EP0000534B1 - Process for the preparation of vinyl oxiranes - Google Patents

Description

The present invention relates to a process for the preparation of vinyloxiranes from polyenes and percarboxylic acids.

Vinyloxiranes are particularly important as monomers because of their bifunctional structure. They are therefore used both in the field of paints and plastics and as organic intermediates. To a large extent, no technical use of vinyloxiranes has taken place since no satisfactory technical process for their production has yet been available.

Many methods for converting olefins to oxiranes are known and attempts have been made to use these methods to produce vinyl oxiranes. For example, US Pat. No. 3,232,957 proposes converting olefins with molecular oxygen in the liquid phase into the epoxides. Column 10, line 15, Example 8 of the cited patent describes the reaction of butadiene with oxygen at 150 ° C. in dicyclopropyl ketone as solvent. However, the vinyl oxirane yield achieved was low; it was only 25%. The use of acetophenone instead of dicyclopropyl ketone as the solvent only yielded a slightly higher yield of vinyl oxirane; it was only 28% (U.S. Patent 3,232,957, column 12, line 15).

The halohydrin method, which has long been known for the production of oxiranes from olefins, has also been used for the production of vinyl oxiranes. For example, the preparation of isoprene oxide from isoprene monochlorohydrin and alkali hydroxide is described in the published Japanese patent application 23 545/64. However, this method has the disadvantage of the formation of undesired chlorinated by-products and environmentally harmful salt waste (Ullmanns Encyklopadie d. Techn. Chemie, Vol. 10, p. 565, left column, line 1 ff .; DAS 1 543 174, column 2, line 15 ff .).

Another method for producing epoxy compounds is based on the reaction of olefins with hydrogen peroxide in the presence of catalysts. The use of this method for the production of vinyloxiranes from polyenes and hydrogen peroxide is described in DAS 2 012 049, p. 15, line 7, example 18, in particular Table I (continued). It reports on the reaction of butadiene with 70% hydrogen peroxide in the presence of trimethyltin hydroxide and the molybdenum salt of acetylacetone as a catalyst. Ethanol was used as the solvent. But even after stirring for 20 hours at 40 ° C., vinyloxirane was only obtained in a yield of 21.7%, based on the hydrogen peroxide used.

Another synthetic principle is based on the reaction of olefins with organic hydroperoxides using catalysts. The use of this synthetic principle for the production of vinyl oxiranes from polyenes and tert-butyl hydroperoxide or cumene hydroperoxide in the presence of molybdenum hexacarbonyl as a catalyst is described by MN Sheng and JG Zajacek (J. Org. Chem. 35, No. 6, (1970) p. 1840 , Table I; U.S. Patent 3,538,124). Although yields of 84-90% are obtained for the conversion of butadiene, isoprene and piperylene into the monoepoxides, this synthetic principle has the crucial disadvantage that the organic hydroperoxide ROOH, where R is a low molecular weight organic radical such as tert-butyl or cumyl , is converted to the corresponding alcohol ROH during the reaction according to the following equation:

The alcohol corresponding to the hydroperoxide (ROOH) used is thus obtained as a by-product, which means that the economics of this process depend on the usability of this alcohol (ROH). If this alcohol cannot be used, it must be converted back into the corresponding hydroperoxide (ROOH) over several process steps.

Another method for the production of vinyloxirane from butadiene is described in DAS 1 593 306 on page 8 in Example 3. Herein butadiene is reacted with tri- (cyclohexylperoxy-) borane at a pressure of 20 bar and a temperature of 100 ° C. The reaction mixture was worked up by distillation to give a fraction boiling between 70 ° C. and 126 ° C. which contained vinyloxirane in an amount which corresponded to a yield of 81.7%. Obviously there are problems with the separation of the vinyl oxirane from the reaction mixture with this method. The stated yield of vinyloxirane is also unsatisfactory.

Pummerer and Reindel describe the reaction of polyenes with percarboxylic acids for the first time in 1933 (R. Pummerer and W. Reindel, Ber. Dtsch.'chem. Ges. 66, pp. 334-339 (1933)). On page 335, line 16 ff., They report on the epoxidation of isoprene with perbenzoic acid in ethyl chloride as a solvent. The only product you get is 2-methyl-2-vinyloxirane in a yield of 30 to 40%. In the reaction of butadiene with perbenzoic acid, they achieve a yield of about 40% for vinyloxirane.

F. C. Frostick et. al. (J. Am. Chem. Soc., 81, 3354, Table IV) cannot be achieved. When butadiene was reacted with peracetic acid, which was prepared by oxidation of acetaldehyde, in ethyl acetate or acetone as the solvent, it achieved a yield of vinyl oxirane of 56%.

The use of special procedural measures, such as those proposed in German PS 1 216 506 for carrying out epoxidations, does not produce satisfactory yields. Example 3, column 8, lines 60 ff. Of this patent describes the reaction of butadiene with peracetic acid in ethyl acetate. Vinyloxirane is obtained in 68% yield.

The use of peracetic acid, which was also prepared by oxidation of acetaldehyde, in acetic acid as a solvent is disclosed in Japanese Patent No. 1,774,046-284, and the use of perisobutyric acid, which was obtained by oxidation of isobutyraldehyde, in isobutyric acid as a solvent is disclosed in US Pat Japanese patent 174 040-202 proposed for the epoxidation of butadiene. However, the use of carboxylic acids as solvents in the production of oxiranes has the disadvantage that many oxiranes react with carboxylic acids to form the acylates with ring opening (D. Swern, "Organic Peroxides", Wiley Interscience, 1971, Vol. 2, p. 376, line 10 ff.), Which can lead to considerable losses in yield.

In DAS 1 190 926 the percarboxylic acid is generated "in situ" during the reaction with butadiene. However, the yield achieved here is also unsatisfactory. Column 15, line 5 ff., Describes the reaction of butadiene at 73-76 ° C in ethyl acetate as a solvent with oxygen in the presence of n-butyraldehyde and cobalt naphthenate as a catalyst. The yield of epoxy is given as 55%. 45% of this is accounted for by butadiene monoxide and 10% by butadiene dioxide.

A further possibility for the production of vinyl oxiranes is described in British PS 735 974. In Example 13, column 8, lines 31 ff., The reaction of butadiene with acetaldehyde monoperacetate prepared by oxidation of acetaldehyde in acetone as solvent at 70 ° C. is described therein. However, vinyloxirane is only obtained in a yield of 33%.

Another synthesis principle for the epoxidation of polyenes is described in US Pat. No. 3,053,856. Here, the reaction of butadiene with hydrogen peroxide is carried out in the presence of acetonitrile, vinyloxirane being obtained as the main product (Example XII). However, in this process it must be accepted that the carboxylic acid amide formed from the nitrile during the reaction is obtained as a by-product which either has to be put to a suitable use or has to be subjected to dehydration in order to be returned to the process.

Finally, GB-PS 846 534 discloses a reaction of butadiene with peracetic acid in a molar ratio of 1.23: 1. The other details of this reaction are not sufficient to give the person skilled in the art a lesson on how to obtain butadiene monoxide in high yields. It is also not known from this document that excess butadiene can be recovered. Because of the high ability of the butadiene to rupture and polymerize and the lack of corresponding information on the fate of the butadiene used in excess, the person skilled in the art suspects that this cannot be recovered and that the use of butadiene in larger excesses offers no advantages. In addition, according to the procedure described in this document, large amounts of environmentally harmful wastewater are produced, which is why it is disadvantageous for a technical application. This document also contains no information about the quality of the peracid used.

worin R₁, R₂, R_4' R₅ und R₆ unabhängig voneinander Wasserstoff, C_i- bis C_4-Alkyl, Vinyl, C₃- bis C₇-Cycloalkyl oder Phenyl bedeuten und worin R, mit R₃, R, mit R₄ oder R, mit R₅ einen carbocyclischen Ring mit bis zu 12 Kohlenstoffatomen bilden können,
mit einer Lösung einer 3 bis 4 Kohlenstoffatome enthaltenden Percarbonsäure in einem aromatischen Kohlenwasserstoff mit 6 bis 12 Kohlenstoffatomen oder in einem chlorierten, 1 bis 18 Kohlenstoffatome enthaltenden Kohlenwasserstoff, die bis zu 5 Gew.-% Wasser, bis zu 2 Gew.-% Wasserstoffperoxid und weniger als 50 ppm Mineralsäure enthält, bei einem Molverhältnis von Polyen zu Percarbonsäure wie 1,5:1 bis 5:1 und bei einer Temperatur von -20°C bis +100°C umsetzt.A process has now been found for the preparation of vinyloxirane and substituted vinyloxirane from polyenes and percarboxylic acids, which is characterized in that a polyene of the formula

wherein R ₁ , R ₂ , R _{4 '} R ₅ and R ₆ independently of one another are hydrogen, C _i - to C ₄ -alkyl, vinyl, C ₃ - to C ₇ -cycloalkyl or phenyl and in which R, with R ₃ , R , with R ₄ or R, with R _{5 can form} a carbocyclic ring with up to 12 carbon atoms,
with a solution of a percarboxylic acid containing 3 to 4 carbon atoms in an aromatic hydrocarbon with 6 to 12 carbon atoms or in a chlorinated hydrocarbon containing 1 to 18 carbon atoms, containing up to 5% by weight of water, up to 2% by weight of hydrogen peroxide and contains less than 50 ppm of mineral acid, with a molar ratio of polyene to percarboxylic acid such as 1.5: 1 to 5: 1 and at a temperature of -20 ° C to + 100 ° C.

worin R₇, R₈, R₉ und R₁₀ unabhängig voneinander Wasserstoff, C₁- bis C_4-Alkyl, Vinyl, C₅- bis C₇-Cycloalkyl oder Phenyl bedeuten und worin R₇ mit R₈, R₇ mit R₉ oder R₇ mit R₁₀ einen carbocyclischen Ring mit bis zu 12 Kohlenstoffatomen bilden können.

worin R₁₁, R₁₂ und R₁₃ unabhängig voneinander Wasserstoff, C₁- bis C_4-Alkyl, Vinyl, C₁- bis C₅ Cycloalkyl oder Phenyl bedeuten und n für eine ganze Zahl von 3 bis 6 steht;

worin R₁₄, R₁₅, R₁₆ und R₁₇ unabhängig voneinander Wasserstoff, C₁- bis C_4-Alkyl, Vinyl, C₅- bis C₇-Cycloalkyl oder Phenyl bedeuten und n für eine ganze Zahl von 2 bis 5 steht;

wobei R₁₈, R₁₉, R₂₀ und R₂, unabhängig voneinander Wasserstoff, C₁- bis C_4-Alkyl, Vinyl, C₅- bis C₇-Cycloalkyl oder Phenyl bedeuten und n für eine ganze Zahl von 1 bis 4 steht.In the context of the compounds of the formula (I), compounds of the following formula (II-V) are particularly suitable:

in which R ₇ , R ₈ , R ₉ and R ₁₀ independently of one another are hydrogen, C ₁ - to C ₄ -alkyl, vinyl, C ₅ - to C ₇ -cycloalkyl or phenyl and in which R ₇ with R ₈ , R ₇ with R ₉ or R ₇ with R _{10 can form} a carbocyclic ring with up to 12 carbon atoms.

wherein R ₁₁ , R ₁₂ and R ₁₃ independently of one another are hydrogen, C ₁ - to C ₄ -alkyl, vinyl, C ₁ - to C ₅ cycloalkyl or phenyl and n is an integer from 3 to 6;

wherein R _14, R _15, R ₁₆ and R ₁₇ are independently hydrogen, C ₁ - to C _4- alkyl, vinyl, C ₅ - to C ₇ -cycloalkyl or represents phenyl and n is an integer from 2 to 5;

where R ₁₈ , R ₁₉ , R ₂₀ and R ₂ , independently of one another, are hydrogen, C ₁ - to C ₄ -alkyl, vinyl, C ₅ - to C ₇ -cycloalkyl or phenyl and n is an integer from 1 to 4 .

• Butadien, Isopren, Piperylen, Cyclopentadien, Methyl-cyclopentadien, 2,4-Dimethyl-1,3-butadien, 1,3-Dimethyl-1,3-butadien, 2,4-Hexadien, 1,3-Hexadien, 1,3,5-Hexatrien, Dimethyl-cyclopentadien, 2-Methyl-1,3-pentadien, 3-Methyl-1,3-pentadien, 4-Methyl-1,3-pentadien, 2-Äthyl-1,3-butadien, 1,3-Cyclohexadien, Methylen-2-cyclopenten, Methylen-2-cyclohexen, 3,4-Dimethyl-1,3-pentadien, 2,4-Dimethyl-1,3-pentadien, 2-Methyl-2,4-hexadien, 2-Methyl-1,3-hexadien, 2-Methyl-1,3,5-hexatrien, 3-Methyl-1,3-hexadien, 4-Methyl-1,3-hexadien, 3-Methyl-1,3,5-hexatrien, Methyl-1,3-cyclohexadien, 1,3-Cycloheptadien, 1,3,5-Cycloheptatrien, Dimethyl-1,3-cyclohexadien, 1-Vinyl-1-cyclohexen, Methyl-1,3-cycloheptadien, 2,5-Dimethyl-1,3-hexadien, 2,5-Dimethyl-2,4-hexadien, 2,5-Dimethyl-1,3,5-hexatrien, 2-Äthyl-1,3-hexadien, 2-Äthyl-1,3,5-hexatrien, 1,3-Cyclooctadien, Cyclooctatetraen, 2,4-Dimethyl-1,3,5-hexatrien, 2,4-Dimethyl-1,3-hexadien, 5,5-Dimethyl-1,3-hexadien, 5,5-Dimethyl-1,3,5-hexatrien, 1,3,7-Octatrien, 2-Methyl-1,3,7-octatrien, 2-Methyl-1,5,7-octatrien, Methyl-1,3-cyclooctadien, 1-Cyclopentyl-1,3-butadien, 2-Cyclopentyl-1,3-butadien, 1,2,3,4-Tetramethyl-cyclopentadien, 2,6-Dimethyl-1,3,7-octatrien, 3,7-Dimethyl-1,3,7-octatrien, 1-Cyclohexyl-1,3-butadien, 2-Cyclohexyl-1,3-butadien, 1-Phenyl-1,3-butadien, 2-Phenyl-1,3-butadien, 1,3,9,11-Dodecatetraen, 1,2,3,4-Tetramethyl-cyclooctatetraen.

The following may be mentioned as polyenes:

• Butadiene, isoprene, piperylene, cyclopentadiene, methyl-cyclopentadiene, 2,4-dimethyl-1,3-butadiene, 1,3-dimethyl-1,3-butadiene, 2,4-hexadiene, 1,3-hexadiene, 1, 3,5-hexatriene, dimethyl-cyclopentadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2-ethyl-1,3-butadiene, 1,3-cyclohexadiene, methylene-2-cyclopentene, methylene-2-cyclohexene, 3,4-dimethyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, 2-methyl-2,4- hexadiene, 2-methyl-1,3-hexadiene, 2-methyl-1,3,5-hexatriene, 3-methyl-1,3-hexadiene, 4-methyl-1,3-hexadiene, 3-methyl-1, 3,5-hexatriene, methyl-1,3-cyclohexadiene, 1,3-cycloheptadiene, 1,3,5-cycloheptatriene, dimethyl-1,3-cyclohexadiene, 1-vinyl-1-cyclohexene, methyl-1,3- cycloheptadiene, 2,5-dimethyl-1,3-hexadiene, 2,5-dimethyl-2,4-hexadiene, 2,5-dimethyl-1,3,5-hexatriene, 2-ethyl-1,3-hexadiene, 2-ethyl-1,3,5-hexatriene, 1,3-cyclooctadiene, cyclooctatetraene, 2,4-dimethyl-1,3,5-hexatriene, 2,4-dimethyl-1,3-hexadiene, 5.5- Dimethyl-1,3-hexadiene, 5,5-dimethyl-1,3,5-hexatriene, 1,3,7-octatriene, 2- Methyl-1,3,7-octatriene, 2-methyl-1,5,7-octatriene, methyl-1,3-cyclooctadiene, 1-cyclopentyl-1,3-butadiene, 2-cyclopentyl-1,3-butadiene, 1,2,3,4-tetramethyl-cyclopentadiene, 2,6-dimethyl-1,3,7-octatriene, 3,7-dimethyl-1,3,7-octatriene, 1-cyclohexyl-1,3-butadiene, 2-cyclohexyl-1,3-butadiene, 1-phenyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3,9,11-dodecatetraene, 1,2,3,4-tetramethyl- cyclooctatetraen.

worin R₂₂ und R₂₃ unabhängig voneinander Wasserstoff, Methyl, Äthyl, Vinyl oder Phenyl bedeuten.Polyenes of the formula are particularly suitable for reaction with percarboxylic acids according to the process of the invention

wherein R ₂₂ and R _{23 are} independently hydrogen, methyl, ethyl, vinyl or phenyl.

• Butadien, Isopren, Piperylen, 1,3-Hexadien, 1,3,5-Hexatrien, 2-Äthyl-1,3-butadien, 1,3-Dimethyl-1,3-butadien, 2,4-Hexadien, 1-Phenyi-1,3-butadien, 2-Phenyl-1,3-butadien, 1-Methy)-1,3-hexadien, 1-Methyl-1,3,5-hexadien, 2-Methyl-1 ,3-pentadien, 2-Methyl-1,3-hexadien, 2-Methyl-1,3,5-hexatrien, 2- Äthyl-1,3-hexadien, 2-Äthyl-1,3,5-hexatrien, 2-Phenyl-1,3,5-hexatrien, 2-Phenyl-1,3-hexadien, 2-Phenyl-1,3-pentadien.

The following may be mentioned in particular as compounds of the formula VI:

• Butadiene, isoprene, piperylene, 1,3-hexadiene, 1,3,5-hexatriene, 2-ethyl-1,3-butadiene, 1,3-dimethyl 1,3-butadiene, 2,4-hexadiene, 1-phenyi-1,3-butadiene, 2-phenyl-1,3-butadiene, 1-methyl) -1,3-hexadiene, 1-methyl-1,3 , 5-hexadiene, 2-methyl-1, 3-pentadiene, 2-methyl-1,3-hexadiene, 2-methyl-1,3,5-hexatriene, 2-ethyl-1,3-hexadiene, 2-ethyl -1,3,5-hexatriene, 2-phenyl-1,3,5-hexatriene, 2-phenyl-1,3-hexadiene, 2-phenyl-1,3-pentadiene.

Butadiene, isoprene, piperylene, cyclopentadiene, 1,3,5-hexatriene and 1,3,7-octatriene are very particularly suitable for reaction with percarboxylic acids by the process according to the invention.

A wide variety of chlorinated hydrocarbons can be used as solvents, such as methylene chloride, chloroform, carbon tetrachloride, 1-chloroethane, 1,2-dichloroethane, 1,1-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chloropropane, 2-chloropropane , 1,2-dichloropropane, 1,3-dichloropropane, 2,3-dichloropropane, 1,2,3-trichloropropane, 1,1,2,3-tetrachloropropane, butyl chloride, 1,2-dichlorobutane, 1,4-dichlorobutane , 2,3-dichlorobutane, 1,3-dichlorobutane, 1,2,3,4-tetrachlorobutane, tert-butyl chloride, amyl chloride, 1,2-dichloropentane, 1,5-dichloropentane, 1,2,3,4- Tetrachloropentane, cyclopentyl chloride, 1,2-dichlorocyclopentyl chloride, hexyl chloride, 1,2-dichlorohexane, 1,6-dichlorohexane, 1,2,3,4-tetrachlorohexane, 1,2,5,6-tetrachlorohexane, cyclohexyl chloride, 1,2- Dichlorohexane, chlorobenzene, heptyl chloride, 1,2-dichlorheptane, 1,2,1,2,3,4-tetrachlorheptane, cycloheptyl chloride, 1,2-dichloroheptane, octyl chloride, 1,2-dichloroctane, 1,2,3,4- Tetrachloroctane, cyclooctyl chloride or 1,2-dichloroctane, and aromatic hydrocarbons substances such as benzene, nitrobenzene, toluene, ethylbenzene, cumene, diisopropylbenzene, xylene or chlorobenzene.

Preferred solvents are the chlorinated hydrocarbons methylene chloride, chloroform, carbon tetrachloride and 1,2-dichloropropane, the aromatic hydrocarbons benzene, nitrobenzene, toluene and chlorobenzene.

A particularly preferred solvent is chlorinated hydrocarbons, 1,2-dichloropropane and aromatic hydrocarbons benzene and chlorobenzene.

Solvent mixtures of chlorinated hydrocarbons and solvent mixtures of aromatic hydrocarbons can also be used. Mixtures of chlorinated and aromatic hydrocarbons can also be used as solvents.

Peracids which can be used according to the invention are perpropionic acid, per-n-butyric acid and perisobutyric acid. Perpropionic acid and perisobutyric acid are preferably used. Perpropionic acid is particularly preferred. The preparation of the mineral acid-free peracids in one of the organic solvents mentioned can e.g. according to the procedure described in DOS 2 262 970.

The inventive method is carried out in a temperature range from -20 to 100 ° C. It is preferred to work at 0-60 ° C, particularly preferably at 10-40 ° C. In special cases, the specified temperatures can also be exceeded or fallen short of.

In addition to working under isothermal conditions, i.e. Maintaining a uniform temperature in the entire reaction mixture, the reaction can also be carried out with the formation of a so-called temperature gradient, which generally increases with the progress of the reaction. However, the reaction can also be carried out in such a way that a gradient of falling temperature is formed as the reaction proceeds.

According to the invention, the molar ratio of olefin to peracid is 1.5: 1 to 5: 1. It is very particularly advantageous to use a molar ratio of 2.0 to 3.0 moles of polyene per mole of peracid.

The method according to the invention can be carried out at a wide variety of pressures. Generally one works at normal pressure; however, the process can also be carried out under negative or positive pressure.

The water content of the percarboxylic acid solution used for the epoxidation should generally be as low as possible and is at most 5% by weight. For example, a percarboxylic acid solution with a water content of up to 1% by weight is suitable. A percarboxylic acid solution which contains less than 0.5% by weight of water is preferably used. A water content of less than 0.1% by weight is particularly preferred, e.g. a water content of 0.01 to 0.1% by weight.

The hydrogen peroxide content of the percarboxylic acid solution used should generally be as low as possible and is at most 2% by weight. It is advantageous to work with a content of less than 1% by weight. It is particularly advantageous to carry out the reaction with a percarboxylic acid solution which has a hydrogen peroxide content below 0.3% by weight, for example a H, O ₂ content of 0.01 to 0.3% by weight.

The mineral acid content of the percarboxylic acid solution to be implemented should be as low as possible and is less than 50 ppm. A mineral acid content of less than 10 ppm is particularly advantageous.

The reaction can be carried out batchwise or continuously in the devices customary for reactions of this type, such as stirred tanks, boiler reactors, tubular reactors, loop reactors or loop reactors.

Glass, stainless steel or enamelled material can be used as materials for carrying out the processes.

Heavy metal ions in the reaction mixture catalyze the decomposition of the percarboxylic acid. Substances are therefore generally added to the percarboxylic acid solution which inactivate the heavy metal ions through complex formation. Known substances of this type are gluconic acid and ethylene diamine tetraacetic acid, sodium silicate, sodium pyrophosphate, sodium hexametaphosphate, disodium dimethyl pyrophosphate or Na ₂ (2-ethylhexyl) 1 (Ploll) 2 (DAS 1 056 596, column 4, line 60 ff.).

The polyene can be introduced into the device used for the reaction in various ways. It can be added to the reactor together with the percarboxylic acid solution, or the two components can be fed to the reactor separately. It is also possible to feed the olefin and the percarboxylic acid solution into the reactor unit at various points. When using several reactors connected in cascade, it may be expedient to introduce all of the olefin into the first reactor. However, the olefin can also be divided between the various reactors.

The heat of reaction is dissipated by internal or external coolers. To remove the heat of reaction, the reaction can also be carried out under reflux, i.e. in boiling reactors.

The reaction is expediently carried out with the most complete possible conversion of the percarboxylic acid. In general, more than 95 mol% of the percarboxylic acid is reacted. It is expedient to convert more than 98 mol% of peracid.

When carrying out the reaction between the polyene and the peracid according to the invention, oxirane yields of 90% of theory and above, based on the percarboxylic acid used, can be achieved.

The reaction mixture is worked up in a manner known per se, for example by distillation. In a preferred implementation of the process, an approximately 20% by weight perpropionic acid solution in 1,2-dichloropropane or benzene is added with stirring to the double molar amount of polyene, which is thermostated at 30 ° C. The perpropionic acid solution contains less than 10 ppm mineral acid; it has a water content of less than 0.1% and a hydrogen peroxide content of less than 0.3%. To complex heavy metal ions, about 0.05% by weight of Na ₅ ( _2- ethylhexyl) ₅ (P ₃ O ₁₀ ) _{2 was} added to the perpropionic acid before the reaction. The progress and the end of the reaction are checked by taking samples from the reaction solution at intervals and determining the still present content of percarboxylic acid by titration. After the reaction has ended, the reaction mixture is fractionated.

The following examples illustrate the invention. Provide all percentages, unless otherwise stated. Percentages by weight.

example 1

Reaction of isoprene with perpropionic acid in 1,2-dichloropropane.

A solution of 235 g (0.5 mol) of perpropionic acid as a 20% solution in 1,2-dichloropropane was added dropwise at 20 ° C. to 85.15 g (1.25 mol) of isoprene while stirring. After the dropping had ended, the mixture was stirred at this temperature for a further 1.5 hours; then the titrimetric analysis showed a peracid conversion of 99%. Gas chromatographic analysis showed that the two isomeric oxiranes 2-methyl-2-vinyl-oxirane and 2- (1-methylethenyl -) - oxirane were formed in a ratio of 4: 1. The overall selectivity of the two oxiranes was 90.5%, based on the perpropionic acid used.

Example 2

Production of vinyl oxirane from butadiene and perpropionic acid.

450 g (1 mol) of perpropionic acid as a 20% solution in benzene were added dropwise to 145.8 g (2.7 mol) of butadiene in 730 g of benzene at 40 ° C. while stirring. After the dropping had ended, stirring was continued for a further 2 hours; then the peracid conversion was 99%. The selectivity of the vinyl oxirane formed, based on the peracid used, was 95% (GC analysis).

Example 3

Continuous production of vinyl oxirane from butadiene and perpropionic acid.

20.17% benzene perpropionic acid was reacted with excess butadiene in a four-stage cascade. The reaction was carried out at a pressure of 2 bar. Butadiene was introduced into the first reactor in gaseous form. The excess of butadiene, based on the perpropionic acid used in the reaction, totaled 170 mol%. The quantities entered into the reaction system every hour were 482 g of butadiene and .1438 g of benzene perpropionic acid. The first reactor of this four-stage cascade, which, like the three subsequent reaction vessels, is equipped with a stirrer and has a content of 1600 ml, is at a temperature of 35 ° C., the second, third and fourth reactors at a temperature of 40 ° each C operated. The perpropionic acid used is converted to 99.8% under these reaction conditions. Behind the fourth reactor, the reaction mixture, which was produced at a rate of 1920 g per hour, and on average the composition: 16.52% butadiene, 11.67% vinyl oxirane, 21.46% propionic acid and 50.08% benzene and 13% water had, after cooling to 30 ° C relaxed in a cutter to normal pressure, with a small part of the butadiene (37 g / h) outgassing and was returned to the reaction system. The mixture obtained after the depressurization was mixed with 2 g / h of 4-tert-butyl catechol and fed to a first distillation column. Here all vinyl oxirane was obtained together with butadiene and part of the benzene as a distillate. This distillate had an average composition of 32.6% butadiene, 27.25% vinyl oxirane, 39.9% benzene and small amounts of water. It was produced in an amount of 822 g per hour and was then separated from the butadiene in a second distillation column . The distillate obtained 268 g of butadiene per hour, which was returned to the reaction system.

From the butadiene-free bottom product, 224 g of vinyloxirane were obtained in a purity of 99.9% as a distillate in a third column. The bottom product of this column was combined with the bottom product of the first column and separated in a fourth column. 361 g of benzene were obtained as the distillate per hour. From the bottom product, 415 g / h of propionic acid were obtained as distillate in a fifth column, while 15 g of a mixture of higher-boiling compounds were obtained per hour at the bottom of this column. These higher boiling compounds consisted essentially of the mono- and dipropionates of 3,4-dihydroxy-1-butene. The yield of vinyloxirane, based on the perpropionic acid used in the reaction system, was 96.7%.

Claims (10)

1. Process for the preparation of vinyloxirane and substituted vinyloxiranes from polyenes and percarboxylic acids, characterised in that a polyene of the formula

wherein R₁, R₂, R₃, R₄, R₅ and R₆ independently of one another denote hydrogen, C,- to C_4-alkyl, vinyl, C₃- to C_7-cycloalkyl or phenyl,
and wherein R, and R₃, R₁ and R₄ or R₁ and R₅ can form a carbocyclic ring with up to 12 carbon atoms, is reacted with a solution of a percarboxylic acid containing 3 to 4 carbon atoms in an aromatic hydrocarbon with 6 to 12 carbon atoms or in a chlorinated hydrocarbon containing 1 to 8 carbon atoms, which solution contains up to 5% by weight of water, up to 2% by weight of hydrogen peroxide and less than 50 ppm of mineral acid, at a molar ratio of polyene to percarboxylic acid of 1.5:1 to 5:1 and at a temperature of -20°C to +100°C.

2. Process according to Claim 1, characterised in that an olefine of the formula

wherein R₇, R₈, R₉ and R₁₀ independently of one another denote hydrogen, C₁- to C_4-alkyl, vinyl, C₅- to C_7-cycloalkyl or phenyl,

and wherein R₇ and R₈, R₇ and R₉, or R₇ and R₁₀ can form a carbocyclic ring with up to 12 carbon atoms, is employed as the polyene.

3. Process according to Claim 1 and 2, characterised in that an olefine of the formula

wherein R₁₁, R₁₂ and R₁₃ independently of one another denote hydrogen, C,- to C_4-alkyl, vinyl, C₃- to C₅- cycloalkyl or phenyl and

n represents an integer from 3 to 6,

is employed as the polyene.

4. Process according to Claim 1 to 3, characterised in that an olefine of the formula

wherein R₁₄, R₁₅, R₁₆ and R₁₇ independently of one another denote hydrogen, C₁- to C_4-alkyl, vinyl, C₅- to C₇ cycloalkyl or phenyl and

n represents an integer from 2 to 5,

is employed as the polyene.

5. Process according to Claim 1 to 4, characterised in that a compound of the formula

wherein R₁₈, R₁₉, R₂₀ and R₂₁ independently of one another denote hydrogen, C₁- to C_4-alkyl, vinyl, C₃- to C₇-cycloalkyl or phenyl and

n represents an integer from 1 to 4,

is employed as the polyene.

6. Process according to Claim 1 to 5, characterised in that an olefine of the formula

wherein R₂₂ and R₂₃ independently of one another denote hydrogen, methyl, ethyl, vinyl or phenyl, is employed as the polyene.

7. Process according to Claim 1 to 6, characterised in that butadiene, isoprene, piperylene, cyclopentadiene, 1,3,5-hexatriene or 1,3,7-octatriene are used as the polyene.

8. Process according to Claim 1 to 7, characterised in that perpropionic acid or perbutyric acid are used as the percarboxylic acid.

9. Process according to Claim 1 to 8, characterised in that benzene, chlorobenzene or 1,2-dichloropropane are used as the solvent.

10. Process according to Claim 1 to 9, characterised in that the reaction is carried out at a molar ratio of olefine to peracid of 1.5 to 3:1.