GB1583398A

GB1583398A - Epoxidation of olefins

Info

Publication number: GB1583398A
Application number: GB4879977A
Authority: GB
Original assignee: Produits Chimiques Ugine Kuhlmann; Ugine Kuhlmann SA
Current assignee: Produits Chimiques Ugine Kuhlmann; Ugine Kuhlmann SA
Priority date: 1976-11-26
Filing date: 1977-11-23
Publication date: 1981-01-28
Also published as: NL7713016A; DE2752626A1; CA1095065A; JPS5368707A; CH624948A5; DE2752626C2; JPS6134431B2; IT1093025B; ES464549A1

Abstract

The epoxidation of an olefin by hydrogen peroxide at a temperature of 0 to 120 DEG C in the presence of a catalyst is carried out in the liquid phase and there is continuously removed, by distillation or entrainment, the water introduced with the hydrogen peroxide as well as the water formed during the reaction.

Description

(54) EPOXIDATION OF OLEFINS (71) We, PRODUITS CHIMIQUES UGINE KUHLMANN, a French Body Corporate, of 25 boulevard de l'Amiral Bruix, 75116 PARIS, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a novel process for the direct epoxydation of olefins in a liquid phase by using hydrogen peroxide in the presence of a catalyst.

, The reaction can be renresented bv the followin eauation:

Epoxides of olefins constitute a class of chemical compounds of considerable industrial importance both in terms of tonnages produced and in terms of their application.

The oldest known method of epoxydation is the method known as the chlorohydrin method which consists in causing an olefin to react with chlorine in an alkaline medium to produce a chlorohydrin, followed by dehydrochlorination of the chlorohydrin using a base such as lime to produce the epoxide. This method, which has been very widely used no longer meets current requirements both from the point of view of energy and from that of ecology.

Thus the efficiency of the method in relation to chlorine is only average and the production of epoxide is accompanied by that of by-products which are difficult to assess and which are pollutants, being the organic chlorinated derivatives corresponding to the olefin used and the chloride of lime.

A more recent and far less pollutant method is the epoxydation of an olefin in an organic medium using a hydroperoxide in the presence of a catalyst. However in this method, the formation of epoxide is accompanied however by the formation of an equivalent or even greater quantitiy of alcohol corresponding to the starting hydroperoxide, an alcohol which it is generally difficult to employ to advantage and which therefore renders the method less attractive from an economic point of view.

The epoxydation of olefins by molecular oxygen has likewise been the subject of considerable research. But it is well known that so far only ethylene can be epoxydised with a satisfactory result. for example using silver-based catalysts, but this technique lacks all selectivity when it is applied to olefines other than ethylene.

In principle, hydrogen peroxide constitutes the oxidising agent of choice because by reason of its very nature it is a non-pollutant oxidising agent. However, its reactivity with olefins is low, if not nil. in the absence of an activating agent. Therefore, different methods of epoxydation have been suggested. These employ, for example, peracids such as peracetic and performic acid or even propionic acids, as in Belgian Patent No. 838,068. However, by reason of the instability of epoxides in an acid medium, such methods are particularly difficult to perform.

Also, various catalytic methods have been described which have the advantage over the former of not employing per-compounds, synthesis of which burdens the process of obtaining the epoxides. For example. it has been suggested to use in an aqueous medium oxides or oxyacids which are derivatives of transition metals such as molybdenum, tungsten, vanadium and cerium. These processes are not satisfactory either, because the usual product is not the epoxide desired, but essentially the corresponding glycol.

It has also been suggested to use peroxodo complexes of these same transition metals, for example in French Patent No. 2,082,811. These complexes are good epoxydising agents, but their regeneration in situ causes such problems that no industrial implementation of this method can be economically envisaged.

We have now found a novel catalytic method of epoxidation using hydrogen peroxide, which avoids the aforesaid drawbacks and which is characterised by high selectivity. The new method is simple to implement and uses a catalyst which has a very long effective life.

Accordingly, the present invention provides a method of epoxidising an olefin which method comprises reacting the olefin with hydrogen peroxide at a temperature of 0 C to 1200C in a single liquid phase and in the presence of a catalyst which is a transition metal of Group IV A, V A or VI A of the Periodic Table of elements according to Mendeleev, or an inorganic derivative thereof, or an inorganic or organic complex thereof, the quantity of catalyst being from 0.0001 to 1 atom gram of metal per mole of hydrogen peroxide, and continuously removing by distillation or entrainment the water introduced by the hydrogen peroxide into the reaction medium and the water formed during the course of reaction.

The method according to the invention is a catalytic process carried out in the liquid phase, and in which an olefin is contacted with hydrogen peroxide in the presence of a catalytic quantity of a transition metal of group IV A, V A or VI A of the Periodic Table of elements according to Mendeleev, or an inorganic or organic derivative of such a metal, at a temperature and pressure such that the water which is formed during the course of reaction or which is provided by the hydrogen peroxide when it is used in the form of an aqueous solution is continually expelled from the reaction system.

The olefins which fall within the scope of the present invention preferably correspond to the general formula:

in which each of R1, R2, R3 and R4, which may be identical or different, represents a hydrogen atom or a linear or branched alkyl radical having from 1 to 30 carbon atoms, or a cycloalkyl radical, branched or otherwise, having from 3 to 12 carbon atoms, or a hydrocarbon radical having 6 to 12 carbon atoms and comprising a benzene ring substituted or unsubstituted by alkyl groups; or R, and R2or R3 and R4 together represent a linear or branched alkylene group having from 3 to 11 carbon atoms; or R, and R3 or R2 and R4 together represent a linear or branched alkylene group having from 1 to 10 carbon atoms. The radicals R1, R2, R3 and R4 may possibly be substituted by functional groups which are stable in the reaction medium such as hydroxy, chloro, fluoro, bromo, iodo, nitro, methoxy, alkoxy, amino, or nitrile atoms or groups or a group of formula

wherein each of R and R' independently represent a hydrogen atom or a hydrocarbyl radical.

The olefins may also be polyunsaturated, that is to say the scope of the present invention includes also polyolefins such as the dienes and trienes, conjugated or otherwise.

Examples of unsaturated compounds which may be epoxidised by the method according to the invention are ethylene, propylene, butene, butadiene, pentenes, hexene-l, hexene-3, heptene-1, octene-1, diisobutylene, nonene-1, limonene, pinene, myrcene, camphene, undecene- 1. dodecene-l tridecene- 1, tetradecene- 1, pentadecene- 1, hexadecene- 1, heptadecene-l, octadecene-1, nonadecene-1, eicosene-1, the trimers and tetramers of prop ylene, the polybutadienes, styrene, methyl styrene, divinyl benzene, indene, stilbene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclooctadiene, cyclododecene, cyc lododecatriene. dicyclopentadiene. methylene cyclopropane, methylene cyclopentane, methylene cyclohexane, vinyl cyclohexene, methyl allyl ketone, allyl chloride, allyl bromide, acrylic acid, methacrylic acid, crotonic acid, vinyl acetic acid, crotyl chloride, methallyl chloride, the dichlorobutenes. allylic alcohol, allyl carbonate, allyl acetate, alkyl acrylates and methacrylates, diallyl maleate, diallyl phthalate, the unsaturated glyacids such as soya bean oil. sunflower seed oil. maize oil. cotton oil, olive oil, ricin oil, cod liver oil, ground nut oil, tall oil. oleine oil and linseed oil, unsaturated fatty acids such as oleic acid, linolenic acid, bilicic acid. erucic acid. oleosteraric acid. myristoleic acid, palmitoleic acid, licanic acid, ricinioleic acid and arachidonic acid, and also the esters thereof.

The catalyst used in the method of the present invention is transition metal of Groups IV A, V A or VI A of the Periodic Table according to Mendeleev. The catalyst may be the metal itself, or a complex of the metal having a zero oxidation state, or in the form of an inorganic or organic derivative in which the metal can have one or more oxidation states. The preferred metals are molybdenum, tungsten, vanadium, chromium and titanium.

Examples of suitable inorganic derivatives of these metals are the oxides, the mixed oxides, the hydroxides, the oxyacids, the heteropolyacids, their salts and their esters, the salts derived from inorganic hydracids and oxyacids and carboxylic or sulphonic organic acids having not more than 20 carbon atoms and the anions of which are stable under the conditions of the reaction.

The complexes of these metals are essentially complexes referred to as organometallic complexes in which the transition metal has an oxydation state of from 0 to + 6 and is substituted with liquids which are either organic or inorganic or both organic and inorganic.

These organometallic compounds generally have the advantage of being relatively readily soluble in an organic medium so that the catalyst is then used in a homogenous medium.

However, there is no major disadvantage in employing an insoluble catalyst and since the reaction system is then heterogenous, it is sufficient to provide adequately strong agitation to ensure effective contact between the various participants in the reaction.

Examples of suitable catalysts are molybdenum, tungsten, chromium, vanadium, titanium zirconium, niobium, the metal carbonyls Mo(CO)6, W(CO)6, the oxides MoO2, Mo2OsS Mo203, MoO3, WO2, W205, WO6, Cry2, Cr203, Cry3, VO2, V203, V205, ZrO2, TiO, TiO2, Ti203, NbO2, Nb203, Nub205, the sulphides MoS2, MoS3, MoS4, Mo2S3, Mo2S5, WS3, WS3, CrS, Cr2S3, V2S3, V2S5, ZrS2, TiS, TiS2, Ti2S3, the oxychlorides of molybdenum, tungsten, chromium, vanadium, zirconium and titanium, the fluorides, chlorides, bromides, iodides, nitrates, sulphates, phosphates, pyrophosphates, polyphosphates, borates, carbonates, formates, acetates, propionates, butyrates, isobutyrates, hexanoates, octanoates, dodecanoates, naphthenates, stearates. oxalates, succinates, flutarates, adipates, benzoates, phthalates and benzene sulphonates of molybdenum, tungsten, titanium, chromium, zirconium and vanadium, complexes such as the acetyl acetonates and phthalocyanines; molybdic acids, tungstic acid, vanadic acid, chromic acid, and corresponding heteropolyacids such as phosphomolybdic or -tungstic acid, arseno-molybdic or-tungstic acid and also all the alkali metal or alkaline earth metal salts of these acids.

Mixtures of the above catalysts may also be used. It is also possible to fix heterogeneous catalysts on supports such as alumina, silica, silicate of alumina, zeolite or even polymers, using known techniques.

The reaction medium must be such that the hydrogen peroxide solution is entirely soluble under the conditions of the reaction. In other words, the method according to the invention must be performed in only a single liquid phase. Moreover, this phase must be as inert as possible in respect of the reagents and the epoxide formed. The reaction may be carried out in certain cases by bringing into contact the reactants, that is to say the olefine and the hydrogen peroxides in the absence of solvent. It is then necessary to work with a sufficiently high molar ratio of olefine: H202, for obvious safety reasons, preferably the said molar ratio is from 2 to 200. Usually, it is preferred to work in a solvent or mixture or organic inert solvents such as for example primary, secondary or tertiary alcohols containing from 1 to 6 carbon atoms, such as methanol, ethanol, n-propanolS isopropanol, butanol-1, butanol-2, tert-butanol, amyl alcohol, isoamyl alcohol, tertiary amyl alcohol, cyclohexanol, ethylene glycol, propylene glycol and glycerol, ethers such as ethyl ether, isopropyl ether, dioxane and tetrahydrofuran, oligomers of ethylene oxide and propylene oxide, their ethers such as dimethoxy diethylene glycol, diethoxy ethylene glycol and diglyme, esters such as the formiates or acetates of alcohols or conventional glycols. Other suitable solvents are dimethyl formamide, nit romethane, and triethyl, trioctyl and ethyl hexyl phosphates.

The preferred modus operandi when epoxidising olefin compounds by the process accord ingsto the invention consists in causing hydrogen peroxide and the olefin to react'in the presence of the catalyst in a solvent by continuously distilling off the water supplied with the hydrogen peroxide and the water formed during the course of reaction. The temperature at which the reaction is carried out is from 0 to 1200C and preferably from 70 to 100 C.

According to the temperature chosen and the reaction system employed (olefin and solvent), the water may be eliminated by working under low pressure when carrying out the reaction at a low temperature or at atmospheric pressure, or even under pressure when working in the vicinity of 100 C. particularly with light olefins. The pressure may therefore vary from 20 mm of mercury to 100 bars if necessary.

Water may be eliminated by simple distillation if the boiling points of the olefin, the solvent and the epoxide lend themselves to it. It is also possible to carry out azeotropic distillation either by taking advantage of the fact that there is an azeotrope between water and the olefin involved, or by incorporating into the medium a co-solvent which has this property. Examples of cosolvents are benzene toluene, n-pentane, cyclohexane and anisole. Finally, it is possible to entrain the water by virtue of its vapour tension at a given temperature by continually passing a gas through the reaction medium, such a gas being possibly the olefin itself in the case of light olefins.

The choice of reaction temperature depends naturally on the stability of the hydrogen peroxide in the reaction medium chosen, For working at a high temperature (80 to 1200C), it is preferable to opt for an acid medium. However, by virtue of the instability of epoxides in this type of medium, it is advantageous to introduce into the medium an organic or inorganic compound serving as a buffer, for example a tertiary amine, pyridine, an alkaline phosphate or an alkaline acetate.

The reaction time depends upon the nature of the catalyst used, the solvent and the olefin involved. It may range from a few minutes to 100 hours and more. The reactants may be used in equimolecular quantities but it is also possible to use a molar deficiency or an excess of one or other of the reactants. As an indication, it is possible to use from 0.1 to 50 moles of olefin per mole of hydrogen peroxide but preferably from 1 to 10 moles will be used.

The catalyst is used at the rate of 0.0001 to 1 gram atom of metal per mole of hydrogen peroxide. However, a molar ratio of from 0.001 to 0.1 gram atom per mole of hydrogen peroxide is preferred.

The quantity of solvent or mixture of solvents is determined by the quantity needed to maintain a single liquid phase and avoid any segregation phenomena. The quantity is normally from 25% to 55% of the total volume of the reaction medium.

The reactants may be used in their conventional commercial form. Hydrogen peroxide in particular may be used in the form of commercial aqueous solutions titrating at 30 to 70%by weight H202. However, taking into account the fact that the method of the invention implies a continual elimination of the water present in the reaction medium, it goes without saying that the use of aqueous solutions of hydrogen peroxide titrating more than 70% by weight and in particular 85 to 95 % by weight is recommended. It is then preferable previously to dissolve the concentrated hydrogen peroxide in the solvent which is used as a reaction medium and to proceed thus with dilute organic solutions, for obvious reasons of safety. Thus, in some cases the hydrogen peroxide can be used in the form of an organic solution thereof, preferably containing from 1 to 30% by weight H202.

The following Examples illustrate the invention. Selectivity is defined as being the number of moles of epoxides formed in relation to the number of moles of hydrogen peroxide reacted.

Example 1 Into a 500 cc reactor provided with magnetic agitating means and a reflux condenser fitted with a Florentine system, are placed 41 g amyl alcohol, 0.05 g molybdenum oxide (MoO3), 0.3 g disodium phosphate (Na2HPO4) and 41 g cyclohexene (0.5 moles). This mixture is brought to the boiling temperature of cyclohexene, 81"C, and over 12 minutes, 5.7 g of an aqueous solution of hydrogen peroxide, 30% by weight (0.5 moles) are added. The mixture is left to react for 2 hours, the water being continually eliminated by azeotropic distillation with cyclohexene, the temperature being maintained at 80 to 900C. The reaction medium was then found to contain 0.012 moles hydrogen peroxide. By gas phase chromatography, 0.024 moles cyclohexene epoxide were measured, corresponding to a rate of conversion of hydrogen peroxide of 76% for a selectivity of 63%.

Example 2 Example 1 is repeated, but the catalyst is replaced by 0.1 g molybdyl acetyl acetonate.

After two hours of reaction, 0.014 moles hydrogen peroxide is determined chemically.

Gaseous phase chromatography indicated the presence of 0.034 moles cyclohexene epoxide, corresponding to a rate of conversion of hydrogen peroxide of 72%for a selectivity of 94%.

Example 3 In a stainless steel reactor with an effective volume of 3 litres are placed 200 cc amyl alcohol, 5 g molybdyl acetyl acetonate, and 5 g disodium phosphate (Na2HPO4). The reactor is closed and a pump is used to introduce 420 g liquid propylene (10 moles). This mixture is brought to 85"C and maintained at this temperature. The propylene comes to boiling at 40 bars and the heating is regulated in such a way as to distil 12.6 moles per hour of propylene.

Then, by means of dispensing pumps, 48.5 g per hour of an aqueous solution of hydrogen peroxide, 70% by weight (1 mole), and 533 g per hour propylene (12.7 moles per hour) are introduced. The water introduced. along with the reaction water and the propylene oxide formed are entrained by the flow of distilling propylene gas and are condensed in a condenser at 0 C. Thus are collected 81.7 g per hour of an aqueous solution of propylene oxide titrating at 60.3% by weight, which corresponds to a propylene oxide yield of 85% in respect of the hydrogen peroxide used.

Example 4 Into a glass reactor of 300 cc capacity are successively placed 41 g amyl alcohol, 82 g cyclohexene (1 mole) and 0.1 gvanadyl acetyl acetonate and 0.1 g disodium phosphate. This mixture is brought to the boiling temperature of cyclohexene (81"C) and progressively 2.5 g of an aqueous solution of hydrogen peroxide, 67.4%by weight (0.050 moles) are introduced.

Reaction is allowed to take place for 1 hour, the water being continuously eliminated by azeotre,pic distillation with cyclohexene, the temperature being maintained at 80 to 900C.

After 1, 'hour of reaction, 0.010 moles of unreacted hydrogen peroxide is determined in the medium and also 0.018 moles of cyclohexene epoxide, which corresponds to a conversion of hydrogen peroxide of 80% and a selectivity of 45%.

Example 5 Into a 300 cc glass reactor are introduced 87 g of the dimethyl ether of diethylene glycol (CH30CH2CH20CH2CH2 0 CH3), 82 g cyclohexene (1 mole), 0.2 g molybdenum hexacarbonyl Mo (CO)6, 0.15 g disodium phosphate and 6.6 g cyclohexene epoxide (0.068 moles).

The mixture is raised to the boiling temperature of the cyclohexene (81"C) then in half-anhour 2.81 g of an aqueous solution of hydrogen peroxide at 70% by weight are introduced (0.058 moles), dissolved in 20 g of solvent while continually eliminating the water from the reaction medium by azeotropic distillation winth cyclohexene. At the end of addition, there is determined in the reaction medium 0.006 moles hydrogen peroxide and 0.115 moles cyclohexene epoxideis corresponds to a conversion of 89.7% of hydrogen peroxide for a selectivity of 87%""' Comparative Example Example 2 was repeated but without eliminating the water introduced with the hydrogen peroxide and formed during the course of the reaction. After 2 hours of reaction at 88"C, iodometric analysis showed that there was no longer any hydrogen peroxide in the reaction medium and vapour phase chromatography indicates 1.2 g cyclohexene epoxide, which corresponds to a selectivity of 26% for a hydrogen peroxide conversion rate of 100%.

Example 6 82 g (1 mole) of cyclohexene,62 g of diethylene glycol monoethyl ether, 0.2 g of disodium phosphate, and also 0.2 g of metallic molybdenum in powder form are placed in a reactor.

This mixture is boiled under reflux and then over a period of 40 minutes a solution of 2.6 g of 70% hydrogen peroxide (0.054 mole) in 13.5 g of diethylene glycol monoethyl ether are introduced. The water of the reaction medium is continuously eliminated by azeotropic distillation. After a reaction time of one hour, 0.017 mole of unreacted hydrogen peroxide is measured in the mixture. together with 2.25g of cyclohexene epoxide (0.023 mole), which corresponds to a selectivity of 62% for a hydrogen peroxide conversion rate of 68.5%.

Example 7 Example 6 is repeated. but the molybdenum is replaced by 0.2 g of metallic tungsten in powder form. After a reaction time of 90 minutes, 0.007 mole of unreacted hydrogen peroxide and also 2 g of cyclohexene epoxide (0.021 mole) are measured in the reaction medium, which corresponds to a selectivity of 44.6 % for a hydrogen peroxide conversion rate of 87 %.

Example 8 Example 6 is repeated, but the metallic molybdenum is replaced by 0.2 g of molybdyl acetylacetonate. After a reaction time of one hour, 0.001 mole of unreacted hydrogen peroxide and also 4. 1 g of cyclohexene epoxide (0.042 mole) are measured, which corresponds to a selectivity of 79.2 % for a hydrogen peroxide conversion rate of 98.2 %.

Example 9 82 g of cyclohexene (1 mole). 52 g of diethylene glycol monoethyl ether, 0.2 g of disodium phosphate. and also 0. 175 g of molybdic acid of the formula (NH4)20, MoO3 are placed in the reactor. This mixture is boiled under reflux, and then over a period of 30 minutes a solution of 2.4 g of 70% hydrogen peroxide (0.049 mole) in 20 g of diethylene glycol monoethyl ether is

Claims

WHAT WE CLAIM IS:

1. A method of epoxidising an olefin which method comprises reacting the olefin with hydrogen peroxide at a temperature of 0 C to 1200C in a single liquid phase and in the presence of a catalyst which is a transition metal of Group IV A, VA or VIA of the Periodic Table of elements according to Mendeleev, or an inorganic derivative thereof, or an inorganic or organic complex thereof, the quantity of catalyst being from 0.0001 to 1 atom gram of metal per mole of hydrogen peroxide, and continuously removing by distillation or entrainment the water introduced by the hydrogen peroxide into the reaction medium and the water formed during the course of reaction.

2. A method according to Claim 1, in which the catalyst is molybdenum or tungsten.

3. A method according to Claim 1, in which the catalyst is an inorganic derivative or an inorganic or organic complex of molybdenum or tungsten.

4. A method according to any one of Claims 1 to 3, in which the catalyst is fixed on an inorganic or organic support.

5. A method according to any one of Claims 1 to 4, in which the reaction is carried out in the presence of an organic solvent or mixture of organic solvents inert to the reactants employed and in which the hydrogen peroxide is soluble under the conditions of the reaction.

6. A method according to Claim 5, in which the solvent or mixture of solvents is, or includes one or more of, an ether oxide, an alcohol, a polyol, or an ether or ester of an alcohol or of a polyol.

7. A method according to Claim 6, in which the solvent or mixture of solvents is, or includes one or more of, an oligomer of ethylene oxide or propylene oxide, the corresponding methyl or ethyl ether, or the corresponding esters.

8. A method according to Claim 7, wherein the said ester is a formate, acetate or propionate.

9. A method according to any one of Claims 1 to 8, wherein the olefin is an olefin of the general formula:

in which each of R 1. R2, R3 and R4, which may be identical or different, represents a hydrogen atom or a linear or branched alkyl radical having from 1 to 30 carbon atoms, or a cycloalkyl radical, branched or otherwise, having 3 to 12 carbon atoms, or a hydrocarbon radical having 6 to 12 carbon atoms and comprising a benzene ring substituted or unsubstituted by alkyl groups. or R1 and R2 or R3 and R4 together represent a linear or branched alkylene group having 3 to 11 carbon atoms or R, and R3 or R2 and R4 together represent a linear or branched alkylene group having 1 to 10 carbon atoms; the radicals R1, R2, R3 or R4 optionally being unsaturated and/or substituted by one or more functional groups which are stable in the reaction medium.

10. A method according to Claim 9? wherein the said functional group is chosen from hydroxy, chloro, fluoro, promo iodo, nitro, methoxy, alkoxy, amino and nitrile groups or atoms. and a group of the formula

wherein each of Rand R' independently represent a hydrogen atom or a hydrocarbyl radical.

I I. A method according to Claim 10, in which the olefin is propylene.

12. A method according to any one of the Claims 1 to 11. in which the temperature is from 70 to 1200C.

13. A method according to any one of Claims 1 to 12, in which reaction is carried out at a pressure of from 20 mm Hg to 100 bars.

14. A method according to any one of Claims 1 to 13, in which 0.1 to 50 moles of olefin per mole of hydrogen peroxide is used.

15. A method according to Claim 14, in which 1 to 10 moles of olefin per mole of hydrogen peroxide is used.

16. A method according to any one of Claims 1 to 15. in which the hydrogen peroxide is used in the form of an aqueous solution containing from 70 to 95% by weight H202.

17. A method according to any one of Claims 1 to 15, in which the hydrogen peroxide is used in the form of an organic solution. containing from 1 to 30% by weight H202.

18. A method of epoxidising an olefin substantially as described in any one of Examples 1 to 5.

19. A method of epoxidising an olefin substantially as described in any one of Examples 6 to 16.

20. An olefin epoxide when prepared by a method as claimed in any one of Claims 1 to 18.

21. An olefin epoxide when prepared by a method as claimed in Claim 19.