CN111393321A - Preparation method of 1-cyano-2-propenyl acetate - Google Patents

Abstract

The present invention relates to a preparation method of 1-cyano-2-propenyl acetate. The method includes the following steps: (1) reacting hydrocyanic acid and acrolein in the presence of a first catalyst to obtain a reaction solution containing acrolein cyanohydrin; (2) making the obtained reaction solution containing acrolein cyanohydrin The liquid reacts with the esterifying agent in the presence of the second catalyst to obtain a reaction liquid containing 1-cyano-2-propenyl acetate. The first catalyst and the second catalyst are the same or different, and are each independently N,N-dimethylaminopyridinecarboxylate. According to the preparation method provided by the present invention, the high-efficiency catalyst N,N-dimethylaminopyridine carboxylate can be used as a common catalyst for the two-step reaction, so that the two-step main reaction can be efficiently catalyzed, so that the two-step main reaction can be made close to chemical The measurement ratio is carried out; the yield of the product 1-cyano-2-propenyl acetate can reach more than 99%, and the purity can reach more than 99.5%; and the investment is saved and the product competitiveness is improved.

Description

The preparation method of 1-cyano-2-propenyl acetate

technical field

The invention relates to a preparation method of 1-cyano-2-propenyl acetate, and belongs to the field of organic synthesis.

Background technique

1-cyano-2-propenyl acetate (ACA) is mainly used as an intermediate in the production of the pesticide glufosinate-ammonium.

There are two main synthesis routes of ACA: one is that acrolein is first reacted with hydrocyanic acid or an aqueous solution of hydrocyanic acid to form acrolein cyanohydrin, the obtained acrolein cyanohydrin is reacted with organic acid halides or acid anhydrides to obtain ACA reaction solution, and then The organic phase is obtained by extracting from the reaction solution with ether, and the organic phase is neutralized with sodium carbonate solution, dried with anhydrous sodium sulfate, filtered and rectified to obtain the product ACA; the other is that acrolein is mixed with NaCN or NaCN aqueous solution, and then mixed with NaCN or NaCN aqueous solution. The acid anhydrides are mixed, and the ACA reaction solution is obtained through a one-pot reaction, and the product ACA is obtained after post-treatment.

Patent CN108727220A discloses a method for preparing acrolein cyanohydrin. The method comprises reacting at least one compound of formula (II), such as acrolein, with hydrocyanic acid and at least one base at a temperature of -50-80°C, thereby obtaining a compound containing formula (I) ( A crude product such as acrolein cyanohydrin) and hydrocyanic acid; the hydrocyanic acid therein is at least partially removed by stripping the crude product, thereby obtaining a pure product comprising a compound of formula (I).

(其中，R¹和R²彼此独立地选自氢、具有1-6个碳原子的烷基、苯基、苄基)

(wherein R ¹ and R ² are independently of each other selected from hydrogen, alkyl having 1-6 carbon atoms, phenyl, benzyl)

The base is ammonia, trialkylamine, ammonium salt, preferably triethylamine, ammonium carbonate, ammonium bicarbonate. The invention is preferably carried out under the condition of 30% molar excess of hydrocyanic acid, and after the acrolein cyanohydrin is prepared, the hydrocyanic acid is removed.

In the above reaction process, in order to be converted into acrolein cyanohydrin as completely as possible, an excess of reactant hydrocyanic acid will occur. In this way, not only the waste of raw materials is caused, but also the existence of excess hydrocyanic acid will lead to self-polymerization.

R.M.Nowak [J.Org.Chem.28, p1182-1187] slowly added acrolein to sodium cyanide solution, controlled the temperature at -10～0℃, then added acetic anhydride dropwise, and extracted and purified with ether after the reaction. ACA. When sodium cyanide:acrolein is 2:1 in the reaction process, the reaction yield can reach 90%, but the yield is only 55-65% under equimolar reaction conditions.

H.Ohse and R.Palm [Angew.Chem.78, p1093] mixed 0.77mol of acrolein and 1.12mol of sodium cyanide aqueous solution, then added 0.77mol of acetic anhydride dropwise to the mixture to obtain ACA reaction solution. , ACA products can be obtained after post-processing. During the reaction, the excess of sodium cyanide was about 45%, and the yield of ACA product was 87%.

McIntosh [Can.J.Chem.55, p4200] used solvent dilution to improve the efficiency of ACA reaction. The reaction process used phase transfer catalyst (TEBAC), and dichloromethane was used as solvent, KCN excess was 20%, and the yield was 66 %. The separation and purification steps in the later stage of the method are relatively complicated, and a large amount of waste water is generated that needs to be treated. Although the excess cyanide is less in this process, the cost of separation and recovery of the phase transfer catalyst is also a problem that needs to be considered.

Patent US4336206 discloses the preparation method of ACA. In this method, an aldehyde, an aqueous cyanide solution, an organic acid chloride, or an acid anhydride are reacted in a water-immiscible inert organic solvent, and the molar ratio of aldehyde:cyanide:acid chloride or acid anhydride is about 1:1 to 1.1:1 ~1.1. The reaction process can be batch operation and continuous operation. In Example 4, 814 grams of 26.5% aqueous NaCN solution (4.4 moles) and 800 grams of dichloromethane were added to a 4 liter flask and cooled to 0°C. 236 g of acrolein (4.0 mol) and 449 g of acetic anhydride (4.4 mol) mixed with 180 g of dichloromethane were added dropwise simultaneously over 30 minutes with stirring. The reaction temperature was maintained at 0°C by external cooling. After the dropwise addition was completed, 360 g of water was added to dissolve the precipitated salt, the phases were left to separate, and the lower organic phase was distilled without drying. After dichloromethane was distilled off at atmospheric pressure, 480 g of ACA product with a purity of 98% and a theoretical yield of 96% was obtained by distillation at 20 mbar and 73°C. This method needs to use a large amount of solvent, and will generate a large amount of cyanide-containing waste water, which requires environmental protection treatment, and the environmental protection cost increases, and there is still room for improvement in the purity and yield of the product.

SUMMARY OF THE INVENTION

Invention to solve problem

In view of the problems existing in the above-mentioned different synthesis processes, the present invention provides a method for continuously preparing 1-cyano-2-propenyl acetate. The method starts with acrolein and hydrocyanic acid in the presence of a specific catalyst. From the starting material, 1-cyano-2-propenyl acetate (ie, ACA) is obtained with high purity and high yield through two-step reactions of hydrocyanation addition and esterification.

solution to the problem

According to the method for continuous preparation of 1-cyano-2-propenyl acetate provided by the present invention, it comprises the following steps:

(1) make hydrocyanic acid and acrolein react in the presence of the first catalyst, obtain the reaction solution containing acrolein cyanohydrin;

(2) making the obtained reaction solution containing acrolein cyanohydrin react with the esterifying agent in the presence of the second catalyst to obtain the reaction solution containing 1-cyano-2-propenyl acetate;

The first catalyst and the second catalyst are the same or different, and are each independently N,N-dimethylaminopyridinecarboxylate, preferably N,N-dimethylaminopicolinate, N,N- Dimethylaminopyridine acetate, N,N-dimethylaminopyridine propionate, N,N-dimethylaminopyridine butyrate, N,N-dimethylaminopyridinevalerate, N,N-dimethylaminopyridine Aminopyridine hexanoate, N,N-dimethylaminopyridine octanoate, N,N-dimethylaminopyridine decanoate, N,N-dimethylaminopyridine oxalate, N,N-dimethylaminopyridine Citrate, N,N-dimethylaminopyridine malate, N,N-dimethylaminopyridine succinate, N,N-dimethylaminopyridine adipate, and N,N-dimethylaminopyridine One or more of pyridine sebacate; more preferably N,N-dimethylaminopyridine acetate.

According to the method for continuously preparing 1-cyano-2-propenyl acetate provided by the present invention, wherein, in the step (1), the molar ratio of the hydrocyanic acid to acrolein is 1-1.02:1, The mole number of the added amount of the first catalyst is 0.05-2% of the mole number of the added amount of acrolein, preferably 0.1-1%;

In the step (2), the molar ratio of the esterification agent to acrolein cyanohydrin is 1-1.02:1, and the molar number of the second catalyst added is 0.05-2 mol of the added amount of acrolein. %, preferably 0.1 to 1%.

According to the method for continuous preparation of 1-cyano-2-propenyl acetate provided by the present invention, wherein the esterifying agent is selected from at least one of acid chloride and acid anhydride; wherein the acid chloride includes acetyl chloride, propionyl chloride, Butyryl chloride, acetyl bromide or benzyl chloride; the anhydrides include acetic anhydride, propionic anhydride or butyric anhydride.

According to the method for continuous preparation of 1-cyano-2-propenyl acetate provided by the present invention, wherein, the reaction of the step (1) is carried out in the first reactor,

And the step (1) also includes: detecting the residual amount of acrolein and hydrocyanic acid in the reaction solution containing acrolein cyanohydrin in the middle and upper part of the first reactor, and in the first reaction The top outlet of the device detects the content of residual acrolein in the reaction solution containing acrolein cyanohydrin.

According to the method for continuous preparation of 1-cyano-2-propenyl acetate provided by the present invention, wherein, the reaction of the step (2) is carried out in the second reactor,

And the step (2) also includes, in the middle and upper part of the second reactor, detecting the difference between acrolein cyanohydrin and the esterifying agent in the reaction solution containing 1-cyano-2-propenyl acetate. content, and the residual amount of acrolein cyanohydrin in the reaction solution containing 1-cyano-2-propenyl acetate was detected at the top outlet of the second reactor.

According to the method for continuously preparing 1-cyano-2-propenyl acetate provided by the present invention, each detection in the step (1) and step (2) is performed by using online Raman spectroscopy.

According to the method for continuously preparing 1-cyano-2-propenyl acetate provided by the present invention, in the step (1), the reaction temperature increases from the lower part to the upper part in the first reactor.

According to the method for continuously preparing 1-cyano-2-propenyl acetate provided by the present invention, wherein, in the step (1), the temperature of the lower part of the first reactor is -10～10°C, preferably -5～5℃; the upper temperature is 10～50℃, preferably 20～40℃; the residence time of reactants in the first reactor is 0.1～2h, preferably 0.3～1h.

According to the method for continuously preparing 1-cyano-2-propenyl acetate provided by the present invention, wherein, in the step (2), the reaction temperature in the second reactor is 20-60° C., preferably 30～50℃; the residence time of the reactant in the second reactor is 0.5～2h.

According to the method for continuously preparing 1-cyano-2-propenyl acetate provided by the present invention, wherein, the first reactor and the second reactor each adopt a multi-stage stirring reactor, and the first reactor The number of stirring stages in the second reactor and the second reactor is 6 to 30 stages, preferably 10 to 20 stages.

effect of invention

Compared with the prior art, the beneficial effects of the present invention are:

(1) Through the specific selection of the catalyst, that is, when a high-efficiency catalyst such as N,N-dimethylaminopyridine carboxylate is selected as a common catalyst for the two-step reaction, the two-step main reaction can be efficiently catalyzed, so that the two-step main reaction can be efficiently catalyzed. The two-step main reaction proceeds in a near stoichiometric ratio.

In addition, in a preferred embodiment, online Raman spectroscopy is used to detect and control the two-step reaction, so that the two-step reaction can achieve a reaction closer to the stoichiometric ratio, greatly reducing the probability of side reactions and improving the reaction selectivity, Reduce post-processing steps and costs.

The yield of the product 1-cyano-2-propenyl acetate (calculated according to acrolein) can reach more than 99%, and the purity can reach more than 99.5%.

(2) There is no need to use a solvent in the whole reaction process, which reduces the subsequent steps of removing the solvent. It can simplify the operation and reduce the cost.

(3) In a preferred embodiment, a multi-stage stirring, multi-stage dropping, and grading temperature control reactor is adopted, which makes the operation and control convenient, can save investment and improve product competitiveness.

Description of drawings

Figure 1 is a flow diagram for the continuous preparation of 1-cyano-2-propenyl acetate.

Figure 2 is a comparison of the Raman spectra of hydrocyanic acid, acrolein, and acrolein cyanohydrin.

Figure 3 is a comparison of the Raman spectra of acrylic cyanohydrin and ACA.

Figure 4 is a comparison of Raman spectra of acetic acid and acetic anhydride.

Among them, the meanings represented by the symbols in Figure 1 are as follows:

R1 - first reactor

R2 - Second Reactor

R3 - Evaporator

R4——Distillation column

LM1～LM4——Raman Spectral Detector

Detailed ways

The specific embodiments of the preparation method of 1-cyano-2-propenyl acetate of the present invention will be described in further detail below with reference to the accompanying drawings.

According to the method for continuous preparation of 1-cyano-2-propenyl acetate provided by the present invention, it comprises the following steps:

(1) Hydrocyanic acid and acrolein are reacted in the presence of a first catalyst to obtain a reaction solution containing acrolein cyanohydrin.

(2) The obtained reaction solution containing acrolein cyanohydrin and an esterification agent are reacted in the presence of a second catalyst to obtain a reaction solution containing 1-cyano-2-propenyl acetate.

It will be described in more detail below.

(1) Preparation of acrolein cyanohydrin

In this step reaction, hydrocyanic acid and acrolein are used as raw materials, and under the action of the first catalyst, an addition reaction is carried out in the first reactor R1 to obtain acrolein cyanohydrin. Its reaction formula is as follows:

Wherein, the first catalyst is N,N-dimethylaminopyridinecarboxylate; preferably, N,N-dimethylaminopyridinecarboxylate, N,N-dimethylaminopyridine acetate, N,N-dimethylaminopyridine acetate Methylaminopyridine propionate, N,N-dimethylaminopyridine butyrate, N,N-dimethylaminopyridinevalerate, N,N-dimethylaminopyridinehexanoate, N,N-dimethylaminopyridine Pyridine octanoate, N,N-dimethylaminopyridine decanoate, N,N-dimethylaminopyridine oxalate, N,N-dimethylaminopyridine citrate, N,N-dimethylaminopyridine apple acid salt, N,N-dimethylaminopyridine succinate, N,N-dimethylaminopyridine adipate, N,N-dimethylaminopyridine sebacate; more preferably, N,N- Dimethylaminopyridine acetate.

In a preferred case, in order to ensure that acrolein and hydrocyanic acid are reacted in the required molar ratio in step (1), a Raman spectrum detector LM1 is set in the middle and upper part of the first reactor R1, by detecting acrolein cyanohydrin The residual amount of acrolein and hydrocyanic acid in the reaction solution, calculate the molar ratio of the residual acrolein and hydrocyanic acid in the reaction solution, and use this to determine the amount of additional hydrocyanic acid, so that acrolein can be used in the reaction. completely consumed;

At the same time, a Raman spectrometer LM2 is set at the top outlet of the first reactor R1 to analyze whether the acrolein is completely reacted by detecting the content of the residual acrolein in the acrolein cyanohydrin reaction solution. Fine-tuning of the addition amount to ensure complete consumption of acrolein in the reaction.

The detection by Raman spectroscopy in step (1) is described in detail as follows.

The content of acrolein and hydrocyanic acid in the reaction solution containing acrolein cyanohydrin is analyzed by Raman spectrometer LM1, and the content of acrolein can be determined by the characteristic absorption peak at the wavenumber of 1200cm ^-1 (Fig. 2). The characteristic absorption peak at the wavenumber of 2100cm ^-1 (Fig. 2) determines the content of hydrocyanic acid, from which the molar ratio of residual acrolein to hydrocyanic acid can be calculated, and the supplementary amount of hydrocyanic acid can be determined. After fully reacting in the upper stages of the first reactor R1, it is detected again by the Raman spectroscopic detector LM2 at the top discharge port to analyze whether the acrolein is completely reacted, if not, the acrolein or hydrogen The residual amount of cyanic acid is fine-tuned to the amount of hydrocyanic acid to ensure the complete reaction of acrolein, the flow chart of which is shown in Figure 1.

In step (1), the molar ratio of raw material hydrocyanic acid to acrolein is 1-1.02:1; and the mole number of the first catalyst added is 0.05-2% of the mole of acrolein added, preferably 0.1 ~1%.

Preferably, in step (1), the reaction temperature is gradually increased from the lower part to the upper part of the first reactor R1. Preferably, the temperature of the lower part of the first reactor R1 is controlled at -10-10°C, more preferably -5-5°C; the temperature of the upper part of the first reactor R1 is 10-50°C, more preferably 20-40°C. In addition, the residence time of the reactants in the first reactor R1 is preferably 0.1 to 2 h, more preferably 0.3 to 1 h.

In a preferred case, in step (1), the first reactor R1 is a multi-stage stirred reactor, and the number of stirring stages is 6-30, preferably 10-20. And, more preferably, the reaction temperature of each stage of the stirring zone of the first reactor R1 can be individually controlled.

(2) Preparation of ACA products

Under the action of the second catalyst, acrolein cyanohydrin reacts with the esterifying agent in the second reactor R2 to obtain a reaction solution containing 1-cyano-2-propenyl acetate. Its reaction formula is as follows:

In the step (2), the second catalyst is N,N-dimethylaminopyridine carboxylate; preferably, N,N-dimethylaminopyridinecarboxylate, N,N-dimethylaminopyridine acetate , N,N-dimethylaminopyridine propionate, N,N-dimethylaminopyridine butyrate, N,N-dimethylaminopyridine valerate, N,N-dimethylaminopyridinehexanoate, N,N-dimethylaminopyridine hexanoate ,N-dimethylaminopyridine octanoate, N,N-dimethylaminopyridine decanoate, N,N-dimethylaminopyridine oxalate, N,N-dimethylaminopyridine citrate, N,N - in dimethylaminopyridine malate, N,N-dimethylaminopyridine succinate, N,N-dimethylaminopyridine adipate, and N,N-dimethylaminopyridine sebacate One or more; more preferably, N,N-dimethylaminopyridine acetate.

The second catalyst used in the step (2) may be the same or different from the first catalyst in the step (1). Preferably, the second catalyst is the same as the first catalyst, so that the catalyst may not be replaced during the entire reaction process.

In a preferred case, in order to ensure that in step (2), acrolein cyanohydrin and the esterifying agent are reacted according to the required molar ratio, a Raman spectrum detector LM3 is set in the middle and upper part of the second reactor R2, by detecting the ACA-containing The content of acrolein cyanohydrin and acetic anhydride in the reaction solution is to determine the molar ratio of residual acrolein cyanohydrin and esterification agent, and to determine the amount of additional esterification agent, so that acrolein cyanohydrin can be used in the esterification reaction. completely consumed;

At the same time, a Raman spectrometer LM4 is set on the top outlet pipeline of the second reactor R2 to analyze whether the acrolein cyanohydrin is completely reacted by detecting the residual amount of acrolein cyanohydrin in the reaction solution containing ACA. Then carry out the fine-tuning of the addition amount of the esterifying agent to ensure that the acrolein cyanohydrin is completely consumed in the reaction.

The detection by Raman spectroscopy in step (2) is described in detail as follows.

The content of acrolein cyanohydrin and esterification agents such as acetic anhydride in the ACA-containing reaction solution was analyzed by Raman spectroscopic detector LM3, and acrolein cyanohydrin was determined by the characteristic absorption peak at the wavenumber of 1110 cm ^-1 (Fig. 3). The content of alcohol, the characteristic absorption peak at wavenumber 780cm ^-1 (Fig. 4) is used to determine the content of esterification agent such as acetic anhydride, from which the molar ratio of residual acrolein cyanohydrin to esterification agent such as acetic anhydride can be calculated , and determine the additional amount of esterification agents such as acetic anhydride. After the upper stages of the second reactor R2 are fully reacted, the Raman spectroscopic detector LM4 at the top discharge port is used for detection again to analyze whether the acrolein cyanohydrin is completely reacted. If not, the acrolein cyanohydrin Or the residual amount of the esterifying agent can be fine-tuned to ensure the complete reaction of acrolein cyanohydrin, the flow chart of which is shown in Figure 1.

In the step (2), the molar ratio of the esterification agent to acrolein cyanohydrin is 1 to 1.02:1, and the mole number of the second catalyst added is 0.05 to 2% of the mole number of the acrolein added, preferably 0.1 to 1%.

In step (2), the esterification agent can be a commonly used esterification agent in this field. For example, the esterifying agent may include at least one selected from acid chlorides and acid anhydrides. Among them, preferably, the acid chloride includes acetyl chloride, propionyl chloride, butyryl chloride, acetyl bromide, or benzyl chloride; and preferably, the acid anhydride includes acetic anhydride, propionic anhydride, or butyric anhydride.

Preferably, in step (2), the reaction temperature in the second reactor R2 is 20-60°C, more preferably 30-50°C; and the residence time of the reactants in the second reactor R2 is 0.5～2h.

In step (2), the second reactor R2 preferably uses a multi-stage stirring reactor, and the number of stirring stages is 6-30, preferably 10-20.

In a preferred case, step (2) further comprises: entering the reaction solution containing 1-cyano-2-propenyl acetate into an evaporator for vacuum distillation to remove by-product acetic acid to obtain 1-cyano-2 - Crude propenyl acetate. Subsequently, the crude 1-cyano-2-propenyl acetate is subjected to vacuum distillation in a rectifying column to purify to obtain a 1-cyano-2-propenyl acetate product, and the bottom of the rectifying column is The catalyst can be recycled and applied.

In the above process, the evaporator can use a common evaporation device, preferably a wiped film evaporator.

The core of the present invention is to select a high-efficiency catalyst N,N-dimethylaminopyridine carboxylate, which can be used as a common catalyst for the two-step reaction, and the catalyst can efficiently catalyze the two-step main reaction, thereby making the two-step reaction close to stoichiometric ratio.

In addition, according to a preferred embodiment of the present invention, in terms of the precise control means for the ratio of reaction materials, the present invention adopts online Raman spectroscopy to detect in two stages on each reactor, which can ensure that the materials are reacted according to the required metering ratio, And ensure that the main raw materials react completely.

In addition, according to another preferred embodiment of the present invention, in order to realize the requirement that the reaction system needs to be added dropwise and heated according to a program, the present invention adopts a tower composed of multi-stage stirred reactors whose temperature can be independently controlled at each stage. The reactor is compact in structure and low in equipment investment, thereby reducing the overall production cost and improving the competitiveness of the product.

The flow chart of the preparation method of the 1-cyano-2-propenyl acetate of the present invention will be described in further detail below with reference to FIG. 1 .

(1) Preparation of acrolein cyanohydrin

The acrolein and the catalyst are continuously added from the bottom of the first reactor R1, and the hydrocyanic acid is added from the inlets of all levels in the lower part of the first reactor R1, so that acrolein and hydrocyanic acid are reacted, and the first reactor R1 is added. The reaction temperature is controlled to increase from the lower part to the upper temperature, and the lower temperature is -10～10 ℃, preferably -5～5 ℃; the upper temperature is 10～50 ℃, preferably 20～40 ℃; The residence time in the reactor R1 is 0.1 to 2 h, preferably 0.3 to 1 h.

The content of acrolein and hydrocyanic acid in the acrolein-containing cyanohydrin reaction solution is analyzed through the detection of the online Raman spectrometer LM1 set in the upper part of the first reactor R1, so that the residual acrolein and the residual acrolein can be calculated. Molar ratio of hydrocyanic acid, and determine the amount of hydrocyanic acid added. The additional hydrocyanic acid and acrolein continue to react in the upper part of the first reactor R1, so that the acrolein is fully converted. Through the detection of the online Raman spectroscopic detector LM2 at the top outlet of the first reactor R1 to analyze whether the acrolein is completely reacted, if not, the amount of hydrocyanic acid is fine-tuned to ensure that the acrolein is completely reacted.

(2) Preparation of ACA products

The reaction liquid containing acrolein cyanohydrin coming out from the top of the first reactor R1 is separately added from the lower stages of the second reactor R2, and the esterification agent is sent to the first stage at the lower part of the second reactor R2, and is mixed with the propylene-containing reaction solution. The reaction solutions of aldol and cyanohydrin are mixed and reacted, and the reaction temperature in the second reactor R2 is controlled to be 20-60°C, preferably 30-50°C; the residence time of the reactants in the second reactor R2 is 0.5-2h .

The content of acrolein cyanohydrin and esterification agent in the ACA-containing reaction solution is analyzed through the detection of the online Raman spectrum detector LM3 set in the middle and upper part of the second reactor R2, and the residual acrolein cyanohydrin can be calculated from this and the molar ratio of the esterification agent, and determine the additional amount of the esterification agent. The additional esterifying agent and acrolein cyanohydrin continue to react in the upper part of the second reactor R2, so that the acrolein cyanohydrin is fully converted. Whether the acrolein cyanohydrin is completely reacted is analyzed by the online Raman spectroscopic detector LM4 on the top discharge pipeline of the second reactor R2, if not, the esterification is determined by the residual amount of acrolein cyanohydrin or esterification agent. The amount of agent was fine-tuned to ensure complete reaction of the acrolein cyanohydrin.

The ACA-containing reaction solution is passed into the evaporator R3 for vacuum distillation, the heat medium (such as steam) for heating enters from the bottom, the reaction by-product acetic acid is removed from the top, and the ACA crude product is obtained from the bottom, and the ACA crude product is refined. The lower part of distillation tower R4 is fed to carry out rectification under reduced pressure, and the purified ACA product is obtained from the top of the tower, and the bottom of the tower is a mixture of catalyst and a small amount of by-products, which can be recovered and applied mechanically after neutralization, extraction and salification.

The controller in Figure 1 is the controller for online Raman spectroscopy.

The present invention is further described below in conjunction with the examples, but this does not limit the protection scope of the present invention.

In the following examples and comparative examples, the testing method of the purity of product ACA adopts gas chromatography; and the yield of product ACA adopts the following formula to calculate:

The yield of product ACA = the moles of acrolein corresponding to the product/the moles of acrolein of the raw material

Example 1

The continuous preparation of 1-cyano-2-propenyl acetate was carried out according to the flow chart shown in FIG. 1 . in:

R1 is a multi-stage stirred reactor with a diameter of 0.1m and a height of 1m, with a total of 10 stages.

R2 is a multi-stage stirred reactor with a diameter of 0.1m and a height of 1.1m, with a total of 10 stages.

R3 is a wiped film evaporator,

R4 is a vacuum distillation column.

(1) Preparation of acrolein cyanohydrin

Acrolein at 85.0g/min, catalyst N,N-dimethylaminopyridine acetate at 1.8g/min were continuously added from the bottom of the first reactor R1, and hydrocyanic acid was added from the first reactor at a total amount of 40.0g/min. The lower part of the reactor R1 is added to the 1-5 grades, so that acrolein and hydrocyanic acid are reacted, and the reaction temperature of the 1-3 grades is controlled at about -5 °C, and the reaction temperature of the 4-5 grades is controlled at about 0 °C. , the reaction temperature of the 6th to 10th stages from the lower part of the first reactor R1 is controlled at about 10°C, 20°C, 25°C, 30°C, and 35°C in turn, and the total residence time of the reactants is about 1h.

After the detection of the online Raman spectrum detector LM1 set at the seventh stage of the first reactor R1, it was determined that acrolein had been converted 96.2%, and the molar ratio of residual hydrocyanic acid to acrolein was 1:1.33. The amount of the added hydrocyanic acid is 0.5 g/min, and the added hydrocyanic acid and acrolein continue to react in the 8th to 10th stages of the first reactor R1, so that the acrolein is fully converted. After the detection of the online Raman spectrum detector LM2 at the top outlet of the first reactor R1, the content of acrolein in the reaction solution containing acrolein cyanohydrin has been lower than the detection limit, and it is determined that the acrolein is basically reacted.

(2) Preparation of ACA products

The reaction solution containing acrolein cyanohydrin from the first reactor R1 was respectively added from the 1st to 5th stages in the lower part of the second reactor R2, and acetic anhydride was fed into the first stage in the lower part of the second reactor R2 at 149.1 g/min. , and mixed and reacted with the reaction solution containing acrolein cyanohydrin, the reaction temperature was controlled at 50°C, and the residence time of the reactant was about 0.5h.

After the detection of the online Raman spectroscopic detector LM3 set at the seventh stage of the second reactor R2, it was determined that the conversion rate of acrolein cyanohydrin was 96.6%, and the molar ratio of residual acrolein cyanohydrin to acetic anhydride was 1.23:1 , the amount of acetic anhydride that needs to be added is calculated to be 1.2 g/min, and the additional acetic anhydride and acrolein cyanohydrin continue to react in the 8th to 10th stages of the second reactor R2, so that acrolein cyanohydrin is fully converted. The content of acrolein cyanohydrin in the ACA reaction solution was detected by the online Raman spectrometer LM4 on the top discharge pipeline of the second reactor R2, and the content of acrolein cyanohydrin was lower than the detection limit, confirming that the acrolein cyanohydrin reaction was basically complete.

The ACA-containing reaction solution was passed into the wiped film evaporator R3 for vacuum distillation, the reaction by-product acetic acid was removed from the top of the wiped film evaporator R3, and the crude ACA product was obtained from the bottom. ACA crude product is sent from the lower part of rectifying tower R4 to carry out vacuum distillation, and the ACA product with a content of 99.91% is obtained at the top of the tower at 184.9 g/min. The bottom of the tower is a mixture of catalyst and a small amount of by-products, which can be neutralized, Recycle after extraction and salt formation.

Based on acrolein, 1-cyano-2-propenyl acetate was obtained in a yield of 99.3%.

Example 2

The continuous preparation of 1-cyano-2-propenyl acetate was carried out according to the flow chart shown in FIG. 1 . in:

R1 is a multi-stage stirred reactor with a diameter of 0.1m and a height of 1.5m, with a total of 15 stages.

R2 is a multi-stage stirred reactor with a diameter of 0.2m and a height of 3.2m, with a total of 15 stages.

R3 is a wiped film evaporator,

R4 is a vacuum distillation column.

(1) Preparation of acrolein cyanohydrin

Acrolein was continuously added from the bottom of the first reactor R1 at 255.0g/min, catalyst N,N-dimethylaminopyridine citrate at 2.7g/min, and hydrocyanic acid was added from the first reactor at a total amount of 120.0g/min. The lower part of the reactor R1 is added in the 1st to 8th grades, so that acrolein and hydrocyanic acid are reacted, and the reaction temperature of the 1st to 4th grades is controlled at about -5°C, and the reaction temperature of the 5th to 8th grades is controlled at about 5°C. , the reaction temperature of the 9th to 15th stages from the lower part of the first reactor R1 is controlled at about 10°C, 20°C, 25°C, 30°C, 35°C, 40°C, and 45°C in turn, and the total residence time of the reactants is about is 0.5h.

After detection by the online Raman spectroscopic detector LM1 set at the 10th stage of the first reactor R1, it is determined that acrolein has been converted 96.8%, and the molar ratio of residual hydrocyanic acid to acrolein is 1:1.27. The amount of hydrocyanic acid is 0.4 g/min, and the added hydrocyanic acid and acrolein continue to react in the 11th to 15th stages of the first reactor R1, so that the acrolein is fully converted. After the detection of the online Raman spectrum detector LM2 at the top outlet of the first reactor R1, the content of acrolein in the reaction solution containing acrolein cyanohydrin has been lower than the detection limit, and it is determined that the acrolein is basically reacted.

(2) Preparation of ACA products

The reaction solution containing acrolein cyanohydrin from the first reactor R1 was added in stages 1 to 8 in the lower part of the second reactor R2, and acetic anhydride was fed into the first stage in the lower part of the second reactor R2 at 447.2 g/min. , and mixed and reacted with the reaction solution containing acrolein cyanohydrin, the reaction temperature was controlled at 30°C, and the residence time of the reactants was about 2.0h.

After the detection of the online Raman spectroscopic detector LM3 set at the 10th stage of the second reactor R2, it was determined that the conversion rate of acrolein cyanohydrin was 96.9%, and the molar ratio of residual acrolein cyanohydrin to acetic anhydride was 1.21:1 , the amount of acetic anhydride that needs to be added is calculated to be 2.9 g/min, and the added acetic anhydride and acrolein cyanohydrin continue to react in the 11th to 15th stages of the second reactor R2, so that acrolein cyanohydrin is fully converted. The content of acrolein cyanohydrin in the ACA-containing reaction solution was detected by the online Raman spectrometer LM4 on the top discharge pipeline of the second reactor R2, and the content of acrolein cyanohydrin was lower than the detection limit, confirming that the acrolein cyanohydrin reaction was basically complete.

The ACA-containing reaction solution was passed into the wiped film evaporator R3 for vacuum distillation, the reaction by-product acetic acid was removed from the top of the wiped film evaporator R3, and the crude ACA product was obtained from the bottom. ACA crude product is sent from the lower part of rectifying tower R4 to carry out rectification under reduced pressure, and the ACA product with a content of 99.89% is obtained at the top of the tower at 556.7 g/min. Recycle after extraction and salt formation.

Based on acrolein, 1-cyano-2-propenyl acetate was obtained in 99.6% yield.

Example 3

The continuous preparation of 1-cyano-2-propenyl acetate was carried out according to the flow chart shown in FIG. 1 . in:

R1 is a multi-stage stirred reactor with a diameter of 0.1m and a height of 2.0m, with a total of 20 stages.

R2 is a multi-stage stirred reactor with a diameter of 0.2m and a height of 3.6m, with a total of 20 stages.

R3 is a wiped film evaporator,

R4 is a vacuum distillation column.

(1) Preparation of acrolein cyanohydrin

Acrolein at 566.7g/min, catalyst N,N-dimethylaminopyridine adipate at 1.2g/min were continuously added from the bottom of the first reactor R1, and hydrocyanic acid was added from the first reactor at a total amount of 266.7g/min. The lower part of the reactor R1 is added in the 1st to 12th grades, so that acrolein and hydrocyanic acid are reacted. The reaction temperature of the 13th to 20th stages from the lower part of the first reactor R1 is controlled at about 10°C, 20°C, 25°C, 25°C, 30°C, 30°C, 35°C, and 40°C in sequence, and the total stay of the reactants is The time is about 0.3h.

After detection by the online Raman spectrometer LM1 set at the 14th stage of the first reactor R1, it is determined that acrolein has been converted 97.2%, and the molar ratio of residual hydrocyanic acid to acrolein is 1:1.35. The amount of hydrocyanic acid was 2.6 g/min, and the additional hydrocyanic acid and acrolein continued to react in the 15th to 20th stage of the first reactor R1, so that the acrolein was fully converted. After the detection of the online Raman spectrum detector LM2 at the top outlet of the first reactor R1, the content of acrolein in the reaction solution containing acrolein cyanohydrin has been lower than the detection limit, and it is determined that the acrolein is basically reacted.

(2) Preparation of ACA products

The reaction solution containing acrolein cyanohydrin from the first reactor R1 was added in stages 1 to 12 at the lower part of the second reactor R2, and acetic anhydride was fed into the first stage at the lower part of the second reactor R2 at 996.6 g/min , and mixed and reacted with the reaction solution containing acrolein cyanohydrin, the reaction temperature was controlled at 40°C, and the residence time of the reactants was about 1.0h.

After the detection of the online Raman spectroscopic detector LM3 set at the 14th stage of the second reactor R2, it was determined that the conversion rate of acrolein cyanohydrin was 97.3%, and the molar ratio of residual acrolein cyanohydrin to acetic anhydride was 1.26:1 , the amount of acetic anhydride that needs to be added is calculated to be 7.0g/min. The added acetic anhydride and acrolein cyanohydrin continue to react in the 15th to 20th stage of the second reactor R2, so that acrolein cyanohydrin is fully converted. The content of acrolein cyanohydrin in the ACA-containing reaction solution was detected by the Raman spectrometer LM4 on the top discharge pipeline of the second reactor R2, and the content of acrolein cyanohydrin was lower than the detection limit, confirming that the reaction of acrolein cyanohydrin was basically complete.

The ACA-containing reaction solution was passed into the wiped film evaporator R3 for vacuum distillation, the reaction by-product acetic acid was removed from the top of the wiped film evaporator R3, and the crude ACA product was obtained from the bottom. The crude ACA product is fed from the lower part of the rectifying tower R4 for vacuum distillation, and the ACA product with a content of 99.83% is obtained at the top of the tower at 1237 g/min. The bottom of the tower is a mixture of catalyst and a small amount of by-products, which can be neutralized and extracted , After the salt is formed, it is recycled and applied.

Based on acrolein, 1-cyano-2-propenyl acetate was obtained in 99.5% yield.

Comparative Example 1

The continuous preparation of 1-cyano-2-propenyl acetate was carried out according to the flow chart shown in FIG. 1 . in:

R1 is a multi-stage stirred reactor with a diameter of 0.1m and a height of 1m, with a total of 10 stages.

R2 is a multi-stage stirred reactor with a diameter of 0.1m and a height of 1.1m, with a total of 10 stages.

R3 is a wiped film evaporator,

R4 is a vacuum distillation column.

(1) Preparation of acrolein cyanohydrin

Acrolein at 85.0g/min and catalyst triethylamine at 0.15g/min are continuously added from the bottom of the first reactor R1, and the total amount of hydrocyanic acid is respectively 40.0g/min from 1-5 at the bottom of the first reactor R1. Add in the grade to make acrolein react with hydrocyanic acid, and the reaction temperature of the 1st to 3rd grades is controlled at about -5°C, and the reaction temperature of the 4th to 5th grades is controlled at about 0°C, from the lower part of the first reactor R1 The reaction temperature of the 6th to 10th stages from the above is controlled at about 10°C, 20°C, 25°C, 30°C, and 35°C in sequence, and the total residence time of the reactants is about 1.5h.

After the detection of the online Raman spectrum detector LM1 set at the seventh stage of the first reactor R1, it is determined that acrolein has been converted 90.2%, and the molar ratio of residual hydrocyanic acid to acrolein is 1:1.45. The amount of the added hydrocyanic acid is 0.6 g/min, and the added hydrocyanic acid and acrolein continue to react in the 8th to 10th stages of the first reactor R1, so that the acrolein is fully converted. After the detection of the online Raman spectrum detector LM2 at the top outlet of the first reactor R1, the content of acrolein in the reaction solution containing acrolein cyanohydrin has been lower than the detection limit, and it is determined that the acrolein is basically reacted.

(2) Preparation of ACA products

The reaction solution containing acrolein cyanohydrin from the first reactor R1 was respectively added from the 1st to 5th stages in the lower part of the second reactor R2, and acetic anhydride was fed into the first stage in the lower part of the second reactor R2 at 149.1 g/min. , and mixed and reacted with the reaction solution containing acrolein cyanohydrin, the reaction temperature was controlled at 50°C, and the residence time of the reactant was about 0.5h.

After the detection of the online Raman spectroscopic detector LM3 set at the seventh stage of the second reactor R2, it was determined that the conversion rate of acrolein cyanohydrin was 91.6%, and the molar ratio of residual acrolein cyanohydrin to acetic anhydride was 1.76:1 , the amount of acetic anhydride that needs to be added is calculated to be 5.2 g/min, and the additional acetic anhydride and acrolein cyanohydrin continue to react in the 8th to 10th stages of the second reactor R2, so that acrolein cyanohydrin is fully converted. The content of acrolein cyanohydrin in the ACA reaction solution was detected by the online Raman spectrometer LM4 on the top discharge pipeline of the second reactor R2, and the content of acrolein cyanohydrin was lower than the detection limit, confirming that the acrolein cyanohydrin reaction was basically complete.

The ACA-containing reaction solution was passed into the wiped film evaporator R3 for vacuum distillation, the reaction by-product acetic acid was removed from the top of the wiped film evaporator R3, and the crude ACA product was obtained from the bottom. ACA crude product is sent from the lower part of rectifying tower R4 to carry out rectification under vacuum, and the ACA product with a content of 84.78% is obtained at the top of the tower at 184.9 g/min. Recycle after extraction and salt formation.

Based on acrolein, 1-cyano-2-propenyl acetate was obtained in a yield of 82.6%.

Comparative Example 2

(1) Preparation of acrolein cyanohydrin

Acrolein at 85.0g/min, catalyst N,N-dimethylaminopyridine acetate at 1.8g/min were continuously added from the bottom of the conventional stirring reactor (replacing R1), and hydrocyanic acid was added at a total amount of 40.0g/min respectively. It was added from the lower part of the conventional reactor, and the total residence time of the reactants was about 1.5h.

(2) Preparation of ACA products

The obtained reaction solution containing acrolein cyanohydrin is added at the bottom of the conventional stirring reactor (replacement R2), and acetic anhydride is fed into the lower part of this reactor with 149.1 g/min, and is mixed and reacted with the reaction solution containing acrolein cyanohydrin, The reaction temperature was controlled at 50°C, and the residence time of the reactants was about 0.5h.

The ACA-containing reaction solution was passed into the wiped film evaporator R3 for vacuum distillation, the reaction by-product acetic acid was removed from the top of the wiped film evaporator R3, and the crude ACA product was obtained from the bottom. ACA crude product is sent from the lower part of rectifying tower R4 to carry out rectification under vacuum, and the ACA product with a content of 91.44% is obtained at the top of the tower at 185.9 g/min. Recycle after extraction and salt formation.

Based on acrolein, 1-cyano-2-propenyl acetate was obtained in a yield of 89.6%.

It can be seen from the above Example 1-3 and Comparative Example 1-2 that according to Example 1-3 of the present invention, the yield of the product 1-cyano-2-propenyl acetate (calculated according to acrolein) can be It can reach more than 99.3%, and the purity can reach more than 99.83%. In Comparative Example 1, which uses the same multi-stage stirring first reactor R1 and second reactor R2 as in Example 1, but does not use the catalyst of the present invention, its product 1-cyano-2-propenylethyl The yield of the acid ester was only 82.6%, and the purity was only 84.78%. In Comparative Example 2, it did not use the multi-stage stirring first reactor R1 and the second reactor R2 of the present invention, but only used the same catalyst as in Example 1, and its product was 1-cyano-2-propenylacetic acid The yield of the ester was 89.6% and the purity was 91.44%.

Claims (10)

1. A method for preparing 1-cyano-2-propenyl acetate, comprising the steps of:

(1) reacting hydrocyanic acid and acrolein in the presence of a first catalyst to obtain a reaction solution containing acrolein cyanohydrin;

(2) reacting the obtained reaction liquid containing acrolein cyanohydrin with an esterifying agent in the presence of a second catalyst to obtain a reaction liquid containing 1-cyano-2-propenyl acetate;

the first catalyst and the second catalyst are the same or different and are each independently N, N-dimethylaminopyridine carboxylate, preferably N, N-dimethylaminopyridine formate, N-dimethylaminopyridine acetate, N-dimethylaminopyridine propionate, N-dimethylaminopyridine butyrate, N-dimethylaminopyridine valerate, N-dimethylaminopyridine hexanoate, N-dimethylaminopyridine octanoate, N-dimethylaminopyridine decanoate, N-dimethylaminopyridine oxalate, N-dimethylaminopyridine citrate, N-dimethylaminopyridine malate, N-dimethylaminopyridine succinate, N-dimethylaminopyridine adipate, N-dimethylaminopyridine succinate, N-dimethylaminopyridine butyrate, N-dimethylaminopyridine valerate, N-dimethylaminopyridine octanoate, N, And one or more of N, N-dimethylaminopyridine sebacate; more preferably N, N-dimethylaminopyridine acetate.

2. The process for producing 1-cyano-2-propenyl acetate according to claim 1, wherein,

in the step (1), the molar ratio of hydrocyanic acid to acrolein is 1-1.02: 1, and the mole number of the added amount of the first catalyst is 0.05-2% of the mole number of the added amount of acrolein, preferably 0.1-1%;

in the step (2), the molar ratio of the esterifying agent to the acrolein cyanohydrin is 1-1.02: 1, and the molar number of the added amount of the second catalyst is 0.05-2%, preferably 0.1-1% of the molar number of the added amount of the acrolein.

3. The production method of 1-cyano-2-propenyl acetate according to claim 1 or 2, wherein the esterifying agent is selected from at least one of acid chloride and acid anhydride; wherein the acid chloride comprises acetyl chloride, propionyl chloride, butyryl chloride, acetyl bromide, or benzyl chloride; the acid anhydride comprises acetic anhydride, propionic anhydride or butyric anhydride.

4. The process for producing 1-cyano-2-propenylacetate according to any one of claims 1 to 3, wherein the reaction of the step (1) is carried out in a first reactor,

and the step (1) further comprises detecting residual amounts of acrolein and hydrocyanic acid in the reaction liquid containing acrolein cyanohydrin at an upper middle portion of the first reactor, and detecting a content of residual acrolein in the reaction liquid containing acrolein cyanohydrin at a top outlet of the first reactor.

5. The process for producing 1-cyano-2-propenylacetate according to any one of claims 1 to 4, wherein the reaction of the step (2) is carried out in a second reactor,

and the step (2) further comprises detecting the contents of acrolein cyanohydrin and esterifying agent in the reaction liquid containing 1-cyano-2-propenylacetate at an upper middle portion of the second reactor, and detecting the residual amount of acrolein cyanohydrin in the reaction liquid containing 1-cyano-2-propenylacetate at a top outlet of the second reactor.

6. The method for producing 1-cyano-2-propenyl acetate according to claim 4 or 5, wherein each detection in the step (1) and the step (2) is performed by an on-line Raman spectrum.

7. The process for producing 1-cyano-2-propenylacetate according to claim 4, wherein the reaction temperature in the first reactor is increased from a lower portion to an upper portion in the step (1).

8. The method for producing 1-cyano-2-propenyl acetate according to claim 4, wherein in the step (1), the temperature of the lower portion of the first reactor is-10 to 10 ℃, preferably-5 to 5 ℃; the upper temperature is 10-50 ℃, and preferably 20-40 ℃; the residence time of the reactants in the first reactor is 0.1-2 h, preferably 0.3-1 h.

9. The method for producing 1-cyano-2-propenyl acetate according to claim 5, wherein the reaction temperature in the second reactor in the step (2) is 20 to 60 ℃, preferably 30 to 50 ℃; the residence time of the reactants in the second reactor is 0.5-2 h.

10. The process for producing 1-cyano-2-propenylacetate according to claim 4 or 5, wherein the first reactor and the second reactor each employ a multistage stirring reactor, and the number of stirring stages of the first reactor and the second reactor is 6 to 30 stages each, preferably 10 to 20 stages each.

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