Efficient synthesis method of 3-methylthio-propionaldehyde

Abstract

The invention discloses an efficient 3-methylthio-propionaldehyde synthesis method which comprises the following reaction processes: adding methyl mercaptan, acrolein and a COF photocatalyst into a reaction kettle, and reacting under an illumination condition to generate 3-methylthio-propionaldehyde; the illumination condition is provided by a light source with the irradiation wavelength of 450-495 nm. According to the method, the 3-methylthiopropionaldehyde can be prepared at high yield, and the generation amount of a polymer is remarkably reduced.

Description

Technical Field

[0001] This invention belongs to the field of nutritional chemicals technology, specifically relating to an efficient method for synthesizing 3-methylthiopropionaldehyde. Background Technology

[0002] 3-Methylthiopropional (MMP) is an irreplaceable intermediate in the industrial production of methionine and a key component in constructing the sulfur-containing carbon skeleton of methionine. The main industrial synthesis methods for 3-methylthiopropional include: continuous gas-liquid contact method, aqueous phase stratified circulation method, basic amine catalytic-neutralization distillation method, and traditional processes. In the continuous gas-liquid contact method, gaseous acrolein reacts with liquid 3-methylthiopropional containing methanethiol in the gas-liquid contact section. The product is partially recycled after separation, but the sulfur-containing waste gas is difficult to treat and energy consumption is high. In contrast, the aqueous phase stratified circulation method uses 50% less catalyst, but still faces the burden of wastewater treatment. The basic amine catalytic-neutralization distillation method involves a cumbersome acid neutralization step, and the catalyst may participate in side reactions or be entrained by the product. The recovery and regeneration process is complex, potentially leading to catalyst loss and increased costs. Furthermore, residual acid can easily cause polymerization side reactions, resulting in high energy consumption in subsequent distillation separation processes. Additionally, MMP itself may be unstable at high temperatures, leading to loss or decomposition. Traditional processes utilize acrolein vapor absorption in low-temperature MMP followed by reaction with methanethiol; or generate methanethiol using sodium hydrosulfide or dimethyl sulfate, which then reacts with liquid acrolein. These methods produce many byproducts, and pyridine or acetic acid catalysts remain in the crude product, leading to polymerization of 3-methylthiopropional during storage.

[0003] In summary, the existing publicly available technologies have the following problems: First, the raw material acrolein itself is highly reactive and easily undergoes side reactions to generate byproducts such as acrylic acid, acrolein dimer, acrolein trimer, and acrylic acid polymer, which reduces the selectivity of acrolein. Second, the use of organic nitrogen bases and acid-base catalysts such as pyridine or acetic acid makes it difficult to completely separate 3-methylthiopropional during purification, and also accelerates the polymerization of acrolein, affecting the use and storage of 3-methylthiopropional in subsequent production.

[0004] TW152903B discloses a photochemical method for preparing 3-(organosulfur) aldehydes. In the reaction temperature range of approximately 2°C to 60°C, thiols react with α,β-unsaturated aliphatic aldehydes under ultraviolet light (wavelength range of 160nm to 400nm) to generate 3-(organosulfur) aldehyde compounds. However, this method suffers from three technical drawbacks: First, the ultraviolet light (160nm to 400nm) energy is too high, directly initiating homolytic cleavage of the C=C bonds in acrolein, resulting in byproducts such as dimers and trimers accounting for over 30%. Second, without a metal catalyst, the binding pathway between sulfur radicals and acrolein is uncontrollable, leading to 15-20% impurity content in thiohemiacetals. Third, residual photolysis radicals accelerate the polymerization of the product MMP, causing the MMP purity to drop below 90% after 72 hours. Summary of the Invention

[0005] To address the above technical problems, this invention proposes an efficient method for synthesizing 3-methylthiopropionaldehyde.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An efficient method for synthesizing 3-methylthiopropional includes the following reaction process: adding methanethiol, acrolein, and COF photocatalyst into a reaction vessel and reacting under light irradiation to generate 3-methylthiopropional;

[0008] The illumination conditions are provided by a light source with an illumination wavelength of 450-495nm.

[0009] In some preferred embodiments, the COF photocatalyst is a triazine COF and / or a thiadiazole COF, preferably one of thiazine-triazine COF (TT-COF), 2,3,7,8-tetrafluorothiazine-triazine COF (TFT-COF), 2,3,7,8-tetramethylthiazine-triazine COF (TMT-COF), phenothiazine-triazine COF (PTZ-COF), triazine-hydrazone covalent organic framework (TFPT-COF), and thiadiazole covalent organic framework material (TDA-COF);

[0010] Preferably, the amount of the COF photocatalyst is 0.1%-5% of the mass of acrolein, more preferably 0.5%-2%.

[0011] The COF photocatalyst provided by this invention can be simply synthesized with reference to known technologies, or purchased from commercially available finished products.

[0012] For example, the method provided in the literature "Rational Synthesis of Photocatalytic Acridinium-Based Covalent Organic Frameworks via Single-Atom Skeletal Editing, DOI: 10.1002 / ANIE.202514572" and its supporting materials can be referenced and slightly modified to synthesize the triazine-based COF. The specific scheme is as follows:

[0013] Triazine monomer, organic linker, catalyst, and solvent are added to a polyethylene tube and heated to 100-120℃ for 3-5 days. After the reaction, the mixture is filtered, the solid is collected, washed with dichloromethane, and dried. The dried solid is then transferred to a reactor containing a tetrahydrofuran solution of sodium tetrafluoroborate and stirred for 0.5-1 hour. The filtration, washing, and drying processes are repeated. The crude product is dried at 100-120℃ for at least 12 hours to obtain triazine-based COF.

[0014] The triazine monomer is selected from one or more of 1,3,5-tris(4-formylphenyl)triazine, 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine, 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine, and 2,4,6-tri-(4-formyl-biphenyl-4-yl)-1,3,5-triazine;

[0015] The organic linker is selected from one or more of thiaanthracene, 2,3,7,8-tetrafluorothiaanthracene, 2,3,7,8-tetramethylthiaanthracene, phenothiazine, and 2,5-diethoxybenzene-1,4-bis(formylhydrazine);

[0016] The catalyst comprises trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid; the amount of trifluoromethanesulfonic anhydride is 3-6 times the molar amount of the organic linker; the amount of trifluoromethanesulfonic acid is 1.5-3 times the molar amount of the organic linker.

[0017] The solvent is a mixture of chlorobenzene and n-butanol in a volume ratio of 1:(1-4); the mass ratio of the solvent to the organic linker is (10-20):1.

[0018] The tetrahydrofuran solution of sodium tetrafluoroborate has a molar concentration of 0.2-0.5 mol / L, and the total amount used is 1-3 times the volume of the solvent.

[0019] For example, see the reference "Converting the covalent organic framework linkage from hydrazone to thiadiazole toward blue light-powered selective conversion of organic sulfides".

[0020] The method provided by "DOI: 10.1039 / d4ta04548c" and its supporting material for synthesizing the thiadiazole COF specifically adopts the following scheme:

[0021] Triazine hydrazone covalent organic framework (TFPT-COF), 4-dimethylaminopyridine, Lawson's reagent, and toluene solvent were added to a polyethylene tube and heated to 130-150℃ for 24-48 h. After the reaction was completed, the mixture was filtered, the solid was collected, washed with a mixed solvent of N,N-dimethylformamide and tetrahydrofuran, and the crude product was dried at 70-100℃ for more than 12 h to obtain thiadiazole covalent organic framework material (TDA-COF).

[0022] The amount of 4-dimethylaminopyridine used is 3-5 times the mass of the triazine hydrazone covalent organic framework (TFPT-COF);

[0023] The amount of Lawson's reagent used is 2-3 times the mass of the triazine hydrazone covalent organic framework (TFPT-COF), preferably 2 times;

[0024] The amount of toluene used is 10-30 times the mass of the triazine hydrazone covalent organic framework (TFPT-COF), preferably 10 times;

[0025] The volume ratio of the N,N-dimethylformamide and tetrahydrofuran mixed solvent is 1:(1-4); the mass ratio of the mixed solvent to the triazine hydrazone covalent organic framework is (5-20):1.

[0026] In some preferred embodiments, the molar ratio of methanethiol to acrolein is 1:(0.95-1.0).

[0027] In some preferred embodiments, the reaction temperature is 10-30°C, and the preferred reaction time is 1-6 hours.

[0028] In some preferred embodiments, the light source with an illumination wavelength of 450-495nm is a Blue LED lamp.

[0029] In some preferred embodiments, the power of the Blue LED light is 30-50W.

[0030] In some preferred embodiments, after the reaction is complete, the filtrate is obtained by filtration and then separated to obtain the product 3-methylthiopropionaldehyde.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) By using COF photocatalyst and blue light synergistic catalysis, the π→π* absorption band of acrolein is avoided with lower energy compared to ultraviolet light, greatly reducing acrolein self-polymerization. Simultaneously, the COF photocatalyst induces the generation of methanethiol and acrolein free radicals, resulting in highly selective free radical coupling reactions to yield the single product 3-methylthiopropional. The presence of the COF photocatalyst ensures that no photolytic free radicals remain in the reaction system, preventing MMP polymerization of the product and improving product stability.

[0033] (2) The synthesis method of the present invention avoids the use of acid-base catalysts such as organic nitrogen bases, acetic acid or pyridine in the traditional synthesis of 3-methylthiopropionaldehyde, reduces the separation of organic acid-base catalysts and MMP distillation, shortens the process flow and simplifies the operation. The COF photocatalyst is easy to recover and can be recycled multiple times, improving the reaction economy and reducing the production cost.

[0034] (3) The synthesis method of the present invention is simple and efficient, the reaction system is simple, the yield is high, the selectivity is good, the product is single, and no difficult-to-handle byproducts are generated. The yield of 3-methylthiopropionaldehyde can reach more than 99%, and the purity can reach more than 99.5%. Detailed Implementation

[0035] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0036] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional synthesis methods.

[0037] The main performance testing methods involved in the following embodiments of the present invention are as follows:

[0038] (1) Product yield: The yield of 3-methylthiopropionaldehyde was calculated using Equation I.

[0039]

[0040] (2) Product purity: The content of 3-methylthiopropionaldehyde was determined by the area normalization method of gas chromatography;

[0041] (3) Polymer content: The polymer content was determined by the area normalization method of gas chromatography. The polymers included acrolein dimer, acrolein trimer, 3-methylthiopropional dimer and 3-methylthiopropional trimer.

[0042] (4) The gas chromatography test conditions of the present invention are as follows:

[0043] Instrument Model: Agilent 7890B

[0044] Column: DB-5 (30m × 0.25mm × 0.25μm)

[0045] Column temperature: Initial temperature 30℃, increase to 120℃ at 10℃ / min, hold for 5 min, then increase to 250℃ at 20℃ / min, hold for 10 min.

[0046] Inlet temperature: 200℃

[0047] FID detector temperature: 250℃

[0048] Split injection, split ratio 30:1

[0049] Injection volume: 2.0 μL

[0050] N2 flow rate: 40 mL / min

[0051] H2 flow rate: 400 mL / min.

[0052] [Preparation Example 1]

[0053] 5 g of thiaanthracene, 13.57 g of 1,3,5-tris(4-formylphenyl)triazine, 19.56 g of trifluoromethanesulfonic anhydride, 9.78 g of trifluoromethanesulfonic anhydride, 50 mL of chlorobenzene, and 50 mL of n-butanol were added sequentially to a polyethylene tube. The polyethylene tube was placed in an oven at 110 °C and reacted for 3 days. After the reaction was completed, the mixture was filtered, and the filter cake was collected and washed three times with 200 mL of dichloromethane. The washed filter cake was transferred to a reaction vessel containing 200 mL of 0.2 mol / L sodium tetrafluoroborate tetrahydrofuran solution. After stirring for 0.5 hours, the mixture was filtered, and this operation was repeated three times. The crude product was dried in an oven at 110 °C for 12 hours to obtain a solid, namely thiaanthracene-triazine COF (TT-COF).

[0054] 5 g of 2,3,7,8-tetrafluorothiathanthracene, 10.03 g of 1,3,5-tris(4-formylphenyl)triazine, 30.20 g of trifluoromethanesulfonic anhydride, 8.03 g of trifluoromethanesulfonic acid, 50 mL of chlorobenzene, and 150 mL of n-butanol were added sequentially to a polyethylene tube. The polyethylene tube was placed in an oven at 100 °C and reacted for 3 days. After the reaction was completed, the mixture was filtered, and the filter cake was collected and washed three times with 200 mL of dichloromethane. The washed filter cake was transferred to a reaction vessel containing 200 mL of 0.3 mol / L sodium tetrafluoroborate tetrahydrofuran solution. After stirring for 1 hour, the mixture was filtered, and this operation was repeated three times. The crude product was dried in an oven at 100 °C for 12 hours to obtain a solid, namely 2,3,7,8-tetrafluorothiathanthracene-triazine COF (TFT-COF).

[0055] 5 g of 2,3,7,8-tetramethylthiazine, 10.78 g of 1,3,5-tris(4-formylphenyl)triazine, 15.53 g of trifluoromethanesulfonic anhydride, 4.13 g of trifluoromethanesulfonic acid, 100 mL of chlorobenzene, and 100 mL of n-butanol were added sequentially to a polyethylene tube. The polyethylene tube was placed in an oven at 120 °C and reacted for 3 days. After the reaction was completed, the mixture was filtered, and the filter cake was collected and washed three times with 200 mL of dichloromethane. The washed filter cake was transferred to a reaction vessel containing 200 mL of 0.2 mol / L sodium tetrafluoroborate tetrahydrofuran solution. After stirring for 0.5 hours, the mixture was filtered, and this operation was repeated three times. The crude product was dried in an oven at 120 °C for 12 hours to obtain a solid, namely 2,3,7,8-tetramethylthiazine-triazine COF (TMT-COF).

[0056] 5 g of phenothiazine, 14.10 g of 1,3,5-tris(4-formylphenyl)triazine, 21.24 g of trifluoromethanesulfonic anhydride, 5.65 g of trifluoromethanesulfonic acid, 40 mL of chlorobenzene, and 160 mL of n-butanol were added sequentially to a polyethylene tube. The polyethylene tube was placed in an oven at 120 °C and reacted for 3 days. After the reaction was completed, the mixture was filtered, and the filter cake was collected and washed three times with 200 mL of dichloromethane. The washed filter cake was transferred to a reaction vessel containing 200 mL of 0.2 mol / L sodium tetrafluoroborate tetrahydrofuran solution. After stirring for 0.5 hours, the mixture was filtered, and this operation was repeated three times. The crude product was dried in an oven at 120 °C for 12 hours to obtain a solid, namely phenothiazine-triazine COF (PTZ-COF).

[0057] 5 g of 2,5-diethoxybenzene-1,4-bis(formylhydrazine), 9.95 g of 1,3,5-tris(4-formylphenyl)triazine, 29.98 g of trifluoromethanesulfonic anhydride, 7.97 g of trifluoromethanesulfonic acid, 50 mL of chlorobenzene, and 150 mL of n-butanol were added sequentially to a polyethylene tube. The polyethylene tube was placed in an oven at 120 °C and reacted for 3 days. After the reaction was completed, the mixture was filtered, and the filter cake was collected and washed three times with 200 mL of dichloromethane. The washed filter cake was transferred to a reaction vessel containing 200 mL of 0.3 mol / L sodium tetrafluoroborate tetrahydrofuran solution. After stirring for 0.5 hours, the mixture was filtered, and this operation was repeated three times. The crude product was dried in an oven at 120 °C for 12 hours to obtain a solid, namely a triazine-based hydrazone covalent organic framework (TFPT-COF). 2g of triazine hydrazone covalent organic framework (TFPT-COF), 6g of 4-dimethylaminopyridine, 4g of Lawson's reagent, and 30mL of toluene solvent were added to a polyethylene tube and heated to 130℃ for 48h. After the reaction was completed, the mixture was filtered, the solid was collected, and washed with 10mL of N,N-dimethylformamide and 10mL of tetrahydrofuran mixed solvent. The crude product was dried at 80℃ for 12 hours to obtain a solid, which is the thiadiazole covalent organic framework material (TDA-COF).

[0058]

Example 1

[0059] Four 30W Blue LED lights were placed around the reactor. 48.11g of methanethiol, 56.06g of acrolein, and 0.28g of TT-COF were added to the reactor. The lights were turned on, and the reaction was carried out at 25°C for 3 hours. After the reaction was complete, the mixture was filtered to obtain the filtrate, which contained the product 3-methylthiopropional. Analysis showed a product yield of 99.1%, a purity of 99.5%, and a polymer content of 0.09%.

[0060]

Example 2

[0061] Four 30W Blue LED lights were placed around the reactor. 50.64g of methanethiol, 56.06g of acrolein, and 1.12g of TFT-COF were added to the reactor. The lights were turned on, and the reaction was carried out at 10°C for 3 hours. After the reaction was complete, the mixture was filtered to obtain the filtrate, which contained the product 3-methylthiopropional. Analysis showed a product yield of 99.4%, a purity of 99.8%, and a polymer content of 0.03%.

[0062]

Example 3

[0063] Four 50W Blue LED lights were placed around the reactor. 101.28g of methanethiol, 112.12g of acrolein, and 4.48g of TMT-COF were added to the reactor. The lights were turned on, and the reaction was carried out at 20°C for 4 hours. After the reaction was complete, the mixture was filtered to obtain the filtrate, which contained the product 3-methylthiopropional. Analysis showed a product yield of 99.0%, a purity of 99.5%, and a polymer content of 0.14%.

[0064]

Example 4

[0065] Four 40W Blue LED lights were placed around the reactor. 98.18g of methanethiol, 112.12g of acrolein, and 5.61g of PTZ-COF were added to the reactor. The lights were turned on, and the reaction was carried out at 15°C for 6 hours. After the reaction was complete, the mixture was filtered to obtain the filtrate, which contained the product 3-methylthiopropional. Analysis showed a product yield of 99.1%, a purity of 99.5%, and a polymer content of 0.12%.

[0066]

Example 5

[0067] Four 50W Blue LED lights were placed around the reactor. 48.11g of methanethiol, 56.06g of acrolein, and 0.06g of TDA-COF were added to the reactor. The lights were turned on, and the reaction was carried out at 30°C for 1 hour. After the reaction was complete, the mixture was filtered to obtain the filtrate, which contained the product 3-methylthiopropional. Analysis showed a product yield of 97.4%, a purity of 97.8%, and a polymer content of 1.43%.

[0068] Comparative Example 1

[0069] 3-Methylthiopropionaldehyde was prepared using essentially the same method as in Example 2, except that a TFT-COF was not added and the Blue LED lamp was replaced with a UVA-340 lamp.

[0070] After the reaction was completed, the product yield was 43%, the polymer content was 31%, and the proportion of thiohemiacetal impurities was 12%.

[0071] Comparative Example 2

[0072] 3-Methylthiopropionaldehyde was prepared using essentially the same method as in Example 2, except that Blue LED lights were not placed around the reaction vessel.

[0073] After the reaction was completed, the product yield was 41.4% and the polymer content was 1.2%.

[0074] Comparative Example 3

[0075] 3-Methylthiopropionaldehyde was prepared using essentially the same method as in Example 2, except that TFT-COF was not added.

[0076] After the reaction was completed, the product yield was 65.6% and the polymer content was 4.6%.

[0077] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A process for the synthesis of highly efficient 3-methylsulfanylpropanal, characterized by, The reaction process comprises the following steps: adding methyl mercaptan, acrolein and COF photocatalyst into a reaction kettle, and reacting under light irradiation to generate 3-methyl mercaptan propionaldehyde. The light irradiation is provided by a light source with a wavelength of 450-495 nm.

2. The process for the synthesis of highly efficient 3-methylsulfanylpropanal according to claim 1, characterized in that, The COF photocatalyst is preferably one of triazine-based COF and / or thiazole COF, preferably thianthrene-triazine COF, 2,3,7,8-tetrafluorothianthrene-triazine COF, 2,3,7,8-tetramethylthianthrene-triazine COF, phenothiazine-triazine COF, triazine-based hydrazone covalent organic framework, and thiazole covalent organic framework material. Preferably, the amount of the COF photocatalyst is 0.1-5% of the mass of acrolein, preferably 0.5-2%.

3. The process for the synthesis of highly efficient 3-methylsulfanylpropanal according to claim 1, characterized in that, The molar ratio of methyl mercaptan to acrolein is 1:(0.95-1.0).

4. The process for the synthesis of highly efficient 3-methylsulfanylpropanal according to any one of claims 1 to 3, characterized in that, The reaction temperature is 10-30°C, and the reaction time is preferably 1-6h.

5. The process for the synthesis of efficient 3-methylsulfanylpropanal according to claim 1, characterized by, The light source with a wavelength of 450-495 nm is a Blue LED lamp.

6. The process for the synthesis of highly efficient 3-methylsulfanylpropanal according to claim 5, characterized by, The power of the Blue LED lamp is 30-50W.

7. The process for the synthesis of highly efficient 3-methylsulfanylpropanal according to any one of claims 1 to 6, characterized in that, After the reaction, the filtrate is obtained by suction filtration, and the product 3-methyl mercaptan propionaldehyde is separated.

Images