PROCESS FOR OXIDATION OF OLEFINICALLY-UNSATURATED COMPOUNDS

Abstract: The invention provides a process for epoxidising an olefinic double bond in an olefinically-unsaturated compound other than an (α, β)-unsaturated carboxylic acid or a com­ pound containing a six-membered ring wherein 3 to 4 member atoms are carbon atoms having sp² hybrid orbitals, by treatment of a liquid phase mixture of the olefinically-­ unsaturated compound, an aldehyde containing at least two carbon atoms and a suitable solvent with oxygen in the pres­ ence of a catalyst which is soluble in the reaction mixture and which comprises a praseodymium compound. The process has particularly advantageous application to oxidation of aldrin to dieldrin.

Description: This invention relates to a process for epoxidising an olefinic double bond in an olefinically-unsaturated compound other than an α,β-unsaturated carboxylic acid or a compound containing a six-membered ring wherein 3 to 4 member atoms are carbon atoms having sp² hybrid orbitals. GB-A-963,430 discloses a process for the epoxidation of an olefinic compound in which the double bond is in the terminal position and which contains at least 3 carbon atoms, by treatment of a liquid-phase mixture containing the olefinic compound and an aldehyde containing at least two carbon atoms with oxygen, if desired in the presence of a solvent such as ethyl acetate and a catalyst which is preferably soluble in the reaction mixture, such as an organic cobalt or manganese salt. US-A-3,957,690 discloses a process for oxidation of propylene oxide, in the liquid phase, using a heterogeneous catalyst. The catalyst comprises a carrier with one or more oxides of scandium, yttrium, indium, gallium, thallium or rare-earth elements of the lanthanum group applied to its surface. Oxidation is effected using air, at high pressure, e.g. 50 atmospheres, and elevated temperature, e.g. 145 to 170°C. Conversion of propylene tends to be low, e.g. ranging from 13 to 32.5%. According to the present invention there is provided a process for epoxidising an olefinic double bond in an olefinically-unsaturated compound other than an (α,β)-unsaturated carboxylic acid or a compound containing a six-membered ring wherein 3 to 4 member atoms are carbon atoms having sp² hybrid orbitals, by treatment of a liquid phase mixture of the olefinically-unsaturated compound, an aliphatic or aromatic aldehyde containing at least two carbon atoms in an amount of at least one mole per double bond to be oxidized and a suitable solvent with oxygen in the presence of a catalyst which is soluble in the reaction mixture and which comprises a praseodymium salt. The apliphatic aldeyhde, contains e.g. 2 to 6 carbon atoms, the aromatic aldehyde is e.g. benzaldehyde. Aliphatic aldehydes containing 2 to 4 carbon atoms are preferred. Propionaldehyde has been found to be very suitable. During the course of the reaction, the aldehyde is co-oxidised to the corresponding acid, e.g. propionaldehyde is oxidised to propionic acid. The solvent may be any suitable solvent which is substantially inert to oxidation under the reaction conditions employed and which gives rise to a homogeneous reaction mixture. The solvent may be a single solvent or a mixture of solvents, and may conveniently be an ester, a ketone or a carboxylic acid. Advantageously the solvent comprises at least one solvent selected from C₁₋₆ alkyl esters of C₂₋₆ carboxylic acids, C₃₋₆ ketones and C₂₋₆ carboxylic acids, and more preferably the solvent comprises at least one solvent selected from methyl and ethyl esters of acetic and propionic acids, acetone, methyl ethyl ketone, acetic acid and propionic acid. The catalyst is preferably in the form of one or more organic salts, and advantageously the catalyst comprises a C₂₋₆ carboxylic acid, preferably acetate or propionate, salt of praseodymium and optionally of one or more other metals. The catalyst may if desired consist of a praseodymium salt alone or it may for example comprise a mixture of praseodymium and other metal salts in the relative proportions in which they are found in nature. Conveniently therefore the catalyst may comprise a didymium salt. It may sometimes be advantageous for the catalyst additionally to contain a cobalt salt, and/or a uranium or vanadium salt. The aldehyde is used in an amount of at least 1 mol per mol of olefinically-unsaturated compound. Preferably the amount of aldehyde is in the range 1 to 3 mol per mol of olefinically-unsaturated compound. Amounts of aldehyde in the range 1.1 to 2 mole per mol olefinically-unsaturated compound have been found to give very good results. The process of the invention may be effected over a wide range of temperatures. Temperatures in the range from 30°C to the reflux temperature of the reaction mixture are very suitable. Preferred reaction temperatures are in the range 30 to 60°C. The process of the invention has been found to be susceptible of very general application, as is hereinafter evidenced by the examples. However, attempts to apply the reaction conditions of the process of the invention α, β-unsaturated carboxylic acids, e.g. 2-pentenoic acid, crotonic acid or methacrylic acid, or to compounds containing a six-membered ring wherein 3 to 4 member atoms are carbon atoms having sp² hybrid orbitals, e.g. isophorone, terpinolene and γ-terpinene failed to yield isolable epoxide products. When the process of the invention is applied to compounds containing more than one olefinic double bond, it is generally found that the reaction product is a mono-epoxide. Thus the process of the invention has particular utility in situations where selective epoxidation is desired. According to a preferred embodiment of the invention the olefinically-unsaturated compound is aldrin which is epoxidised to dieldrin by the process of the invention. Subject to the exclusion of the (α,β)-unsaturated carboxylic acids and compounds containing six-membered rings wherein 3 to 4 member atoms are carbon atoms having sp² hybrid orbitals, the process of the invention may for example be applied to C 3-30 olefins having 1 to 6 olefinic double bonds, optionally containing ketonic carboxyl groups, optionally containing 1 to 3 alicyclic rings of 3 to 12 ring atoms of which 2 or 3 rings may be fused rings, and optionally bearing 1 to 5 substituents independently selected from -OH, -COOH, -CHO, OR, -COOR, -OCOR, where R represents an alkyl or aryl group (for example a C₁₋₆ alkyl group, e.g. methyl or ethyl, or a phenyl or tolyl group) halo substituents (e.g. chloro) and aryl substituents, e.g. phenyl, tolyl or pyridyl. The invention will be further understood from the following examples thereof which were effected by the following general procedure, and wherein unless otherwise indicated parts, ratios and percentages are parts, ratios and percentages by weight and temperatures are in °C. A solution of the olefinically-unsaturated compound in the chosen solvent was heated under nitrogen to 48°C in a reactor equipped with a mantle through which "FREON TF" (trade mark) (1,1,2-trichloro-1,2,2-trifluoroethane, b.p. 48°C) (also sold as "FREON 113")(trade mark) was circulated as heat-exchange medium, by means of which reaction temperatures were generally maintained in the range 48 to 53°C, unless otherwise stated. Catalyst was introduced as a solution in a suitable solvent (which in appropriate cases was the said chosen solvent, but in other cases was acetic or propionic acid). Propionaldehyde was streamed at constant rate into the reaction mixture and the nitrogen was replaced by oxygen or air. The propionaldehyde was added over the course of 1 to 3 hours, depending on the rate of reaction. The course of the reaction was monitored by hourly withdrawal of a sample which was analysed by gas chromatigraphy, or in some cases by nuclear magnetic resonance or infra-red spectroscopy. Loss of propionaldehyde from the reactor was minimised by means of condensers at 10°C and -20°C coupled in series, condensate being returned to the reactor. Reaction was terminated by replacing the oxygen or air by nitrogen and cooling the reacor to ambient temperature (20°C). After filtration, the reaction mixture, the solvent and the propionic acid produced during the course of the reaction were, in suitable cases (in which the boiling temperatures of the desired end products is significantly lower than those of the solvent and propionic acid, as will be well understood by those skilled in the art), removed under vacuum at temperatures below 60°C. In other cases the reaction mixture was diluted with pentane, washed with saturated aqueous sodium chloride to remove water-soluble species (mostly propionic acid), and volatiles were removed by vacuum distillation. Products were identified by nuclear magnetic resonance and infrared spectroscopy and using gas-liquid chromatography. In the examples which follow, "Di(acetate)3" was didymium acetate ex Lindsay Chemicals Division from which water had been removed by drying in vacuo at 100°C before grinding to a fine powder, having the following metal oxide composition: La₂O₃ (41.83%), CeO₂ (0.11%), Pr₆O₁₁ (17.37%), Nd₂O₃ (29.71%), Sm₂O₃ (5,03%), Gd₂O₃ (3.20%), Yb₂O₃ (0.46%) and remainder (Eu₂O₃, Pm₂O₃, Tb₂O₃, Dy₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Lu₂O₃)(2.29%). Other didymium salts and mixtures were prepared in known manner from this didymium acetate. EXAMPLES 1 to 8 Epoxidation of dodecene-1 Dodecene-1 was epoxidised by the above procedure using a variety of catalysts and using solvent appropriate to the catalyst employed. In each case 0.5 mol dodecene-1 was employed, the volume ratio solvent:dodecene-1 was 3:1, propionaldehyde was added at a rate of 25 ml/h to a final mol. ratio propionaldehyde:dodecene-1 of 1.6:1, oxygen was bubbled through the reaction mixture at a rate from 6 to 10 1/hour. Details of the catalysts used and their quantities, nature of solvent, reaction times, overall molar conversions of dodecene-1 and selectivities to the desired epoxide and product are given in Table I following: EXAMPLE 9 Conversion of Aldrin to Dieldrin Aldrin was epoxidised to Dieldrin by the above procedure using as catalyst a mixture of Di(acetate)₃ and Co(acetate)₂ (weight ratio 100:1) and ethyl acetate as solvent. The volume ratio solvent:Aldrin was 3:1, the final mol ratio of propionaldehyde:Aldrin was 1.7:1, air was bubbled through the reaction mixture at a rate of 100 1/hour (per 100 ml reaction mixture), the catalyst was used at a level of 1.6% based on the weight of Aldrin, and reaction was continued for 15 hours. The ethyl acetate and propionic acid were evaporated off, leaving a solid white residue which was dissolved in dichloromethane, washed with aqueous sodium bicarbonate solution and evaporated to give a white solid product (100% yield based on starting material) which contained 95%w Dieldrin (as determined by gas-liquid chromatography and nuclear magnetic resonance), the remainder being mainly unconverted Aldrin. EXAMPLE 10 Epoxidation of camphene Camphene was epoxidised by the above procedure using the same catalyst as in Example 9 (0.8% based on the weight of camphene, and ethyl acetate as solvent (volume ratio solvent:camphene 3:1). The final mol ratio propionaldehyde:camphene was 1.6:1, oxygen was bubbled through at a rate of 10 1/hour, and reaction time was 5 hours. 86% conversion of starting material was obtained with selectivity to desired epoxide product of 92%. By comparison Mn(acetate)₃ was used as catalyst in a comparable procedure, with acetic acid as solvent, after 7 hours reaction time 94% of camphene was consumed with selectivity to desired epoxide product less than 5%. EXAMPLE 11 Epoxidation of longifilene Longifilene was epoxidised by the above procedure and under the same conditions as in Example 10 except that 1% of catalyst based on the weight of longifilene was employed and reaction time was 5.5 hours. Greater than 96% conversion of longifilene took place, with 81% selectivity to the desired epoxide. By comparison, when Mn(acetate)₃/Co(acetate)₂ (100:1) was used as catalyst in a comparable procedure, with acetic acid as solvent, after 3 hours more than 96% of the longifilene had been consumed but no epoxide was detectable (product contained 61% ketone and 32% acid). EXAMPLE 12 Epoxidation of ▵-3-carene ▵-3-carene was epoxidised by the above procedure, using Di((acetate)₃ as catalyst (1% based on the weight of ▵-3-carene) and ethyl acetate as solvent (volume ratio solvent: ▵-3-carene 3:1). The final mol ratio propionaldehyde:▵-3-carene was 1.5:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 4 hours. 95% conversion of starting material was obtained with selectivity to desired epoxide product of 82%. By comparison, when MN(acetate)₃ was used as catalyst in a comparable procedure, with acetic acid as solvent, after 8 hours reaction time 28% of ▵-3-carene was consumed with selectivity to desired epoxide being less than 5%, much of the product being a polymeric black tar. EXAMPLE 13 Epoxidation of ∝-pinene ∝-pinene was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2:1). The final mol ratio propionaldehyde:starting material was 1.4:, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 8 hours. 92% conversion of starting material was obtained, with selectivity to desired epoxide product of 73%. By comparison, when Mn(acetate)₃ was used as catalyst in a comparable procedure, with acetic or propionic acid as solvent, after 6 hours reaction time more than 96% of starting material was consumed, with selectivity to desired epoxide of less than 5%, the product being mostly in the form of a thick black tar. EXAMPLE 14 Epoxidation of β -pinene β-pinene was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent starting material 2:1). The final mol ratio propionaldehyde:starting material was 1.4:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 5 hours. 83% conversion of starting material was obtained, with selectivity to desired epoxide product of 48%. By comparison, when Mn(acetate)₃ was used as catalyst in a comparable procedure, with propionic acid as solvent, after 9 hours reaction time more than 96% of starting material was consumed, with selectivity to desired epoxide of less than 5%, the product being in the form of a black tar. EXAMPLE 15 Epoxidation of 2,4,4-trimethylpentene 2,4,4-trimethylpentene was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (0.8% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2.5:1). The final mol ratio propionaldehyde:starting material was 1.1:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 6 hours. More than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 89%. Some propionate esters of diols were produced, but no ketone. By comparison, when Mn(acetate)₃ was used as catalyst in a comparable procedure, with acetic acid as solvent, after 18 hours reaction time more than 96% of starting material was consumed, with selectivity to desired epoxide of 74%. At least 20% the reaction product was in the form of ketone. EXAMPLE 16 Epoxidation of pentene-1 Pentene-1 was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) and also with Di(acetate)₃ as catalyst (1% based on the weight of starting material in each case) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.6:1, oxygen was bubbled through at a rate of 6 1/hour in the first case and 9 1/hour in the second case, reaction time was 6 hours in the first case and 5.5 hours in the second case and reaction temperature was 31°C in the first case and 35°C in the second case. In the first case more than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 86%. In the second case 97% of starting material was consumed, with selectivity to desired epoxide of 78%. EXAMPLE 17 Epoxidation of 2,6-dimethylheptadiene 2,6-dimethylheptadiene was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.5% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 1.5:1). The final mol ratio propionaldehyde:starting material was 1.2:1, oxygen was bubbled through at a rate of 7 1/hour, and reaction time was 3.5 hours. More than 96% conversion of starting material was obtained, with selectivity to the 2-epoxide product of 87%. By comparison, when Mn(acetate)₃ was used as catalyst in a comparable procedure, with acetic acid/ethyl acetate as solvent, after 4 hours reaction time 92% of starting material was consumed, with selectivity to desired epoxide of 81%. EXAMPLE 18 Epoxidation of dihydromyrcene Dihydromyrcene was epoxidised by the above procedure, using Di(propionate)₃/Co(propionate)₂ (100:1) (20% solution in propionic acid) as catalyst (0.6% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.1:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 3.5 hours. More than 96% conversion of starting material was obtained, with selectivity to mono epoxide product of 82%. A small amount of diepoxide product was also obtained. EXAMPLE 19 Epoxidation of geraniol Geraniol was epoxidised by the above procedure, using the same catalyst as in Example 18 (0.8% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2.5:1). The final mol ratio propionaldehyde:starting material was 1.5:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 5 hours. 81% conversion of starting material was obtained, with selectivity to mono epoxide product of 78%, the mono epoxide product being a mixture of 2- and 6-epoxides. EXAMPLE 20 Epoxidation of citral Citral, the naturally-occurring mixture of geranial and neral isolable from oil of lemon grass was epoxidised by the above procedure, using the same catalyst as in Examples 18 and 19 (1% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 2:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 4.5 hours. More than 96% conversion of starting material was obtained, with selectivity to 6-epoxide products of 68%. EXAMPLE 21 Epoxidation of ∝-limonene ∝-limonene was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.5:1 oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 4.5 hours. 94% conversion of starting material was obtained, with selectivity to mono epoxide products of 81% (cis:trans, 2:1 [∝]₂₀ D -42°) 10% diepoxide was produced. By comparison, when Mn(acetate)₃/Co(acetate)₂(100:1) was used as catalyst in a comparable procedure, with acetic acid/ethyl acetate as solvent, after 10 hours reaction time 82% of starting material was consumed, with selectivity to mono epoxide of only 22%, the remainder being a mixture of ketones, diols and phenols. EXAMPLE 22 Epoxidation of 1,11-dodecadiene CH₂ = CH.C₈H₁₆.CH = CH₂ 1,11-dodecadiene was epoxidised by the above procedure, using the same catalyst as in Examples 18 to 20 as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2:1). The final mol ratio propion aldehyde:starting material was 1.2:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 3.5 hours. More than 96% conversion of starting material was obtained, with selectivity to mono epoxide product of 91% A small amount of diepoxide was also produced. EXAMPLE 23 Epoxidation of 1,3-nonadiene CH₂ = CH - CH = CH - C₅H₁₁ 1,3-nonadiene was epoxidised by the above procedure, using the same catalyst as in Example 22 as catalyst (0.5% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.5:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 5 hours. 71% conversion of starting material was obtained, with selectivity to mono epoxide product of 58%, the remainder being a polymeric material. EXAMPLE 24 Epoxidation of squalene Squalene was epoxidised by the above procedure, using the same catalyst as in Examples 22 and 23 as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2:1). The final mol ratio propionaldehyde:starting material was 1,2:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 4 hours. 72% conversion of starting material was obtained, with selectivity to mono epoxide product of 36%. Infra-red and nuclear magnetic resonance spectroscopy indicated that the remainder was a complex structure of steroid configuration. By comparison, when Mn(acetate)₃ was used as catalyst in a comparable procedure, with acetic acid/ethyl acetate as solvent, after 3.5 hours reaction time more than 96% of starting material was consumed, but no epoxide was present in the product, which was a complex structure of steroid configuration. EXAMPLE 25 Epoxidation of allyl acetate allyl acetate was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The procedure was similar to the general procedure described above except that ethyl acetate was heated in the reactor to 48°C, the catalyst was introduced and a blend of the allyl acetate, propionaldehyde and more ethyl acetate was streamed into the reactor at constant rate while the oxygen was bubbled through the reaction mixture. The final mol ratio propionaldehyde:starting material was 2:1, oxgygen was bubbled through at a rate of 10 1/hour, and reaction time was 5 hours. 95% conversion of starting material was obtained, with selectivity to desired epoxide product of 63%, 12% being ethyl acetoacetate. EXAMPLE 26 Epoxidation of allyl chloride allyl chloride was epoxidised by a procedure similar to that of Example 26 using Di(acetate)₃ as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 7 hours. 63 % conversion of starting material was obtained, with selectivity to desired epoxide product of 60%, the remainder being a polymeric mass. EXAMPLE 27 Epoxidation of allyl alcohol Allyl alcohol was epoxidised by the above general procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (1% based on the weight of starting material), acetone as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 10 1/hour, and reaction time was 6 hours. 91% conversion of starting material was obtained, with selectivity to desired epoxide product of 43%, the remainder being a polymeric mass. EXAMPLE 28 Epoxidation of allyl phenyl ether Allyl phenyl ether was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (1% based on the weight of starting material), acetone as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 7 hours. 38% conversion of starting material was obtained, with selectivity to desired epoxide product of 41%, 20% being phenol and the remainder a black tar. EXAMPLE 29 Epoxidation of allyl o-tolyl ether Allyl o-tolyl ether was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (1% based on the weight of starting material), acetone as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 6 hours. 62% conversion of starting material was obtained, with selectivity to desired epoxide product of 22%, 15% being o-cresol and the remainder a black tar. EXAMPLE 30 Epoxidation of 1,2,3,6-tetrahydrobenzoic acid 1,2,3,6-tetrahydrobenzoic acid was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (0.5% based on the weight of starting material), ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.6:1, oxygen was bubbled through at a rate of 5 1/hour, and reaction time was 5 hours. More than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 82%. EXAMPLE 31 Epoxidation of 4-pentenoic acid 4-pentenoic acid was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.5% based on the weight of starting material), ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.8:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 6 hours. More than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 68%, the remainder being predominantly a complex mixtue of esters. By comparison, when ∝, β-unsaturated acids, namely 2-pentenoic acid, crotonic acid and methacrylic acid, were subjected to comparable procedures, in each case more than 96% of the starting material was consumed, but no epoxide product was obtained, the only products being mixtures of two or more of formic, acetic and propionic acids. EXAMPLE 32 Epoxidation of ethyl crotonate Ethyl crotonate was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.8% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.6:1, oxygen was bubbled through at a rate of 9 1/hour, and reaction time was 6 hours. 43% conversion of starting material was obtained, with selectivity to desired epoxide product of 68%, the remainder being a polymeric material. EXAMPLE 33 Epoxidation of ethyl methacrylate Ethyl methacrylate was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.8% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.6:1, oxygen was bubbled through at a rate of 9 1/hour, and reaction time was 7 hours. 52% conversion of starting material was obtained, with selectivity to desired epoxide product of 73%. EXAMPLE 34 Epoxidation of 2-allyl pyridine 2-allyl pyridine was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.5% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 4:1). The final mol ratio propionaldehyde:starting material was 1.2:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 6 hours. More than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 23%, the remainder being a polymeric black tar which was insoluble in ethyl acetate. EXAMPLE 35 Epoxidation of 3-allyl pyridine 3-allyl pyridine was epoxidised by the same procedure as in Example 35. More than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 71%, and very little polymer formation. EXAMPLE 36 Epoxidation of 2,3-dimethyl-2-butene 2,3-dimethyl-2-butene was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.8:1, oxygen was bubbled through at a rate of 6 1/hour, reaction time was 3 hours and reaction temperature was 40°C. 67% conversion of starting material was obtained, with selectivity to desired epoxide product of 42%. By comparison, when Mn(acetate)₃/Co(acetate)₂ (100:1) was used as catalyst in a comparable procedure, with acetic acid as solvent, after 6 hours reaction time 72% of starting material was consumed, but no epoxide was produced. EXAMPLE 37 Epoxidation of ∝-methylstyrene ∝-methylstyrene was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (1% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 2:1). The final mol ratio propionaldehyde:starting material was 1.5:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 3 hours. 93% conversion of starting material was obtained, with selectivity to desired epoxide product of 67%. 21% of the starting material was converted to acetophenone. By comparison, when Mn(acetate)₃/Co(acetate)₂ (100:1) was used as catalyst in a comparable procedure, with acetic acid as solvent, after 4 hours reaction time more than 96% of starting material was consumed, with selectivity to desired epoxide of less than 3%. EXAMPLE 38 Epoxidation of cyclododecene Cyclododecene was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.6% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.2:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 3.5 hours. More than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 81%. By comparison, when Mn(acetate)₃ was used as catalyst in a comparable procedure, with acetic acid as solvent, after 4 hours reaction time 78% of starting material was consumed, with selectivity to desired epoxide of 76%. EXAMPLE 39 Epoxidation of cyclododecatriene Cyclododecatriene was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2:1). The final mol ratio propionaldehyde:starting material was 1.5:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 6 hours. More than 96% conversion of starting material was obtained, with selectivity to mono epoxide product of 85%. By comparison, when Mn(acetate)₃ and Mn(acetate)₃/Co(acetate)₂ (100:1) were used as catalysts in comparable procedures, with ethyl acetate/acetic acid and acetic acid, respectively as solvents, after 4 and 7 hours reaction time respectively, in the first case over 90% of starting material was consumed, with selectivity to mono epoxide of only 78%, and in the second case 88% of starting material was consumed, with selectivity to mono epoxy of 66%. EXAMPLE 40 Epoxidation of 1,5,9-trimethylcyclododecatriene 1-5,9-trimethylcyclododecatriene was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.7% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 10 1/hour, and reaction time was 7 hours. 91% conversion of starting material was obtained, with selectivity to mono epoxide product of 88%, no diepoxide being detectable. By comparison, when Mn(acetate)₃ was used as catalyst in a comparable procedure, with ethyl acetate/acetic acid as solvent, after 7.5 hours reaction time 83% of starting material was consumed with selectivity to desired epoxide of 81%. Small amounts of diepoxide were produced. EXAMPLE 41 Epoxidation of cyclooctene Cyclooctene was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2.5:1). The final mol ratio propionaldehyde:starting material was 1.6:1, oxygen was bubbled through at a rate of 10 1/hour, and reaction time was 6 hours. More than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 90%. By comparison, when Mn(acetate)₃/Co(acetate)₂ (100:1) was used as catalyst in a comparable procedure, with ethyl acetate as solvent, after 9 hours reaction time 82% of starting material was consumed, with selectivity to desired epoxide of 68 %. EXAMPLE 42 Epoxidation of cyclooctadiene Cyclooctadiene was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (1% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.6:1, oxygen was bubbled through at a rate of 8 1/hour, and reaction time was 5 hours. 91% conversion of starting material was obtained, with selectivity to desired mono epoxide product of 78%. Small amounts of diols, esters and diepoxide were present in the product. By comparison, when Mn(acetate)₃/Co(acetate)₂ (100:1) was used as catalyst in a comparable procedure, with ethyl acetate as solvent, after 8 hours reaction time 61% of starting material was consumed, with selectivity to desired epoxide of only 52%, ketones, esters and diols were produced, with formation of a black precipitate. EXAMPLE 43 Epoxidation of 1,5-dimethylcyclooctadiene 1,5-dimethylcyclooctadiene was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.8% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2.5:1). The final mol ratio propionaldehyde:starting material was 1.5:1, air was bubbled through at a rate of 14 1/hour, and reaction time was 4 hours. More than 96 % conversion of starting was obtained, with selectivity to desired epoxide product of 76%. By comparison, when Mn(acetate)₃ was used as catalyst in a comparable procedure, with ethyl acetate as solvent, after 6.5 hours reaction time 92% of starting material was consumed, with selectivity to desired epoxide of less than 10%. EXAMPLE 44 Epoxidation of 1,4-dimethyl[3.3.0]bicyclooct-3-ene 1,4-dimethyl[3.3.0]bicyclooct-3-ene was epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (0.6% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 1.5:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 3 hours. More than 96% conversion of starting was obtained, with selectivity to desired epoxide product of 91%. EXAMPLE 45 Epoxidation of naturally-occurring caryophyllene Naturally-occurring caryophyllene was epoxidised by the above procedure, using Di(acetate)₃ as catalyst (1% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 2:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 10 1/hour, and reaction time was 8 hours. 91% conversion of starting material was obtained, with selectivity to desired epoxide product of 84%. This reaction was repeated using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 10 1/hour, and reaction time was 6 hours. 92% conversion of starting material was obtained, with selectivity to mono epoxide product of 81%. By comparison, when Mn(acetate)₃/Co(acetate)₂ (100:1) was used as catalyst in a comparable procedure, with acetic acid as solvent, after 4.5 hours reaction time 94% of starting material was consumed, with selectivity to mono epoxide of only 52%. EXAMPLE 46 Epoxidation of cedar-wood terpenes Naturally-occurring cedar-wood terpenes (cedrene) were epoxidised by the above procedure, using(acetate)₃ as catalyst (1% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 3:1). The final mol ratio propionaldehyde:starting material was 2:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 8 hours. 88% conversion of starting material was obtained, with selectivity to desired epoxide product of 68%. By comparison, when Mn(acetate)₃/Co(acetate)₂ (100:1) was used as catalyst in a comparable procedure, with acetic acid as solvent, after 5 hours reaction time 96% of starting material was consumed, with selectivity to desired epoxide of only 5%, most of the product being a mixture of ketones and acids. EXAMPLE 47 Epoxidation of α and β-chamigrene ∝ and β-chamigrene were epoxidised by the above procedure, using Di(acetate)₃/Co(acetate)₂ (100:1) as catalyst (1% based on the weight of starting material) and ethyl acetate as solvent (volume ratio solvent:starting material 2:1). The final mol ratio propionaldehyde:starting material was 1.5:1, oxygen was bubbled through at a rate of 10 1/hour, and reaction time was 9 hours. 92% conversion of starting material was obtained, with selectivity to mono epoxide product of 78%. EXAMPLE 48 Epoxidation of 4-terpeneol 4-terpeneol was epoxidised by the above procedure, using Di(propionate)₃/Co(propionate)₂ (100:1) (20% solution in propionic acid) as catalyst (0.6% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 1.5:1). The final mol ratio propionaldehyde:starting material was 1.5:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 4.5 hours. More than 96% conversion of starting material was obtained, with selectivity to desired epoxide product of 87%. EXAMPLE 49 Epoxidation of 8-terpenol 8-terpenol was epoxidised by the above procedure, using Di(propionate)₃/UO₂(propionate)₂/Co(propionate)₂ (1:0.27:10⁻⁵)(10% in propionic acid) as catalyst (0.5% based on the weight of starting material) and acetone as solvent (volume ratio solvent:starting material 2.5:1). The final mol ratio propionaldehyde:starting material was 1.1:1, oxygen was bubbled through at a rate of 6 1/hour, and reaction time was 7 hours. 52% conversion of starting material was obtained, with selectivity to desired epoxide product of 81%. COMPARATIVE EXAMPLES O to Q When isophorone was subject to comparable procedures using Di(acetate)₃/Co(acetate)₂ (100:1) (1% based on weight of starting material), ethyl acetate as solvent (volume ratio solvent:starting material 3:1), final mol ratio propionaldehyde:starting material of 1.1:1, and bubbling oxygen through at a rate of 12 1/hour for a reaction time of 16 hours, less than 5% of starting material was consumed and no epoxide was produced. Similarly, attempts to epoxidise terpinolene and γ-terpinene failed to yield epoxide products.

Claims: A process for epoxidising an olefinic double bond in an olefinically-unsaturated compound other than an (α,β)-unsaturated carboxylic acid or a compound containing a six-membered ring wherein 3 to 4 member atoms are carbon atoms having sp² hybrid orbitals, which comprises reacting a liquid phase mixture of the olefinically-unsaturated compound, an aliphatic or aromatic aldehyde containing at least two carbon atoms in an amount of at least one mole per double bond to be oxidized and a suitable solvent with oxygen in the presence of a catalyst which is soluble in the reaction mixture, characterized in that said catalyst comprises a praseodymium salt. A process according to claim 1 wherein the aliphatic aldehyde contains two to four carbon atoms. A process according to claim 2 wherein the aldehyde is propionaldehyde. A process according to claims 1 to 3 wherein the solvent comprises at least one solvent selected from C₁₋₆ alkyl esters of C₂₋₆ carboxylic acids, C₃₋₆ ketones and C₂₋₆ carboxylic acids. A process according to claim 4 wherein the solvent comprises at least one solvent selected from methyl and ethyl esters of acetic and propionic acids, acetone, methyl ethyl ketone, acetic acid and propionic acid. A process according to any of claims 1 to 5 wherein the catalyst comprises a C₂₋₆ carboxylic acid salt of praseodymium and optionally of one or more other metals. A process according to claim 6 wherein the catalyst comprises a didymium salt. A process according to claim 6 or 7 wherein the catalyst contains a cobalt salt. A process according to any of claims 6 to 8 wherein the catalyst contains a uranium or vanadium salt. A process according to any of claims 6 to 9 wherein the carboxylic acid salt comprises acetate or propionate. A process according to any of claims 1 to 10 wherein the aldehyde is used in an amount in the range 1 to 3 mol per mol of olefinically-unsaturated compound. A process according to any of claims 1 to 10 wherein the reaction temperature is in the range from 30°C to the reflux temperature of the reaction mixture. A process according to any of claims 1 to 11 wherein the reaction temperature is in the range from 30 to 60°C. A process according to any of claims 1 to 13 wherein aldrin is epoxidised to dieldrin.

Inventors: MULDER, ALBERTUS JOHAN
Applicants: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1984
Main classification: C07D301
IPC codes: C07D303, C07D301, C07D401, B01J31, C07B61, C07D405