WO2007033582A1

WO2007033582A1 - A method for preparing amides by heterogeneous oximation and rearrangement

Info

Publication number: WO2007033582A1
Application number: PCT/CN2006/002434
Authority: WO
Inventors: Hean Luo; Jian Wu; Guoqing Liu; Yaling Zhu
Original assignee: Xiangtan University
Priority date: 2005-09-23
Filing date: 2006-09-18
Publication date: 2007-03-29
Also published as: JP5249033B2; CN100386307C; JP2009508884A; CN1762985A

Abstract

Disclosed is a method for preparing amides from aliphatic and/or alicyclic ketones as raw materials by heterogeneous oximation and rearrangement, which comprises steps of catalytically reacting ketones, hydrogen peroxide and ammonia in the presence of a inert solvent to obtain a solution of ketoxime, carrying out Beckmann rearrangement of the resultant in oily phase by use of oleum, hydrolyzing and neutralizing the product to obtain the desired amides.

Description

Method for preparing amide by heterogeneous deuteration rearrangement

Technical field

The present invention relates to a process for the preparation of an amide, which further describes the preparation of an amide by heterogeneous ammoximation and heterogeneous Beckmann rearrangement using a ketone as a starting material. Background technique

An amide is a compound of a carboxylic acid molecule in which a hydroxyl group is replaced by an amino group or an amine group, and can also be regarded as an acyl derivative of ammonia, a primary amine or a secondary amine. Most of the amides having the formula RCONH2 are crystalline at room temperature, have good water solubility, and are excellent solvents and polymer raw materials. The preparation of the amide usually has a method of amine acylation, dehydration of the ammonium carboxylate salt, partial hydrolysis of the nitrile, and rearrangement of the ketoxime. Both aliphatic ketones and aromatic ketones can be condensed with derivatives of ammonia such as hydroxylamine to form the corresponding ketoxime. The acidic substance such as concentrated sulfuric acid or phosphorus pentachloride is used as a catalyst, and the hydroxyl group on the nitrogen atom in the molecule is exchanged with the group on the carbon atom on the opposite side of the double bond to form an amide. This type of reaction is a Beckmann rearrangement. A series of amides can be synthesized by ketone synthesis of ketone oxime and then Beckmann rearrangement. The use of aliphatic simple amides in industrial applications is not very extensive, but the rearrangement of cyclohexanone oxime to caprolactam has important industrial significance. Caprolactam, the scientific name ε-caprolactam, is an important petrochemical product widely used in the manufacture of nylon and engineering plastics. The industrial production methods of caprolactam mainly include cyclohexanone-hydroxylamine method, cyclohexamidine photonitrosation method and toluene method. The first two methods use benzene as raw material, hydrogenation of benzene to form cyclohexanone, oxidation to cyclohexanone, cyclohexanone and hydroxylamine to carry out deuteration reaction to obtain cyclohexanone oxime, followed by rearrangement and refining process. The finished caprolactam is obtained. Due to the different processes for preparing hydroxylamine, the cyclohexanone-hydroxylamine process route mainly includes hydroxylamine sulfate (HSO method), nitric oxide reduction method (NO method) and hydroxylamine phosphate method (HPO method). The above three synthetic methods all have industrialized devices, but the proportion of HSO method and NO method is small. The process of preparing hydroxylamine by HSO method is complicated and has a great influence on the environment; the NO method uses pure oxygen, which is demanding on the process and more The important issue is that both methods are by-product low-value ammonium sulfate and are subject to market acceptance. The HPO method does not produce ammonium sulfate by the circulation of the inorganic process liquid, and there is no waste water discharge, and the process is more reasonable, but there are also deficiencies in which the control requirements are very fine. The cyclohexanone ammoximation process uses titanium silicalite as a catalyst, and cyclohexanone is directly synthesized with ammonia and hydrogen peroxide to obtain cyclohexanone oxime. The process is short, avoiding complicated hydroxylamine synthesis process and SOx. Or the production of NOx, and not by-produced ammonium sulfate, is environmentally friendly. EP 0 203 831 discloses the use of titanium silicalite to catalyze the ammoximation of cyclohexanone. EP 0 496 385 and EP 0 561 040 disclose two or more steps of the ammoximation process to increase the conversion and yield of the reaction. In order to solve the problems of catalyst separation and efficiency in the ammoximation process, CN02100227 and CN02100228 disclose a method for continuously separating and separating the ammoniated product and the catalyst, and the catalyst is recycled, thereby improving the utilization rate of hydrogen peroxide. In order to reduce the production costs of hydrogen peroxide and helium, EP 0 069 045 and US Pat. No. 5,599,987 disclose an integrated process for the oxidation of isopropanol and ammoximation of cyclohexanone, using titanium silicalite as a catalyst, tert-butanol as a solvent, hydrogen peroxide, ammonia The cyclohexanone is subjected to an ammoximation reaction, and the obtained cyclohexanone is subjected to extraction and purification, and the solvent and excess ammonia are recycled and separated for recycling. The above-mentioned ammoximation technology has a common feature. The reaction process requires the addition of a water-miscible lower alcohol (e.g., tert-butanol) as a solvent to increase the solubility of the product in the system to facilitate the reaction. However, the selected solvent cannot be stably present in the fuming sulfuric acid system, and must be subjected to multiple separation processes such as distillation and extraction before the rearrangement reaction, and the main disadvantages are as follows:

(1) The process is complex and energy consumption is large;

(2) Distillation and extraction are carried out at higher temperatures, the stability of the ruthenium solution is relatively poor, and trace impurities are formed in the subsequent rearrangement, which brings difficulties to the refining process;

(3) The material that enters the subsequent rearrangement is in the molten state. The pipeline in the production needs heat preservation and heat tracing, which is easy to block, which brings inconvenience to the parking and production operations. On the other hand, the cyclohexanone oxime Beckmann rearrangement reaction consumes fuming sulfuric acid, and the by-product ammonium sulphate is a low-value product. U.S. Patent Nos. 4,804,754 and 5,246,571 disclose multi-stage rearrangement techniques in which nicotinic acid reacts with most of the rhodium at lower temperatures and higher acid to enthalpy ratios to ensure that the viscosity is not too high at low temperatures, inhibiting side reactions; It reacts with a small amount of hydrazine at a slightly higher reaction temperature than the previous one and lower molar ratio of strontium to ensure complete reaction, reduce acid consumption, and meet the requirements of low sulfuric acid consumption and high finished product quality.

U.S. Patent Nos. 3,991,047 and 4,812,442 teach the use of an ammonium salt metathesis process to avoid the consumption of sulfuric acid and the production of by-produced ammonium sulfate. The rearrangement products are controlled with aqueous ammonia to control the pH of the reaction to obtain ammonium hydrogen sulfate and caprolactam. Caprolactam is separated by extraction, and ammonia hydrogen sulfate is subjected to pyrolysis reaction to produce sulfur dioxide, ammonia gas and water, and then sulfur dioxide is made into sulfuric acid and recycled. U.S. Patent No. 3,912,721 discloses a sulfuric acid recycle process which is not neutralized by gaseous ammonia, but is further diluted to a 50% aqueous solution, and the caprolactam is extracted by nonylphenol and washed with an alkali solution to remove residual sulfuric acid, caprolactam. The extraction rate is greater than 99.5%. The aqueous sulfuric acid solution containing organic impurities is concentrated, thermally cracked to produce sulfur dioxide, and then dehydrated and catalyzed to produce fuming sulfuric acid. However, current methods for reducing sulfuric acid consumption and by-products in terms of reaction and separation have the following problems:

(1) The reduction of multi-stage rearrangement by-products is small. Under low acid and low temperature conditions, the viscosity of the material is large, which is unfavorable for mass transfer and reaction.

(2) The ammonium salt metathesis and sulfuric acid cycle process have high energy consumption and high cost, so they are not economical.

Disclosure of the Invention An object of the present invention is to provide a process for preparing a amide which is simpler in process, less likely to cause clogging during production, improved reaction quality, reduced sulfuric acid consumption, and lower by-product of ammonium sulfate by-product. The object of the present invention is achieved by: 'the heterogeneously catalyzed oximation of ketone, hydrogen peroxide and ammonia in the presence of a solvent which is inert under a fuming sulfuric acid system to form a ketoxime; The phase product is also extracted with an inert solvent, and the extracted phase is mixed with the organic phase product of the oximation reaction to obtain an inert solvent solution of ketone oxime. The solution is subjected to heterogeneous Beckmann rearrangement reaction to form an amide under the action of fuming sulfuric acid. The inert solvent is an alkane or a cyclic alkane, or a mixture thereof.

The ketone is an aliphatic ketone, or a cycloaliphatic ketone, or an aromatic ketone; preferably having a carbon number of from 3 to 10. In the presence of titanium-silicon molecular sieves, cyclohexanone, hydrogen peroxide and ammonia are used as raw materials, and the volatile substances in the fuming sulfuric acid system are alkane or cycloterpene hydrocarbons, and their mixtures are inert solvents, which form a ring through heterogeneous catalytic reaction. cyclohexanone oxime; the product was an inert solvent by extraction, containing some free Beckmaim rearrangement reaction occurs so fuming sulfuric acid _3, performed after hydrolysis dwell predetermined time, generating the severity of two phases; the light phase is an inert solvent, the heavy phase is The caprolactam-sulfuric acid solution is neutralized with ammonia or ammonia, and the ammonium sulfate is crystallized to obtain caprolactam. The light phase is an inert solvent which can be recycled to the deuteration reaction.

The inert solvent is derived from an alkane or a cyclonon hydrocarbon having 4 to 8 carbon atoms, or a mixture thereof. The deuteration method provided by the present invention will obtain a two-phase product, the light phase is a solvent, the heavy phase is water, and the cyclohexanone oxime is distributed in two phases in a certain ratio. However, the rearrangement process must be carried out in a waterless system. Therefore, the cyclohexanone oxime of the aqueous phase needs to be further separated. The simplest and most effective method is to extract the aqueous phase with the inert solvent of the reaction, and the obtained extract phase has the same composition as the light phase of the deuteration reaction, and can be mixed. The concentration of the cyclohexanone oxime solution after mixing is 5% to 80% by weight, preferably 10 to 20%, which is determined depending on the type of the solvent and the like. An important improvement of the present invention against the original process is that: The inventors have changed the idea. In the present invention, two heterogeneous reaction integration processes are employed. The solvent used in the Beckmann rearrangement reaction is the same as the deuteration reaction solvent, and the solvent is contained. The rearrangement system of fuming sulfuric acid can be stably present without any reaction by itself. Therefore, the deuterated product does not need to be purified by conventional separation means such as distillation or extraction. Although the industrial cyclohexanone oxime rearrangement is carried out in fuming sulfuric acid, the method provided by the present invention mainly reflects the following differences:

(1) cyclohexanone oxime is dissolved in an inert solvent and fed as a solution;

(2) The solvent may be completely vaporized and condensed and recovered during the rearrangement process, or partially vaporized, and the solvent obtained by the hydrolysis after the reaction is recovered together with the condensate;

(3) The recovered solvent can be recycled to the ammoximation reaction. The heterogeneous ammonia-solvent rearrangement integration process provided by the invention has greater improvement and simplification than the original process, and greatly saves cost, and can generate good economic value, which is embodied in the following aspects:

(1) The processes of alcohol distillation, toluene extraction and toluene distillation necessary for the ammoximation process using a lower alcohol as a solvent are omitted, and the process is simple and convenient to operate.

(2) The cyclohexanone oxime obtained by the ammoximation reaction enters the subsequent rearrangement in a solution mode rather than a melt mode, thereby overcoming the disadvantages of the existing process being easily clogged, and at the same time making the Beckmann rearrangement reaction temperature further lowered.

(3) The solvent rearrangement solves the problems of poor mass transfer effect caused by the increase in viscosity of the material under low temperature and low acid amount, and can improve the reaction quality and further reduce the consumption of sulfuric acid and by-products. The heterogeneous reaction process provided by the present invention provides higher conversion and yield in the following process ranges:

The inert solvent and the starting ketone are disposable feeds;

Hydrogen peroxide and ammonia are added in a stepwise manner, or after mixing, the dropping time is 10 minutes to 5 hours, preferably 30 minutes to 2 hours, after the completion of the addition, the reaction can be terminated or extended for 10 minutes to 2 hours before the reaction is terminated; the molar ratio of hydrogen peroxide to cyclohexanone is 1.0 to 5.0, preferably 1.0 to 1.2; The molar ratio to the ketone is from 0.5 to 10. In the deuteration reaction, the concentration of the inert solvent is 20% to 80% by mass percentage; the deuteration reaction temperature is 10 to 120 ° C, preferably 60 to 80 ° C. The molar ratio of fuming sulfuric acid to cyclohexanone oxime in the heterogeneous rearrangement process (so _{3 in} fuming sulfuric acid is converted to sulfuric acid) is 0.5 to 4.0, preferably 1.0 to 1.3, which may be lower than the ratio of existing industrial production. , corresponding to the reduction in secondary production. The concentration of free S0 ₃ in the fuming sulfuric acid used is from 2% to 65%, preferably from 5% to 20%, and can be adjusted according to the change in the total amount of acid.

The rearrangement reaction temperature is 30 to 15 (TC, preferably 60 to 80 ° C, which depends on the kind of the solvent and the operating pressure; the reaction residence time is from 1 minute to 2 hours, preferably from 10 to 30 minutes.

The following examples are merely illustrative of the invention and are not to be construed as limiting the scope of the invention.

Example 1: 45.0 g of n-hexane, 15.2 g of methyl ethyl ketone, and 1.5 g of titanium silicon molecular sieve were added to a 250 ml glass stirred magnetic stirrer. After mixing well, the temperature was raised to 65 Ό, and 27.5% (1 by weight) of hydrogen peroxide was slowly added dropwise. 28.0 g and 25% (by weight) ammonia water 30.0 g. The mixture was added dropwise at a constant rate for 2.5 hours, and the reaction was continued for 1 hour. • Stirring is maintained during the reaction and the temperature is controlled at 65 °C. After cooling and standing to separate the heavy phase, it was extracted with 45.0 g of n-hexane three times, and the extract phase was mixed with the reaction light to obtain 105.6 g of a methyl ethyl ketone oxime-n-hexane solution, a gas chromatographic analysis mass concentration of 16.8%, and a methyl ethyl ketone conversion rate of 99.5. %, the selectivity of methyl ethyl ketone oxime was 97.1%. To another 250 ml reactor, 15.8 g of fuming sulfuric acid having a S0 ₃ concentration of 5% was added, and a methyl ethyl ketone oxime solution was slowly added dropwise. The reaction temperature was 68 ° C, and the vaporized n-hexane was completely condensed and refluxed for a total reaction time of 30 minutes. The aqueous phase was hydrolyzed, neutralized, and analyzed by liquid chromatography to obtain 17.6 g of N-methylpropionamide, and the rearrangement yield was 99.2%. Example 2: A cyclohexane, cyclohexanone and titanium silica molecular sieve catalyst was previously added to a 250 ml magnetically stirred glass reactor, and the amount of cyclohexane was cyclohexane: cyclohexanone = 3.0:1 (molar ratio, lower The same), the titanium silicon molecular sieve mass percentage is 2.2%. When the temperature is raised to 70~71 °C, the hydrogenation reaction is started by adding hydrogen peroxide and ammonia water. The total amount of hydrogen peroxide and ammonia is hydrogen peroxide: ammonia: cyclohexanone = 1.1:1.9:1. The dropping time was 2 hours, and the reaction was continued for 1.1 hours after the completion of the dropwise addition. Stirring during the reaction, temperature control At 71 °C. The aqueous phase product of the reaction is extracted three times with an equivalent amount of cyclohexane, and the extracted phase is mixed with the organic phase product of the reaction to obtain a cyclohexane oxime solution in cyclohexane. The content of cyclohexanone and cyclohexanone oxime in the solution was analyzed by gas chromatography, and conversion and selectivity were calculated. The conversion of cyclohexanone was 99.4%, and the selectivity of cyclohexanone oxime was 98.3%.

Comparative Example 2: The reaction portion of Example 2 was repeated except that the solvent was tert-butanol. Since the alcohol and water are mutually soluble, the extraction process of Example 2 is not required, and the product is directly analyzed by gas chromatography. The reaction result is a cyclohexanone conversion rate of 98.9% and a cyclohexanone oxime selectivity of 98.2%.

Example 3: In a 250 ml glass reactor, 39.2 g of cyclohexane, 15.1 g of cyclohexanone, and 3.8 g of a titanium silicalite catalyst were charged. The concentration was 27.5% (by weight) of 23.5 g of hydrogen peroxide and 33.2 g of ammonia water, and the mixture was added dropwise to the reaction vessel at a constant rate for 2.1 hours.釆 Magnetic stirring, oil temperature control, the reaction temperature under normal pressure is about 72 °C. After the completion of the addition, the reaction was continued for 1 hour, and the mixture was cooled and allowed to stand, and 55.1 g of a light phase was separated. The heavy phase was extracted three times with 39.0 g of cyclohexane, and the extract phase was mixed with a light phase to obtain 95.3 g of a cyclohexanone oxime solution. In a further concentration of S0 ₃ was added 250ml reaction kettle was 15.8g 8% fuming sulfuric acid was slowly added dropwise a solution of cyclohexanone oxime. At normal pressure, the temperature control of the oil is 80 ° C, mechanically stirred, and the vaporized cyclohexane is partially condensed and refluxed, and the total reaction time is 20 minutes. After the reaction was terminated, 6.0 g of water was added dropwise to ice water to carry out a hydrolysis reaction, and the temperature was controlled to not exceed 30 °C. The aqueous phase was neutralized, and 16.9 g of caprolactam was obtained by chromatography, and the rearrangement yield was 98.8%, and the molar ratio of sulfuric acid to caprolactam was 1.10. Comparative Example 3: The deuterated portion was the same as in Example 3 except that the solvent was tert-butanol. The obtained hydrazine-tert-butanol-water solution contained 15.8% of cyclohexanone oxime, 35.5% of t-butanol, 46.5% of water, distilled off t-butanol, and the hydrazine aqueous solution was extracted three times with 51.0 g of toluene, and the extracted phase was further removed by distillation. , obtained pure 肟 17.1g. To another 250 ml reactor, 20.9 g of fuming sulfuric acid having a S0 ₃ concentration of 20% was added, and the molten cyclohexanone oxime was slowly added dropwise. The control temperature of the oil is 120 ° C, mechanical stirring, and the total reaction time is 20 minutes. The hydrolysis, neutralization and the like were the same as in Example 3. By liquid chromatography, 16.8 g of caprolactam was obtained, and the rearrangement yield was 98.5%, and the molar ratio of sulfuric acid to caprolactam was 1.50.

Example 4: The deuteration and rearrangement steps were the same as in Example 3 except that the solvent was n-heptane and the corresponding reaction temperature was 98 °C. The deuteration reaction results in a conversion of cyclohexanone of 99.8%, a selectivity of cyclohexanone oxime of 97.3%, and a rearrangement yield of 99.0%.

Claims

Patent claim

1. A method for preparing an amide by heterogeneous deuteration rearrangement, wherein a ketone, a hydrogen peroxide and an ammonia are subjected to a heterogeneous catalytic oximation reaction to form a ketoxime in the presence of a solvent which is inert under a fuming sulfuric acid system; The aqueous phase product of the reaction is also extracted with an inert solvent, and the extracted phase is mixed with the organic phase product of the oximation reaction to obtain an inert solvent solution of ketone oxime. The solution is subjected to heterogeneous Beckmann rearrangement under the action of fuming sulfuric acid. The reaction produces an amide.

2. A method of preparing an amide by heterogeneous deuterated rearrangement according to claim 1, wherein the inert solvent is an alkane or a cycloalkane, or a mixture thereof.

3. A method of preparing an amide by heterogeneous deuterated rearrangement according to claim 1, wherein the ketone is an aliphatic ketone or a cycloaliphatic ketone or an aromatic ketone.

4. A method for preparing an amide according to a heterogeneous deuteration rearrangement according to claim 1, wherein in the presence of titanium silicalite, cyclohexanone, hydrogen peroxide and ammonia are used as raw materials, and the fuming sulfuric acid system is The inert substance alkane or cycloalkane, or a mixture thereof is an inert solvent, which produces a cyclohexanone oxime by heterogeneously catalyzed reaction; after the product is extracted by an inert solvent, Beckmann rearrangement occurs under the action of fuming sulfuric acid containing free S0 ₃ The reaction, after a certain period of time, is hydrolyzed to form a light and heavy two phase; the light phase is an inert solvent, the heavy phase is a lactam-sulfuric acid solution, and the heavy phase is neutralized with ammonia gas or ammonia, and ammonium sulfate is crystallized to obtain caprolactam.

5. A heterogeneous deuterated rearrangement process for the preparation of an amide according to claim 4, wherein the lightly inert solvent is recycled to the oximation reaction.

A method for preparing an amide by heterogeneous deuterated rearrangement according to claim 4, wherein said inert solvent is derived from an alkane or a cycloalkane having 4 to 8 carbon atoms, or a mixture thereof.

7. A method for preparing an amide by heterogeneous deuterated rearrangement according to claim 4, wherein the concentration of the inert solvent in the deuteration reaction is 20% to 80% by mass percent; hydrogen peroxide and cyclohexanone The molar ratio is 1.0-5.0, and the molar ratio of ammonia to ketone is 0.5~10o.

A method for preparing an amide by heterogeneous deuteration rearrangement according to claim 4, wherein the deuteration reaction temperature is 10 to 120 °C.

9. A method for preparing an amide according to a heterogeneous deuteration rearrangement according to claim 7 or 8, wherein the molar ratio of hydrogen peroxide to cyclohexanone is 1.0 to 1.2; and the temperature of the deuteration is 60 to 80 °C.

10. A method for preparing an amide according to a heterogeneous deuteration rearrangement according to any one of claims 4-8. The method, the inert solvent and the cyclohexanone are used for the one-time feeding; the hydrogen peroxide and the ammonia water are respectively gradually added dropwise, or the mixing method is followed by the dropping method, and the dropping time is 10 minutes to 5 hours, and the reaction can be terminated or extended after the feeding is completed. The reaction was terminated after 2 minutes to 2 hours.

11. A method for preparing an amide by heterogeneous deuteration rearrangement according to claim 4, wherein the molar ratio of fuming sulfuric acid to cyclohexanone oxime during the rearrangement reaction is from 0.5 to 4.0, and S0 in fuming sulfuric acid _{3 is} converted to sulfuric acid; the concentration of free S0 ₃ in the fuming sulfuric acid used is 2% to 65%.

12. A method for preparing an amide by heterogeneous deuteration rearrangement according to claim 11, wherein the molar ratio of fuming sulfuric acid to cyclohexanone oxime during the rearrangement reaction is 1.0 to 1.3, and S0 in fuming sulfuric acid. _{3 is} converted to sulfuric acid; the concentration of free S0 ₃ in the fuming sulfuric acid used is 5% to 20%. .

A method for preparing an amide by heterogeneous deuteration rearrangement according to claim 4, wherein the reaction temperature is from 30 to 150 ° C and the reaction residence time is from 1 minute to 2 hours.

A method for preparing an amide by heterogeneous deuteration rearrangement according to claim 13, wherein the reaction temperature is 60 to 80 ° C and the reaction residence time is 10 to 30 minutes.