CN111393321A - Preparation method of 1-cyano-2-propenyl acetate - Google Patents
Preparation method of 1-cyano-2-propenyl acetate Download PDFInfo
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- CN111393321A CN111393321A CN202010431484.0A CN202010431484A CN111393321A CN 111393321 A CN111393321 A CN 111393321A CN 202010431484 A CN202010431484 A CN 202010431484A CN 111393321 A CN111393321 A CN 111393321A
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- C07C253/08—Preparation of carboxylic acid nitriles by addition of hydrogen cyanide or salts thereof to unsaturated compounds
- C07C253/10—Preparation of carboxylic acid nitriles by addition of hydrogen cyanide or salts thereof to unsaturated compounds to compounds containing carbon-to-carbon double bonds
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- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
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Abstract
The invention relates to a preparation method of 1-cyano-2-propenyl acetate. The method comprises 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) 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 a N, N-dimethylaminopyridine carboxylate. According to the preparation method provided by the invention, the high-efficiency catalyst N, N-dimethylamino pyridine carboxylate is used as a catalyst shared by the two-step reaction, so that the two-step main reaction can be efficiently catalyzed, and the two-step main reaction can be carried out according to a near stoichiometric ratio; the yield of the product 1-cyano-2-propenyl acetate can reach more than 99 percent, and the purity can reach more than 99.5 percent; and the investment is saved, and the product competitiveness is improved.
Description
Technical Field
The invention relates to a preparation method of 1-cyano-2-propenyl acetate, belonging to the field of organic synthesis.
Background
1-cyano-2-propenyl acetate (ACA) is mainly used as an intermediate for producing glufosinate-ammonium as a pesticide.
The synthesis routes of ACA are mainly two: one is that acrolein reacts with hydrocyanic acid or hydrocyanic acid aqueous solution to produce acrolein cyanohydrin first, acrolein cyanohydrin got reacts with organic acyl halide or acid anhydride to get ACA reaction solution, extract organic phase from reaction solution with ether, organic phase is neutralized by sodium carbonate solution, anhydrous sodium sulfate is dried, filtered, rectified to get product ACA; the other is that acrolein is mixed with NaCN or NaCN aqueous solution, then mixed with acid anhydride, and reacted by a one-pot method to obtain ACA reaction liquid, and then the ACA product is obtained by post-treatment.
Patent CN108727220A discloses a process for the preparation of acrolein cyanohydrin. The process 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 to 80 ℃, thereby obtaining a crude product containing a compound of formula (I) (such as acrolein cyanohydrin) and hydrocyanic acid; the hydrocyanic acid is at least partially removed from the crude product by stripping, whereby a pure product comprising the compound of the formula (I) is obtained.
The alkali is ammonia, trialkylamine and ammonium salt, preferably triethylamine, ammonium carbonate and ammonium bicarbonate. The invention is preferably carried out with a 30% molar excess of hydrocyanic acid, after the preparation of acrolein cyanohydrin, hydrocyanic acid is removed.
In the course of the above reaction, an excess of the reactant hydrocyanic acid occurs in order to convert it as completely as possible into acrolein cyanohydrin. This not only wastes raw materials, but also causes self-polymerization due to the presence of excess hydrocyanic acid.
R.M. Nowak [ J.org.chem.28, p1182-1187] acrolein is slowly added into a sodium cyanide solution, the temperature is controlled to be-10-0 ℃, then acetic anhydride is dripped, and after reaction, ether is used for extraction and refining to obtain the ACA. When sodium cyanide is present during the reaction: when the ratio of acrolein to acrolein is 2:1, the reaction yield can reach 90%, but the yield under the condition of equimolar reaction is only 55-65%.
H.Ohse and R.Palm [ Angew.chem.78, p1093] mixing 0.77mol of acrolein and 1.12mol of aqueous solution of sodium cyanide, dripping 0.77mol of acetic anhydride into the mixture to react to obtain ACA reaction liquid, and carrying out post-treatment to obtain the ACA product. The excess of NaCN in this reaction was about 45% and gave an ACA product in 87% yield.
McIntosh [ Can.J. chem.55, p4200] uses solvent dilution to increase the ACA reaction efficiency, and uses phase transfer catalyst (TEABC) and dichloromethane as solvent, with KCN in 20% excess and 66% yield. The separation and purification steps at the later stage of the method are complicated, and a large amount of waste water is generated to be treated, and although the cyanide excess in the process is less, the separation and recovery cost of the phase transfer catalyst is a problem to be considered.
Patent US4336206 discloses a process for the preparation of ACA. In this process, an aldehyde, an aqueous cyanide solution, an organic acid chloride or an acid anhydride is reacted in an inert water-immiscible organic solvent, and the aldehyde: cyanide compound: the molar ratio of acid chlorides or acid anhydrides is about 1:1 to 1.1. The reaction process may be a batch operation or a continuous operation. In example 4 of these, 814 g of 26.5% NaCN aqueous solution (4.4 mol) and 800 g of methylene chloride were charged into a 4L flask and cooled to 0 ℃. 236 g of acrolein (4.0 mol) and 449 g of acetic anhydride (4.4 mol) in admixture with 180 g of methylene chloride are each added dropwise simultaneously over 30 minutes with stirring. The reaction temperature was maintained at 0 ℃ by external cooling. After the completion of the dropwise addition, 360g of water was added to dissolve the precipitated salt, the mixture was allowed to stand for phase separation, and the lower organic phase was distilled without drying. After removal of the dichloromethane by distillation at atmospheric pressure, 480 g of ACA product with a purity of 98% and a theoretical yield of 96% were also obtained by distillation at 20mbar and 73 ℃. The method needs to use a large amount of solvent, generates a large amount of cyanide-containing salt wastewater, needs to be subjected to environment-friendly treatment, increases the environment-friendly cost, and still has room for improving the purity and yield of the product.
Disclosure of Invention
Problems to be solved by the invention
In order to solve the problems of the different synthesis processes, the invention provides a method for continuously preparing 1-cyano-2-propenyl acetate, which takes acrolein and hydrocyanic acid as starting materials and obtains the 1-cyano-2-propenyl acetate (namely ACA) with high purity and high yield through two-step reaction of hydrocyanation addition and esterification in the presence of a specific catalyst.
Means for solving the problems
According to the present invention, there is provided a method for continuously 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.
The method for continuously preparing the 1-cyano-2-propenyl acetate provided by the invention is characterized in that in the step (1), the molar ratio of the hydrocyanic acid to the acrolein is 1-1.02: 1, the addition amount of the first catalyst is 0.05-2% of the addition amount of the acrolein, and is 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.
The method for continuously preparing 1-cyano-2-propenyl acetate according to the present invention is provided, 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.
The method for continuously preparing 1-cyano-2-propenyl acetate according to the present invention, 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.
The process for continuously preparing 1-cyano-2-propenyl acetate according to the present invention, wherein the reaction of the step (2) is carried out in the 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.
According to the method for continuously preparing the 1-cyano-2-propenyl acetate, provided by the invention, each detection in the step (1) and the step (2) is carried out by adopting an online Raman spectrum.
According to the present invention, there is provided a process for continuously producing 1-cyano-2-propenylacetate, wherein, in the step (1), the reaction temperature is increased from the lower portion to the upper portion in the first reactor.
The method for continuously preparing the 1-cyano-2-propenyl acetate, provided by the invention, is characterized in that in the step (1), the temperature of the lower part of the first reactor is-10 ℃, and preferably-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.
The method for continuously preparing the 1-cyano-2-propenyl acetate, provided by the invention, is characterized in that in the step (2), the reaction temperature in the second reactor is 20-60 ℃, and preferably 30-50 ℃; the residence time of the reactants in the second reactor is 0.5-2 h.
According to the method for continuously preparing the 1-cyano-2-propenyl acetate, the first reactor and the second reactor respectively adopt a multi-stage stirring reactor, and the stirring stages of the first reactor and the second reactor are respectively 6-30 stages, preferably 10-20 stages.
ADVANTAGEOUS EFFECTS OF INVENTION
Compared with the prior art, the invention has the beneficial effects that:
(1) by the specific selection of the catalyst, that is, when a highly efficient catalyst such as N, N-dimethylaminopyridine carboxylate is selected as a catalyst common to the two-step reaction, it is possible to efficiently catalyze the progress of the two-step main reaction, so that the two-step main reaction can be conducted in a near stoichiometric ratio.
In addition, in the preferred embodiment, the detection control is carried out on the two-step reaction by adopting the on-line Raman spectrum, so that the reaction which is further close to the stoichiometric ratio can be realized by the two-step reaction, the probability of side reaction is greatly reduced, the reaction selectivity is improved, and the post-treatment steps and the cost are reduced.
The yield (calculated according to acrolein) of the product 1-cyano-2-propenyl acetate can reach more than 99 percent, and the purity can reach more than 99.5 percent.
(2) The solvent is not needed in the whole reaction process, so that the subsequent steps of removing the solvent are reduced. The operation can be simplified and the cost can be reduced.
(3) In the preferred embodiment, a multistage stirring, multistage dripping and graded temperature control reactor is adopted, so that the operation and the control are convenient, the investment can be saved, and the product competitiveness is improved.
Drawings
FIG. 1 is a flow chart for the continuous preparation of 1-cyano-2-propenyl acetate.
FIG. 2 is a comparison of Raman spectra of hydrocyanic acid, acrolein, and acrolein cyanohydrin.
FIG. 3 is a comparison of the Raman spectra of cyanohydrin acrylate and ACA.
FIG. 4 is a comparison of the Raman spectra of acetic acid and acetic anhydride.
Wherein, each symbol in fig. 1 represents the following meanings:
r1-first reactor
R2-second reactor
R3-evaporator
R4-rectifying tower
L M1-L M4 Raman spectrum detector
Detailed Description
The following will explain in further detail a specific embodiment of the process for producing 1-cyano-2-propenyl acetate according to the present invention with reference to the drawings.
According to the present invention, there is provided a method for continuously preparing 1-cyano-2-propenyl acetate, comprising the steps of:
(1) reacting hydrocyanic acid with acrolein in the presence of a first catalyst to obtain a reaction liquid 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.
This will be described in more detail below.
(1) Preparation of acrolein cyanohydrin
The reaction takes hydrocyanic acid and acrolein as raw materials, and the addition reaction is carried out in a first reactor R1 under the action of a first catalyst to obtain the acrolein cyanohydrin. The reaction formula is as follows:
wherein the first catalyst is N, N-dimethylamino pyridine carboxylate; preferably, N, N-dimethylaminopyridine formate, N, N-dimethylaminopyridine acetate, N, N-dimethylaminopyridine propionate, N, N-dimethylaminopyridine butyrate, N, N-dimethylaminopyridine valerate, N, N-dimethylaminopyridine 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, N, N-dimethylaminopyridine sebacate; more preferably, N, N-dimethylaminopyridine acetate.
Preferably, in order to ensure that the acrolein and the hydrocyanic acid react according to the required molar ratio in the step (1), a Raman spectrum detector L M1 is arranged at the middle upper part of the first reactor R1, the residual amount of the acrolein and the hydrocyanic acid in the acrolein-cyanohydrin reaction liquid is detected, the molar ratio of the residual acrolein and the hydrocyanic acid in the obtained reaction liquid is calculated, and the amount of the supplemented hydrocyanic acid is determined according to the residual amount of the acrolein and the hydrocyanic acid, so that the acrolein can be completely consumed in the reaction;
meanwhile, a Raman spectrum detector L M2 is arranged at the top outlet of the first reactor R1, whether the acrolein is completely reacted or not is analyzed by detecting the content of residual acrolein in the acrolein-cyanohydrin reaction liquid, and if the acrolein is not completely reacted, the addition amount of hydrocyanic acid is finely adjusted to ensure that the acrolein is completely consumed in the reaction.
The detection by raman spectroscopy in step (1) is specifically described below.
The Raman spectrum detector L M1 is used for analyzing the content of acrolein and hydrocyanic acid in the reaction liquid containing acrolein cyanohydrin, and the wave number can be 1200cm-1The acrolein content was determined by the characteristic absorption peak of (FIG. 2) at a wavenumber of 2100cm-1After sufficient reaction at the upper stages of the first reactor R1, a check was again performed by Raman spectroscopy detector L M2 at the top outlet to analyze whether acrolein was completely reacted, and if not, the amount of hydrocyanic acid was finely adjusted by the residual amount of acrolein or hydrocyanic acid to ensure complete reaction of acrolein, the flow chart of which is shown in FIG. 1.
In the step (1), the molar ratio of the raw material hydrocyanic acid to the acrolein is 1-1.02: 1; and the first catalyst is added in a mole number of 0.05-2%, preferably 0.1-1% of the mole number of the acrolein.
In a preferable case, in the step (1), the reaction temperature is gradually increased from the lower portion to the upper portion of the first reactor R1. Preferably, the temperature of the lower part of the first reactor R1 is controlled to be-10 ℃, and more preferably-5 ℃; the upper temperature of the first reactor R1 is 10 to 50 ℃, and more preferably 20 to 40 ℃. In addition, the residence time of the reactant in the first reactor R1 is preferably 0.1 to 2 hours, and more preferably 0.3 to 1 hour.
Preferably, in the step (1), the first reactor R1 is a multi-stage stirring reactor, and the number of stirring stages is 6-30 stages, preferably 10-20 stages. Moreover, it is more preferable that the reaction temperature of each stirring zone of the first reactor R1 can be controlled independently.
(2) Preparation of ACA products
Under the action of the second catalyst, acrolein cyanohydrin reacts with an esterifying agent in the second reactor R2 to obtain a reaction liquid containing 1-cyano-2-propenyl acetate. The reaction formula is as follows:
in the step (2), the second catalyst is N, N-dimethylamino pyridine carboxylate; preferably, one or more of N, N-dimethylaminopyridine formate, N, N-dimethylaminopyridine acetate, N, N-dimethylaminopyridine propionate, N, N-dimethylaminopyridine butyrate, N, N-dimethylaminopyridine valerate, N, N-dimethylaminopyridine 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 sebacate; more preferably, N, N-dimethylaminopyridine acetate.
The second catalyst used in step (2) may be the same as or different from the first catalyst used in step (1), and preferably the second catalyst is the same as the first catalyst, so that the catalyst may not be replaced during the entire reaction.
Preferably, in order to ensure that the acrolein cyanohydrin reacts with the esterifying agent in the required molar ratio in the step (2), a Raman spectrum detector L M3 is arranged at the middle upper part of the second reactor R2, the molar ratio of the residual acrolein cyanohydrin to the esterifying agent is determined by detecting the content of the acrolein cyanohydrin and acetic anhydride in the ACA-containing reaction liquid, and the amount of the supplementary esterifying agent is determined according to the content, so that the acrolein cyanohydrin can be completely consumed in the esterification reaction;
meanwhile, a Raman spectrum detector L M4 is arranged on an outlet pipeline at the top of the second reactor R2, whether the acrolein cyanohydrin is completely reacted or not is analyzed by detecting the residual amount of the acrolein cyanohydrin in the reaction liquid containing the ACA, and if the acrolein cyanohydrin is not completely reacted, the addition amount of the esterifying agent is finely adjusted to ensure that the acrolein cyanohydrin is completely consumed in the reaction.
The detection by raman spectroscopy in step (2) is specifically described below.
The content of acrolein cyanohydrin and an esterifying agent such as acetic anhydride in the reaction solution containing ACA is analyzed by Raman spectrum detector L M3 with wavenumber of 1110cm-1Determination of the acrolein cyanohydrin content by means of the characteristic absorption peaks (FIG. 3) with wave number of 780cm-1The characteristic absorption peaks from here (FIG. 4) are used to determine the amount 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 the amount of esterification agent, such as acetic anhydride, added, the amount of esterification agent, such as acetic anhydride, can be determined after sufficient reaction at the upper stages of the second reactor R2, analysis of whether or not the acrolein cyanohydrin has been completely reacted is carried out by detecting again at the top discharge Raman spectrum detector L M4, and if not, the amount of esterification agent is fine-tuned by the residual amount of acrolein cyanohydrin or esterification agent to ensure complete reaction of acrolein cyanohydrin, the flow chart of which is shown in FIG. 1.
In the step (2), the molar ratio of the esterifying agent to the acrolein cyanohydrin is 1-1.02: 1, and the mole number of the added amount of the second catalyst is 0.05-2%, preferably 0.1-1% of the mole number of the added amount of the acrolein.
In step (2), the esterification agent may employ an esterification agent commonly used in the art. For example, the esterifying agent may include at least one selected from the group consisting of acid chlorides and acid anhydrides. Wherein, preferably, the acid chloride comprises acetyl chloride, propionyl chloride, butyryl chloride, acetyl bromide, or benzyl chloride; and preferably, the acid anhydride comprises acetic anhydride, propionic anhydride, or butyric anhydride.
Preferably, in the step (2), the reaction temperature in the second reactor R2 is 20-60 ℃, more preferably 30-50 ℃; and the residence time of the reactant in the second reactor R2 is 0.5-2 h.
In the step (2), the second reactor R2 preferably uses a multi-stage stirring reactor, and the stirring stage number thereof is 6-30 stages, preferably 10-20 stages.
Preferably, step (2) further comprises: the reaction solution containing 1-cyano-2-propenyl acetate is put into an evaporator for reduced pressure distillation to remove the by-product acetic acid, and crude 1-cyano-2-propenyl acetate is obtained. And then, carrying out vacuum rectification on the 1-cyano-2-propenyl acetate crude product in a rectifying tower to purify the crude product to obtain a 1-cyano-2-propenyl acetate product, wherein the catalyst at the bottom of the rectifying tower can be recycled and reused.
In the above process, the evaporator may be a conventional evaporation apparatus, and preferably a wiped film evaporator.
The core of the invention is that the high-efficiency catalyst N, N-dimethylamino pyridine carboxylate is selected, the N, N-dimethylamino pyridine carboxylate can be used as a catalyst shared by two-step reactions, and the catalyst can efficiently catalyze the two-step main reactions, so that the two-step reactions can be carried out according to a near stoichiometric ratio.
In addition, according to the preferred embodiment of the invention, on the basis of a precise control means of the mixture ratio of the reaction materials, the online Raman spectrum is adopted to carry out two-stage detection on each reactor, so that the materials can be ensured to react according to the required metering ratio, and the main raw materials can be ensured to react completely.
In addition, according to another preferred embodiment of the invention, in order to meet the requirement that the reaction system needs to be dripped and heated according to the program, the invention adopts a tower reactor formed by combining a plurality of stages of stirring reactors with independent temperature control, the reactor has compact structure and low equipment investment, thereby reducing the comprehensive production cost and improving the product competitiveness.
The flow of the process for producing 1-cyano-2-propenyl acetate according to the present invention is described in further detail below with reference to FIG. 1.
(1) Preparation of acrolein cyanohydrin
Continuously adding acrolein and a catalyst from the bottom of a first reactor R1, respectively adding hydrocyanic acid from inlets of each stage at the lower part of the first reactor R1, reacting the acrolein and the hydrocyanic acid, and controlling the reaction temperature of the first reactor R1 to be increased from the lower part to the upper part, wherein the lower part temperature is-10 ℃, and preferably-5 ℃; the upper temperature is 10-50 ℃, and preferably 20-40 ℃; the residence time of the reactants in the first reactor R1 is 0.1-2 h, preferably 0.3-1 h.
The content of acrolein and hydrocyanic acid in the acrolein-containing cyanohydrin reaction liquid was analyzed by detection by an online Raman spectrum detector L M1 provided at the upper part of the first reactor R1, whereby the molar ratio of residual acrolein to hydrocyanic acid was calculated and the amount of hydrocyanic acid added was determined, the added hydrocyanic acid was continuously reacted with acrolein at the upper part of the first reactor R1 to sufficiently convert acrolein, analysis was made as to whether acrolein was completely reacted or not by detection by an online Raman spectrum detector L M2 at the top outlet of the first reactor R1, and the amount of hydrocyanic acid was finely adjusted to ensure complete reaction of acrolein if not.
(2) Preparation of ACA products
The reaction liquid containing acrolein cyanohydrin coming out from the top of the first reactor R1 is respectively added from each stage at the lower part of the second reactor R2, an esterifying agent is sent to the 1 st stage at the lower part of the second reactor R2 and is mixed with the reaction liquid containing acrolein cyanohydrin for reaction, and the reaction temperature in the second reactor R2 is controlled to be 20-60 ℃, and preferably 30-50 ℃; the residence time of the reactants in the second reactor R2 is 0.5-2 h.
The contents of acrolein cyanohydrin and esterifying agent in the ACA-containing reaction solution were analyzed by an on-line raman spectroscopy detector L M3 provided at the middle upper portion of the second reactor R2, from which the molar ratio of residual acrolein cyanohydrin to esterifying agent was calculated and the amount of the added esterifying agent was determined, the added esterifying agent and acrolein cyanohydrin were continuously reacted at the upper portion of the second reactor R2 to sufficiently convert the acrolein cyanohydrin, whether the acrolein cyanohydrin was completely reacted was analyzed by an on-line raman spectroscopy detector L M4 on the top discharge line of the second reactor R2, and if not completely reacted, the amount of esterifying agent was finely adjusted by the residual amount of acrolein cyanohydrin or esterifying agent to ensure complete reaction of the acrolein cyanohydrin.
Introducing the reaction liquid containing ACA into an evaporator R3 for reduced pressure distillation, introducing a heating medium (such as steam) for heating from the lower part, removing acetic acid as a reaction by-product from the top, obtaining a crude product of ACA from the bottom, introducing the crude product of ACA from the lower part of a rectifying tower R4 for reduced pressure rectification, obtaining a purified ACA product from the top of the tower, and recovering a mixture of a catalyst and a small amount of the by-product from the bottom of the tower, wherein the mixture can be recycled after neutralization, extraction and salification.
The controller in fig. 1 is a controller for on-line raman spectroscopy.
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
In the following examples and comparative examples, the purity of the product ACA was measured by gas chromatography; and the yield of the product ACA is calculated using the following formula:
yield of ACA product is equal to mole number of acrolein corresponding to product/mole number of acrolein raw material
Example 1
The continuous preparation of 1-cyano-2-propenyl acetate was carried out according to the scheme shown in FIG. 1. Wherein:
r1 is a multi-stage stirring reactor with the diameter of 0.1m and the height of 1m, the total number of stages is 10,
r2 is a multi-stage stirring reactor with the diameter of 0.1m and the height of 1.1m, the total number of stages is 10,
r3 is a wiped film evaporator,
r4 is a vacuum rectification tower.
(1) Preparation of acrolein cyanohydrin
Acrolein of 85.0g/min and N, N-dimethylaminopyridine acetate of catalyst of 1.8g/min are continuously added from the bottom of a first reactor R1, hydrocyanic acid is respectively added from 1-5 stages at the lower part of the first reactor R1 in a total amount of 40.0g/min, so that the acrolein and the hydrocyanic acid react, wherein the reaction temperature of 1-3 stages is controlled to be about-5 ℃, the reaction temperature of 4-5 stages is controlled to be about 0 ℃, the reaction temperature of 6-10 stages from the lower part of the first reactor R1 is controlled to be about 10 ℃, 20 ℃, 25 ℃, 30 ℃ and 35 ℃ in sequence, and the total retention time of reactants is about 1 h.
The detection of an online Raman spectrum detector L M1 arranged at the 7 th stage of the first reactor R1 determines that the acrolein is converted by 96.2 percent, the molar ratio of the residual hydrocyanic acid to the acrolein is 1:1.33, the amount of hydrocyanic acid required to be added is calculated to be 0.5g/min according to the calculation, the added hydrocyanic acid and the acrolein continue to react at the 8 th to 10 th stages of the first reactor R1 so that the acrolein is fully converted, and the detection of the online Raman spectrum detector L M2 at the top outlet of the first reactor R1 determines that the acrolein content in the reaction liquid containing the acrolein cyanohydrin is lower than the detection limit and the acrolein is basically reacted completely.
(2) Preparation of ACA products
The reaction liquid containing acrolein cyanohydrin from the first reactor R1 is added from 1-5 stages at the lower part of the second reactor R2, acetic anhydride is fed into the 1 st stage at the lower part of the second reactor R2 at 149.1g/min, and is mixed with the reaction liquid containing acrolein cyanohydrin and reacts, the reaction temperature is controlled at 50 ℃, and the residence time of reactants is about 0.5 h.
The detection of an online Raman spectrum detector L M3 arranged at the 7 th stage of a second reactor R2 determines that the conversion rate of acrolein cyanohydrin is 96.6 percent, the molar ratio of residual acrolein cyanohydrin to acetic anhydride is 1.23:1, the amount of acetic anhydride required to be supplemented is calculated to be 1.2g/min, the supplemented acetic anhydride and the acrolein cyanohydrin continuously react at the 8 th to 10 th stages of the second reactor R2 to fully convert the acrolein cyanohydrin, the content of the acrolein cyanohydrin in the ACA reaction liquid is lower than the detection limit through the detection of the online Raman spectrum detector L M4 on a discharge pipeline at the top of the second reactor R2, and the substantial complete reaction of the acrolein cyanohydrin is determined.
Introducing the ACA-containing reaction solution into a wiped film evaporator R3 for reduced pressure distillation, removing acetic acid as a reaction byproduct from the top of the wiped film evaporator R3, and obtaining crude ACA from the bottom. The crude ACA is fed from the lower part of a rectifying tower R4 for decompression and rectification, the ACA product with the content of 99.91 percent is obtained at the tower top at 184.9g/min, and the mixture of the catalyst and a small amount of by-products is at the tower bottom and can be recycled and reused after neutralization, extraction and salification.
1-cyano-2-propenyl acetate was obtained in a yield of 99.3% calculated as acrolein.
Example 2
The continuous preparation of 1-cyano-2-propenyl acetate was carried out according to the scheme shown in FIG. 1. Wherein:
r1 is a multi-stage stirring reactor with the diameter of 0.1m and the height of 1.5m, the total number of stages is 15,
r2 is a multi-stage stirring reactor with the diameter of 0.2m and the height of 3.2m, the total number of stages is 15,
r3 is a wiped film evaporator,
r4 is a vacuum rectification tower.
(1) Preparation of acrolein cyanohydrin
Acrolein of 255.0g/min and N, N-dimethylaminopyridine citrate of 2.7g/min are continuously added from the bottom of a first reactor R1, hydrocyanic acid is respectively added from 1-8 stages at the lower part of the first reactor R1 in a total amount of 120.0g/min, so that the acrolein and the hydrocyanic acid react, wherein the reaction temperature of 1-4 stages is controlled to be about-5 ℃, the reaction temperature of 5-8 stages is controlled to be about 5 ℃, the reaction temperature of 9-15 stages from the lower part of the first reactor R1 is controlled to be about 10 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃ and 45 ℃ in turn, and the total retention time of reactants is about 0.5 h.
The detection of an online Raman spectrum detector L M1 arranged at the 10 th stage of the first reactor R1 confirms that the acrolein is converted by 96.8 percent, the molar ratio of the residual hydrocyanic acid to the acrolein is 1:1.27, the amount of hydrocyanic acid required to be added is calculated to be 0.4g/min according to the calculation, the added hydrocyanic acid and the acrolein continue to react at the 11 th to 15 th stages of the first reactor R1 so that the acrolein is fully converted, and the detection of the online Raman spectrum detector L M2 at the top outlet of the first reactor R1 confirms that the acrolein content in the reaction liquid containing the acrolein cyanohydrin is lower than the detection limit, and the acrolein is basically reacted completely.
(2) Preparation of ACA products
The reaction liquid containing acrolein cyanohydrin from the first reactor R1 is added from 1-8 stages at the lower part of the second reactor R2, acetic anhydride is fed into the 1 st stage at the lower part of the second reactor R2 at 447.2g/min, and is mixed with the reaction liquid containing acrolein cyanohydrin and reacts, the reaction temperature is controlled at 30 ℃, and the residence time of reactants is about 2.0 h.
The detection of an online Raman spectrum detector L M3 arranged at the 10 th stage of a second reactor R2 determines that the conversion rate of acrolein cyanohydrin is 96.9%, the molar ratio of residual acrolein cyanohydrin to acetic anhydride is 1.21:1, the amount of acetic anhydride required to be supplemented is calculated to be 2.9g/min, the supplemented acetic anhydride and the acrolein cyanohydrin continuously react at the 11 th to 15 th stages of the second reactor R2 to fully convert the acrolein cyanohydrin, and the detection of the online Raman spectrum detector L M4 on a discharge pipeline at the top of the second reactor R2 determines that the acrolein cyanohydrin content in the ACA-containing reaction liquid is lower than the detection limit and the substantial complete reaction of the acrolein cyanohydrin.
Introducing the ACA-containing reaction solution into a wiped film evaporator R3 for reduced pressure distillation, removing acetic acid as a reaction byproduct from the top of the wiped film evaporator R3, and obtaining crude ACA from the bottom. The ACA crude product is fed from the lower part of a rectifying tower R4 to be rectified under reduced pressure, the ACA product with the content of 99.89 percent is obtained at the tower top at 556.7g/min, and the mixture of the catalyst and a small amount of by-products is at the tower bottom and can be recycled and reused after neutralization, extraction and salification.
1-cyano-2-propenyl acetate was obtained in a yield of 99.6% calculated as acrolein.
Example 3
The continuous preparation of 1-cyano-2-propenyl acetate was carried out according to the scheme shown in FIG. 1. Wherein:
r1 is a multi-stage stirring reactor with the diameter of 0.1m and the height of 2.0m, the total number of stages is 20,
r2 is a multi-stage stirring reactor with the diameter of 0.2m and the height of 3.6m, the total number of stages is 20,
r3 is a wiped film evaporator,
r4 is a vacuum rectification tower.
(1) Preparation of acrolein cyanohydrin
Acrolein of 566.7g/min and N, N-dimethylaminopyridine adipate of a catalyst of 1.2g/min are continuously added from the bottom of the first reactor R1, hydrocyanic acid is respectively added from 1-12 stages at the lower part of the first reactor R1 of 266.7g/min, so that the acrolein and the hydrocyanic acid react, wherein the reaction temperature of 1-6 stages is controlled to be about 0 ℃, the reaction temperature of 7-12 stages is controlled to be about 5 ℃, the reaction temperature of 13-20 stages from the lower part of the first reactor R1 is controlled to be about 10 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃ and 40 ℃ in turn, and the total retention time of reactants is about 0.3 h.
The on-line Raman spectrum detector L M1 arranged at the 14 th stage of the first reactor R1 is used for detecting, the conversion of acrolein is determined to be 97.2%, the molar ratio of residual hydrocyanic acid to acrolein is 1:1.35, the amount of hydrocyanic acid required to be supplemented is calculated to be 2.6g/min according to the calculation, the supplemented hydrocyanic acid and the acrolein continue to react at the 15 th to 20 th stages of the first reactor R1, so that the acrolein is fully converted, and the content of the acrolein in the reaction liquid containing the acrolein cyanohydrin is determined to be lower than the detection limit through the detection of the on-line Raman spectrum detector L M2 at the top outlet of the first reactor R1, so that the substantial reaction completion of the acrolein is determined.
(2) Preparation of ACA products
The reaction liquid containing acrolein cyanohydrin from the first reactor R1 is added from 1-12 stages at the lower part of the second reactor R2, acetic anhydride is fed into the 1 st stage at the lower part of the second reactor R2 at 996.6g/min, and is mixed with the reaction liquid containing acrolein cyanohydrin and reacts, the reaction temperature is controlled at 40 ℃, and the residence time of reactants is about 1.0 h.
The detection of an online Raman spectrum detector L M3 arranged at the 14 th stage of a second reactor R2 determines that the conversion rate of acrolein cyanohydrin is 97.3%, the molar ratio of residual acrolein cyanohydrin to acetic anhydride is 1.26:1, the amount of acetic anhydride required to be supplemented is calculated to be 7.0g/min, the supplemented acetic anhydride and the acrolein cyanohydrin continuously react at the 15 th to 20 th stages of the second reactor R2 to fully convert the acrolein cyanohydrin, and the detection of the Raman spectrum detector L M4 on a discharge pipeline at the top of the second reactor R2 determines that the acrolein cyanohydrin content in the ACA-containing reaction liquid is lower than the detection limit and the substantial complete reaction of the acrolein cyanohydrin.
Introducing the ACA-containing reaction solution into a wiped film evaporator R3 for reduced pressure distillation, removing acetic acid as a reaction byproduct from the top of the wiped film evaporator R3, and obtaining crude ACA from the bottom. The ACA crude product is fed from the lower part of a rectifying tower R4 to be rectified under reduced pressure, the ACA product with the content of 99.83 percent is obtained at the tower top at 1237g/min, and the mixture of the catalyst and a small amount of by-products is at the tower bottom and can be recycled and reused after neutralization, extraction and salification.
1-cyano-2-propenyl acetate was obtained in a yield of 99.5% calculated as acrolein.
Comparative example 1
The continuous preparation of 1-cyano-2-propenyl acetate was carried out according to the scheme shown in FIG. 1. Wherein:
r1 is a multi-stage stirring reactor with the diameter of 0.1m and the height of 1m, the total number of stages is 10,
r2 is a multi-stage stirring reactor with the diameter of 0.1m and the height of 1.1m, the total number of stages is 10,
r3 is a wiped film evaporator,
r4 is a vacuum rectification tower.
(1) Preparation of acrolein cyanohydrin
Acrolein is continuously added at 85.0g/min, a catalyst triethylamine is continuously added at 0.15g/min from the bottom of the first reactor R1, hydrocyanic acid is respectively added from 1-5 stages at the lower part of the first reactor R1 at the total amount of 40.0g/min, so that the acrolein and the hydrocyanic acid react, wherein the reaction temperature of 1-3 stages is controlled to be about-5 ℃, the reaction temperature of 4-5 stages is controlled to be about 0 ℃, the reaction temperature of 6-10 stages from the lower part of the first reactor R1 is controlled to be about 10 ℃, 20 ℃, 25 ℃, 30 ℃ and 35 ℃ in turn, and the total retention time of reactants is about 1.5 h.
The detection of an online Raman spectrum detector L M1 arranged at the 7 th stage of the first reactor R1 determines that the acrolein is converted by 90.2 percent, the molar ratio of the residual hydrocyanic acid to the acrolein is 1:1.45, the amount of hydrocyanic acid required to be added is calculated to be 0.6g/min according to the calculation, the added hydrocyanic acid and the acrolein continue to react at the 8 th to 10 th stages of the first reactor R1 so that the acrolein is fully converted, and the detection of the online Raman spectrum detector L M2 at the top outlet of the first reactor R1 determines that the acrolein content in the reaction liquid containing the acrolein cyanohydrin is lower than the detection limit and the acrolein is basically reacted completely.
(2) Preparation of ACA products
The reaction liquid containing acrolein cyanohydrin from the first reactor R1 is added from 1-5 stages at the lower part of the second reactor R2, acetic anhydride is fed into the 1 st stage at the lower part of the second reactor R2 at 149.1g/min, and is mixed with the reaction liquid containing acrolein cyanohydrin and reacts, the reaction temperature is controlled at 50 ℃, and the residence time of reactants is about 0.5 h.
The detection of an online Raman spectrum detector L M3 arranged at the 7 th stage of a second reactor R2 determines that the conversion rate of acrolein cyanohydrin is 91.6%, the molar ratio of residual acrolein cyanohydrin to acetic anhydride is 1.76:1, the amount of acetic anhydride required to be supplemented is calculated to be 5.2g/min, the supplemented acetic anhydride and the acrolein cyanohydrin continuously react at the 8 th to 10 th stages of the second reactor R2 to fully convert the acrolein cyanohydrin, and the detection of the online Raman spectrum detector L M4 on a discharge pipeline at the top of the second reactor R2 determines that the acrolein cyanohydrin in the ACA reaction liquid is basically completely reacted.
Introducing the ACA-containing reaction solution into a wiped film evaporator R3 for reduced pressure distillation, removing acetic acid as a reaction byproduct from the top of the wiped film evaporator R3, and obtaining crude ACA from the bottom. The ACA crude product is fed from the lower part of a rectifying tower R4 to be rectified under reduced pressure, the ACA product with the content of 84.78 percent is obtained at the tower top at 184.9g/min, and the mixture of the catalyst and a small amount of by-products is at the tower bottom and can be recycled and reused after neutralization, extraction and salification.
1-cyano-2-propenyl acetate was obtained in a yield of 82.6% calculated as acrolein.
Comparative example 2
(1) Preparation of acrolein cyanohydrin
Acrolein was fed continuously at 85.0g/min, catalyst N, N-dimethylaminopyridine acetate at 1.8g/min from the bottom of a conventional stirred reactor (instead of R1), hydrocyanic acid was fed separately at the lower part of the conventional reactor in a total amount of 40.0g/min, and the total residence time of the reactants was about 1.5 h.
(2) Preparation of ACA products
The resulting reaction liquid containing acrolein cyanohydrin was fed from the lower part of a conventional stirred reactor (instead of R2), acetic anhydride was fed to the lower part of the reactor at 149.1g/min, and mixed and reacted with the reaction liquid containing acrolein cyanohydrin, the reaction temperature was controlled at 50 ℃ and the residence time of the reactants was about 0.5 h.
Introducing the ACA-containing reaction solution into a wiped film evaporator R3 for reduced pressure distillation, removing acetic acid as a reaction byproduct from the top of the wiped film evaporator R3, and obtaining crude ACA from the bottom. The ACA crude product is fed from the lower part of a rectifying tower R4 to be rectified under reduced pressure, the ACA product with the content of 91.44 percent is obtained at the tower top at 185.9g/min, and the mixture of the catalyst and a small amount of by-products is at the tower bottom and can be recycled and reused after neutralization, extraction and salification.
1-cyano-2-propenyl acetate was obtained in a yield of 89.6% calculated as acrolein.
As can be seen from the above examples 1-3 and comparative examples 1-2, according to examples 1-3 of the present invention, the yield (in terms of acrolein) of the product 1-cyano-2-propenylacetic acid ester can be up to 99.3% or more, and the purity can be up to 99.83% or more. In comparative example 1, which was the same as in example 1, the first reactor R1 and the second reactor R2 were stirred in multiple stages, but the catalyst of the present invention was not used, the yield of the product, 1-cyano-2-propenylacetate, was only 82.6% and the purity was only 84.78%. In comparative example 2, which did not employ the multistage stirring first reactor R1 and second reactor R2 of the present invention, only the same catalyst as in example 1 was employed, and the yield of the product, 1-cyano-2-propenylacetate, 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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