CN105037151B - Preparation method of 3-alkoxy alkyl propionate - Google Patents

Abstract

The invention belongs to the technical field of chemical synthesis and provides a preparation method of alkyl 3-alkoxy propionate. The method uses solid base as a catalyst, and uses alkyl acrylate and low-carbon alcohol as raw materials to undergo a heterogeneous catalytic alkoxylation reaction. The low-carbon alcohol and the light component of alkyl acrylate are recycled to the alkoxy reaction step; the tower still obtains the heavy component mainly containing the product 3-alkoxy alkyl propionate. The heavy component material in the reactor of the light-removing rectification tower is separated through the refining rectification tower, and the 3-alkoxy alkyl propionate product is obtained at the top of the tower, and a small amount of high boilers are in the tower reactor. The raw material used in the present invention, as the catalyst solid base, is separated and recovered through the rectification tower, and can be directly put into the reaction again without further processing, which greatly increases the utilization efficiency of the raw material and the catalyst, reduces the production cost, and does not cause environmental pollution. pollute.

Description

A kind of preparation method of 3-alkoxy propionic acid alkyl ester

technical field

The invention belongs to the technical field of chemical synthesis and relates to a preparation method of alkyl 3-alkoxy propionate.

Background technique

Methyl 3-methoxypropionate and ethyl 3-ethoxypropionate are green and environmentally friendly organic solvents, widely used in electronics, cleaning, coatings, printing inks and other industries, and are also important solvents in organic synthesis and pharmaceutical industries. intermediate.

Patent CN101906038A discloses a method for preparing methyl 3-methoxypropionate by catalytic oxidation of 1,3-propanediol. This method uses metal oxides loaded with precious metal gold or palladium as catalysts. Oxygen is needed in the reaction process, and there is relatively Big potential safety hazard, and the highest yield of methyl 3-methoxypropionate is only 53%.

Literature [Qin Bingchang, etc. Applied Chemical Industry, 2007,36 (6): 596-598.] reported methyl acrylate and methyl alcohol under the catalysis of sodium methylate to prepare 3-methoxy propionate methyl ester, in methanol excess 1.2 times, the amount of sodium methoxide is 1.3% of the mass of methyl acrylate, react at 50°C for 3.5h, after the reaction is completed, neutralize sodium methoxide with glacial acetic acid, and the yield of methyl 3-methoxypropionate can reach 97% . Literature [Zhang Jibo, et al. Journal of Jilin Institute of Chemical Technology, 2011, 28(3): 1-3.] First prepare sodium methoxide with sodium hydroxide, methanol and anhydrous sodium sulfate at 65°C, and then methyl acrylate Add it to the above mixture, and after the reaction is over, neutralize sodium methoxide with sodium bisulfate. When the excess of methanol is 1.5 times, the amount of sodium hydroxide is 10%, and the reaction is carried out at 55° C. for 6 hours, the yield of methyl 3-methoxypropionate can reach more than 97%. Patent CN1258518C discloses a method for preparing methyl 3-methoxypropionate. In this method, methanol and sodium methoxide or potassium methoxide whose quality is 5.3% to 14.3% of methanol are stirred in a reactor for more than 10 hours, and then methanol Under the condition of 2-3 times excess, react at 45-60° C. for 2-6 hours, after the reaction, use concentrated sulfuric acid and concentrated phosphoric acid to neutralize the catalyst, and the yield of methyl methoxypropionate is up to 91.4%. Patent CN101423475B discloses a method for obtaining ethyl 3-ethoxy propionate by reacting ethyl acrylate and ethanol under the action of alkali metal or alkali metal alkoxide catalyst. When the reaction temperature is 0-80°C, the molar ratio of ethanol to ethyl acrylate is 2-3:1, the amount of catalyst is 1.5%-3% of the mass of ethyl acrylate, and the reaction time is 1-16h, the 3- The highest yield of ethyl ethoxy propionate was 89.9%. After the reaction, the catalyst is neutralized with concentrated sulfuric acid, acetic acid, hydrochloric acid, phosphoric acid, formic acid or nitric acid.

The above-mentioned method for preparing methyl 3-methoxypropionate and ethyl 3-ethoxypropionate by using an alkali metal alkoxide catalyst, because the catalyst and the reaction mixture are compatible and belong to a homogeneous reaction, all need to neutralize the alkali with acid Non-reactive catalysts not only lead to catalysts that cannot be reused and increase production costs, but also form sodium salts that need to be further treated and produce waste water that pollutes the environment.

Contents of the invention

The purpose of the present invention is to solve the problem that the yield of 3-alkoxy alkyl propionate is not high or the production cost is high and the environment is not friendly in the existing preparation method, and a kind of alkoxylation is provided to prepare 3-alkoxy A new approach to alkyl propionates.

In order to solve the above problems, the present invention adopts the following technical solutions to realize

1. The present invention provides a kind of preparation method of alkyl 3-alkoxy propionate, this method is loaded on the solid alkali that obtains on solid carrier with alkali metal alkoxide as catalyzer, with alkyl acrylate and lower carbon alcohol as catalyst Raw materials, after the three are mixed, a heterogeneous catalytic alkoxylation reaction occurs, and then the 3-alkoxy alkyl propionate product is separated, which specifically includes the following steps: 1) fresh low-carbon alcohol stream, fresh acrylic acid alkyl Base ester stream and solid base catalyst, join in the alkoxylation reactor, heterogeneous catalyzed alkoxylation reaction takes place; After the reaction is finished, obtain containing unreacted low carbon alcohol, acrylate alkyl ester and product 3- The reaction material stream of alkyl alkoxy propionate;

2) The alkoxylation reaction material liquid stream is separated in the light-removing rectification tower, and the unreacted low-carbon alcohol and alkyl acrylate light component material stream are recovered at the top of the tower, and the main product containing Alkyl 3-alkoxypropionate heavy fraction stream;

3) The heavy component stream mainly containing the product 3-alkoxy alkyl propionate is separated in the refining distillation tower, and the 3-alkoxy alkyl propionate product with a mass fraction of more than 99.5% is obtained at the top of the tower The stream is a high boiler in the tower kettle.

The low-carbon alcohol stream refers to the stream formed by the low-carbon alcohol liquid, which means the same substance as the low-carbon alcohol; the alkyl acrylate stream refers to the stream formed by the alkyl acrylate, and the same substance as the alkyl acrylate.

2. The preparation method of the 3-alkoxy alkyl propionate provided in above-mentioned 1, wherein, after step 2) the alkoxylation reaction feed liquid stream is separated in the light-removing rectification tower, the untreated The reacted low-carbon alcohol and alkyl acrylate light component stream, combined with fresh low-carbon alcohol stream and fresh alkyl acrylate stream, enters the alkoxylation reactor and is recycled for alkoxylation reaction step.

3. The preparation method of the 3-alkoxy alkyl propionate provided in the above 1, wherein, step 2) the number of theoretical plates required for the lightening rectification tower (6) is 6 to 20, preferably 9 to 14 block; the required reflux ratio is 0.1-7, preferably 0.4-1.2; the required vacuum degree is 0.05-0.095MPa, preferably 0.08-0.09MPa.

4. The preparation method of the 3-alkoxy alkyl propionate provided in the above 1, wherein, step 3) the number of theoretical plates required for the refining distillation column (9) is 6 to 20, preferably 9 to 14; The required reflux ratio is 0.1-10, preferably 0.4-1.0; the required vacuum degree is 0.07-0.1 MPa, preferably 0.085-0.095 MPa.

5. The preparation method of the 3-alkoxy alkyl propionate provided in the above 1, wherein, in the alkoxylation reaction, the molar ratio of the alkyl acrylate to the lower alcohol is 1: 1～1: 2, and the amount of solid base It is 0.5wt%-2wt% of the mass of alkyl acrylate, and the reaction temperature is 0-80°C; the water content in fresh low-carbon alcohol stream and fresh alkyl acrylate stream is lower than 0.03%.

6. The preparation method of the 3-alkoxy alkyl propionate provided in the above 1, wherein, after step 2) the dehydrogenation distillation column (6) is stable, the flow rate of each stream is the alkoxylation reaction material liquid flow The stock (5) is 480-500kg/h, the light component stream (7) is 105-110kg/h, and the heavy fraction stream (8) is 392-395kg/h.

7. The preparation method of the 3-alkoxy alkyl propionate provided in the above-mentioned 1, wherein, after step 3) the refining rectification column (9) is stable, the flow rate of each stream is the heavy fraction material stream (8) is 390-395kg/h, high boiler (11) is 3.7-7.28kg/h, 3-methoxymethyl propionate product stream (10) is 385.69-390.00kg/h.

8. The preparation method of the 3-alkoxy alkyl propionate provided in the above-mentioned 1, wherein, the obtaining process of the solid base catalyst is as follows: the alkali metal alkoxide is dissolved in the corresponding alcohol, and the solid carrier is added to the above-mentioned alcohol solution At the same time, add toluene with the same mass as alcohol, and stir and reflux for 2 to 12 hours under nitrogen atmosphere; after the reflux is completed, cool to room temperature, wash with toluene, and vacuum dry the obtained solid at 60 to 80°C for 5 hours to obtain a solid Alkaline catalyst; the solid carrier is silicon oxide or silicon-containing molecular sieve, and the molecular sieve is preferably MCM-41, SBA-15, ZSM-5.

Correspondence means that the alcohol used is set according to the alkali metal alkoxide. If the alkali metal alkoxide is sodium methoxide, the corresponding alcohol is methanol; if the alkali metal alkoxide is sodium ethoxide or potassium ethoxide, the corresponding alcohol is ethanol ;And so on.

9. the preparation method of the 3-alkoxy alkyl propionate provided by above-mentioned 8, wherein, described alkali metal alkoxide is sodium methylate or sodium ethylate or potassium methylate or potassium ethylate; The quality of described alkali metal alcoholate is 10-50% of the mass of the solid carrier.

10. The preparation method of the 3-alkoxy alkyl propionate provided in the above 1, wherein the lower alcohol is an alkyl alcohol with 1-6 carbon atoms, preferably an alkyl alcohol with 1-4 carbon atoms Alkyl alcohol; further, an alkyl alcohol with 1-3 carbon atoms is used, preferably methanol or ethanol; the alkyl acrylate is methyl acrylate or ethyl acrylate.

Compared with the traditional preparation method of alkyl 3-alkoxypropionate, the object of the present invention is to improve the use efficiency of reactants and catalysts and reduce losses through refined design of reaction and separation processes. According to the limitations of the reaction raw materials, catalysts, and reaction conditions provided by the present invention, the target product can be obtained and the goal can be achieved through corresponding steps.

Beneficial effects of the present invention:

1. The present invention optimizes the amount of reaction raw materials and reaction conditions by selecting a solid alkali catalyst, and the reaction product is separated through rectification towers twice, and the mass fraction reaches more than 99.5%, which is higher than the purity obtained by the prior art. The whole reaction process is simple, Easy to operate.

2. After the raw material used in the present invention, the solid alkali as catalyst is separated and recovered through the rectifying tower, it does not need to be reprocessed, and can be directly put into the reaction again for recycling, avoiding the use of acid neutralizer, and greatly increasing the raw material and catalyst utilization efficiency, reducing the loss of raw materials and catalysts, reducing production costs, and not causing environmental pollution.

3. The whole process of the present invention can realize automatic control, the reaction process is precise and controllable, the labor cost is reduced, the reaction efficiency is improved, and it is suitable for large-scale industrial production.

Description of drawings

Figure 1: Process flow chart of heterogeneously catalyzed alkoxylation reaction of alkyl 3-alkoxypropionate

Among them, 1-low carbon alcohol stream; 2-alkyl acrylate stream; 3-solid base catalyst; 4-alkoxylation reactor; 5-alkoxylation reaction material liquid stream; Rectification tower; 7-de-light rectification tower top recovers unreacted low-carbon alcohol and alkyl acrylate light component material stream; 8-de-light rectification tower tank mainly contains product 3-alkoxy propionic acid Alkyl ester heavy component stream; 9-refining distillation column; 10-residual high boiler; 11-3-alkoxy alkyl propionate product stream.

detailed description

The present invention will be further described below in conjunction with the examples, and the experimental methods that do not specify specific conditions in the following examples generally follow the known methods in the art.

detailed description:

The volume of the alkoxylation reactor in the following examples is 3 m ³ ; the diameters of the lightening rectification tower and the refining rectification tower are both 500 mm.

Example 1:

Dissolve 10kg of sodium methoxide in 200kg of methanol, add 20kg of MCM-41 into the above alcohol solution, and add toluene of the same mass as the alcohol at the same time, stir and reflux for 2 hours under a nitrogen atmosphere; After washing 3 times, the obtained solid matter was vacuum-dried at 80° C. for 5 h to obtain a solid base catalyst with a sodium methoxide content of 50% (the sodium methoxide content is the mass ratio of sodium methoxide to carrier MCM-41).

In a ^3m3 alkoxylation reactor, add 1200kg of fresh methyl acrylate, 893kg of fresh methanol, and 6kg of 50% sodium methoxide catalyst loaded on MCM-41, and react at 30°C for 2h. After the reaction, filter the catalyst and react The product is analyzed by gas chromatography, and the mass composition of methyl acrylate, methyl alcohol, methyl 3-methoxypropionate and high boilers is respectively 0.11%, 20.68%, 78.91% and 0.3%, and the conversion rate of methyl acrylate is 99.81%. %, the yield of methyl methoxypropionate is 99.29%. The obtained alkoxylation reaction solution passes through the dehydrogenation rectification tower and the refining rectification tower successively with the flow rate of 500kg/h for continuous separation, and after the refining rectification tower reaches stability, the product A Methyl oxypropionate, the mass fraction reaches 99.90%.

Operation parameters of the rectification tower: The theoretical plate number of the light-removing rectification tower is 12, the reflux ratio is 0.45, the vacuum degree is 0.08MPa, and the 6th tray at the feeding position; the theoretical plate number of the refining rectification tower is 9, and the reflux ratio is 0.41 , Vacuum degree 0.09MPa, the seventh tray at the feeding position.

See Table 1 for the flow rate of each stream after the rectification column reaches stability.

Table 1

Example 2:

Dissolve 10kg of potassium methoxide in 100kg of methanol, add 100kg of SBA-15 into the above alcohol solution, and add toluene of the same mass as the alcohol at the same time, stir and reflux for 2 hours under a nitrogen atmosphere; After washing with toluene 3 times, the obtained solid matter was vacuum-dried at 80° C. for 5 h to obtain a solid base catalyst with a potassium methoxide content of 10% (the potassium methoxide content is the mass ratio of potassium methoxide to carrier SBA-15).

In a ^3m3 alkoxylation reactor, add 1780kg of fresh methyl acrylate, 268.1kg of fresh methanol, and 429.2kg of a mixture of methyl acrylate and methanol, including 20kg of methyl acrylate, 401.9kg of methanol, and a total of methyl acrylate , Methanol consumption is respectively 1800kg and 676kg. 27kg of 10% potassium methylate catalyst loaded on SBA-15 was reacted at 80°C for 0.2h. After the reaction was over, the catalyst was filtered out, and the reaction product was analyzed by gas chromatography. Methyl acrylate, methanol, methyl 3-methoxypropionate The mass composition of high boiler and high boiler is respectively 0.51%, 20.08%, 78.91% and 0.5%, the conversion rate of methyl acrylate is 99.13%, and the yield of methyl methoxypropionate is 98.27%. The obtained alkoxylation reaction solution is continuously separated through the dehydrogenation rectification tower and the refining rectification tower at a flow rate of 500kg/h. After the rectification tower reaches stability, the product methoxypropane is obtained from the overhead distillate of the refining tower. Acid methyl ester, mass fraction reaches 99.75%.

Operating parameters of the rectification tower: The theoretical plate number of the light-removing rectification tower is 10, the reflux ratio is 1.0, the vacuum degree is 0.085MPa, and the fifth tray at the feeding position; the theoretical plate number of the refining rectification tower is 8, and the reflux ratio is 0.6 , Vacuum degree 0.09MPa, the 6th tray at the feeding position.

See Table 2 for the flow rate of each stream after the rectification column reaches stability.

Table 2

Example 3:

Dissolve 20kg of potassium ethoxide in 700kg of absolute ethanol, add 100kg of ZSM-5 into the above alcohol solution, and add toluene of the same mass as the alcohol at the same time, stir and reflux for 2 hours under a nitrogen atmosphere; after the reflux, cool to room temperature, After washing 3 times with 100kg toluene, the obtained solid matter was vacuum-dried at 80° C. for 5 h to obtain a solid base catalyst with a potassium ethylate content of 20% (the potassium ethylate content is the mass ratio of potassium ethylate to carrier ZSM-5).

In a ^5m3 alkoxylation reactor, add 2000kg of fresh ethyl acrylate, 40kg of 20% potassium ethoxide catalyst supported by ZSM-5, and drop 1288kg of fresh ethanol into the reactor at 0°C, and the total dropping time For 4h, after the dropwise addition, the insulation reaction was 2h. After the reaction, the catalyst was filtered out, and the reaction product was analyzed by gas chromatography. The mass compositions of ethyl acrylate, ethanol, 3-ethoxy ethyl propionate and high boilers were respectively 0.41%, 20.18%, 79.01% and 0.4%, the conversion rate of ethyl acrylate was 99.25%, and the yield of ethyl 3-ethoxypropionate was 98.53%. The obtained alkoxylation reaction solution is continuously separated through the dehydrogenation rectification tower and the refining rectification tower at a flow rate of 500kg/h. After the rectification tower reaches stability, the product 3-ethoxy Ethyl propionate, the mass fraction reaches 99.62%.

Operating parameters of the rectification tower: The theoretical plate number of the light-removing rectification tower is 12, the reflux ratio is 1.2, the vacuum degree is 0.085MPa, and the fourth tray at the feeding position; the theoretical plate number of the refining rectification tower is 12, and the reflux ratio is 0.8 , Vacuum degree 0.085MPa, the seventh tray at the feeding position.

See Table 3 for the flow rate of each stream after the rectification column reaches stability.

table 3

Example 4:

Dissolve 20kg of sodium ethoxide in 500kg of absolute ethanol, add 50kg of SiO ₂ into the above alcohol solution, and simultaneously add toluene of the same mass as the alcohol, and stir and reflux for 2 hours under a nitrogen atmosphere; after the reflux is completed, cool to room temperature and use After 100kg of toluene was washed 3 times, the solid matter obtained was vacuum-dried at 80° C. for 5 h to obtain a solid base catalyst with a sodium ethylate content of 40% (the sodium ethylate content was the mass ratio of sodium ethylate to the carrier SiO ₂ ).

In a ^3m3 alkoxylation reactor, 1780kg of fresh ethyl acrylate was added, and 248.1kg of a mixture of ethyl acrylate and ethanol was recovered, including 20kg of ethanol for acrylic acid and 225.8kg of ethanol (1:3). 18kg of sodium ethoxide catalyst loaded on _SiO2 , 1274.2kg of fresh ethanol was added dropwise into the reactor at 50°C. The total dropwise addition time was 2h. After gas chromatography analysis, the mass composition of ethyl acrylate, ethanol, ethyl 3-ethoxypropionate and high boilers were 0.31%, 20.48%, 78.91% and 0.3%, respectively, and the conversion rate of ethyl acrylate was 99.43%. , the conversion rate of ethyl acrylate was 99.45%, and the yield of ethyl ethoxy propionate was 98.88%. The obtained alkoxylation reaction solution is continuously separated through the dehydrogenation rectification tower and the refining rectification tower at a flow rate of 500kg/h. After the rectification tower reaches stability, the product 3-ethoxy Ethyl propionate, the mass fraction can reach 99.76%.

Operating parameters of the rectification tower: The theoretical plate number of the light removal rectification tower is 14, the reflux ratio is 0.6, the vacuum degree is 0.09MPa, the fourth tray at the feeding position; the number of the refining distillation tower is 10, the reflux ratio is 1.0, The vacuum degree is 0.095MPa, and the feeding position is the 6th tray. See Table 4 for the flow rate of each stream after the rectification column reaches stability.

Table 4

It can be known that the above-mentioned embodiments are only exemplary implementations adopted to illustrate the principles of the invention, but the present invention is not limited thereto, and those skilled in the art can make various improvements and changes without departing from the essence of the present invention. These improvements And changes also belong to the protection scope of the present invention.

Claims (9)

1. A preparation method for 3-alkoxy alkyl propionate, characterized in that: the method uses alkali metal alkoxide as a catalyst to carry the solid base obtained on a solid carrier, and uses alkyl acrylate and lower alcohol As a raw material, heterogeneously catalyzed alkoxylation reaction occurs after the three are mixed, and then separated to obtain 3-alkoxy propionate alkyl ester product, which specifically includes the following steps: 1) fresh low-carbon alcohol stream (1) , fresh alkyl acrylate stream (2) and solid base catalyst (3), join in the alkoxylation reactor (4), heterogeneous catalyzed alkoxylation takes place; After reaction finishes, obtain containing unreacted The reaction feed stream (5) of low-carbon alcohol, alkyl acrylate and product 3-alkoxy propionate; 2) The alkoxylation reaction material liquid stream (5) is separated in the light-removing rectification tower (6), and unreacted low-carbon alcohol and alkyl acrylate light component material stream (7) are recovered at the top of the tower ), obtain the heavy component stream (8) mainly containing product 3-alkoxy propionate alkyl ester in tower still; 3) The heavy component stream (8) mainly containing the product 3-alkoxy alkyl propionate is separated in the refining distillation column (9), and the 3-alkoxy group with a mass fraction of more than 99.5% is obtained at the top of the tower The alkyl propionate product stream (11) is a high boiler (10) in the tower still; the low-carbon alcohol is methanol or ethanol; the alkyl acrylate is methyl acrylate or ethyl acrylate. 2. the preparation method of the described 3-alkoxy propionate alkyl ester of claim 1 is characterized in that: step 2) alkoxylation reaction material liquid stream (5) is in lightening rectification column (6) After being separated in, the unreacted lower alcohol and alkyl acrylate light component stream (7) that tower top obtains, with fresh lower alcohol stream (1), fresh alkyl acrylate stream (2) After being combined, they enter the alkoxylation reactor (4) and are recycled for use in the alkoxylation reaction step. 3. the preparation method of the described 3-alkoxy propionate alkyl ester of claim 1 is characterized in that: step 2) the required theoretical plate number of lightening rectification column (6) is 10～14; The required reflux ratio is 0.45~1.2; the required vacuum degree is 0.08~0.09MPa. 4. the preparation method of 3-alkoxy propionate alkyl ester described in claim 1 is characterized in that: step 3) the required theoretical plate number of refining rectification column (9) is 8～12; The reflux ratio is 0.4~1.0; the required vacuum degree is 0.085~0.095MPa. 5. the preparation method of the described 3-alkoxy propionate alkyl ester of claim 1 is characterized in that: in the alkoxylation reaction, the molar ratio of alkyl acrylate and lower carbon alcohol is 1:1～1:2 , the solid base consumption is 0.5wt%～2wt% of the alkyl acrylate mass, and the reaction temperature is 0～80°C; the water content in the fresh low-carbon alcohol stream (1) and the fresh alkyl acrylate stream (2) is equal Less than 0.03%. 6. the preparation method of the described 3-alkoxy propionate alkyl ester of claim 1 is characterized in that: after step 2) lightening rectification column (6) stabilizes, each stream flow rate is alkoxylated The reaction feed stream (5) is 480-500kg/h, the light component stream (7) is 105-110kg/h, and the heavy component stream (8) is 392-395kg/h. 7. the preparation method of 3-alkoxy alkyl propionate as claimed in claim 1 is characterized in that: after step 3) the refining rectifying tower (9) is stable, each stream flow rate is heavy component material stream (8) is 390-395kg/h, high boiler (10) is 3.7-7.28kg/h, 3-alkoxy alkyl propionate product stream (11) is 385.69-390.00kg/h. 8. the preparation method of the described 3-alkoxy propionate alkyl ester of claim 1 is characterized in that: the obtaining process of solid base catalyst (3) is as follows: alkali metal alkoxide is dissolved in the corresponding alcohol, and The solid carrier is added to the above alcohol solution, and toluene of the same mass as the alcohol is added at the same time, and stirred and refluxed for 2 to 12 hours under a nitrogen atmosphere; Vacuum drying at °C for 5 hours to obtain a solid base catalyst (3); the solid carrier is silicon oxide or silicon-containing molecular sieves, and the molecular sieves are MCM-41, SBA-15, or ZSM-5. 9. the preparation method of the described 3-alkoxy propionate alkyl ester of claim 8 is characterized in that: described alkali metal alcoholate is sodium methylate or sodium ethylate or potassium methylate or potassium ethylate; Described alkali metal alcoholate The mass of the salt is 10-50% of the mass of the solid carrier.