl amine was performed by using catalyst A in an identical procedure as in example 2. The time taken for the completion of reaction was 3 hours. N-(l-methylethylindine) -1-methylethylamine N-oxide of 92% yield was obtained.
The main advantages of the present invention are:
1. The present process is eco-friendly and very simple.
2. The catalyst is cheap, non-corrosive, recyclable for several times and heterogeneous in nature.
3. The reaction conditions are very mild, being the reaction temperature ranges between 10-25°C.
4. The hydrogen peroxide used is 30% by weight, which is more environmentally friendly.
5. The process is economical.
6. The process is accomplished in a short time to afford high productivity.
7. The amount of effluents formed in this process is minimized because the catalyst and solvent are recovered/recycled and reused.
8. The process provides high quality of the product without resulting in gel formation during the course of reaction.
Table 1 Reusability of the catalyst in the oxidation of N-methylmorpholine catalyzed by tungstate exchanged with Mg/Al (3:1) layered double hydroxides (catalyst A) using aqueous hydrogen peroxidea

(Table Removed)
aIsolated yields

Table 2. Oxidation of tertiary amines catalyzed by anion of transition metal oxides exchanged layered double hydroxides using aqueous hydrogen peroxide8

(Table Removed)
aReaction conditions as exemplified in example 2 bIsolated yields

Table 3: Oxidation of secondary amines catalyzed by anion of transition metal oxides exchanged layered double hydroxides using aqueous hydrogen peroxidea

(Table Removed)
+Reaction conditions as exemplified in example 2 bIsolated yields

Claim:
1. A process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines which comprises; reacting a tertiary or secondary aliphatic amine with hydrogen peroxide as an oxidant in presence of a recyclable heterogeneous layered double hydroxide exchanged with one of the anions of transition metal oxides as a catalyst in water miscible organic solvent at a temperature ranging between 10-25°C for a period of 1-6 hours under continuous stirring and separating the product by simple filtration and subsequently evaporation of solvents by known methods.
2. A process as claimed in claims 1 wherein the heterogeneous catalyst used is layered double hydroxide with transition metal oxides selected from a group consisting of tungstate, molybdate, vanadate and their polyanions as polyoxometalates having formula I : [MII(1-x)M111 x(OH)2][M"-]^. zH2O, which is derived from LDH having formula II [MII(1-x)M111 X(OH)2][AN-] X/2. ZH2O where Mn- is an anion of transition metal oxide selected from nitrate, chloride and M11 is a divalent cation selected from the group consisting of Mg2+, Mn2+, Fe2+, V2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+ and M1II is a trivalent ion selected from the group consisting of Al3+, Cr3+, V3+, Mn3+, Fe3+ and Co3+, x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4.
3. A process as claimed in claim 1 & 2 wherein the tertiary amines, having the general formula R1R2NR3 wherein R1, R2 and R3 are the same or different and are the straight-chain or branched- chain groups selected from alkyl, alkenyl and aralkyls having C1-C24 carbons selected from dimethyl decyl amine, dimethyl docyl amine, dimethylbenzylamine, cyclic amines from imidazolines pyrididines, N-substituted piperazinesm, or N-substituted morpholines such as N-methylmorpholine.
4. A process as claimed in claims 1-3 wherein the secondary amines used in the system are having general formula R1R2NH wherein R1 and R2 are the same or different and are the straight-chain or branched chain groups selected from alkyl, alkenyl and aralkyls having C1- C24 carbons selected from dibutyl amine, dibenzyl amine, N-benzyl phenethylamine, N-phenyl benzylamine, cyclic amines selected from piperidine, 1,2,3,4 tetrahydro isoquinoline.
5. A process as claimed in claims 1-4 wherein 10 - 50% by weight of aqueous hydrogen peroxide is added slowly in a controlled manner during the period specified.
6. A process as claimed in claims 1-5 wherein the catalyst introduced in the system is 6-12 weight % anion of transition metal oxides selected from tungstate, molybdate, vanadate and their polynions as polyoxometalates.
7. A process as claimed in claims 1 -6 wherein the water miscible organic solvent used for the reactions is selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and isobutyl alcohol.
8. A process as claimed in claims 1-7 wherein the amount of hydrogen peroxide used ranges between 2 to 6 moles per mole of secondary or tertiary amine.
9. A process for the preparation of high quality amine oxides from secondary and tertiary aliphatic amines substantially as herein described with reference to the examples.

Documents:

1094-del-2000-abstract.pdf

1094-del-2000-claims.pdf

1094-del-2000-complete specification (granted).pdf

1094-del-2000-correspondence-others.pdf

1094-del-2000-correspondence-po.pdf

1094-del-2000-description (complete).pdf

1094-del-2000-form-1.pdf

1094-del-2000-form-19.pdf

1094-del-2000-form-2.pdf

1094-del-2000-form-3.pdf

1094-del-2000-petition-137.pdf

1094-del-2000-petition-138.pdf

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Patent Number

242320

Indian Patent Application Number

1094/DEL/2000

PG Journal Number

35/2010

Publication Date

27-Aug-2010

Grant Date

23-Aug-2010

Date of Filing

30-Nov-2000

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	BOYAPATI MANORANJAN CHOUDARY	INDIAN INSTITUTE OF CHEMICAL TECHNOLOGY,HYDERABAD-500 007, ANDHRA PRADESH, INDIA.
2	BALAGAM BHARATHI	INDIAN INSTITUTE OF CHEMICAL TECHNOLOGY,HYDERABAD-500 007, ANDHRA PRADESH, INDIA.
3	MANNEPALLI LAKSHMI KANTAM	INDIAN INSTITUTE OF CHEMICAL TECHNOLOGY,HYDERABAD-500 007, ANDHRA PRADESH, INDIA.
4	CHINTA REDDY VENKAT REDDY	INDIAN INSTITUTE OF CHEMICAL TECHNOLOGY,HYDERABAD-500 007, ANDHRA PRADESH, INDIA.
5	KONDAPURAM VIJAYA RAGHAVAN	INDIAN INSTITUTE OF CHEMICAL TECHNOLOGY,HYDERABAD-500 007, ANDHRA PRADESH, INDIA.

PCT International Classification Number

C07D 217/22

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA