CS249234B1 - Method of alkanic monocarboxyl acids by means of alkenes ozonization - Google Patents

Abstract

The solution relates to a process for preparing alkanes monocarboxylic acid by ozonation alkenes in monocarboxylic solution acids and / or alcohols C 1 to C 6 s subsequent oxidative decomposition of the product ozonization and distillation separation a mixture of monocarboxylic acids; the solvent is recirculated in the process. The essence of the process of preparing alkanes monocarboxylic acids is that of ozonization and oxidative decomposition of the ozonation product run in scraped reactors film liquids that are connected in series. Gas moves countercurrently with respect to to the direction of fluid flow. The solution can be used to prepare alkanes monoicarboxylic acids applicable for the production of salts, in particular type soaps and for the manufacture of catalysts. Next up can be used to make esters as additives to plastics and for the production of ester lubricating oils and as a basic raw material in organic syntheses.

Description

The invention relates to a process for the preparation of alkanic monocarboxylic acids by ozonizing alkenes with subsequent oxidative decomposition of the ozonation product and rectifying the isolation of the product. Virtually all of the mono-carboxylic acids used to make their salts, such as soaps and catalysts, can be prepared as described above. The monocarboxylic acids are applied for the production of esters which can be used mainly as plastic additives as synthetic lubricating oils and as a basic raw material in organic syntheses.

A device for the continuous ozonization of alkene compounds, particularly higher alkenes, oleic acid, linoleic acid and others in the form of an aqueous emulsion or dispersion is described. The device is characterized in that in the flow direction of the reaction products, regular packed bodies and static mixing elementary mixing paths with a reduced hydraulic diameter (NSR Pat. 2,754,366) are formed.

Furthermore, ozonization of 1-alkenes containing from 8 to 30 carbon atoms in the molecule is protected by the action of ozone on an aqueous emulsion of a solution of the alkene starting material in an organic solvent followed by hydrolytic cleavage of the reaction product. The liquid and gaseous reactant is co-current contacted in the reactor to form a turbulently flowing liquid film. The gaseous reactant in the reactor is moved by a high turbulent zigzag flow over the liquid film or through the liquid film at a rate calculated on an empty tube of at least 2 m.s ^-1 at a residence time of at most 2 seconds. The reactor is filled with geometrically regular filling bodies with a surface area of more than 100 m ² . m ' ³ . The resulting heat of reaction is removed by evaporation of the water in situ. Preferably, tube bundle reactors (NSR Pat. 3,005,514) are applied.

The present invention provides a process for the preparation of alkanic monocarboxylic acids by ozonizing alkenes, followed by oxidative decomposition of the ozonation product and distillation of the reaction product. SUMMARY OF THE INVENTION The invention provides that the individual alkenes having from 3 to 40 carbon atoms per molecule or mixtures thereof at a concentration of 5 to 25% by weight are introduced after dissolution in a reactive solvent which is a single carboxylic acid having 1 to 6 carbon atoms per molecule or their mixtures, individual alcohols containing 1 to 6 carbon atoms in the molecule, or mixtures thereof, or mixtures of carboxylic acids and alcohols in contact with ozone in a wiped-off liquid film. The alkene solution in the reactive solvent is contacted with a mixture of ozone and oxygen or air having an ozone content of 1 to 12% by weight in the wiped-off film of the liquid. The molar ratio of ozone to alkene or alkene mixture is 0.95-1.5 at -60-60 ° C and 0.01-0.5 MPa. The ozonation product is subsequently contacted in a second reactor with a wiped-off liquid-oxygen film. The molar oxygen ratio calculated on the starting alkene or mixture of alkenes is 0.45 to 0.75. A temperature of 70 to 120 ° C is maintained in the liquid film. The pressure in the reactor is in the range of 0.01 to 0.5 MPa. The product withdrawn from the oxidative decomposition is fractured into the target product and reactively the solvent, which is returned to the process.

The raw materials for this process may be compounds containing 3 to 40 carbon atoms per molecule, such as chemical individuals, mixtures of positional and / or geometric isomers of alkenes with the same number of carbon atoms in the molecule, or mixtures of alkenes prepared for example by cracking alkanes, mixtures of lower alkene oligomers, mixtures of alkenes prepared by dehydrogenation of alkanes, as well as mixtures of alkenes prepared by pyrolysis of hydrocarbon fractions. Alkenes containing different functional groups in the molecule such as cyclanic, aromatic, halogens and the like can also be used.

The lower limit of the alkene concentration in the solvent set at 5% by weight is given by the economics of utilization of the apparatus, in some cases also by the solubility of the alkenes in the reactive solvent so as not to form two phases of the liquid. The upper limit of 25% by weight of alkenes in the reactive solvent is a condition that the reaction proceeds through the formation of ester hydroperoxides or alkoxyhydroperoxides, as opposed to the ozonation of the alkenes in the ozone-forming hydrocarbon solvents, with the possible subsequent formation of polymeric bile ozonide reducing products. At the same time, care must be taken not to create conditions for the formation of a greater quantity of explosive products, difficult to prevent their concentration at certain locations of the apparatus. The concentration of alkenes in the reactive solvent can be in the range of 5 to 25% by weight, preferably 10 to 20% by weight.

Either individual monocarboxylic acids containing 1 to 6 carbon atoms per molecule, or any mixtures thereof, either individual alcohols containing 1 to 6 carbon atoms per molecule, or any mixtures thereof, or any mixtures of alcohols and carboxylic acids may be used as reactive solvents. The choice of reactive solvent is dictated by its physical properties, such as pour point and boiling point, and its chemical reactivity.

The low freezing point of the reactive solvent allows the ozonation of alkenes at very low temperatures, which is important in the ozonation of 3 to 6 carbon atoms in the molecule.

The boiling point of the reactive solvent should preferably differ by at least 20 ° C from the boiling point of the fatty alkanoic acid, unless the target product is the same acid as the reactive solvent.

The solvent of the alkenes coming into contact with the ionone should be reactive. It is intended to prevent the formation of ozonide and to form thermally more stable ester hydroperoxides or alkoxyhydroparoxides.

The ozone used in the reaction is usually prepared at a concentration of 1 to 12% by weight in oxygen or air, preferably at a concentration of 2 to 8% by weight ozone in oxygen. This eliminates the formation of nitrogen oxides. The upper limit of the ozone concentration is conditioned by the economy of its preparation and by the operational reliability of ozonation with regard to the removal of reaction heat.

The reaction enthalpy of the alkene ozonization is about 419 kj.mol ^-1 . The oxygen or air used for the preparation of ozone must be free of foreign matter. The moisture content has a negative effect on the process economy.

The molar ratio of ozone to alkene feedstock may range from 0.95 to 1.5, preferably 1.05 to 1.2. A certain excess of ozone is supposed to compensate for recombination to oxygen, the ozone coating requirement for side reactions.

The temperature in the wiped-off film of the liquid is dependent on the immole weight of the alkane feedstock and the type of reactive solvent used. It can vary from -60 to +60 ° C. The upper temperature limit of the ozonator must be below the decomposition temperature of the ozonation product.

The pressure in the wiped-off ozonization reactor depends on the molar mass of the reactive solvent, the molar mass of acetic acid, the temperature in the ozonation reactor and the strength of the glass parts of the ozonator. Its value ranges from 0.01 to 0.5 MPa.

Perfect contact of the gas and liquid phases has a significant influence on the quality of ozone utilization.

The molar oxygen ratio, calculated with respect to the alkenes entering the ozonization reactor, in the second wiped-off oxidation reactor should be in the range of 0.45 to 0.75.

The temperature in the second oxidation reactor may be in the range of 70 to 120 ° C, preferably 80 to 90 ° C.

The total pressure in the second oxidation reactor depends on the boiling point of the reactive solvent, the molar mass of the acetic acid and the resistance of the reactor system. It can range from 0.01 to 0.5 MPa.

The actual reaction of the alkene with ozone takes place in a device which forms a thin wiped film of a liquid consisting of an alkene dissolved in a reactive solvent. The liquid film isa is formed by mechanically wiping the liquid coming into the upper part of the tempered cylinder, which, under the influence of gravity, spirals downwards, contacting with ozone present in oxygen or air flowing in a co-current or better countercurrent in the gap between two cylindrical surfaces. The lower temperature limit at which the reaction of ozone with alkenes takes place is ensured by tempering the cylinder on which the liquid film is formed by wiping. It is given by the freezing point of the reaction mixture and the economic aspects.

In the next stage of the process, the alkene ozonation product is contacted in the reactor with a scraped liquid-oxygen film or part of the off-gas from the ozonization process. The off-gas is divided into the fraction returned after treatment to the ozone generator and the fraction intended for the oxidative cleavage of the ozone product of the alkenes to monocarboxylic acids and aldehydes which are oxidized by oxygen to the monocarboxylic acids.

The small amount of ozone present in oxygen supports the process of oxidation of aldehydes to monocarboxylic acids. A small excess of oxygen accelerates the reaction of oxidation of aldehydes to monocarboxylic acids.

The thermal coloring of the oxidative decomposition of the alkene ozone product in a carboxylic acid solution consists of two components, namely the decomposition of the alkene ozone product, ester hydroperoxides, to monocarboxylic acids and aldehydes, and the oxidation of aldehydes to monocarboxylic acids.

The lower limit of the temperature of the oxidative decomposition is given by the rate of the course of the two mentioned reactions, namely the decomposition of the product of the ozonation of alkenes and the oxidation of aldehydes to monocarboxylic acids. At temperatures below 50 ^b C, the reactions are very slow. At temperatures above 120 ° C, oxidation of the methylene groups in the hydrocarbon chains is already possible. The optimum temperature is 75 ° C. The pressure in the second reactor is practically identical to the pressure in the Ozonization reactor.

With regard to the composition of the final reaction product and the reactive solvent used, it is necessary to choose the method of separating the final reaction product into the target products and the recirculating solvent. Treatment of the 1-alkenes as the starting material yields methanoic acid, which is separated from the reaction mixture by simple distillation as a result of the favorable difference in boiling points relative to the solvent.

In other cases, for the separation of monocarboxylic acids into chemical individuals, the system and rectification columns are required. In most cases, these columns operate at reduced pressure. If higher alkene feedstocks are used, it is necessary to use short-path distillation under ex249234 of theatrically reduced pressure to isolate the product or to obtain the product as a distillation residue without further treatment.

The main advantage of the process according to the invention is that a small amount of raw material is involved in the reaction in the exposed sections. There is no possibility of explosion of the intermediates or their concentration in places with a reduced flow rate of the liquid reactant. The temperature in the films formed is very well controlled and kept within a very narrow range. There is no local overheating of the reaction mixture.

The liquid phase turbulence is intense as a result of the continuous mixing and spreading of the film. By suitable design of the wiper device elements it is also possible to achieve a good mixing of the supplied gas-containing zone. This also avoids the formation of aerosols which increase the possibility of explosive mixtures and the loss of products.

In this process, the addition of water to remove the heat of reaction is not required, as described in the cited procedures. This eliminates the complex dosing of the emulsion, reduces the corrosion problems of the device, simplifies the problems of product separation by rectification. No need to supply evaporative heat for water. The devices are not loaded with large volumes of water, steam.

The process of the invention achieves complete conversion of the alkenes. The ozone conversion is close to 100%. The selectivity of the formation of monocarboxylic acids exceeds a high value of 90%. Any impurities present in the alkene feedstock such as dienes and aromatics are decomposed by ozone.

By way of illustration, examples are provided but are not intended to limit the scope of the invention. Example 1

A mixture of 15 parts by weight of 1-dodecene and 85 parts by weight of butanoic acid is cooled to 0 [deg.] C. and fed continuously to the top of the wiped-bed reactor in an amount of 18 kg of 1-dodecene. nr ² . h ^-1 . The pressure in the reactor is maintained at 1 bar. A mixture of 3% by weight of ozone in oxygen in the amount corresponding to 1.05 mole of ozone per mole of 1-dodecene is fed countercurrently. The reaction mixture withdrawn from the ozonation reactor is continuously pumped into the upper part of the liquid-wiped oxidation reactor, where it is countercurrently contacted with oxygen in an amount of 0.75 moles of oxygen per mole of 1-dodecene fed to the ozonization reactor. The temperature in the liquid film is maintained at 85 ° C.

The reaction mixture withdrawn from the bottom of the oxidation reactor is pumped to the rectification column, where it is rectified into methane, butanoic acid and decanoic acid. it is preferred to work by withdrawing a mixture of methanoic acid and butanoic acid at the top of the rectification column and undecanoic acid at the bottom of the column. The mixture of methanoic acid and butanoic acid is separated in the second rectifying k-olone and the hulic acid is returned to the process. The product obtained is methanoic acid and undecanoic acid of a purity of 95.1% by weight in water

-Extract 94 ° / o theory.

Example 2

The procedure is the same as in Example 1, except that a mixture of ethylene oligomers containing from 12 to 18 carbon atoms per molecule having the following composition is used as the starting material:

1-dodecene 16.8% by weight,

1-tetradecene 31.5%, 1-hexadecene 33.2% and 1-octadecene 18.5%.

parts by weight of said feedstock and 85 parts by weight of butanoic acid at 20 ° C are fed continuously to the top of the wiped-bed reactor in an amount of 15 kg of feedstock. m * ² .

. h ^_1 . The pressure in the reactor was maintained at 0.2 MPa. A mixture of 5% by weight of ozone in oxygen in an amount corresponding to 1.1 moles of ozone per mole of alkene is fed countercurrently.

The reaction mixture is oxidatively decomposed with 0.6 moles of oxygen, calculated on a mole of the starting alkene, maintaining the temperature at 90 ° C.

Subsequently, methanoic acid and butanoic acid are distilled off from the reaction mixture.

The mixture of monocarboxylic acids remaining in the residue is separated by n-and two portions. A mixture of monocarboxylic acids containing 11 and 13 carbon atoms per molecule is withdrawn at the top of the k-olons, and a mixture of monocarboxylic acids containing 15 and 17 carbon atoms per molecule is withdrawn at the bottom.

A mixture of monocarboxylic acids produced in an amount of 16.3 kg. br ¹ has the following composition:

undecanoic acid 17.1 wt.%, tridecanoic acid 31.7 wt.%, pentadecanoic acid 33.0 wt. and heptadecanoic acid 18.2 wt.

The mixture of undecanoic acid and iridecanoic acid obtained is 7.9 kg. Ir ¹ has the following composition:

% wt. % undecanoic acid and 65 wt. tridecanoic acid.

The mixture of pentadecanoic acid and betadecanoic acid was formed in an amount of 8.3 kg.

. h ^_1 has the following composition:

% wt. % pentadecanoic acid and 36 wt. heptadecanoic acid.

The yield of these monocarboxylic acids is close to theoretical.

Example 3

120 parts by weight of the positional and geometric isomers of dodecene, obtained by catalytic dehydrogenation of n-dodecane, comprising:

4.8 wt. 1-dodecene,

19.2% wt. 2-dodecene,

19.2 ° / o 3-dodecene,

23.0% wt. 4-dodecene,

22.2% wt. 5-dodecene a

11.6% wt. 6-Dodecene is mixed with 80 wt. pentanoic acid. The mixture was cooled to -10 ^Q C and pumped at a rate of 20 kg dodecene. m ~ ² . h ^-1 into the upper part of the first liquid-stripped reactor. A temperature of -10 ° C was maintained in the wiped film. Oxygen containing 5 wt.% Is countercurrently fed to the bottom of the reactor. of 1.1 mole of ozone per mole of dodecene.

The reaction mixture withdrawn from the bottom of the ozonation reactor is pumped to the top of the second wiped-off oxidation reactor. A temperature of 85 ° C is maintained in the liquid film. At the bottom of the oxidation reactor, oxygen from the ozonization reactor is fed countercurrently in an amount of 0.75 moles of oxygen per mole of dodecenes fed to the ozonization reactor. A mixture of monocarboxylic acids containing 1 to 11 carbon atoms per molecule is recovered from the bottom of the oxidation reactor in a yield of 93% of theory.

The composition of the monocarboxylic acids obtained is as follows:

0.9 wt. methanoic acid,

4.9 wt. ethanoic acid,

6.1% wt. propanoic acid,

8.7% wt. butanoic acid,

9.7% hmpt. pentanoic acid (without pentanoic acid used as reactive solvent in the process),

11.6% rumble, hexanoic acid,

12.4 wt. heptanoic acid,

14.2% wt. octanoic acid,

13.0 wt. nonanoic acid,

14.2 wt. decanoic acid and

3.8% w / w undecanoic acid.

The rest of the holi unidentified impurities. Example 4

A mixture of 5 parts by weight of propene and 95 parts by weight of methanol cooled to -55 ° C is fed continuously to the top of the stripped-bed reactor at a rate of 10 kg of propene. m ^-2 . h ^-1 . The reactor pressure was maintained at 1 bar. A mixture of 1% by weight of ozone in air in a quantity corresponding to 1.15 moles of ozone per mole of propene is fed countercurrently.

The reaction mixture is oxidatively decomposed with 0.75 moles of oxygen, calculated per mole of propene at 0.5 MPa and at 120 ° C. Oxidative decomposition takes place in the wiped-off liquid film.

The resulting ethanoic acid and metanoic acid are isolated after liberation from the esters via sodium salts decomposed with hydrochloric acid and rectified. The yield of methanoic acid is 80% of theory and the yield of ethanoic acid is 89% of theory, with a purity of 97.1% by weight.

Example 5

A mixture of 25 parts by weight of ethylene oligomers having an average carbon number of 38.1 and 75 parts by weight of 1-hexanol heated to 60 DEG C. is fed continuously to the top of the wiped film reactor at 25 kg of ethylene oligomers. m ^-2 . h ^-1 . The reactor pressure is maintained at 0.2 MPa. A mixture of 10.1% by weight of ozone in oxygen in an amount corresponding to 1.5 moles of ozone per mole of ethylene oligomers is fed countercurrently.

The reaction mixture is oxidatively decomposed with 0.55 moles of oxygen, calculated per mole of ethylene oligomers, maintaining the temperature at 75 ° C in a wiped-off liquid film.

After distillation of methanoic acid and 1-hexanole, a pasty consistency was obtained, representing a mixture of the higher aliphatic acids in a yield of 97% of theory and showing an acid number of 98.1 mg KOH / g.

Claims (1)

A process for the preparation of alkanic monocarboxylic acids by ozonation of alkenes, subsequent oxidative decomposition of the ozonation product and distillation of the reaction product, characterized in that the individual alkenes containing 3 to 40 carbon atoms in the molecule or mixtures thereof are introduced after dissolution in a reactive solvent which is a single carboxylic acid. acids containing 1 to 6 carbon atoms per molecule, or mixtures thereof, individual alcohols containing 1 to 6 carbon atoms per molecule, or mixtures thereof, or mixtures of carboxylic acids and alcohols, to a solution containing 5 to 25% by weight alkenes, in contact with the ozone mixture and OF THE INVENTION of oxygen or air having an ozone content of 1 to 12% by weight in a wiped film of a liquid, wherein the molar ratio of ozone to alkene or alkene mixture is 0.95 to 1.5 at -60 to -60 ° C at 0, The ozonation product is then contacted in a second reactor with a spiked liquid-oxygen film, at a mole ratio of oxygen to the starting alkene or mixture of alkenes of 0.45 to 0.75, and maintaining a temperature of 70-70 in the liquid film. 120 ° C, a pressure of 0.01 to 0.5 MPa, and the product withdrawn from the oxidative decomposition is fractured to the target product and reactive solvent, which is returned to the process.