Indian Patents. 271230:SUPPORTED UNDECAPHOSPHOTUNGSTATE CATALYST FOR AEROBIC EPOXIDATION OF ALKENES

Title of Invention	SUPPORTED UNDECAPHOSPHOTUNGSTATE CATALYST FOR AEROBIC EPOXIDATION OF ALKENES
Abstract	A heterogeneous catalyst comprising supported undecaphosphotungstate. A process for selective epoxidation of cycloalkene comprising reacting a cyclic olefin with an oxidizing agent in the presence of catalyst comprising supported undecaphosphotungstate on neutral alumina.

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION (See section 10; rule 13) Title of the invention - SUPPORTED UNDECAPHOSPHOTUNGSTATE CATALYST FOR AEROBIC EPOXIDATION OF ALKENES 2. Applicant(s) (a) NAME : M. S. University of Baroda (b) NATIONALITY : Indian (c) ADDRESS: Sayajigunj, Vadodara 390 002, Gujarat, India 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed: Field of Invention The present invention relates to a heterogeneous catalyst comprising lacunary polyoxometalate supported by neutral alumina. The invention also relates to a process for the selective aerobic epoxidation of cycloalkenes, in liquid phase comprising the heterogeneous catalyst. Background and Prior Art of the Invention US 5466838 disclose the process for production of epoxide using an iron or a copper containing catalyst. Various olefins have been studied in the presence of molecular oxygen at 25° C using dichloromethane as a solvent. In all cases, aldehyde has been used to promote the oxidation process. Oxidation of cyclohexene gives 100% conversion with 79% yield for cyclohexene oxide using Fe as well as Cu(OH)2 as a catalyst. 100% conversion with 97% selectivity for cyclohexene oxide was obtained from Fe2C>3 catalyst. US 5744620 disclose a process for selective oxidation of cyclic olefins in the presence of air or molecular oxygen catalyzed by metallosalen type of catalysts. The patent describes more effective oxidation of cyclohexene using different metal ions such as Co, Ru, Fe and V. The metallosalen catalyst was taken in acetonitrile, and then molecular oxygen was bubbled to the reaction mixture followed by addition of cyclic olefin in the presence of a sacrificial co-reductant (i.e. isobutyraldehyde). The oxidation products consist of alcohol and ketone along with epoxide. The V metallosalen complex was most reactive among all with 86% selectivity for cyclohexene oxide, US 5175316 discloses a different process for epoxidation which involves the mixture of cyclohexene, cyclohexene oxide, cyclohexanol and cyclohexenone dissolved in cyclohexene as a solvent at temperatures between 100° to 200° C under 10-130 bar pressure. The mixture of products was oxidized and the initial concentration of cyclohexene decreased from 6.8 weight % to 0.39 weight % and hence increasing the concentration of cyclohexene oxide from 0.03% to 5.78%. A number of research papers are available on the oxidation of cyclic olefins, especially, cyclohexene using molecular oxygen. S Dapurkar et al. (App. Catal. A., 2008, 346, 112) have reported the use of Cr-MCM-41 for solvent free oxidation of cyclic olefins using 1 atm of molecular oxygen. The cyclohexene oxidation resulted in 52.2% conversion with 71.1% selectivity for 2-cyclohexen -1-one at 343K temperature for 24 h reaction time. Other minor products include cyclohexene oxide, 2-cyclohexen-l-oI and 1-cyclohexenel-hydroperoxide. Apart from these products the oxidation process also resulted in formation of cyclohexanol or cyclohexanone as minor products. Dapurkar et al. have disclosed the process of oxidation of cyclohexene under solvent free conditions. They have reported the allylic oxidation of cycloalkenes, especially cyclohexene. 52.2% conversion was obtained with molecular oxygen under solvent free conditions over Cr-MCM-41 as the catalytic system. They have reported the formation of Cy-none as the major product while, Cy-oxide was obtained as minor product with only 3.1% selectivity. Further, they have also reported the formation of other minor products such as Cy-ol and Cy-HP. Amarasekara et al. have reported (Cat Comm. 2007, 8, 1132) immobilization of the metallosalen complex on the silica gel matrix using the sol-gel process and its use as a catalyst for oxidation of alkenes using molecular oxygen. The paper deals with oxidation of various alkenes apart from cyclohexene. The oxidation process was carried out at room temperature by using butryaldehdye as a co-reductant with acetonitrile as a solvent. Cyclohexene oxidation resulted in 71% conversion with 34% selectivity for cyclohexene oxide, the major product formed was 2-cyclohexene-1-one along with 21% of diol. X. Tong et al. reported (Tetrahedron, 63 (2007), 7634-39) highly efficient metal free oxidation of olefins by molecular oxygen under mild conditions in the presence of 1,4-diamino-2,3-dichloro-anthraquinone and N-hydroxyphthalimide. Oxidation of cyclohexene resulted in 89% conversion with 71% selectivity for 2-cyclohexen-l-one and minor products of cyclohexene oxide, 2-cyclohexen-l-ol and 2-cyclohexenel-hydroperoxide under 0.3 Mpa pressure and 80°C. The epoxide selectivity was lower than 5%. J. Tong et al. reported chitosan supported Salophen Mn (III) complexes for aerobic oxidation of cyclohexene. Different catalyst containing varying amounts of metal was supported on chitosan support. Cyclohexene oxidation resulted in 83.6% conversion with 61.3% selectivity for 2-cyclohexen-l-one and other minor quantities of cyclohexene oxide, 2-cyclohexen-l-ol and 2-cyclohexenel-hydroperoxide. The reaction was carried out using acetonitrile or dichloroethane as a solvent at 70°C for 24h. A.S.C. Chang et al, describe (Chem Comm., 2003, 1058) an efficient catalytic system for epoxidation of cyclic olefins using molecular oxygen. They report the use of ruthenium complex for aerobic epoxidation of cyclic alkenes. Oxidation of cyclohexene results in epoxide as a major product with 99.9% conversion and 90.1% selectivity for epoxide. The reaction was carried out at room temperature by using isobutryaldehyde as a co-reductant in the presence of dichloroethane as solvent. R. M. Wang et al. reported (J. Mol Catal A 147 (1999), 173-178) the use of amino acid Schiff base manganese complex for aerobic oxidation of cyclohexene. The major products were 2-cyclohexen-l-one, 2-cyclohexen-l-ol and 2-cyclohexene-l-hydroperoxide. The catalytic reaction was carried out by varying different temperatures and the effect of additives. 74.8% conversion was obtained with 75.1% selectivity for ketone and alcohol and 29.6% selectivity for 2-cyclohexene-l-hydroperoxide after 14h. Polymer-supported metallo-phthalocyanines have also been reported to catalyze the epoxidation of cyclohexene using dioxygen as the oxidant by M. Gebler (J Inorg Nucl Chem. 1981,43,2759). US 5250739 disclose a process for cyclohexene oxidation using a metal substituted heteropolyanion of Dawson type. The process involves mainly the production of 2-cyclohexene-1-ol and 2-cyclohexene-l-one with molecular oxygen as an oxidant in the presence of various solvents such as 1,2-dichloroethane, 1,2-dichloromethane, acetone, acetonitrile etc. among the various metal substituted heteropolyanions the Ir substituted heteropolyanion showed the higher activity with TOF=2.9 h'1 at 38°C for 118h. G. Maayan and R. Neumann have reported (Chem. Comm., 2005, 4595) the use of Ag and Ru nano-particles stabilized by Vanadium substituted phosphomolybdate supported on alumina matrix for epoxidation of alkenes using molecular oxygen. The cyclohexene epoxidation was carried out at 160° C for lh by bubbling O2. The Ag nanoparticles (50%) showed higher selectivity for cyclohexene oxide as compared to Ru nanoparticles (41), along with some other side products. The oxidation reaction was carried out using trifluoromethyl benzene as solvent and using anisole as an internal standard. Neumann et al. have used α-alumina to support the Mn-POM nanoparticles, where (M= Ag, Ru, Pd). The reaction was carried out at 160°C using trifluoromethyl benzene as a solvent. Moreover, only 50% conversion was obtained with Ag-POM nanoparticles with 50% selectivity towards cyclohexene oxide. Other allylic oxidation products were also obtained in addition to cyclohexene oxide. The other nanoparticles did not give any significant conversion values. The prior art have used either ketone or alcohol as a major oxidation products along with small amount of epoxide. Due the known importance of epoxide and the increasing demand of green oxidation processes the present catalyst is an excellent candidate. The synthesis and characterization of lacunary polyoxometalates supported onto hydrous Zirconia is available and the same has been published in a publication provided by the inventors (Anajli Patel et al, 12-tungstophosphoric and 12-tungtosilicicacid supported onto hydrous Zirconia for liquid phase tert-butylation of m-cresol, Catalysis letters (2007) 117; 146-152). However the said catalyst does not provide required conversion to the end product and selectivity for the same. Object of the Invention It is an object of the present invention to provide a new heterogeneous catalyst. A further object of the invention is to provide a catalyst comprising of launary polyoxometalate and alumina for the oxidation of alkenes. Yet another object of the present invention is to provide an improved process for the selective aerobic epoxidation of cycioalkene in solvent free liquid phase. Yet another object of the invention is to provide an economic and efficient process of epoxidation useful in polymer industry. Summary of the invention According to one aspect of the present invention there is provided a heterogeneous catalyst comprising supported undecaphosphotungstate on neutral alumina. According to another aspect of the present invention there is provided a process for selective epoxidation of cycioalkene comprising, reacting a cyclic olefin with an oxidizing agent in the presence of catalyst comprising supported undecaphosphotungstate on neutral alumina. Brief Description of the Accompanying Drawings Figure 1 illustrates FT-IR spectrum of (PW11)2/Al2O3 Figure 2 illustrates Thermal Gravimetric Analysis of(PW11)2/Al2O3 Figure 3 illustrates 31P MAS NMR for (PW11)2/Al2O3 Figure 4 illustrates Powder X-Ray Diffraction pattern for (PW11)2/Al2O3 Figure 5 illustrates SEM images of AI2O3 and (PW11)2/Al2O3 Detailed Description of the Invention Oxidation of cyclohexene is an industrially important reaction, especially in the polymer industry. The novel alumina supported undecatungstophosphonate of the present invention is successful for solvent free oxidation of alkenes with molecular oxygen. The supported Iacunary polyoxometalates is represented by the formula I (PW11)2/Al2O3 wherein W=Tungsten (polyoxometalate Na7PWnO39). The present invention provides a solvent free liquid phase catalytic oxidation process achieving 85% conversion with 100 % selectivity towards single selective product i.e. cyclohexene oxide under solvent free condition using supported phosphotungstate as the catalytic system. The reaction carried out in the present invention is able to achieve a higher TON of 6029. TON number is TURN OVER NUMBER and is defined as: TON = moles of product / moles of catalyst The present invention provides an efficient process for the oxidation of cycloolefins in solvent free liquid phase mild conditions. The examples of cyclic olefins are cyclopentene, cyclohexene cycloheptene and cylcooctene. The present process provides 85% conversion and 100.0% selectivity for cyclohexene oxide. The process of the present invention is advantageous that it involves the simple solvent free oxidation process. The oxidizing agent for the present epoxidation process is selected from molecular oxygen, PhIO, Tert-butyl hydrogen peroxide and hydrogen peroxide. The oxidation of alkenes was carried out in a 100 ml three necked round bottom flask which is provided with a double walled air condenser, magnetic stirrer and a guard tube. Oxidation reaction was carried out in a batch type reactor operated under atmospheric pressure. In a typical reaction, measured amount of catalysis was added to a three necked flask containing alkene at 80°C (for styrene) and 50°C (for cyclic olefins). The reaction was started by bubbling O2 into the liquid. The reaction was carried out by varying different parameters such as amount of the catalyst and reaction time. After completion of the reaction, the liquid product was extracted with dichloromethane, dried with magnesium sulphate and analyzed on Gas Chromatography using RTX-5 capillary column. Product identification was done by comparison with authentic samples and finally by a combined Gas Chromatography Mass Spectrometry. Detailed Description of the Accompanying Drawings Figure 1 shows FT-IR spectra of (PW102/AI2O3 shows bands at 752 cm"1, 950 cm"', and at 1091 and 1045 cm-1 corresponding to the symmetric stretching of W-O-W, W=O and P=O bonds respectively. Figure 2 shows TGA of (PWnVAbCh shows 3 % weight loss in the temperature range 120-180°C due to loss of adsorbed water. There is 4% weight loss at 370°C corresponding to the loss of coordinated water. Further it does not show any weight loss up to 541 °C, indicating the synthesized catalyst is stable up to 541 °C. Figure 3 shows 3IP MAS NMR for (PW11)2/A1203 shows one strong resonance at -7.2 ppm. Figure 4 shows The XRD pattern of (PW1O2/AI2O3 shows the amorphous nature of the materials indicating that the crystallinity of the PWn is lost on supporting it onto AI2O3. Figure 5 shows surface of the support is distinctly altered. It exhibit considerable surface shinning after supporting of the PWu. Pictures taken at higher magnification (5000x) shows clearly the alternation and shining of the surface. The present invention is illustrated by the following non-limiting examples. The methodology described is for the purpose of description and should not be taken as limitation. Example 1: Synthesis of the Catalyst Catalyst was synthesized in two steps. The first step involves the synthesis of the mono lacunary undecatungstophosphate (PWjj) following the methods reported by Brevard et al. Sodium tungstate dehydrate (0.22 mol, 72.5 g) and anhydrous disodium hydrogen phosphate (0.02 mol, 2.84 g) were dissolved in 150-200 ml of conductivity water and was heated to 80-90°C followed by the addition of concentrated nitric acid in order to adjust the pH 4.8. The volume was then reduced to half by evaporation and the heteropolyanion was separated by liquid-liquid extraction with 80-100 ml of acetone. The extraction was repeated until the acetone extract shows absence of NO3" ions (ferrous sulphate test). The extracted sodium salt was dried in air. The second step involves the supporting of the PW11 on to the support of neutral alumina (AI2O3) by dry impregnation method. A series of catalysts containing 10-40% PWn were synthesized by impregnating AI2O3 (1 g) with an aqueous solution of PW11 (0.1-GA g in 10-40 ml of conductivity water) with stirring for 35h and then dried at 100° C for 10 h. The obtained materials were designated as (PW11)2/Al2O3, (PW11)2/Al2O33, (PW„)3/ AI2O3 and (PWn)4/ A1203. The catalyst obtained is well characterized by various physicochemical techniques like Chemical stability, FT-IR (Figure 1), TGA (Figure 2), P31 MAS NMR (Figure 3), XRD (Figure A), SEM and Surface Area measurement (BET) (Figure 5). The FT-IR spectra of (PW11)2/Al2O3 shows bands at 752 cm"', 950 cm-1, and at 1091 and 1045 cm-1 corresponding to the symmetric stretching of W-O-W, W=0 and P=0 bonds respectively. The presence of there bands indicates the Keggin unit remains intact even after supporting it onto a support. TGA of (PW1O2/AI2O3 shows 3 % weight loss in the temperature range 120-180°C due to loss of adsorbed water. There is 4% weight loss at 370°C corresponding to the loss of coordinated water. Further it does not show any weight loss up to 541°C, indicating the synthesized catalyst is stable up to 541°C. 31P MAS NMR for (PW11)2/A1203 shows one strong resonance at -7.2 ppm. Edwards et ai. have reported that depending upon the amount of the Keggin species (active species) onto the support different chemical shifts are expected in the 31P MAS NMR indicating the presence of various species [J. Edwards, C. Thiel, B. Benac, J. Knifton, Cat Lett, 51 (1998) 77 - 83]. The resonance at -4ppm is due to the adsorbed phosphorus species derived from the highly fragmented Keggin unit, while the resonance at - 8ppm is due to the partially fragmented Keggin unit. Slight shift from the reported value may be due to the difference in the type of support used. Thus 3IP MAS NMR indicates the retainment of the PWi 1 structure after supporting it onto neutral alumina 10 ' I 1 DEC 2810 The XRD pattern of (PW11)2/Al2O3 shows the amorphous nature of the materials indicating that the crystallinity of the PWn is lost on supporting it onto AI2O3. Further, it does not show any diffraction lines of lacunary PW11 indicating a very high dispersion of solute as a non-crystalline form on the support surface. It is observed from the figure 5 that surface of the support is distinctly altered. It exhibits considerable surface shinning after supporting of the PW11. Pictures taken at higher magnification (5000x) shows clearly the alternation and shining of the surface. The total surface area for ( (PW11)2/Al2O3 was evaluated by BET adsorption desorption curve and was found to be 99.0m2/g. Example 2: Catalytic Activity The synthesized catalyst was used for evaluation of the catalytic activity by studying the oxidation of alkenes using molecular oxygen. The results obtained are provided in table given below: Table 1: Aerobic Oxidation of alkenes using (PW11)2/Al2O3 aOxidant Alkene bConversion (%) Products Selectivity (%) TON o2 Styrene 58 Benzaldehyde Styrene oxide 44 56 4265 cCyclohexene 85 Cyclohexene oxide 100 6029 Ccis-Cyclooctene 3.5 Cyclooctene oxide 100 2584 * Amount of catalysis, 25 mg: temperature, 80 C (styrene), 50 C (cyclic olefins): Alkenes 100 mmol; Oxidant O2 latm; time, 4h, c24 h; amount of active PWn on the support, 4.16 mg, Conversion based on substrate. The control experiment was carried out with AI2O3 under the optimized conditions. It was observed that no conversion was obtained for any of the alkenes indicating that AI2O3 is inactive towards oxidation of alkenes indicating the catalytic activity is only duetoPWn. The catalyst of the present invention is effectively used for styrene as well as for Cyclohexene. The present catalyst is restricted to epoxidation of certain cyclic olefins, the process is not applicable for cyclic-olefins having bulker size and also not for alkenes which are sterically hindered e.g. Cyclooctene Example 3 The comparison of catalytic data involving undecatungstophospho (aqua) ruthenate (II) (PRuWn) and the catalyst of the present invention PW11/AI2O3 was carried out in the present invention although there were critical differences observed between the two as provided herein under as 1. Firstly, the PRuWn falls under the cater gory of transition metal substituted polyoxometalates (TMSP), while the present catalyst i.e. (PW11)2/Al2O3 is a lacunary polyoxometalate (LPOM). 2. In the present invention, a heterogeneous catalyst was synthesized supporting the lacunary phosphotungstate (PWn) onto neutral alumina (AI2O3), while in case of PRuWi 1 the catalyst itself behaves as a heterogeneous catalyst under given oxidation conditions. 3. Also, Ru catalyst requires more time to activate, consequently higher conversion is not obtained whereas in the present invention, no activation process is required. The catalyst was PWnRu was synthesized supporting onto A1203 [(PW11Ru)2/Al2O]3 and oxidation of cyclohexene was studied under same conditions. The obtained results are shown in Table 2 Table 2. Comparative data for (PW11)2/A2O3 and(PW11Ru)2/Al2O3 for oxidation of Cyclohexene aCataIyst % Conversion %Selectivity Cy60 (PW11)2/A2O3 (present invention) 85% 100 (PW11Ru)2/Al2O3 72% aAlkene, 100 mmol; oxidant 02 1 atm; catalyst, 7.9 ymol; temperature, 80°C time 24 h. As observed from table 2, (PW11Ru)2/Al2O3 gives only 72% conversion under identical experimental conditions. Hence, it is clear that the present invention is superior over the earlier reported unsupported as well as the supported catalyst. We Claim: 1. A heterogeneous catalyst comprising supported undecaphosphotungstate. 2. The catalyst as claimed in claim 1 wherein said catalyst undecaphosphotungstate is lacunary polyoxometalates supported on neutral alumina. 3. The catalyst as claimed in claim I wherein said supported lacunary polyoxometalates is represented by the formula I (PW11)2/A2O3 (I) wherein W=Tungsten (polyoxometalate Na7PW1 1O39). 4. The catalyst as claimed in claim 1 wherein said catalyst has activity of 6029 turn over number. 5. The catalyst as claimed in claim 1 wherein said catalyst is adapted for selective epoxidation of cycloalkene. 6. A process for selective epoxidation of cycloalkene comprising reacting a cyclic olefin with an oxidizing agent in the presence of catalyst comprising supported undecaphosphotungstate on neutral alumina. 7. The process as claimed in claim 6 wherein said cyclic olefin is a member selected from the group consisting of cyclopentene, cyclohexene cycloheptene and cylcooctene. 8. The process as claimed in claim 7 wherein said cyclic olefin is cyclohexene. 9. The process as claimed in claim 7 wherein said oxidizing agent is selected from molecular oxygen, PhIO, Tert-butyl hydrogen peroxide and hydrogen peroxide. 10. The process as claimed in claim 7 wherein said reaction is conducted in solvent free liquid phase mild reaction conditions having reaction temperature of 50°C with a reaction time of 24hrs. 11. A catalyst as substantially described herein with reference to the accompanied figures and examples. 12. A process for selective epoxidation of cycloalkene as substantially described herein with reference to the accompanied examples.

Full Text

FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
Title of the invention - SUPPORTED UNDECAPHOSPHOTUNGSTATE CATALYST
FOR AEROBIC EPOXIDATION OF ALKENES
2. Applicant(s)
(a) NAME : M. S. University of Baroda
(b) NATIONALITY : Indian
(c) ADDRESS: Sayajigunj, Vadodara 390 002, Gujarat, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

Field of Invention
The present invention relates to a heterogeneous catalyst comprising lacunary polyoxometalate supported by neutral alumina. The invention also relates to a process for the selective aerobic epoxidation of cycloalkenes, in liquid phase comprising the heterogeneous catalyst.
Background and Prior Art of the Invention
US 5466838 disclose the process for production of epoxide using an iron or a copper containing catalyst. Various olefins have been studied in the presence of molecular oxygen at 25° C using dichloromethane as a solvent. In all cases, aldehyde has been used to promote the oxidation process. Oxidation of cyclohexene gives 100% conversion with 79% yield for cyclohexene oxide using Fe as well as Cu(OH)2 as a catalyst. 100% conversion with 97% selectivity for cyclohexene oxide was obtained from Fe2C>3 catalyst.
US 5744620 disclose a process for selective oxidation of cyclic olefins in the presence of air or molecular oxygen catalyzed by metallosalen type of catalysts. The patent describes more effective oxidation of cyclohexene using different metal ions such as Co, Ru, Fe and V. The metallosalen catalyst was taken in acetonitrile, and then molecular oxygen was bubbled to the reaction mixture followed by addition of cyclic olefin in the presence of a sacrificial co-reductant (i.e. isobutyraldehyde). The oxidation products consist of alcohol and ketone along with epoxide. The V metallosalen complex was most reactive among all with 86% selectivity for cyclohexene oxide,
US 5175316 discloses a different process for epoxidation which involves the mixture of cyclohexene, cyclohexene oxide, cyclohexanol and cyclohexenone dissolved in cyclohexene as a solvent at temperatures between 100° to 200° C under 10-130 bar pressure. The mixture of products was oxidized and the initial concentration of

cyclohexene decreased from 6.8 weight % to 0.39 weight % and hence increasing the concentration of cyclohexene oxide from 0.03% to 5.78%.
A number of research papers are available on the oxidation of cyclic olefins, especially, cyclohexene using molecular oxygen.
S Dapurkar et al. (App. Catal. A., 2008, 346, 112) have reported the use of Cr-MCM-41 for solvent free oxidation of cyclic olefins using 1 atm of molecular oxygen. The cyclohexene oxidation resulted in 52.2% conversion with 71.1% selectivity for 2-cyclohexen -1-one at 343K temperature for 24 h reaction time.
Other minor products include cyclohexene oxide, 2-cyclohexen-l-oI and 1-cyclohexenel-hydroperoxide. Apart from these products the oxidation process also resulted in formation of cyclohexanol or cyclohexanone as minor products.
Dapurkar et al. have disclosed the process of oxidation of cyclohexene under solvent free conditions. They have reported the allylic oxidation of cycloalkenes, especially cyclohexene. 52.2% conversion was obtained with molecular oxygen under solvent free conditions over Cr-MCM-41 as the catalytic system. They have reported the formation of Cy-none as the major product while, Cy-oxide was obtained as minor product with only 3.1% selectivity. Further, they have also reported the formation of other minor products such as Cy-ol and Cy-HP.
Amarasekara et al. have reported (Cat Comm. 2007, 8, 1132) immobilization of the metallosalen complex on the silica gel matrix using the sol-gel process and its use as a catalyst for oxidation of alkenes using molecular oxygen. The paper deals with oxidation of various alkenes apart from cyclohexene. The oxidation process was carried out at room temperature by using butryaldehdye as a co-reductant with acetonitrile as a solvent. Cyclohexene oxidation resulted in 71% conversion with 34% selectivity for cyclohexene oxide, the major product formed was 2-cyclohexene-1-one along with 21% of diol.

X. Tong et al. reported (Tetrahedron, 63 (2007), 7634-39) highly efficient metal free oxidation of olefins by molecular oxygen under mild conditions in the presence of 1,4-diamino-2,3-dichloro-anthraquinone and N-hydroxyphthalimide. Oxidation of cyclohexene resulted in 89% conversion with 71% selectivity for 2-cyclohexen-l-one and minor products of cyclohexene oxide, 2-cyclohexen-l-ol and 2-cyclohexenel-hydroperoxide under 0.3 Mpa pressure and 80°C. The epoxide selectivity was lower than 5%.
J. Tong et al. reported chitosan supported Salophen Mn (III) complexes for aerobic oxidation of cyclohexene. Different catalyst containing varying amounts of metal was supported on chitosan support. Cyclohexene oxidation resulted in 83.6% conversion with 61.3% selectivity for 2-cyclohexen-l-one and other minor quantities of cyclohexene oxide, 2-cyclohexen-l-ol and 2-cyclohexenel-hydroperoxide. The reaction was carried out using acetonitrile or dichloroethane as a solvent at 70°C for 24h.
A.S.C. Chang et al, describe (Chem Comm., 2003, 1058) an efficient catalytic system for epoxidation of cyclic olefins using molecular oxygen. They report the use of ruthenium complex for aerobic epoxidation of cyclic alkenes. Oxidation of cyclohexene results in epoxide as a major product with 99.9% conversion and 90.1% selectivity for epoxide. The reaction was carried out at room temperature by using isobutryaldehyde as a co-reductant in the presence of dichloroethane as solvent.
R. M. Wang et al. reported (J. Mol Catal A 147 (1999), 173-178) the use of amino acid Schiff base manganese complex for aerobic oxidation of cyclohexene. The major products were 2-cyclohexen-l-one, 2-cyclohexen-l-ol and 2-cyclohexene-l-hydroperoxide. The catalytic reaction was carried out by varying different temperatures and the effect of additives. 74.8% conversion was obtained with 75.1% selectivity for ketone and alcohol and 29.6% selectivity for 2-cyclohexene-l-hydroperoxide after 14h.
Polymer-supported metallo-phthalocyanines have also been reported to catalyze the epoxidation of cyclohexene using dioxygen as the oxidant by M. Gebler (J Inorg Nucl Chem. 1981,43,2759).

US 5250739 disclose a process for cyclohexene oxidation using a metal substituted heteropolyanion of Dawson type. The process involves mainly the production of 2-cyclohexene-1-ol and 2-cyclohexene-l-one with molecular oxygen as an oxidant in the presence of various solvents such as 1,2-dichloroethane, 1,2-dichloromethane, acetone, acetonitrile etc. among the various metal substituted heteropolyanions the Ir substituted heteropolyanion showed the higher activity with TOF=2.9 h'1 at 38°C for 118h.
G. Maayan and R. Neumann have reported (Chem. Comm., 2005, 4595) the use of Ag and Ru nano-particles stabilized by Vanadium substituted phosphomolybdate supported on alumina matrix for epoxidation of alkenes using molecular oxygen. The cyclohexene epoxidation was carried out at 160° C for lh by bubbling O2. The Ag nanoparticles (50%) showed higher selectivity for cyclohexene oxide as compared to Ru nanoparticles (41), along with some other side products. The oxidation reaction was carried out using trifluoromethyl benzene as solvent and using anisole as an internal standard.
Neumann et al. have used α-alumina to support the Mn-POM nanoparticles, where (M= Ag, Ru, Pd). The reaction was carried out at 160°C using trifluoromethyl benzene as a solvent. Moreover, only 50% conversion was obtained with Ag-POM nanoparticles with 50% selectivity towards cyclohexene oxide. Other allylic oxidation products were also obtained in addition to cyclohexene oxide. The other nanoparticles did not give any significant conversion values.
The prior art have used either ketone or alcohol as a major oxidation products along with small amount of epoxide. Due the known importance of epoxide and the increasing demand of green oxidation processes the present catalyst is an excellent candidate.
The synthesis and characterization of lacunary polyoxometalates supported onto hydrous Zirconia is available and the same has been published in a publication provided by the inventors (Anajli Patel et al, 12-tungstophosphoric and 12-tungtosilicicacid supported onto hydrous Zirconia for liquid phase tert-butylation of m-cresol, Catalysis letters (2007) 117; 146-152). However the said catalyst does not provide required conversion to the end product and selectivity for the same.

Object of the Invention
It is an object of the present invention to provide a new heterogeneous catalyst.
A further object of the invention is to provide a catalyst comprising of launary polyoxometalate and alumina for the oxidation of alkenes.
Yet another object of the present invention is to provide an improved process for the selective aerobic epoxidation of cycioalkene in solvent free liquid phase.
Yet another object of the invention is to provide an economic and efficient process of epoxidation useful in polymer industry.
Summary of the invention
According to one aspect of the present invention there is provided a heterogeneous catalyst comprising supported undecaphosphotungstate on neutral alumina.
According to another aspect of the present invention there is provided a process for selective epoxidation of cycioalkene comprising, reacting a cyclic olefin with an oxidizing agent in the presence of catalyst comprising supported undecaphosphotungstate on neutral alumina.
Brief Description of the Accompanying Drawings
Figure 1 illustrates FT-IR spectrum of (PW11)2/Al2O3
Figure 2 illustrates Thermal Gravimetric Analysis of(PW11)2/Al2O3

Figure 3 illustrates 31P MAS NMR for (PW11)2/Al2O3
Figure 4 illustrates Powder X-Ray Diffraction pattern for (PW11)2/Al2O3

Figure 5 illustrates SEM images of AI2O3 and (PW11)2/Al2O3

Detailed Description of the Invention
Oxidation of cyclohexene is an industrially important reaction, especially in the polymer industry.
The novel alumina supported undecatungstophosphonate of the present invention is successful for solvent free oxidation of alkenes with molecular oxygen. The supported Iacunary polyoxometalates is represented by the formula I
(PW11)2/Al2O3
wherein W=Tungsten (polyoxometalate Na7PWnO39).
The present invention provides a solvent free liquid phase catalytic oxidation process achieving 85% conversion with 100 % selectivity towards single selective product i.e. cyclohexene oxide under solvent free condition using supported phosphotungstate as the catalytic system.
The reaction carried out in the present invention is able to achieve a higher TON of 6029. TON number is TURN OVER NUMBER and is defined as:
TON = moles of product / moles of catalyst
The present invention provides an efficient process for the oxidation of cycloolefins in solvent free liquid phase mild conditions. The examples of cyclic olefins are cyclopentene, cyclohexene cycloheptene and cylcooctene.
The present process provides 85% conversion and 100.0% selectivity for cyclohexene oxide. The process of the present invention is advantageous that it involves the simple solvent free oxidation process.

The oxidizing agent for the present epoxidation process is selected from molecular oxygen, PhIO, Tert-butyl hydrogen peroxide and hydrogen peroxide.
The oxidation of alkenes was carried out in a 100 ml three necked round bottom flask which is provided with a double walled air condenser, magnetic stirrer and a guard tube. Oxidation reaction was carried out in a batch type reactor operated under atmospheric pressure. In a typical reaction, measured amount of catalysis was added to a three necked flask containing alkene at 80°C (for styrene) and 50°C (for cyclic olefins). The reaction was started by bubbling O2 into the liquid. The reaction was carried out by varying different parameters such as amount of the catalyst and reaction time. After completion of the reaction, the liquid product was extracted with dichloromethane, dried with magnesium sulphate and analyzed on Gas Chromatography using RTX-5 capillary column. Product identification was done by comparison with authentic samples and finally by a combined Gas Chromatography Mass Spectrometry.
Detailed Description of the Accompanying Drawings
Figure 1 shows FT-IR spectra of (PW102/AI2O3 shows bands at 752 cm"1, 950 cm"', and at 1091 and 1045 cm-1 corresponding to the symmetric stretching of W-O-W, W=O and P=O bonds respectively.

Figure 2 shows TGA of (PWnVAbCh shows 3 % weight loss in the temperature range 120-180°C due to loss of adsorbed water. There is 4% weight loss at 370°C corresponding to the loss of coordinated water. Further it does not show any weight loss up to 541 °C, indicating the synthesized catalyst is stable up to 541 °C. Figure 3 shows 3IP MAS NMR for (PW11)2/A1203 shows one strong resonance at -7.2 ppm.
Figure 4 shows The XRD pattern of (PW1O2/AI2O3 shows the amorphous nature of the materials indicating that the crystallinity of the PWn is lost on supporting it onto AI2O3.
Figure 5 shows surface of the support is distinctly altered. It exhibit considerable surface shinning after supporting of the PWu. Pictures taken at higher magnification (5000x) shows clearly the alternation and shining of the surface.
The present invention is illustrated by the following non-limiting examples. The methodology described is for the purpose of description and should not be taken as limitation.
Example 1:
Synthesis of the Catalyst
Catalyst was synthesized in two steps.
The first step involves the synthesis of the mono lacunary undecatungstophosphate (PWjj) following the methods reported by Brevard et al. Sodium tungstate dehydrate (0.22 mol, 72.5 g) and anhydrous disodium hydrogen phosphate (0.02 mol, 2.84 g) were dissolved in 150-200 ml of conductivity water and was heated to 80-90°C followed by the addition of concentrated nitric acid in order to adjust the pH 4.8. The volume was then reduced to half by evaporation and the heteropolyanion was separated by liquid-liquid extraction with 80-100 ml of acetone. The extraction was repeated until the acetone extract shows absence of NO3" ions (ferrous sulphate test). The extracted sodium salt was dried in air.

The second step involves the supporting of the PW11 on to the support of neutral alumina (AI2O3) by dry impregnation method. A series of catalysts containing 10-40% PWn were synthesized by impregnating AI2O3 (1 g) with an aqueous solution of PW11 (0.1-GA g in 10-40 ml of conductivity water) with stirring for 35h and then dried at 100° C for 10 h. The obtained materials were designated as (PW11)2/Al2O3, (PW11)2/Al2O33, (PW„)3/ AI2O3 and (PWn)4/ A1203.
The catalyst obtained is well characterized by various physicochemical techniques like Chemical stability, FT-IR (Figure 1), TGA (Figure 2), P31 MAS NMR (Figure 3), XRD (Figure A), SEM and Surface Area measurement (BET) (Figure 5).
The FT-IR spectra of (PW11)2/Al2O3 shows bands at 752 cm"', 950 cm-1, and at 1091 and 1045 cm-1 corresponding to the symmetric stretching of W-O-W, W=0 and P=0 bonds respectively. The presence of there bands indicates the Keggin unit remains intact even after supporting it onto a support.
TGA of (PW1O2/AI2O3 shows 3 % weight loss in the temperature range 120-180°C due to loss of adsorbed water. There is 4% weight loss at 370°C corresponding to the loss of coordinated water. Further it does not show any weight loss up to 541°C, indicating the synthesized catalyst is stable up to 541°C.
31P MAS NMR for (PW11)2/A1203 shows one strong resonance at -7.2 ppm. Edwards et ai. have reported that depending upon the amount of the Keggin species (active species) onto the support different chemical shifts are expected in the 31P MAS NMR indicating the presence of various species [J. Edwards, C. Thiel, B. Benac, J. Knifton, Cat Lett, 51 (1998) 77 - 83]. The resonance at -4ppm is due to the adsorbed phosphorus species derived from the highly fragmented Keggin unit, while the resonance at - 8ppm is due to the partially fragmented Keggin unit. Slight shift from the reported value may be due to the difference in the type of support used. Thus 3IP MAS NMR indicates the retainment of the PWi 1 structure after supporting it onto neutral alumina
10
' I 1 DEC 2810

The XRD pattern of (PW11)2/Al2O3 shows the amorphous nature of the materials indicating that the crystallinity of the PWn is lost on supporting it onto AI2O3. Further, it does not show any diffraction lines of lacunary PW11 indicating a very high dispersion of solute as a non-crystalline form on the support surface.
It is observed from the figure 5 that surface of the support is distinctly altered. It exhibits considerable surface shinning after supporting of the PW11. Pictures taken at higher magnification (5000x) shows clearly the alternation and shining of the surface.
The total surface area for ( (PW11)2/Al2O3 was evaluated by BET adsorption desorption curve and was found to be 99.0m2/g.
Example 2:
Catalytic Activity
The synthesized catalyst was used for evaluation of the catalytic activity by studying the oxidation of alkenes using molecular oxygen. The results obtained are provided in table given below:
Table 1: Aerobic Oxidation of alkenes using (PW11)2/Al2O3

aOxidant Alkene bConversion
(%) Products Selectivity
(%) TON
o2 Styrene 58 Benzaldehyde Styrene oxide 44 56 4265

cCyclohexene 85 Cyclohexene oxide 100 6029

Ccis-Cyclooctene 3.5 Cyclooctene oxide 100 2584
* Amount of catalysis, 25 mg: temperature, 80 C (styrene), 50 C (cyclic olefins):

Alkenes 100 mmol; Oxidant O2 latm; time, 4h, c24 h; amount of active PWn on the support, 4.16 mg, Conversion based on substrate.
The control experiment was carried out with AI2O3 under the optimized conditions. It was observed that no conversion was obtained for any of the alkenes indicating that AI2O3 is inactive towards oxidation of alkenes indicating the catalytic activity is only duetoPWn.
The catalyst of the present invention is effectively used for styrene as well as for Cyclohexene. The present catalyst is restricted to epoxidation of certain cyclic olefins, the process is not applicable for cyclic-olefins having bulker size and also not for alkenes which are sterically hindered e.g. Cyclooctene
Example 3
The comparison of catalytic data involving undecatungstophospho (aqua) ruthenate (II) (PRuWn) and the catalyst of the present invention PW11/AI2O3 was carried out in the present invention although there were critical differences observed between the two as provided herein under as
1. Firstly, the PRuWn falls under the cater gory of transition metal substituted polyoxometalates (TMSP), while the present catalyst i.e. (PW11)2/Al2O3 is a lacunary polyoxometalate (LPOM).
2. In the present invention, a heterogeneous catalyst was synthesized supporting the lacunary phosphotungstate (PWn) onto neutral alumina (AI2O3), while in case of PRuWi 1 the catalyst itself behaves as a heterogeneous catalyst under given oxidation conditions.
3. Also, Ru catalyst requires more time to activate, consequently higher conversion is not obtained whereas in the present invention, no activation process is required.

The catalyst was PWnRu was synthesized supporting onto A1203 [(PW11Ru)2/Al2O]3 and oxidation of cyclohexene was studied under same conditions. The obtained results are shown in Table 2
Table 2. Comparative data for (PW11)2/A2O3 and(PW11Ru)2/Al2O3 for oxidation of
Cyclohexene

aCataIyst % Conversion %Selectivity Cy60
(PW11)2/A2O3
(present
invention) 85% 100
(PW11Ru)2/Al2O3 72%

aAlkene, 100 mmol; oxidant 02 1 atm; catalyst, 7.9 ymol; temperature, 80°C time 24 h.
As observed from table 2, (PW11Ru)2/Al2O3 gives only 72% conversion under identical experimental conditions. Hence, it is clear that the present invention is superior over the earlier reported unsupported as well as the supported catalyst.

We Claim:
1. A heterogeneous catalyst comprising supported undecaphosphotungstate.
2. The catalyst as claimed in claim 1 wherein said catalyst undecaphosphotungstate is lacunary polyoxometalates supported on neutral alumina.
3. The catalyst as claimed in claim I wherein said supported lacunary polyoxometalates is represented by the formula I
(PW11)2/A2O3 (I)
wherein W=Tungsten (polyoxometalate Na7PW1 1O39).
4. The catalyst as claimed in claim 1 wherein said catalyst has activity of 6029 turn over number.
5. The catalyst as claimed in claim 1 wherein said catalyst is adapted for selective epoxidation of cycloalkene.
6. A process for selective epoxidation of cycloalkene comprising reacting a cyclic olefin with an oxidizing agent in the presence of catalyst comprising supported undecaphosphotungstate on neutral alumina.
7. The process as claimed in claim 6 wherein said cyclic olefin is a member selected from the group consisting of cyclopentene, cyclohexene cycloheptene and cylcooctene.
8. The process as claimed in claim 7 wherein said cyclic olefin is cyclohexene.
9. The process as claimed in claim 7 wherein said oxidizing agent is selected from molecular oxygen, PhIO, Tert-butyl hydrogen peroxide and hydrogen peroxide.
10. The process as claimed in claim 7 wherein said reaction is conducted in solvent free liquid phase mild reaction conditions having reaction temperature of 50°C with a reaction time of 24hrs.

11. A catalyst as substantially described herein with reference to the accompanied figures and examples.
12. A process for selective epoxidation of cycloalkene as substantially described herein with reference to the accompanied examples.

Documents:

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Patent Number

271230

Indian Patent Application Number

3280/MUM/2010

PG Journal Number

07/2016

Publication Date

12-Feb-2016

Grant Date

10-Feb-2016

Date of Filing

01-Dec-2010

Name of Patentee

M.S. UNIVERSITY OF BARODA

Applicant Address

SAYAJIGUNJ, VADODARA 390 002, GUJRAT, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	SHRINGARPURE, PRAGATI A	17, DARSHAN PARK, V.I.P. ROAD, KARELIBAUG VADODARA, GUJRAT INDIA.
2	PATEL, ANJALI	30A/GINTANJALI SOCIETY, NOVINO TARASALI RING ROAD, MAKARPURA-10, VADODARA, GUJARAT, INDIA

PCT International Classification Number

C07D301/00; B01J 21/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA