JP5249033B2 - Process for producing amides by heterogeneous oximation and rearrangement - Google Patents

Description

The present invention relates to a method for producing an amide, and more particularly, to a method for producing an amide from a ketone as a raw material by heterogeneous ammonia oximation and heterogeneous Beckmann rearrangement.

Amides are compounds in which the hydroxy group in the carboxylic acid is substituted with an amino group or an amine, and examples thereof include ammonia, acyl derivatives of primary amines, and secondary amines. Amides having a large number of carbons and represented by the molecular formula RCONH ₂ are in a crystalline state at room temperature, have good water solubility, and are excellent raw materials for solvents and polymers. In general, amide formation includes methods such as acylation of amine, dehydration condensation of carboxylic acid and amine, hydrolysis of nitrile, and rearrangement of ketoxime.

A ketoxime is produced by a condensation reaction between an aliphatic ketone or an aromatic ketone and an ammonia derivative such as hydroxyamine. Using an oxidizing substance such as high-concentration sulfuric acid or phosphorus pentachloride as a catalyst, the hydroxy group on the nitrogen in the oxime molecule is released, and one of the two alkyl groups substituted for carbon is rearranged to form an amide. Is generated. Such a reaction is a Beckmann rearrangement reaction.

A series of amides can be synthesized by synthesizing a ketoxime with a ketone and applying the Beckmann rearrangement reaction. Aliphatic amides never have wide industrial applications, but it is industrially important to produce caprolactam by rearrangement of cyclohexanone oxime.

The scientific name for caprolactam is ε-caprolactam, which is an important petrochemical product, and is widely applied to nylon and engineering plastics. Methods for industrial production of caprolactam include the cyclohexanone-hydroxylamine method, the photonitration method of cyclohexane and the phenylmethane method. Of the two methods, phenylmethane is used as a raw material, and hydrogen is added to phenylmethane to produce cyclohexane, which is further oxidized to produce cyclohexanone, which then undergoes an oximation reaction between cyclohexanone and hydroxylamine. Cyclohexanone oxime was produced and caprolactam product was obtained through rearrangement and purification process. Due to the process differences of the hydroxylamine produced, the process flow of cyclohexanone-hydroxylamine mainly includes the hydroxylamine sulfate method (HSO method), the nitric oxide reduction method (NO method) and the hydroxylamine phosphate method (HPO method). ) There are three methods.

All of the above-mentioned three kinds of synthesis methods are equipped with industrialization equipment, but the usage ratio of the HSO method and NO method is low, and the process of producing hydroxylamine by the HSO method is complicated and greatly affects the environment. The NO method uses pure oxygen and requires strict process control. The most important problem is that these two methods generate low commercial ammonium sulfate as a by-product and are influenced by the market acceptance capacity. It is that you are. The HPO method has a problem that ammonium sulfate is not produced as a by-product due to the circulation of the inorganic process liquid, industrial wastewater is not discharged, and the process is more rational, but requires very precise control.

The process of cyclohexanone ammonia oximation is catalyzed by titanium silicon molecular sieve, and cyclohexanone is directly synthesized with ammonia and hydrogen peroxide solution to obtain cyclohexanone oxime, which has a short process flow and synthesizes complex hydroxylamine. The process and the production of SOx or NOx are avoided, and ammonia sulfate is not a by-product, which is environmentally friendly. Patent Document EP0208311 discloses a process of cyclohexanone ammonia oximation using titanium silicon molecular sieve as a catalyst. Patent documents EP 0 396 385 and EP 0561040 disclose improving the conversion and yield of the reaction by a two-stage or multi-stage ammonia oximation process. In order to solve problems such as catalyst separation and efficiency in the process of ammonia oximation, Patent Documents CN02100227 and CN02100228 disclose a method for continuous precipitation separation of products of ammonia oximation and catalyst, and peroxidation by cyclic use of the catalyst. The utilization rate of hydrogen water was improved.

In order to reduce the production costs of hydrogen peroxide and oximes, patent documents EP0690045 and US Pat. No. 5,599,987 disclose a process that combines the oxidation of isopropyl alcohol and the ammonia oximation of cyclohexanone. At this time, titanium silicon molecular sieve is used as catalyst, tertiary butanol as solvent, hydrogen peroxide, ammonia solution and cyclohexanone are used for ammonia oximation reaction, and the resulting cyclohexanone is extracted, purified, solvent and excess ammonia. Was recycled by distillation and separation.

The ammonia oximation technology has a common feature, and in the reaction process, a hydrophilic lower alcohol (eg, tertiary butanol) should be added as a solvent, improving the solubility of the product in the reaction system, Became easier to do. However, the above-mentioned solvent cannot be stably present in the fuming sulfuric acid system and has several disadvantages because it undergoes several separation processes such as distillation and extraction before the rearrangement reaction.

(1) The process flow is complicated and energy consumption is large.
(2) Since both distillation and extraction are performed at a high temperature, the stability of the oxime solution is relatively poor, and a trace amount of impurities is generated in the subsequent rearrangement reaction, which makes the purification process difficult.
(3) The substance to be supplied to the subsequent rearrangement reaction is a molten oxime, which requires heat retention and tracing of the pipe passage during production, is easily clogged, and is inconvenient for opening / closing of the switch and production operation.

On the other hand, fuming sulfuric acid is consumed in the process of the Beckmann rearrangement reaction of cyclohexanone oxime, and the by-product ammonium sulfate is a low commercial value product. U.S. Pat. Nos. 4,804,754 and 5,264,571 disclose higher order rearrangement reaction techniques that react fuming acid with most oximes under conditions of low temperature and high acid content oxime, and viscosity under low temperature. Was kept so low that side reactions were suppressed. Subsequent is slightly higher than the previous primary reaction temperature, and also reacts with a small portion of oxime under conditions of low acid content oxime molar ratio, ensuring complete reaction, reducing acid consumption, low sulfuric acid consumption and Meet the demand for high quality products.

US Patents US3991047 and US4081442 adopt a metathesis method of ammonium salt to avoid consumption of sulfuric acid and by-product ammonium sulfate, and pH value of reaction when neutralizing the product of rearrangement reaction with ammonia solution It was disclosed that ammonia hydrogen sulfate and caprolactam can be obtained. Caprolactam is separated by extraction. In addition, ammonia hydrogen sulfate produces sulfur dioxide, ammonia liquid and water by a thermal decomposition reaction, and sulfur dioxide is again produced in sulfuric acid for recycling. US Pat. No. 3,912,721 is provided with a sulfuric acid circulation method, which is not neutralized with ammonia, diluted to a 50% aqueous solution, extracted with alkylated phenol, extracted with caprolactam, and washed with alkaline solution to remove residual sulfuric acid; The extraction rate of caprolactam is 99.5% or more. A sulfuric acid aqueous solution containing organic impurities generates sulfur dioxide by concentration and thermal decomposition, and after being subjected to a dehydration catalytic reaction, it is used again to produce fuming sulfuric acid.

However, the current method of reducing sulfuric acid consumption and by-products from the viewpoint of reaction and separation has the following problems.
(1) The reduction width of the by-product of the higher order rearrangement reaction is small, and the viscosity of the substance is large under conditions of low acid amount and low temperature, which is disadvantageous for mass transfer and reaction.
(2) The energy consumption of the metathesis method of ammonium salt and the sulfuric acid circulation process is large and the cost is high, which is uneconomical.

The object of the present invention is to focus on the problems of the prior art, the process is simpler, less prone to clogging in the production process, improve the quality of the reaction, reduce the consumption of sulfuric acid, and the amide with less by-product ammonium sulfate. It is to provide a method of producing.

The object of the present invention can be achieved by the following method. The presence of a solvent exhibiting inactive at fuming sulfuric acid, ketone, perform heterogeneous oximes reaction under the action of catalyst using hydrogen peroxide and ammonia, to produce a ketoxime. The aqueous layer product of oximation reaction, and extracted with a similar inert solvent and the inert solvent used in the oximation reaction, after mixing the extract layers in the organic layer the product of oximation reaction, ketoxime An inert solvent solution is obtained, and the solution undergoes a heterogeneous Beckmann rearrangement reaction under the action of fuming sulfuric acid to produce an amide.

The inert solvent is paraffin hydrocarbon, cycloparaffin, or a mixture thereof.

The ketone is an aliphatic ketone, a cyclic aliphatic ketone, or an aromatic ketone. Moreover, it is preferable that carbon number is 3-10.

Under the presence of the titanium silicon molecular sieve, cyclohexanone, hydrogen peroxide solution and ammonia as raw materials, paraffin hydrocarbon or cycloparaffin, which is a substance that becomes inactive in fuming sulfuric acid system, or a mixture thereof as an inert solvent, Cyclohexanone oxime is produced by heterogeneous catalysis. The product is extracted with an inert solvent, then subjected to a Beckmann rearrangement reaction under the action of fuming sulfuric acid containing a certain amount of free radical SO _3, and after a certain period of time, it is hydrolyzed to form a light layer and a multilayer. Generated. The light layer is an inert solvent, and the multilayer is a solution of caprolactam and sulfuric acid. The multilayer is neutralized with ammonia or an ammonia solution, and ammonium sulfate is recrystallized to obtain caprolactam.

The light inert solvent can be circulated until the oximation reaction.

The inert solvent is selected from paraffin hydrocarbons having 4 to 8 carbon atoms, cycloparaffins, or mixtures thereof.

In the oximation process provided by the present invention, a bilayer product is obtained, the light layer is the solvent, the overlay is water, and the cyclohexanone oxime is distributed in both layers at a constant rate. However, since the rearrangement reaction process should be conducted in an anhydrous system, the cyclohexanone oxime in the aqueous layer should be further separated. The simplest and most effective method is to extract the aqueous layer with an inert solvent of the reaction, and the resulting extracted layer has the same composition as the light layer of the oximation reaction and can be mixed. The concentration of the mixed cyclohexanone oxime solution is preferably 5% to 80% by weight, more preferably 10 to 20%. This is determined by the type of solvent.

The present invention makes the following important improvements over the conventional process, and the inventor changed the concept, and the present invention employs a process integrating two heterogeneous reactions and is used for the Beckmann rearrangement reaction. The solvent is the same as the solvent for the oximation reaction. Since the solvent can exist stably in the rearrangement reaction system containing fuming sulfuric acid and does not perform any reaction itself, the product of oximation needs to be purified by pure separation methods such as distillation and extraction. Absent.

Industrially, even if all the rearrangement reactions of cyclohexanone oxime are carried out in fuming sulfuric acid, the method provided by the present invention mainly has the following differences.

(1) Cyclohexanone oxime is dissolved in an inert solvent and supplied in a solution system.
(2) In the course of the rearrangement reaction, all of the solvent can be recovered by vaporization and condensation, or partially evaporated, and after the reaction, the solvent and the condensate obtained by hydrolysis are recovered together.
(3) The recovered solvent can be circulated until the ammonia oximation reaction.

The combined process of heterogeneous ammonia oximation and solvent rearrangement provided in the present invention is a significant improvement over conventional processes, resulting in simplification and significant cost savings and better economics. Offered value. Specifically, it is the following method.

(1) In the ammonia oximation process using a low carbon alcohol as a solvent, the steps such as distillation of the required alcohol, extraction of phenylmethane and distillation of phenylmethane are omitted, and the process is simple and convenient for operation. .
(2) The cyclohexanone oxime obtained from the ammonia oximation reaction is supplied to the subsequent rearrangement reaction not in the melt mode but in the solution mode, overcoming the drawbacks of clogging of conventional processes, and at the same time further increasing the temperature of the Beckmann rearrangement reaction. It is possible to decrease.
(3) In the solvent rearrangement reaction, problems such as the effect of mass transfer accompanying the increase in material viscosity at low temperature and low acid content are solved, improving the quality of the reaction, and further consuming and substituting sulfuric acid. Product can be reduced.

In the heterogeneous reaction process provided by the present invention, a high conversion rate and a high yield can be obtained within the scope of the following process.

The inert solvent and the raw material ketone are added all at once.

The hydrogen peroxide solution and the ammonia solution are each gradually dropped or mixed and dropped, and the dropping time is preferably 10 minutes to 5 hours, more preferably 30 minutes to 2 hours. After the addition of the raw materials is completed, the reaction is stopped, or the reaction is stopped after extending for 10 minutes to 2 hours.

The molar ratio of the hydrogen peroxide solution and cyclohexanone is preferably 1.0 to 5.0, and more preferably 1.0 to 1.2. The molar ratio of ammonia to ketone is 0.5-10.

In the oximation reaction, the concentration of the inert solvent is 20 to 80% by weight, and the temperature of the oximation reaction is preferably 10 to 120 ° C, more preferably 60 to 80 ° C.

In the process of the heterogeneous rearrangement reaction, the molar ratio of fuming sulfuric acid to cyclohexanone oxime (SO3 in fuming sulfuric acid converted to sulfuric acid) is preferably 0.5 to 4.0, and preferably 1.0 to 1.3. More preferred. This is lower than the ratio of conventional industrial production and reduces the amount of corresponding by-products. The concentration of free radical SO3 in the fuming sulfuric acid used is preferably 2% to 65%, more preferably 5% to 20%. This is adjusted by changing the total acid amount.

The temperature of the rearrangement reaction is preferably 30 to 150 ° C, more preferably 60 to 80 ° C. This is determined by the type of solvent and the operating pressure. The reaction residence time is preferably 1 minute to 2 hours, more preferably 10 to 30 minutes.

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

(Example 1) 45.0 g of hexane, 15.2 g of butanone, and 1.5 g of titanium silicon molecular sieve were previously added to a 250 ml glass reaction kettle with a magnetic stirrer, and mixed well, and then heated to 65 ° C. Then, 28.0 g of 27.5 wt% aqueous hydrogen peroxide and 30.0 g of 25 wt% ammonia solution were gradually added dropwise. The solution was added dropwise at a constant rate over 2.5 hours, and reacted continuously for 1 hour. In the reaction process, the temperature was controlled at 65 ° C. while stirring. After separating the multiple layers by cooling and standing, 45.0 g of hexane was used and extracted in three portions. The extracted layer was mixed with the light layer produced by the reaction, and 105.6 g of a solution of butanone oxime and hexane was obtained. Obtained. As a result of analysis by gas chromatography, the mass concentration was 16.8%, the conversion of butanone was 99.5%, and the selectivity for butanone oxime was 97.1%. In another 250 ml reaction kettle, 15.8 g of fuming sulfuric acid having a SO3 concentration of 5% was added and the butanone oxime solution was gradually added dropwise. The reaction temperature was 68 ° C., and all the evaporated hexane was condensed and refluxed, and the total reaction time was 30 minutes. As a result of carrying out hydrolysis, neutralizing the aqueous layer and analyzing by liquid chromatography, it was 17.6 g of N-methylpropionamide, and the yield of rearrangement was 99.2%.

(Example 2) A catalyst of cyclohexane, cyclohexanone and titanium silicon molecular sieve was added in advance into a glass reaction vessel with a magnetic stirrer of 250 ml, and the cyclohexane dose was cyclohexane: cyclohexanone = 3.0: 1 (molar ratio, below) The weight percentage of titanium silicon molecular sieve is 2.2%. When the temperature was raised to 70 to 71 ° C., a hydrogen peroxide solution and an ammonia solution were dropped, and an oximation reaction was performed. The total amount of the hydrogen peroxide solution and ammonia was hydrogen peroxide solution: ammonia: cyclohexanone = 1.1: 1.9: 1. The dropping time was 2 hours, and the reaction was continued for 1.1 hours after the dropping. In the reaction process, the temperature was controlled at 71 ° C. with stirring. The aqueous layer product produced by the reaction was extracted in three portions using the same amount of cyclohexane as the reaction, and the extracted layer was mixed with the organic layer product produced by the reaction to obtain a cyclohexane solution of cyclohexanone oxime. . The cyclohexanone and cyclohexanone oxime contents were analyzed by gas chromatography, and the conversion and selectivity were calculated. The conversion of cyclohexanone was 99.4% and the selectivity for cyclohexanone oxime was 98.3%.

(Comparative Example 2) The same reaction as in Example 2 was performed except that the solvent was tertiary butanol. Since the alcohol and water are dissolved in layers, the extraction process of Example 2 is not required, and the product was directly analyzed by gas chromatography. As a result, the conversion of cyclohexanone was 98.9%, and cyclohexanone oxime The selectivity of was 98.2%.

(Example 3) 39.2 g of cyclohexane, 15.1 g of cyclohexanone, and 3.8 g of titanium silicon molecular sieve catalyst were previously added to a 250 ml glass reaction kettle. Using 23.5 g of hydrogen peroxide water and 33.2 g of ammonia solution each having a concentration of 27.5% by weight, it was added dropwise to the reaction kettle at a constant speed, and the raw material charging time was 2.1 hours. Adopting temperature control by magnetic stirring and oil bath, the reaction was carried out at a reaction temperature of about 72 ° C. under normal pressure. After completion of the raw material input, the reaction was continued for 1 hour, cooled and allowed to stand, 55.1 g of the light layer was separated, 39.0 g of cyclohexane was divided into three equal parts, the multi-layer was extracted, and the extracted layer was turned into a light layer By mixing, 95.3 g of cyclohexanone oxime solution was obtained. In another 250 ml reaction kettle, 15.8 g of fuming sulfuric acid having a SO3 concentration of 8% was added, and the cyclohexanone oxime solution was gradually added dropwise. The temperature was controlled at 80 ° C. by an oil bath under normal pressure, and the vaporized cyclohexane was partially condensed and refluxed by mechanical stirring. The total reaction time at this time was 20 minutes. After stopping the reaction, 6.0 g of water was added dropwise in an ice water bath to conduct a hydrolysis reaction, and the temperature was controlled not to exceed 30 ° C. The aqueous layer was neutralized and analyzed by liquid chromatography. As a result, it was 16.9 g of caprolactam, the yield of rearrangement was 98.8%, and the converted molar ratio of sulfuric acid to caprolactam was 1.10. .

(Comparative Example 3) An oximation reaction was carried out in the same manner as in Example 3 except that the solvent was tertiary butanol. The resulting oxime / tertiary butanol / water solution contained 15.8% cyclohexanone oxime, 35.5% tertiary butanol, and 46.5% water, and removed the tertiary butanol by distillation. The aqueous solution was extracted three times with 51.0 g of phenylmethane, and the extracted layer again removed phenylmethane by distillation to obtain 17.1 g of pure oxime. In another 250 ml reaction kettle, 20.9 g of fuming sulfuric acid having a SO ₃ concentration of 20% was added, and the molten cyclohexanone oxime was gradually added dropwise. The temperature was controlled at 120 ° C. by an oil bath, and the total reaction time was 20 minutes with mechanical stirring. The processes such as hydrolysis and neutralization were the same as in Example 3. As a result of analysis by liquid chromatography, caprolactam was 16.8 g, the rearrangement yield was 98.5%, and the converted molar ratio of sulfuric acid and caprolactam. The ratio was 1.50.

(Example 4) The steps of oximation and rearrangement were performed in the same manner as in Example 3 except that the solvent was normal heptane. The corresponding reaction temperature was 98 ° C. As a result of the oximation reaction, the conversion of cyclohexanone is 99.8%, the selectivity of cyclohexanone oxime is 97.3%, and the yield of rearrangement is 99.0%.

Claims (13)

Heterogeneous oximes under the action of catalysts using ketones, hydrogen peroxide and ammonia in the presence of solvents which are inert in fuming sulfuric acid systems selected from paraffin hydrocarbons, or cycloparaffins, or mixtures thereof Performing a chelating reaction to produce ketoxime;
The aqueous layer product of the oximation reaction is extracted with an inert solvent similar to the inert solvent used during the oximation reaction, and the extracted layer is mixed with the organic layer product of the oximation reaction before the ketoxime reaction. A solution of an inert solvent is obtained, and the solution undergoes a heterogeneous Beckmann rearrangement reaction under the action of fuming sulfuric acid to produce an amide;
To produce amides by heterogeneous oximation and rearrangement. The ketone is an aliphatic ketone, a cyclic aliphatic ketone, or an aromatic ketone.
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 1. In the presence of titanium silicon molecular sieve, heterogeneous using cyclohexanone, hydrogen peroxide solution and ammonia as raw materials, paraffin hydrocarbons or cycloparaffins which are inactive in fuming sulfuric acid system, or mixtures thereof as inert solvent Producing cyclohexanone oxime by a catalytic reaction,
The product is extracted with an inert solvent, then subjected to Beckmann rearrangement under the action of fuming sulfuric acid containing a certain amount of free radical SO ₃ , hydrolyzed after a certain period of time, and a light layer and a multilayer are separated. Generating,
The light layer is an inert solvent, the multilayer is a solution of caprolactam and sulfuric acid, neutralizes the multilayer with ammonia or ammonia solution, and ammonium sulfate is crystallized to obtain caprolactam.
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 1. The inert solvent in the light layer circulates until the oximation reaction,
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 3 . The inert solvent is selected from paraffin hydrocarbons having 4 to 8 carbon atoms, or cycloparaffins, or a mixture thereof.
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 3 . In the oximation reaction, the concentration of the inert solvent is 20 to 80% by weight, the molar ratio of aqueous hydrogen peroxide to cyclohexanone is 1.0 to 5.0, and the molar ratio of ammonia to ketone is 0.5. -10
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 3 . The temperature of the oximation reaction is 10 to 120 ° C.
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 3 . The molar ratio of the hydrogen peroxide solution and cyclohexanone is 1.0 to 1.2, and the temperature of the oximation reaction is 60 to 80 ° C.
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 3 . The inert solvent and cyclohexanone are added all at once, and the hydrogen peroxide solution and the ammonia solution are gradually dropped or mixed and dropped, and the dropping time is 10 minutes to 5 hours. After stopping the reaction, or after extending for 10 minutes to 2 hours,
A method for producing an amide by heterogeneous oximation and rearrangement according to any one of claims 3-7 . In the rearrangement reaction, the molar ratio of fuming sulfuric acid to cyclohexanone oxime is 0.5 to 4.0, and SO _{3 in} fuming sulfuric acid is converted to sulfuric acid, and free radical SO ₃ in the fuming sulfuric acid used. The concentration of is 2% to 65%,
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 3 . In the rearrangement reaction, the molar ratio of fuming sulfuric acid to cyclohexanone oxime is 1.0 to 1.3, and SO _{3 in} fuming sulfuric acid is converted to sulfuric acid, and free radical SO ₃ in the fuming sulfuric acid used. The concentration of is 5% to 20%,
11. A process for producing an amide by heterogeneous oximation and rearrangement according to claim 10 . The temperature of the rearrangement reaction is 30 to 150 ° C., and the reaction residence time is 1 minute to 2 hours.
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 3 . The temperature of the rearrangement reaction is 60 to 80 ° C., and the reaction residence time is 10 to 30 minutes.
A process for producing an amide by heterogeneous oximation and rearrangement according to claim 12 .