Method for preparing caprolactam

Abstract

The invention relates to a method for preparing caprolactam, which is characterized in that: a # imgabs0 # acidic compound with temperature control phase transfer catalysis characteristics is adopted as a catalyst to catalyze cyclohexanone-oxime rearrangement reaction to prepare caprolactam, and the catalyst is recycled and reused; the conditions of the rearrangement reaction are as follows: the molar ratio of cyclohexanone-oxime to the catalyst is (10: 1)-(200: 1), the mass ratio of cyclohexanone-oxime to the organic solvent is (1: 1)-(1: 5), the reaction temperature is 40-150 DEG C, and the reaction time is 1-8 hours. The method has the characteristics that the # imgabs 1 # acidic compound with the temperature control phase transfer catalysis characteristic is used as a catalyst to catalyze cyclohexanone-oxime rearrangement reaction to prepare caprolactam, and has the characteristics of high-temperature homogeneous reaction-low-temperature two-phase separation; the reaction conditions are mild, the catalyst has good catalytic activity, the product yield is high, and the solvent and the catalyst are easy to separate and can be used.

Description

Technical Field

[0001] The present invention relates to a method for preparing caprolactam, that is, to a method having temperature-controlled phase transfer catalysis characteristics. The acidic compound is used as a catalyst to catalyze the rearrangement reaction of cyclohexanone oxime to prepare caprolactam. Background Art

[0002] Nylon series chemical fibers play an important strategic role in the national economy, social development and national security. Caprolactam is an important raw material for the synthesis of nylon-6. It is prepared by the Beckmann rearrangement reaction of cyclohexanone oxime using concentrated sulfuric acid or fuming sulfuric acid as a catalyst. The catalyst has many side reactions, poor product selectivity, complex product separation operations, and difficulty in separating / reusing the catalyst after use during the catalytic reaction process. These defects have become a technical bottleneck restricting the development of the caprolactam industry and have seriously affected the transformation and upgrading of my country's nylon fiber industry. Therefore, by creating a new catalytic system with strong catalytic activity, good selectivity, easy separation and recycling, it is of great academic significance and potential application prospects to achieve efficient conversion of caprolactam under mild conditions and separation, recovery and reuse of the catalytic system.

[0003] The temperature-controlled phase separation catalytic system combines the advantages of homogeneous catalysis and multiphase separation, fully reflecting the characteristics of "high temperature homogeneous reaction-low temperature two-phase separation", and has been well applied in organic reactions such as catalytic alkylation, hydrodeoxygenation and oxidative desulfurization. The invention discloses a method for preparing caprolactam by catalyzing the rearrangement reaction of cyclohexanone oxime using an acidic compound as a catalyst. The invention has the advantages of mild reaction conditions, high catalyst activity, good stability, etc., and the reaction process has the characteristics of "high temperature homogeneous reaction-low temperature two-phase separation". After the reaction, the catalyst separates by itself and can be reused, realizing the reaction-separation integration of the process and the separation, recovery and recycling of the catalyst. The invention provides a new clean way for the preparation of caprolactam. Summary of the invention

[0004] The purpose of the present invention is to replace the conventional method for preparing caprolactam under concentrated sulfuric acid or oleum catalytic system and to develop a method for preparing caprolactam cleanly under mild reaction conditions.

[0005] Based on the above, the present invention relates to a method for preparing caprolactam, characterized in that a temperature-controlled phase transfer catalytic catalyst is used. The acidic compound is used as a catalyst to catalyze the rearrangement reaction of cyclohexanone oxime to prepare caprolactam, and the catalyst is recovered and reused; the conditions of the rearrangement reaction are: the molar ratio of cyclohexanone oxime to the catalyst is 10:1-200:1, the mass ratio of cyclohexanone oxime to the organic solvent is 1:1-1:5, the reaction temperature is 40-150°C, and the reaction time is 1-8h; the acidic catalyst is composed of equimolar The acidic compounds alkyl sultone and monoalkoxy polyoxyethylene ether are dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and then the ethyl acetate is removed by reduced pressure distillation to obtain the obtained product; the monoalkoxy polyoxyethylene ether is one of monomethoxy polyoxyethylene ether with a molecular weight of 400-800, monoethoxy polyoxyethylene ether with a molecular weight of 400-800, or monododecyl polyoxyethylene ether with a molecular weight of 600-1400; the alkyl sultone is one of 1,3-propane sultone or 1,4-butane sultone; and the organic solvent is one of toluene, cyclohexane, or a mixture of the two in a volume ratio of 1:9 to 9:1.

[0006] The present invention solves this technical problem through the following technical solutions:

[0007] A novel catalyst with temperature-controlled phase transfer catalysis prepared from 1,3-propane sultone and monomethoxy polyoxyethylene ether with a molecular weight of 600 Acidic compounds are used as an example to illustrate the specific technical solution, wherein the The acid catalyst is named [MPEG600-C3SO3H], others The naming method of acid catalysts is similar.

[0008] Equimolar 1,3-propane sultone and monomethoxy polyoxyethylene ether with a molecular weight of 600 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acid catalyst [MPEG600-C3SO3H].

[0009] 0.1 mol cyclohexanone oxime, 0.003 mol Acidic catalyst [MPEG600-C3SO3H] and toluene with a mass number three times that of the raw material cyclohexanone oxime were put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor was sealed and the air in the reactor was replaced with nitrogen for three times, the materials in the reactor were heated to 110°C and kept stirring for 4 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the reaction mixture was transferred to a separating funnel and allowed to stand for stratification. The upper layer was an organic phase of the product and solvent toluene, and the lower layer was a catalyst phase. After the upper product phase was subjected to reduced pressure distillation to remove the solvent toluene, the product caprolactam was obtained, and the yield was 99.5%; the lower catalyst phase was directly used for the circulation experiment.

[0010] Compared with the traditional method, the present invention has the following characteristics:

[0011] 1. This has the characteristics of temperature-controlled phase transfer catalysis The preparation of caprolactam by the rearrangement reaction of cyclohexanone oxime catalyzed by acidic compounds has the characteristics of "high temperature homogeneous reaction-low temperature two-phase separation".

[0012] 2. The reaction conditions are mild, the catalyst has good catalytic activity, the product yield is high, and the solvent and catalyst are easy to separate and can be used. Specific implementation methods

[0014] The method of the present invention is further described below in conjunction with embodiments, which are not intended to limit the present invention.

[0015] Example 1: Equimolar amounts of 1,3-propane sultone and monomethoxy polyoxyethylene ether with a molecular weight of 600 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acid catalyst [MPEG600-C3SO3H].

[0016] 0.1 mol cyclohexanone oxime, 0.003 mol Acidic catalyst [MPEG600-C3SO3H] and toluene 3 times the mass number of raw material cyclohexanone oxime were put into a pressure reactor equipped with magnetic stirring and thermometer. After sealing the reactor and replacing the air in the reactor with nitrogen for 3 times, the materials in the reactor were heated to 110°C and kept stirring for 4 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the reaction mixture was transferred to a separating funnel and allowed to stand for stratification. The upper layer was the organic phase of the product and toluene, and the lower layer was the catalyst phase. After the upper product phase was subjected to reduced pressure distillation to remove the solvent toluene, the product caprolactam was obtained, and the yield was 99.5%; the lower catalyst phase was directly used for the circulation experiment.

[0017] Comparative Example 1: 0.1 mol of cyclohexanone oxime, 0.003 mol of 70% concentrated sulfuric acid and 3 times the mass of toluene of the raw material cyclohexanone oxime were put into a pressure reactor equipped with a magnetic stirrer and a thermometer. The reactor was sealed and the air in the reactor was replaced by nitrogen for 3 times. The materials in the reactor were heated to 110°C and stirred for 4 hours. After the reaction was completed, the reactor was quickly cooled to room temperature in a water bath, and the reaction mixture was transferred to a separating funnel and allowed to stand for stratification. The upper layer was the product organic phase, and the lower layer was the waste acid phase. The waste acid phase was extracted three times with toluene of the same mass as cyclohexanone oxime. The product organic phases were combined and the solvent was removed by reduced pressure distillation to obtain the product caprolactam, and the yield was 85.1%.

[0018] Comparative Example 2: 0.1 mol of cyclohexanone oxime, 0.003 mol of 1-ethyl-3-propylsulfonyl chloride hexafluoroborate imidazole salt and 3 times the mass of toluene of the raw material cyclohexanone oxime were put into a pressure reactor equipped with a magnetic stirrer and a thermometer. The reactor was sealed and the air in the reactor was replaced by nitrogen 3 times. After the reactor was sealed and the air in the reactor was replaced by nitrogen 3 times, the materials in the reactor were heated to 110°C and stirred for 4 hours. After the reaction was completed, the reactor was quickly cooled to room temperature in a water bath, and the reaction mixture was transferred to a separating funnel and allowed to stand for stratification. The upper layer was the product organic phase, and the lower layer was the catalyst phase. The upper product organic phase was distilled to remove toluene to obtain the product caprolactam with a yield of 87.6%.

[0019] Example 2: Equimolar amounts of 1,4-butane sultone and methoxy polyoxyethylene ether with a molecular weight of 600 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acid catalyst [MPEG600-C4SO3H].

[0020] 0.1 mol cyclohexanone oxime, 0.003 mol The acidic catalyst [MPEG600-C4SO3H] and toluene with a mass number three times that of the raw material cyclohexanone oxime are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for three times, the materials in the reactor are heated to 110°C and stirred for 4 hours. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, and extracted three times with toluene of the same mass as cyclohexanone oxime. The extracts are combined and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.4%; the residual acidic catalyst [MPEG600-C4SO3H] can be reused after the residual extractant toluene is removed by reduced pressure distillation.

[0021] Example 3: Equimolar amounts of 1,3-propane sultone and methoxy polyoxyethylene ether with a molecular weight of 400 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acid catalyst [MPEG400-C3SO3H].

[0022] 0.1 mol cyclohexanone oxime, 0.01 mol The acidic catalyst [MPEG400-C3SO3H] and the raw material cyclohexanone oxime and toluene of the same mass number are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for 3 times, the materials in the reactor are heated to 150°C and stirred for 1 hour. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, and extracted three times with toluene of the same mass as cyclohexanone oxime. The extracts are combined and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.1%; the residual acidic catalyst [MPEG400-C3SO3H] can be reused after the residual extractant toluene is removed by reduced pressure distillation.

[0023] Example 4: Equimolar amounts of 1,4-propane sultone and methoxy polyoxyethylene ether with a molecular weight of 800 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acid catalyst [MPEG800-C4SO3H].

[0024] 0.1 mol cyclohexanone oxime, 0.01 mol The acidic catalyst [MPEG800-C4SO3H] and a mixture of toluene and cyclohexane (volume ratio of 1:9) with a mass number of 5 times that of the raw material cyclohexanone oxime are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for 3 times, the materials in the reactor are heated to 40°C and stirred for 8 hours. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, and extracted three times with a mixture of toluene and cyclohexane (volume ratio of 1:9) with a mass equal to that of cyclohexanone oxime. The extracts are combined and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.0%; the residual acidic catalyst [MPEG800-C4SO3H] can be reused after the residual extractant toluene is removed by reduced pressure distillation.

[0025] Example 5: Equimolar amounts of 1,3-propane sultone and monoethoxy polyoxyethylene ether with a molecular weight of 400 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acidic catalyst [EPEG400-C3SO3H].

[0026] 0.2 mol cyclohexanone oxime, 0.001 mol The acidic catalyst [EPEG400-C3SO3H] and cyclohexane with a mass number 5 times that of the raw material cyclohexanone oxime are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for 3 times, the materials in the reactor are heated to 100°C and stirred for 3 hours. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, and extracted three times with cyclohexane of the same mass as cyclohexanone oxime. The extracts are combined and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.0%; the residual acidic catalyst [EPEG400-C3SO3H] can be reused after the residual extractant toluene is removed by reduced pressure distillation.

[0027] Example 6: Equimolar amounts of 1,4-propane sultone and monoethoxy polyoxyethylene ether with a molecular weight of 600 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acidic catalyst [EPEG600-C4SO3H].

[0028] 0.2 mol cyclohexanone oxime, 0.01 mol The acidic catalyst [EPEG600-C4SO3H] and cyclohexane with a mass number three times that of the raw material cyclohexanone oxime are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for three times, the materials in the reactor are heated to 110°C and stirred for 3 hours. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, extracted three times with toluene of the same mass as cyclohexanone oxime, the extracts are combined, and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.0%; the residual acidic catalyst [EPEG600-C4SO3H] can be reused after the residual extractant cyclohexane is removed by reduced pressure distillation.

[0029] Example 7: Equimolar amounts of 1,3-propane sultone and monoethoxy polyoxyethylene ether with a molecular weight of 800 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acidic catalyst [EPEG800-C3SO3H].

[0030] 0.1 mol cyclohexanone oxime, 0.001 mol The acidic catalyst [EPEG800-C3SO3H] and a mixture of toluene and cyclohexane (volume ratio of 1:9) with a mass number of 3 times that of the raw material cyclohexanone oxime are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for 3 times, the materials in the reactor are heated to 120°C and stirred for 2 hours. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, and extracted three times with a mixture of toluene and cyclohexane (volume ratio of 1:9) with a mass equal to that of cyclohexanone oxime. The extracts are combined and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.0%; the residual acidic catalyst [EPEG800-C3SO3H] can be reused after the residual extractant is removed by reduced pressure distillation.

[0031] Example 8: Equimolar amounts of 1,3-propane sultone and monododecyl polyoxyethylene ether with a molecular weight of 600 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acidic catalyst [DPEG600-C3SO3H].

[0032] 0.1 mol cyclohexanone oxime, 0.003 mol The acidic catalyst [DPEG600-C3SO3H] and a mixture of toluene and cyclohexane (volume ratio of 1:1) with a mass number of 3 times that of the raw material cyclohexanone oxime are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for 3 times, the materials in the reactor are heated to 80°C and stirred for 4 hours. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, extracted three times with toluene of the same mass as cyclohexanone oxime, the extracts are combined, and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.0%; the residual acidic catalyst [DPEG600-C3SO3H] can be reused after the residual extractant cyclohexane is removed by reduced pressure distillation.

[0033] Example 9: Equimolar amounts of 1,3-propane sultone and monododecyl polyoxyethylene ether with a molecular weight of 1400 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acidic catalyst [DPEG1400-C3SO3H].

[0034] 0.1 mol cyclohexanone oxime, 0.003 mol The acidic catalyst [DPEG1400-C3SO3H] and a mixture of toluene and cyclohexane (volume ratio of 1:1) with a mass number of 3 times that of the raw material cyclohexanone oxime are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for 3 times, the materials in the reactor are heated to 80°C and stirred for 4 hours. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, extracted three times with toluene of the same mass as cyclohexanone oxime, the extracts are combined, and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.0%; the residual acidic catalyst [DPEG1400-C3SO3H] can be reused after the residual extractant cyclohexane is removed by reduced pressure distillation.

[0035] Example 10: Equimolar amounts of 1,3-propane sultone and monododecyl polyoxyethylene ether with a molecular weight of 1000 were dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and ethyl acetate was removed by vacuum distillation to obtain Acidic catalyst [DPEG1000-C3SO3H].

[0036] 0.1 mol cyclohexanone oxime, 0.003 mol The acidic catalyst [DPEG1000-C3SO3H] and a mixture of toluene and cyclohexane (volume ratio of 1:1) with a mass number of 3 times that of the raw material cyclohexanone oxime are put into a pressure reactor equipped with a magnetic stirrer and a thermometer. After the reactor is sealed and the air in the reactor is replaced by nitrogen for 3 times, the materials in the reactor are heated to 80°C and stirred for 4 hours. After the reaction is completed, the reactor is quickly cooled to room temperature in a water bath, extracted three times with toluene of the same mass as the cyclohexanone oxime, the extracts are combined, and the extractant is removed by reduced pressure distillation to obtain the product caprolactam, and the yield is 99.0%; the residual acidic catalyst [DPEG1000-C3SO3H] can be reused after the residual extractant cyclohexane is removed by reduced pressure distillation.

[0037] Example 11: Recover the obtained Acidic catalyst [MPEG600-C3SO3H], 0.1 mol cyclohexanone oxime and toluene 3 times the mass number of the raw material cyclohexanone oxime were put into a pressure reactor equipped with a magnetic stirrer and a thermometer. The reactor was sealed and the air in the reactor was replaced with nitrogen for 3 times. The materials in the reactor were heated to 110°C and stirred for 4 hours. After the reaction was completed, the reactor was quickly cooled to room temperature in a water bath, and the reaction mixture was transferred to a separating funnel and allowed to stand for stratification. The upper layer was an organic phase of the product and toluene, and the lower layer was a catalyst phase. After the upper product phase was subjected to reduced pressure distillation to remove the solvent toluene, the product caprolactam was obtained, and the yield was 99.2%; and the recovered product of this embodiment was The acid catalyst [MPEG600-C3SO3H] was reused 10 times under the same experimental conditions, and the yield of the product caprolactam obtained after 10 repeated uses was greater than 98.1%.

[0038] Example 12: Recovery from Example 2 Acidic catalyst [MPEG600-C4SO3H], 0.1 mol cyclohexanone oxime and toluene 3 times the mass of the raw material cyclohexanone oxime were put into a pressure reactor equipped with a magnetic stirrer and a thermometer. The reactor was sealed and the air in the reactor was replaced with nitrogen 3 times. The materials in the reactor were heated to 110°C and stirred for 4 hours. After the reaction was completed, the reactor was quickly cooled to room temperature in a water bath, extracted three times with toluene of the same mass as cyclohexanone oxime, and the extracts were combined and the extractant was removed by reduced pressure distillation to obtain the product caprolactam, and the yield was 99.1%; and the recovered product of this embodiment was The acid catalyst [MPEG600-C4SO3H] was reused 10 times under the same experimental conditions, and the yield of the product caprolactam obtained after 10 repeated uses was greater than 97.8%.

Claims

1. A method for preparing caprolactam, characterized in that Using temperature-controlled phase transfer catalysis The acidic compound is used as a catalyst to catalyze the rearrangement reaction of cyclohexanone oxime to prepare caprolactam, and the catalyst is recovered and reused; the conditions of the rearrangement reaction are: the molar ratio of cyclohexanone oxime to the catalyst is 10:1-200:1, the mass ratio of cyclohexanone oxime to the organic solvent is 1:1-1:5, the reaction temperature is 40-150°C, and the reaction time is 1-8h; the acidic catalyst is composed of equimolar The acidic compounds alkyl sultone and monoalkoxy polyoxyethylene ether are dissolved in ethyl acetate with a mass number twice that of the two, and refluxed under normal pressure for 3 hours, and then the ethyl acetate is removed by reduced pressure distillation to obtain the obtained product; the monoalkoxy polyoxyethylene ether is one of monomethoxy polyoxyethylene ether with a molecular weight of 400-800, monoethoxy polyoxyethylene ether with a molecular weight of 400-800, or monododecyl polyoxyethylene ether with a molecular weight of 600-1400; the alkyl sultone is one of 1,3-propane sultone or 1,4-butane sultone; and the organic solvent is one of toluene, cyclohexane, or a mixture of the two in a volume ratio of 1:9 to 9:1.

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