FIELD OF THE INVENTION

The present invention relates to synthesis and use of recyclable organic promoters in the preparation of epoxides of cyclic and acyclic aryl olefins using hydrogen peroxide as an oxidant. Particularly the present invention involves the use of a recyclable organic promoter, an inorganic base and a metal salt as a catalyst for the synthesis of epoxides from alkenes viz., styrene, indene, 1,2-dihydronapthalene and chromenes in the presence of hydrogen peroxide as an oxidant. The product epoxides obtained from the above olefins have their application in flavors, fragrance, agrochemicals and pharmaceuticals industry.

BACK GROUND OF THE INVENTION

Epoxides of cyclic and acyclic aryl olefins are versatile intermediates in synthetic chemistry as stereospecific ring opening of these leads to compounds with industrial application. The synthesis of epoxides from olefins is a second order reaction which produces lots of heat during the course of the reaction which needs to be taken care of to avoid over-oxidized and thermal -degraded side products.

The production of epoxides from olefins gathers lots of attention from the industry and is a process of great economic significance. Typically epoxides are formed from alkenes in the presence of an oxygen donor with often involvement of an external catalyst. Several oxidizing agents such as commercial bleach, organic hydroperoxides, organic per acids, iodosyl arines, oxones, molecular oxygen (in the form of pure oxygen or air) and hydrogen peroxide have been used for production of epoxides from alkene.

Among the several oxidants used for epoxidation of olefins hydrogen peroxide gathers prime focus as it is an environment friendly oxidant as it produces water as sole by-product at the end of the reaction. However, hydrogen peroxide by itself is a poor oxidant for epoxidation reaction and requires the use of an activator and or a catalyst due to the poor-leaving tendency of the hydroxide ion. (G. Strukul, Catalytic Oxidation with Hydrogen Peroxide as oxidant: Kluwer: Dordrecht, 1992 and J. O. Edwards, In Peroxide Reaction Mechanism; O. J. Edward, Ed. Interscience: New York, 1962; pp, 67). Transition metal salts or complexes have been used as catalyst for alkene epoxidation with aqueous H ₂ O ₂ (E. N. Jacobsen, In Comprehensive Organometallic Chemistry II; E. W. Abel, F. G. Stone, E. Wilkinson, Eds. Pergamon: New York, 1995. Vol. 12 p. 1097; H. R. Tetzlaff, J. H. Espenson, Inorg. Chem. 38 (1999) 881). Other methods for activation of H ₂ O ₂ include forming reactive peroxy acids from carboxylic acids (D. Swern , In Organic peroxides; D. Swern Eds. Wiley Interscience, New York 1971 Vol. 2 p. 355) forming peroxycarboximidic acid from acetonitrile (G. B. Payne P. H. Deming, P. H. William, J. Org. Chem. 26 (1961) 659) generation of peroxyurea (G. Majetich, R. Hicks, Synlett. (1996) 694), or using perborate or sodium percarbonate in strongly basic solution (A. McKillop, W. R. Sanderson, Terahedron, 51 (1995) 6145).

A method for activating hydrogen peroxide with bicarbonate ion in alcohol/water solvents was described by R. S. Drago et al. in Proceeding of 1997 ERDEC Scientific Conference on Chemical and Biological Defense Research and D. E. Richardson et al. in Proceeding of 1998 and ERDEC Scientific Conference on Chemical and Biological Defense Research, ERDEC, 1999. In the bicarbonate-activated peroxide system, the active oxidant peroxymonocarbonate ion, HCO ₄ ^" is presumably produced via the perhydration of CO ₂ (D. E. Richardson et al., J. Am. Chem. Soc, 122 (2000) 1729). Peroxymonocarbonate is an anionic peracid and is a potent oxidant in aqueous solution. Similarly nitriles have also been shown to activate hydrogen peroxide via in-situ production of potent epoxidising reagent-peroxyimidic acids in alkaline media (in general known as Payne system; G. B. Payne et al, J. Org. Chem. 26 (1961) 659; G. B. Payne, Tetrahedron 18 (1962) 763).

Reference may be made to a catalytic process for the preparation of epoxides from olefins in US7,235,676 (2007), which involves an olefin, an inorganic base, an organic promoter (2.6- 20 equivalents with respect to olefin) and a small amount of transition metal salt as a catalyst. A maximum conversion of 99% and a selectivity of 98% was obtained in case of styrene under biphasic reaction condition. However, the drawback associated with this process is the high solubility of the organic promoter, which is used in large excess, ends up as a waste at the end of the reaction and is hard to get rid of from the aqueous affluent.

Reference may be made to US7, 169,945 (2007) which discloses a process for epoxidation of olefins in the presence of titanium containing zeolites using hydrogen peroxide as an oxidant where deactivation of the catalyst was significantly reduced by incorporating one or more nitrogen containing species. However the drawback associated with this process is the usage of an organic solvent and also the yield of propylene oxide obtained from epoxidation of propene was not very high (maximum yield of 42%). Moreover this process was not suitable for higher alkenes.

Reference may be made to US7,345,182 (2008) which discloses a process for epoxidation of styrene with molecular oxygen using metal exchanged zeolites more specifically cobalt exchanged zeolites in an organic solvent. However, the drawbacks associated with this process are 1) use of an organic solvent of high boiling point in large quantity to achieve high conversion 2) high reaction temperature (-80 °C) 3) only GC conversions are reported no isolated yield was provided 4) for highest conversion of styrene the styrene oxide selectivity was 85.9%.

Reference may be made to US7,482,478 (2009) which discloses a process of diastereoselective epoxidation of allylically substituted alkenes using bicarbonate activated hydrogen peroxide and catalytic amount of manganese porphyrin to give product turnover number ranging from 50 to 3000. However the drawback associated with this process are (1) requirement of an organic solvent and (2) the process gives a maximum yield of 88% with a maximum selectivity of 93% using costly porphyrin based catalyst.

Reference may be made to US7,981,951 (2011) which discloses for producing epoxides from olefins that comprised of mixing an olefin containing two or more double bonds, a transition metal catalyst, a solvent, a buffering agent and hydrogen peroxide as an oxidant. This product gives corresponding product epoxide at greater than 90% by weight of total epoxidized product and a selectivity of greater than 90% by weight of total epoxidized product. However the drawback associated with this process 1) this process demonstrated examples of cycloaliphatic olefins with two double bonds 2) uses large amount of organic solvent and phosphate buffer.

Reference may be made to US8,080,677 (2011) which unveils a process for epoxidation of olefins which involves an olefin, a Lewis acid oxidation catalyst (MTO), an organic base (pyridine or its N-oxides), and a solvent system comprising of organic -water miscible solvent in the presence of hydrogen peroxide as an oxidant to give epoxides in 90% yield and 95% selectivity. However the drawback associated with this process 1) The system is pressurized either by the alkene itself or by using some pressurized gas 2) example of gaseous and smaller aliphatic olefins were demonstrated 3) works well only with expensive organic bases like pyridine N-oxides 4) use large excess of organic solvents 5) uses expensive methyl trioxorhenium as Lewis acid oxidation catalyst.

Reference may be made to an article by Mizuno et al. in Angew. Chem. Int. Ed. 50 (2011) 12062 which reports an efficient heterogeneous catalyst for epoxidation of olefins by a supported tungsten oxide catalyst in presence of hydrogen peroxide as an oxidant in dimethyl carbonate as a solvent. The product epoxides were obtained in high yield (up to 99%) and selectivity (up to 99%). However the drawback associated with this process 1) the yield was significantly reduced when the reaction was carried out in 20 mmol scale for cyclooctene (99% to 88%).

Reference may be made to an article by Lau et al. in Chem. Commun. 47 (2011) 4273 which reports a process for epoxidation of alkene with hydrogen peroxide catalyzed by a manganese(V) nitrido complex in presence of an organic solvent and acetic acid to give epoxides in high yield and selectivity. However the drawback associated with this process 1) In this report no reaction was done in larger scale and also isolated yield was not mentioned.

Reference may be made to EP2, 123,645 (2008) which discloses a process for epoxidation of olefins that comprised of reacting an olefin with a mixture obtained by mixing an acid anhydride and urea peroxide in an appropriate solvent. However the drawback associated with this process is the use of a corrosive anhydride which was not safe.

Reference may be made to WO2011/062608 which unveils a process of epoxidation of allyl chloride with hydrogen peroxide solution of predetermined pH which is adjusted with the help pyridine derived solid base, and TS-1 as catalyst in methanol as solvent and chlorobenzene as co-solvent to give epichlorohydrin. The drawback of this system is 1) This process requires use of an organic solvent along with a hazardous halogenated organic co- solvent 2) The protocol was not demonstrated with olefins other than allyl chloride. 3) produce high molecular byproducts.

Reference may be made to WO 2011/095296 which discloses a process for oxidation of olefinically unsaturated compounds in the presence of a water soluble manganese complex, an acid or buffer solution of an acid and an oxidant. The drawback of this system 1) the selection of olefin is restricted to heteroatom containing olefin.

Reference may be made to EP 1,841,753 (2009) which unveils an energy minimizing process for epoxidation of an olefin by reacting with hydrogen peroxide in presence of methanol as solvent and TS-1 in at least two reaction stages including under high pressure to obtain a mixture of epoxide, unreacted olefin and methanol. The drawbacks of the current process 1) required hazardous methanol solvent 2) operated at high pressure 3) only gaseous olefin was demonstrated for this epoxidation protocol.

Reference may be made to an article by Li et al. in Green Chem. 11 (2009) 2047 which reports a simple and green oxidation system containing water, lactone and lipase for the conversion of alkene to corresponding epoxides using hydrogen peroxide as the source of oxygen. The drawback of this system 1) long reaction time particularly with styrene as substrate 2) uses organic solvent for the reaction 3) uses enzyme based catalyst which is prone to denaturation.

OBJECTS OF THE INVENTION

The main object of the present invention is to provide an improved process for the synthesis of epoxides from olefins using a recyclable organic promoter.

Another object of the present invention is to provide an improved process of aryl alkene epoxidation using an inorganic base, a metal salt as a catalyst, a recyclable organic promoter in the absence or presence of an organic solvent at a reaction temperature of 10-30 °C and time of4-12h.

Yet another object of the present invention is to utilize a metal source as a catalyst and to produce styrene oxide from styrene in >95% yield and >96% selectivity in absence of an organic solvent.

Yet another objective of the process is to use a recyclable organic promoter for the promotion of epoxidation of alkenes under moderate reaction temperature and pressure and to minimize the waste. Yet another object of the present invention is to develop a catalytic process for epoxidation of alkene using H ₂ O ₂ as an oxidant.

SUMMERY OF THE INVENTION

Accordingly, present invention provides a process for the preparation of epoxides from alkenes comprising the steps of:

i. mixing alkene, transition metal salt, an inorganic base and an organic promoter in the mole ratio ranging between 860: 1 :270:200 to 860: 1 :357: 1200 to obtain a mixture;

ii. continuous stirring the mixture as obtained in step (i) with 50% hydrogen peroxide for period in the range of 2 to 10 hr followed by filtering and separating the reaction mixture by layer separation method to obtain aqueous layer and organic layer;

iii. distillating the organic layer to obtain epoxide.

In an embodiment of the present invention, alkenes used are selected from the group consisting of substituted or unsubstituted styrene, indene, 1,2-dihydronaphthalene and substituted or unsubstituted chromones.

In another embodiment of the present invention, transition metal salt used is selected from the group consisting of cobalt, manganese, nickel, copper, iron, chromium and vanadium and the counter ion is selected from the group consisting of chloride, bromide, iodide, carbonate, bicarbonate, perchlorate, sulphate, nitrate, acetate or phosphate.

In yet another embodiment of the present invention, the inorganic base used is selected from the group consisting of carbonates and bicarbonates of alkali metals selected from lithium, sodium, potassium and cesium.

In yet another embodiment of the present invention, concentration of the promoter used is in the range of 0.003 mol to 4.0 mol.

In yet another embodiment of the present invention, the organic promoter is recovered by simple filtration from the reaction mass. In yet another embodiment of the present invention, the temperature of the reaction is maintained in the range of -10 to 80 °C.

In yet another embodiment of the present invention, the aging period of the reaction mixture is maintained in the range of 3 to 15 h.

In yet another embodiment, present invention provides a process for the preparation of organic promoter comprising the steps of:

i. mixing cyanuric chloride and an organic compound having diamino group in the ratio ranging between 1 : 1 to 1 :6 at temperature in the range of 25 to 28 °C to obtain a powder;

ii. heating the powder as obtained in step (i) at 3-7 °C/min rate till it reaches 140 to 150 °C followed by keeping at 140 to 150 °C for 5 to 6 hours to obtain solid mass;

iii. cooling the solid mass as obtained in step (ii) at room temperature in the range of 25 to 30°C followed by washing , drying at 25 to 30 °C under vacuum to obtain organic promoter.

In yet another embodiment of the present invention, amino compounds used are selected from the group consisting of urea, thiourea, Ν,Ν-dimethylurea, ethylenediamine, o- phenylenediamine, m-phenylenediamine, p-phenylenediamine, trans- 1,2-diamimo cyclohexane

In yet another embodiment of the present invention epoxidation reactions may be conducted under triphasic conditions in the absence of an organic solvent.

The contemporary invention divulges the catalytic oxidative process for the conversion of alkenes to their corresponding epoxides.

DETAIL DESCRIPTION OF THE INVENTION

Present invention provides an improved process for the synthesis of epoxides from olefins using a recyclable organic promoter which comprises of reacting an olefin with a system composed of an inorganic base, a recyclable organic promoter in the presence of a transition metal salt catalyst and hydrogen peroxide as an oxidant under triphasic heterogeneous system. After separation of the heterogeneous organic promoter by filtration or centrifugation, the resulting epoxide is separated from the aqueous layer by layer separation method or by solvent extraction method depending on the nature of the epoxide.

The process comprises the reaction of alkenes with oxygen atom in the existence of the inorganic salts and specific organic co-promoter to produce the epoxide yields under the suitable catalytic conversion condition. The laboratory scale reaction was done with the laboratory reagent grade alkenes as a substrate in 250 ml two necked round bottom flask set on the stirring device and fitted with an efficient water condenser by keeping 20 °C temperature of the reaction mass with continuous stirring to yield the analogous epoxides from the alkenes. For the epoxidation, slow addition of hydrogen peroxide was required to form in situ highly active peroxo intermediate species, which is key point for the formation of epoxide. According to the above mentioned process the catalytic oxidation of alkenes proceeds through the following reaction scheme.

Inorgan c promotor & organ c co-promotor

The present invention of epoxidation reaction encompasses the triphasic homogeneous system by the combination of both, inorganic and recyclable organic promoters. The concentration range of alkene used in the present invention was 0.007 to 15 mol, from which, 0.01 to 10 mol concentration range was preferred for catalytic conversion of alkene to epoxide by using hydrogen peroxide as an oxidant at a moderate temperature and atmospheric pressure. When the alkene concentration was in the range of 0.1 to 0.8 mol in combination with inorganic promoter in the range of 0.033 to 0.1 mol and recyclable organic co-promoter in the range of 20 to 50 g with respect to alkene, greater yield conversion of alkene oxide was obtained. The alkene oxide product was extracted from the reaction mass and characterized by GC and ¾ NMR.

In the present invention the catalytic conversion of the alkenes to their epoxides proceeds through normal temperature and atmospheric pressure of solvent, which is water in the present disclosure. At low temperature, below 5 to 15 °C the catalytic conversion of alkenes to their respective epoxides is very slow, between 35 to 40 % even after 8 h. Increase of the temperature ploddingly to 50 °C helps for the achievement of the complete conversion of alkenes to their resultant epoxides in lower reaction time. In consequence of the present invention, due to the strong interaction of transition metal salts with the π electrons of alkenes, the transition metal salt plays a very crucial role for the electrophilic activation of alkenes; therefore the metal salts may be added to the reaction mixture in the concentration range of 0.011 mol to 0.05 mol. Less than 15 % conversion of epoxide obtains with a very small quantity of metal salts which sloths the catalytic reaction during the epoxidation process, hence the ideal quantity of transition metal salts is required for the essential catalytic transformation. In contrast, higher amount of transition metal salts decrease the yield formation of epoxide because at the same time of conversion of alkene to epoxide it has ability to decompose the hydrogen peroxide, which led to need more quantity of hydrogen peroxide, which may unfavorably effect on the economics of the invented process.

The addition period of hydrogen peroxide is important followed by the aging of the reaction to achieve higher yields and conversion of epoxide. Decrease the time period of addition of hydrogen peroxide less than 2 hour followed by aging of the reaction less than 4 hour resulted in poor conversion of alkene to epoxide. No improvement has occurred by increasing the time of addition and subsequent aging period beyond 6 h and 15 h respectively. The time may be varied in the range of 2 to 10 h, especially in the range of 3 to 6 h followed by aging in the range of 2 to 20 h preferably in the range of 3 to 15 h.

It was observed that the concentration of hydrogen peroxide used may vary in the range of 5 to 55%, appropriately in the range of 10 to 50 % for obtaining higher oxygen atom efficiency with respect to the alkenes. Furthermore, the optimal quantity of transition metal salt is essential accompanied by the hydrogen peroxide as it tends to decompose hydrogen peroxide later on too.

A combination of metal salts with hydrogen peroxide forms a highly active peroxo intermediate species, which enhances the conversion of alkenes to epoxides. The preparation of alkene oxides throughout the present invention is suitable for wide variety of applications of epoxides.

The epoxidation reaction was affected by the use of transition metal salts as a catalyst in combination with an inorganic base and an organic solvent wherein the conversion and selectivity of epoxides were higher than those of reported in past literature. The reaction method of the present invention does not have need of any special device and the use of hazardous and corrosive chlorine gas is dispensed. In the present invention the catalytic procedure for the preparation of epoxides from alkene, gives oxides having high purity yields in absence of organic solvents at moderate temperature. The inventive steps adopted in the presence invention are:

i. The efficient organic co -promoter is used in the catalytic epoxidation of the alkene with great recyclability.

ii. The epoxidation reaction does not require higher temperature and pressure; it is carried out at a low temperature and atmospheric pressure.

iii. The epoxidation reaction gets rid of the need of anhydrous condition and the catalytic conversion takes place in aqueous medium.

iv. since there is no need of organic solvent for the epoxidation reaction to occur, the process is eco-benign.

v. The epoxidation reaction is affected using inexpensive transition metal salt as a catalyst and the need for expensive tungstic acid, complexes of molybdic acid and silver containing catalyst is dispensed.

In a typical catalytic course of reaction, the appropriate transition metal salt, alkene, inorganic salt and recyclable organic additive in water was taken in a reaction vessel at a required temperature. The oxidant was added at a defined rate and after completion of reaction epoxide was separated in a separating funnel by using suitable non-halogen solvents and purified by distillation or crystallization as the case may be. The purity of the product was determined by Gas Chromatography and ¾ NMR.

EXAMPLES

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

A mixture of cyanuric chloride (10 g; 0.05 mol) and urea (9 g; 0.15 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-1. Yield: 10 g; 72.20 %. Melting point: >300 °C.

EXAMPLE 2

A mixture of cyanuric chloride (10 g; 0.05 mol) and urea (12 g; 0.2 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-2. Yield: 10.11 g; 72.99 %. Melting point: >300 °C.

EXAMPLE 3

A mixture of cyanuric chloride (10 g; 0.05 mol) and urea (15 g; 0.25 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-3. Yield: 10.73 g; 77.47 %. Melting point: >300 °C.

EXAMPLE 4

A mixture of cyanuric chloride (10 g; 0.05 mol) and urea (18 g; 0.3 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-4. Yield: 11.23 g; 89.04 %. Melting point: >300 °C.

EXAMPLE 5 A mixture of cyanuric chloride (10 g; 0.05 mol) and thiourea (22.83 g; 0.3 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-5. Yield: 9.87 g; 59.96 %. Melting point: >200 °C.

EXAMPLE 6

A mixture of cyanuric chloride (10 g; 0.05 mol) and N,N-dimethylurea (26.43 g; 0.3 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-6. Yield: 12.81 g; 69.50 %. Melting point: >200 °C

EXAMPLE 7

The cyanuric chloride (10 g; 0.05 mol) and ethylenediamine (20 mL; 0.3 mol) was mixed thoroughly at 28 °C in a glass vessel which was then heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-7. Yield: 8.22 g; 59.31 %. Melting point: >300 °C.

EXAMPLE 8

A mixture of cyanuric chloride (10 g; 0.05 mol) and o-phenylenediamine (32 g; 0.3 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-8. Yield: 15.11 g; 69.66 %. Melting point: >200 °C EXAMPLE 9

A mixture of cyanuric chloride (10 g; 0.05 mol) and m-phenylenediamine (32 g; 0.3 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-9. Yield: 14.13 g; 65.14 %. Melting point: >200 °C

EXAMPLE 10

A mixture of cyanuric chloride (10 g; 0.05 mol) and p-phenylenediamine (32 g; 0.3 mol) was finely grinded in a mortar with the help of a pestle at 28 °C. The powder thus obtained was transferred to a glass vessel which was heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-10. Yield: 14.15 g; 65.23 %. Melting point: >200 °C

EXAMPLE 11

The cyanuric chloride (10 g; 0.05 mol) and trans- 1,2-diamimo cyclohexane (36.22 mL; 0.3 mol) was mixed thoroughly at 28 °C in a glass vessel which was then heated at 5 °C/min rate till it reaches 150 °C. The reaction mixture was kept at 150 °C for 6 hours. Thereafter the resulting solid mass was allowed to cool to room temperature (28 °C) and washed with water (50 mL x 3) followed by acetone (50 mL x 3) and dried at 30 °C under vacuum to give a white solid hereafter referred as TAP-11. Yield: 15.86 g; 69.92 %. Melting point: >200 °C

EXAMPLE 12

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-1 (10 g), sodium bicarbonate (3.27 g; 0.039 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 20 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 22.57 % with 97.20 % selectivity.

EXAMPLE 13

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-2 (10 g), sodium bicarbonate (3.27 g; 0.039 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 35 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 35.00 % with 95.26 % selectivity.

EXAMPLE 14

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-3 (10 g), sodium bicarbonate (3.27 g; 0.039 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 45.5 % with 94 % selectivity.

EXAMPLE 15

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-4 (10 g), sodium bicarbonate (3.27 g; 0.039 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 66.4 % with 94 % selectivity.

EXAMPLE 16

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-5 (10 g), sodium bicarbonate (3.27 g; 0.039 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 46.14 % with 92.11 % selectivity.

EXAMPLE 17

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-6 (10 g), sodium bicarbonate (3.27 g; 0.039 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 40 % with 91.28 % selectivity.

EXAMPLE 18

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-7 (10 g), sodium bicarbonate (2.26 g; 0.027 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 30.4 % with 94.2 % selectivity.

EXAMPLE 19

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-8 (10 g), sodium bicarbonate (2.26 g; 0.027 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 25.4 % with 94.8 % selectivity. EXAMPLE 20

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-9 (10 g), sodium bicarbonate (2.26 g; 0.027 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 33.7 % with 94.6 % selectivity.

EXAMPLE 21

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-10 (10 g), sodium bicarbonate (2.26 g; 0.027 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 40.2 % with 93.87 % selectivity.

EXAMPLE 22

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-11 (10 g), sodium bicarbonate (2.26 g; 0.027 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 37.1 % with 94.29 % selectivity.

EXAMPLE 23

To a mechanically stirred mixture of styrene (5 mL; 0.043 mol), material TAP-4 (7.5 g), sodium bicarbonate (1.34 g; 0.016 mol) and manganese sulphate (0.016 g; 0.00011 mol) in 10 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (7.5 mL; 0.13 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 10 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 72.07 % with 94.45 % selectivity.

EXAMPLE 24

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-4 (10 g), sodium bicarbonate (2.77 g; 0.033 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 15 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (20 mL; 0.34 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 61.16 % with 95.44 % selectivity.

EXAMPLE 25

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-4 (8 g), sodium bicarbonate (3.27 g; 0.039 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 35 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (15 mL; 0.26 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 60.50 % with 92.25 % selectivity.

EXAMPLE 26

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-4 (8 g), sodium bicarbonate (2.26 g; 0.027 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (30 mL; 0.52 mol) drop-wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 75.45 % with 96.48 % selectivity.

EXAMPLE 27

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-4 (8 g), sodium bicarbonate (2.77 g; 0.033 mol), manganese sulphate (0.027 g; 0.00018 mol) and tert- butyl alcohol (2 mL; 0.02 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (30 mL; 0.52 mol) drop-wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 87.55 % with 95.52 % selectivity.

EXAMPLE 28

To a mechanically stirred mixture of styrene (10 mL; 0.087 mol), material TAP-4 (10 g), sodium bicarbonate (2.77 g; 0.033 mol), manganese sulphate (0.027 g; 0.00018 mol) and tert- butyl alcohol (2 mL; 0.02 mol) in 40 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (30 mL; 0.52 mol) drop-wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 90.68 % with 95.55 % selectivity.

EXAMPLE 29

To a mechanically stirred 8 pH mixture of styrene (10 mL; 0.087 mol), material TAP-4 (10 g), sodium bicarbonate (2.77 g; 0.033 mol), sodium carbonate (0.19 g; 0.0018 mol), manganese sulphate (0.027 g; 0.00018 mol) and tert-butyl alcohol (2 mL; 0.02 mol) in 30 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (30 mL; 0.52 mol) drop-wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 92.66 % with 92.66 % selectivity.

EXAMPLE 30

To a mechanically stirred 8 pH mixture of styrene (20 mL; 0.174 mol), material TAP-4 (20 g), sodium bicarbonate (4.5 g; 0.054 mol), sodium carbonate (0.402 g; 0.0038 mol), manganese sulphate (0.045 g; 0.0003 mol) and tert-butyl alcohol (2 mL; 0.02 mol) in 60 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (60 mL; 1.04 mol) drop-wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 30 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 90.82 % with 95.78 % selectivity.

EXAMPLE 31

To a mechanically stirred 8 pH mixture of styrene (10 mL; 0.087 mol), material TAP-4 (10 g), sodium bicarbonate (2.26 g; 0.027 mol), sodium carbonate (0.190 g; 0.0018 mol) and manganese sulphate (0.027 g; 0.000018 mol) in 40 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (0.52 mol) drop-wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 20 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 88.86 % with 96.00 % selectivity.

EXAMPLE 32

To a mechanically stirred 8 pH mixture of styrene (20 mL; 0.174 mol), material TAP-4 (20 g), sodium bicarbonate (4.5 g; 0.054 mol), sodium carbonate (0.402 g; 0.0038 mol) and manganese sulphate (0.045 g; 0.0003 mol) in 60 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (60 mL; 1.04 mol) drop-wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 30 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 91.13 % with 97.36 % selectivity.

EXAMPLE 33

To a mechanically stirred 8 pH mixture of styrene (20 mL; 0.174 mol), material TAP-4 (20 g), sodium bicarbonate (4.5 g; 0.054 mol), sodium carbonate (0.402 g; 0.0038 mol) and manganese sulphate (0.027 g; 0.00018 mol) in 60 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (42 mL; 0.72 mol) drop-wise over a period of 4.5 h. After 5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 30 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 65.81 % with 95.61 % selectivity. EXAMPLE 34

To a mechanically stirred mixture of styrene (50 mL; 0.43 mol), material TAP-4 (50 g), sodium bicarbonate (11 g; 0.13 mol) and manganese sulphate (0.081 g; 0.00054 mol) in 150 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (150 mL; 2.60 mol) drop- wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 50 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 93.23 % with 97.09 % selectivity.

EXAMPLE 35

To a mechanically stirred mixture of styrene (50 mL; 0.43 mol), material TAP-4 (30 g), sodium bicarbonate (11 g; 0.13 mol) and manganese sulphate (0.081 g; 0.00054 mol) in 120 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (150 mL; 2.60 mol) drop- wise over a period of 6 h. After 6.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 50 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 82.14 % with 97.08 % selectivity.

EXAMPLE 36

To a mechanically stirred mixture of styrene (100 mL; 0.87 mol), material TAP-4 (20 g), sodium bicarbonate (23 g; 0.27 mol) and manganese sulphate (0.081 g; 0.00054 mol) in 300 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (300 mL; 5.20 mol) drop- wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 100 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 85.17 % with 98.67 % selectivity.

EXAMPLE 37

To a mechanically stirred mixture of styrene (100 mL; 0.87 mol), material TAP-4 (50 g), sodium bicarbonate (23 g; 0.27 mol) and manganese sulphate (0.081 g; 0.00054 mol) in 300 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (300 mL; 5.20 mol) drop- wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 100 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 91.56 % with 97.07 % selectivity.

EXAMPLE 38

To a mechanically stirred mixture of styrene (100 mL; 0.87 mol), material TAP-4 (50 g), sodium bicarbonate (23 g; 0.27 mol) and manganese sulphate (0.081 g; 0.00054 mol) in 300 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (300 mL; 5.20 mol) drop- wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 100 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 91.56 % with 97.07 % selectivity.

EXAMPLE 39

To a mechanically stirred mixture of styrene (100 mL; 0.87 mol), material TAP-4 (35 g), sodium bicarbonate (23 g; 0.27 mol) and manganese sulphate (0.081 g; 0.00054 mol) in 300 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (300 mL; 5.20 mol) drop- wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 100 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 92.80 % with 96.82 % selectivity.

EXAMPLE 40

To a mechanically stirred mixture of styrene (100 mL; 0.87 mol), material TAP-4 (25 g), sodium bicarbonate (23 g; 0.27 mol) and manganese sulphate (0.081 g; 0.00054 mol) in 300 ml of water at 20 °C is added 50 % aqueous hydrogen peroxide (300 mL; 5.20 mol) drop- wise over a period of 8 h. After 8.5 h the reaction mixture was filtered and the organic layer of the reaction mixture was separated by a separating funnel. The aqueous layer was extracted with 4 x 100 mL diethyl ether. The combined organic layer was distilled to yield styrene oxide. The conversion to epoxide is 93.50 % with 97.46 % selectivity.

EXAMPLES 41-50

The epoxidation of styrene was done exactly in the same manner including quantities as per the procedure given in EXAMPLE 40 except that the material TAP-4 used in EXAMPLE 40 was recovered by filtration , washed with acetone (3 x 100 mL) and dried in air and used as recycled TAP-4, hence forth designated as R-TAP-4. Accordingly in subsequent examples till Example 50 R-TAP-4 as recyclable organic promoter was used as described above. The results are given in Table 1.

Table 1

EXAMPLE R-TAP-4 Conversion (%) Selectivity (%)

Recovered from

EXAMPLE 41 EXAMPLE 40 93.2 97.21

EXAMPLE 42 EXAMPLE 41 93.57 96.88

EXAMPLE 43 EXAMPLE 42 94.20 96.97

EXAMPLE 44 EXAMPLE 43 94.11 97.02

EXAMPLE 45 EXAMPLE 44 94.48 97.31

EXAMPLE 46 EXAMPLE 45 93.48 96.54

EXAMPLE 47 EXAMPLE 46 92.98 96.09

EXAMPLE 48 EXAMPLE 47 94.1 97.01

EXAMPLE 49 EXAMPLE 48 94.4 97.12

EXAMPLE 50 EXAMPLE 49 93.4 97.07

EXAMPLE 51

To a mechanically stirred mixture of indene (2 mL; 0.017 mol), material TAP-4 (1 g), sodium bicarbonate (0.394 g; 0.0047 mol) and manganese sulphate (5 mg; 0.03 mmol) in 5 ml of water 20 °C is added 50 % aqueous hydrogen peroxide (6 mL; 0.1 mol) in three equal portions over a period of 6 hours. After 10 hours the reaction mixture was extracted with 4 x 5 ml diethyl ether. The combined organic layer was dried over anhydrous sodium sulphate. Removal of solvent yielded indene oxide in 49% yield with selectivity 95%.

EXAMPLE 52

To a mechanically stirred mixture of 1,2-dihydronaphthalene (1.3 g; 0.01 mol), material TAP-4 (1 g), sodium bicarbonate (0.394 g; 0.0047 mol) and manganese sulphate (5 mg; 0.03 mmol), 5 ml of water at 25 °C is added 50 % aqueous hydrogen peroxide (6 mL; 0.1 mol) in three equal portions over a period of 6 hours. After 8 hours the reaction mixture was extracted with 4 x 5 ml diethyl ether. The combined organic layer was dried over anhydrous sodium sulphate. Removal of solvent yielded 1,2-dihydronaphthalene oxide in 52 % yield with selectivity 95%.

EXAMPLE 53

To a mechanically stirred mixture of chromene (1.3 g; 0.01 mol), material TAP-4 (1 g), sodium bicarbonate (0.394 g; 0.0047 mol) and manganese sulphate (5 mg; 0.03 mmol), in 5 ml of water at 25 °C is added 50 % aqueous hydrogen peroxide (6 mL; 0.1 mol) in three equal portions over a period of 6 hours. After 8 hours the reaction mixture was extracted with

4 x 5 ml diethyl ether. The combined organic layer was dried over anhydrous sodium sulphate. Removal of solvent yielded chromene oxide in 61 % yield with selectivity 95%.

EXAMPLE 54

To a mechanically stirred mixture of styrene (1 mL; 0.01 mol), material TAP-4 (1 g), sodium bicarbonate (0.394 g; 0.0047 mol) and manganese (II) acetate (2 mg; 0.135 mmol) in 10 ml of water at 30 °C is added 50 % aqueous hydrogen peroxide (9 mL; 0.15 mol) in three equal portions over a period of 4.5 hours. After 6 hours the reaction mixture was extracted with 4 x

5 ml diethyl ether. The combined organic layer was dried over anhydrous sodium sulphate. Removal of solvent yielded styrene oxide in 56 % yield with selectivity 80%.

EXAMPLE 55

To a mechanically stirred mixture of styrene (1 mL; 0.01 mol), material TAP-4 (1 g), sodium bicarbonate (0.394 g; 0.0047 mol) and nickel (II) acetate (8 mg; 0.05 mmol) in 10 ml of water at 25 °C is added 50 % aqueous hydrogen peroxide (9 mL; 0.15 mol) in three equal portions over a period of 6 hours. After 8 hours the reaction mixture was extracted with 4 x 5 ml diethyl ether. The combined organic layer was dried over anhydrous sodium sulphate. Removal of solvent yielded styrene oxide in 45 % yield with selectivity 68%.

EXAMPLE 56

To a mechanically stirred mixture of styrene (1 mL; 0.01 mol), material TAP-4 (1 g), sodium bicarbonate (0.394 g; 0.0047 mol) and manganese (II) acetate (3 mg; 0.19 mmol) in 10 ml of water at 30 °C is added 50 % aqueous hydrogen peroxide (9 mL; 0.15 mol) in three equal portions over a period of 6 hours. After 8 hours the reaction mixture was extracted with 4 x 5 ml diethyl ether. The combined organic layer was dried over anhydrous sodium sulphate. Removal of solvent yielded styrene oxide in 87 % yield with selectivity 82%.

EXAMPLE 57

To a mechanically stirred mixture of styrene (1 mL; 0.01 mol), material TAP-4 (1 g), potassium bicarbonate (0.51 g; 0.0037 mol) and manganese sulphate (7 mg; 0.05 mmol) in 10 ml of water at 25 °C is added 50 % aqueous hydrogen peroxide (9 mL; 0.15 mol) in three equal portions over a period of 6 hours. After 7 hours the reaction mixture was extracted with 4 x 5 ml diethyl ether. The combined organic layer was dried over anhydrous sodium sulphate. Removal of solvent yielded styrene oxide in 90 % yield with selectivity 90%.

ADVANTAGES OF THE INVENTION

1. Good isolated yields of epoxides are achievable with inexpensive reagents under mild reaction conditions.

2. Organic ligand based metal complexes are not required for the activation of hydrogen peroxide and alkenes under the reaction conditions used in the present invention.

3. Only smaller quantity of commercial LR grade transition metal salt is required to carry the reaction to completion even at 1 Kg scale at reasonable time shows ability of this epoxidation protocol was suited for commercial production of epoxides.

4. Inorganic salts and organic compounds used to activate hydrogen peroxide are inexpensive and of commercial grade.

5. Under the defined reaction conditions the organic solvent is not required particularly for the liquid alkenes.

6. Epoxidation reactions are run under aerobic condition and no prior oxygen free conditions are required.

7. Final work up protocol at higher scale (at lKg scale) does not require solvent extraction as water insoluble epoxides form a separate layer and thus can be physically separated.

8. Organic promoter used for the reaction can be separated out from the reaction mass just by filtration or centrifugation hence minimizing the waste to a significant extent.

9. Organic promoter used in this reaction is highly recyclable and could be reused for more than 10 cycles without any loss in its activity.