A method for synthesizing laurylaldehyde

Abstract

The application relates to a lauric aldehyde synthesis method and relates to the field of chemical synthesis, and comprises the following steps: under the action of a composite catalyst, lauryl alcohol is reacted with an oxidant in a solvent to obtain lauric aldehyde, and the pH of a reaction system is 7-10; wherein the composite catalyst comprises a metal halide and a TEMPO derivative; the TEMPO derivative is selected from one or more of 4-hydroxy-TEMPO and 4-methoxy-TEMPO; and the oxidant is a hypochlorite. The application solves the problems of high cost and difficulty in obtaining raw materials in the prior art, and has the advantages of mild catalytic reaction conditions, simple post-treatment steps, high reaction yield, high product purity, low production cost and suitability for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical synthesis, in particular to a method for synthesizing lauryl aldehyde. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing the understanding of the general background of the application and does not necessarily constitute an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.

[0003] Lauryl aldehyde, also known as dodecanal, is a colorless transparent oily liquid or leaf-shaped crystal, which is oxidized to form lauric acid. It exists in nature in essential oils such as lemon oil, lime oil and bergamot oil. Lauryl aldehyde has an aldehyde and oil aroma. It has sweet floral and citrus fragrance. It can be used in small amounts in flower fragrance type household perfumes such as lily of the valley, orange flower, violet, etc. In food flavor, it can be used to prepare banana, citrus, mixed fruit and other fruit flavor. Lauryl aldehyde is the raw material of 2-hydroxy-3-dodecyl-1,4-naphthoquinone, the main intermediate of chloronicotinyl. Its synthesis method has been reported at home and abroad.

[0004] Currently, the existing literature and patent technology content on the synthesis method of laurinaldehyde mainly involves the following: (1) lauryl alcohol oxidation process: the literature (Catalysis Communications (2015), 65, 34-40 and Journal of the American Chemical Society (2005), 127 (25), 9251-9254) uses lauryl alcohol as raw material, in the presence of ruthenium catalyst, with iodosylbenzene or N-methylmorpholine N-oxide to obtain the product, the reaction route uses ruthenium catalyst and iodosylbenzene and other raw materials with high cost, and the used oxidant will produce a large amount of hazardous waste by-products, and the amount of three wastes is greatly increased, which is not conducive to industrial production. Patent JP2007320899 uses lauryl alcohol as raw material, and is oxidized by tellurium oxide (CAS: 959850-95-4) to obtain the product, but tellurium oxide is difficult to obtain, there is no market sales, and the synthesis cost is high, which is not conducive to industrial production. The literature (Organic Reactions (Hoboken, NJ, United States) (1990), 39) uses cobalt dichloride catalyst for reaction, and the literature (Monatshefte fuer Chemie (1998), 129 (12), 1305-1308) uses metal catalyst such as chromic acid for catalytic reaction for oxidation, because the wastewater of heavy metal catalyst is difficult to treat, which leads to environmental protection problems, and the amount of three wastes is relatively large, which is not suitable for industrial production. The literature (Synlett (2010), (7), 1110-1114) and Advanced Synthesis & Catalysis (2006), 348 (9), 1016-1020) uses sodium bicarbonate, potassium bromide and catalyst 4-(2-propynyl oxygen)-TEMPO or CAS 1196039-91-4 under the action of sodium hypochlorite to oxidize to obtain the product, although the raw materials are cheap and easy to obtain, but the catalyst is difficult to obtain, which is not suitable for industrial production.

[0005] (2) lauric acid reduction process: the literature (Journal of the Chemical Society (1943), 84-6) uses lauric acid as raw material, in the presence of titanium dioxide, with formic acid heated to 200°C to reduce to obtain the product, the process reaction temperature is too high, which requires high equipment, and is not conducive to industrial production. The literature (Beilstein Journal of Organic Chemistry (2015), 11, 2245-2251) uses lauric acid as raw material, uses glucose, 5'-ATP and magnesium chloride to reduce the product under the action of reductive enzyme, the cost of this route is high, which is not conducive to industrialization. SUMMARY

[0006] Invention objectives

[0007] The application aims to provide a laurylaldehyde synthesis method, which solves the problems of high cost and difficult to obtain raw materials in the prior art, has mild catalytic reaction conditions, simple post-processing steps, high reaction yield, high product purity, low production cost and is suitable for industrial production.

[0008] Solution

[0009] To achieve the object of the application, the application provides a laurylaldehyde synthesis method, which comprises the following steps:

[0010] Under the action of the composite catalyst, lauryl alcohol reacts with an oxidizing agent in a solvent to obtain laurylaldehyde, and the pH of the reaction system is 7-10 (optionally 7.5-9.5, or 8-9); wherein the composite catalyst comprises a metal halide and a TEMPO derivative; the TEMPO derivative is selected from one or more of 4-hydroxy-TEMPO and 4-methoxy-TEMPO; and the oxidizing agent is a hypochlorite.

[0011] Optionally, a strong base weak acid salt is used to adjust the pH; optionally, the amount of water added is the amount of water used to dissolve the strong base weak acid salt; optionally, the amount of water added is the amount of water used to prepare a saturated or nearly saturated strong base weak acid salt solution; optionally, the strong base weak acid salt is one or more of alkali metal bicarbonate and alkali metal carbonate; and optionally, the strong base weak acid salt is selected from one or more of sodium bicarbonate, potassium bicarbonate, sodium carbonate and potassium carbonate.

[0012] Further, the oxidizing agent is added in batches in a reaction solution containing the composite catalyst and lauryl alcohol to prepare laurylaldehyde.

[0013] Further, the oxidizing agent is added in batches in a reaction solution containing the composite catalyst and lauryl alcohol with a pH of 7-10 (optionally 7.5-9.5, or 8-9) to prepare laurylaldehyde.

[0014] Optionally, the solvent comprises an organic solvent and water; optionally, the volume ratio of the organic solvent to lauryl alcohol is (10-50):1, or (15-18):1; and optionally, the mass ratio of water to lauryl alcohol is (10-50):1, or (15-18):1.

[0015] Further, the organic solvent is immiscible with water, and optionally, the organic solvent is selected from at least one of dichloromethane, dichloroethane, trichloromethane and toluene.

[0016] Optionally, the solvent is used in a reaction solution containing the composite catalyst and lauryl alcohol.

[0017] Optionally, the pH of the reaction system is adjusted before adding the oxidizing agent.

[0018] Optionally, stirring is performed during the reaction.

[0019] Further, the hypochlorite salt is selected from at least one of metal hypochlorite, such as sodium hypochlorite, calcium hypochlorite; optionally, the hypochlorite salt is calcium hypochlorite solid, and optionally, the calcium hypochlorite solid is 60% calcium hypochlorite powder.

[0020] Further, the metal halide is selected from metal iodide and / or metal bromide; optionally, the metal halide is metal bromide; optionally, the metal halide is selected from one or more of potassium bromide, sodium bromide, cuprous bromide, potassium iodide, sodium iodide, cuprous iodide; optionally, the metal halide is alkali metal bromide, and optionally, the metal halide is selected from at least one of potassium bromide and sodium bromide.

[0021] Further, in the composite catalyst, the molar ratio of the metal halide to the TEMPO derivative is 1:(0.01-0.2), optionally 1:(0.06-0.15), optionally 1:(0.09-0.12), optionally 1:(0.95-0.12), and optionally 1:(0.1-0.11).

[0022] Further, the molar ratio of lauryl alcohol to the metal halide is 1:(0.01-0.5), optionally 1:(0.05-0.2), optionally 1:(0.06-0.12), and optionally 1:(0.08-0.1).

[0023] Further, the mass ratio of lauryl alcohol to the oxidizing agent is preferably 1:0.5-1.

[0024] Further, the reaction temperature is -1-5°C, 0-5°C, optionally 0.01-5°C, and optionally 0.01-3°C.

[0025] Further, the reaction time is 0.5-1.5h, and optionally 0.5-1.0h.

[0026] In the synthesis method, the reaction temperature and the reaction time can be conventional parameters or optimized.

[0027] Further, the synthesis method further comprises a step of post-treating the reacted material to obtain laurylaldehyde, and optionally, the post-treatment comprises recovering the solvent; and optionally, the recovery of the solvent is performed under the condition of controlling the temperature to be lower than 70°C and reduced pressure distillation.

[0028] Further, the post-treatment further comprises adding a trace amount of stabilizer, and the stabilizer is optionally at least one of tea polyphenol, tocopherol, butylated hydroxyl anisole, butylated hydroxyl toluene, and tertiary butyl hydroquinone.

[0029] A preferred solution is:

[0030] In the reaction solution containing the composite catalyst and lauryl alcohol, the pH is 8-9, calcium hypochlorite is added (optionally in batches), and then post-treatment is performed to obtain lauryl aldehyde.

[0031] The pH is adjusted by alkali metal bicarbonate and / or alkali metal carbonate, and the alkali metal is optionally sodium or potassium.

[0032] The solvent optionally comprises an organic solvent and water; the volume ratio of the organic solvent to lauryl alcohol is optionally (10-50):1, and is more preferably (15-18):1; the mass ratio of water to lauryl alcohol is optionally (10-50):1, and is more preferably (15-18):1; and the solvent is optionally added to the reaction solution containing the composite catalyst and lauryl alcohol.

[0033] The organic solvent is optionally immiscible with water, and the organic solvent is optionally at least one of dichloromethane, dichloroethane, trichloromethane, and toluene.

[0034] The metal halide in the composite catalyst is optionally an alkali metal bromide, and the alkali metal bromide is optionally sodium bromide and / or potassium bromide.

[0035] The TEMPO derivative is optionally one or more of 4-hydroxy-TEMPO and 4-methoxy-TEMPO.

[0036] Further, the post-treatment comprises recovering the solvent and adding a trace amount of stabilizer.

[0037] The recovering of the solvent is optionally performed under the condition of controlling the temperature to be lower than 70°C and reducing pressure distillation.

[0038] The stabilizer is optionally at least one of tea polyphenol, tocopherol, butylated hydroxyl anisole, butylated hydroxyl toluene, and tertiary butyl hydroquinone.

[0039] Further, the mass ratio of the lauryl alcohol to the stabilizer is preferably 1:0.00001-0.0001, and is more preferably 1:0.00006-0.00008.

[0040] Beneficial effects

[0041] (1) The synthetic method of the present application has mild catalytic reaction conditions, simple post-treatment steps, high reaction yield, high product purity, low production cost, and is suitable for industrial production.

[0042] (2) The solvent recovered by the present application can be directly reused; the chemical oxygen demand (COD) of the wastewater of the present application is 20 mg / L, and a part of the wastewater can be directly reused and directly discharged. A trace amount of stabilizer is added before distillation to avoid oxidation of the product during distillation, and a product with high purity is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0043] One or more embodiments are illustrated by way of example in the figures that form a part of this patent specification. These example illustrations serve the purpose of explanation only, and are not intended to limit the embodiments. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0044] Figure 1 The high performance liquid chromatogram of the product of Example 1 of the present application, the peak at about 8.342 min represents the product laurinaldehyde, and the other peaks are impurities.

[0045] Figure 2 The high performance liquid chromatogram of the product of Comparative Example 1 of the present application, the peak at about 8.576 min represents the product laurinaldehyde, and the other peaks are impurities.

[0046] Figure 3 The high performance liquid chromatogram of the product of Comparative Example 2 of the present application, the peak at about 8.533 min represents the product laurinaldehyde, and the other peaks are impurities.

[0047] Figure 4 The high performance liquid chromatogram of the product of Comparative Example 4 of the present application, the peak at about 8.537 min represents the product laurinaldehyde, and the other peaks are impurities.

[0048] Figure 5 The high performance liquid chromatogram of the product of Comparative Example 5 of the present application, the peak at about 8.546 min represents the product laurinaldehyde, and the other peaks are impurities. DETAILED DESCRIPTION

[0049] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall into the scope of the present application. Unless otherwise clearly indicated, in the entire specification and claims, the term "comprise" or its variants such as "comprises" or "comprising" should be understood as including the stated elements or components, and not excluding other elements or components.

[0050] In addition, in order to better illustrate the present application, a large number of specific details are given in the specific embodiments below. Those skilled in the art should understand that the present application can also be implemented without some specific details. In some embodiments, the raw materials, elements, methods, means and the like which are well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present application.

[0051] In the following embodiments, the raw materials used are basically commercially available products, wherein 4-hydroxy-TEMPO, 4-methoxy-TEMPO, TEMPO and 60% calcium hypochlorite solid are purchased from Macklin.

[0052] In the following embodiments, the filtrate of the filtered aqueous phase after separation can be directly discharged, because its COD is low and meets the direct discharge standard.

[0053] Example 1

[0054] Into the reaction bottle, 16g of sodium bicarbonate and 190g of water were sequentially added, 0.6g of sodium bromide, 200ml of dichloroethane (DCE), 12.5g of lauryl alcohol, and 0.106g of 4-hydroxy-TEMPO, the pH of the reaction solution was 8-9, the stirring was started, the temperature was reduced to 0-3℃, and then 8.25g of 60% calcium hypochlorite solid powder was added in batches (the feeding time was about 15-20min), the temperature was controlled at about 0℃, 5min after the feeding was completed, the sample was taken, and after the raw materials were reacted and analyzed, the stirring was stopped, and the separation was performed. The aqueous phase after separation was directly filtered, the filter cake was washed once with 50ml of DCE, the separation was performed, the organic phase was combined, and the filtrate of the filtered aqueous phase could be directly discharged. 0.75mg of tea polyphenol was added to the organic phase, the temperature was controlled to be less than 70℃, the vacuum degree was -0.09Mpa, the solvent was recovered by vacuum distillation, and the product was obtained (the spectrum result of the sample test is shown in Figure 1 The purity was 99% and the yield was 98%.

[0055] Example 2

[0056] Into a reaction flask, add 10 g sodium carbonate and 190 g water, 0.69 g potassium bromide, 200 ml DCE, 12.5 g lauryl alcohol, and 0.106 g 4-hydroxy-TEMPO, the pH of the reaction solution is 8-9, start stirring, cool to 0-3°C, under nitrogen protection, then add 8.25 g 60% calcium hypochlorite solid powder in batches (the feeding time is about 15-20 min), control the temperature at about 0°C, 5 min after the feeding is completed, sample, until the raw materials are reacted and analyzed, stop stirring, and separate the liquid. The water phase after separation is directly filtered, the filter cake is washed once with 50 ml DCE, the organic phase is combined, and the filtrate of the water phase after filtration can be directly discharged. Add 0.75 mg tocopherol to the organic phase, control the temperature to be less than 70°C, vacuum degree-0.09 Mpa, reduce pressure distillation to recover the solvent, and the product is obtained. The purity is 99%, and the yield is 97%.

[0057] Example 3

[0058] Into a reaction flask, add 10 g sodium carbonate and 190 g water, 0.69 g potassium bromide, 200 ml DCE, 12.5 g lauryl alcohol, and 0.106 g 4-hydroxy-TEMPO, the pH of the reaction solution is 8-9, start stirring, cool to 0-3°C, under nitrogen protection, then add 8.25 g 60% calcium hypochlorite solid powder in batches (the feeding time is about 15-20 min), control the temperature at about 0°C, 5 min after the feeding is completed, sample, until the raw materials are reacted and analyzed, stop stirring, and separate the liquid. The water phase after separation is directly filtered, the filter cake is washed once with 50 ml DCE, the organic phase is combined, and the filtrate of the water phase after filtration can be directly discharged. Add 0.75 mg butylated hydroxyanisole to the organic phase, control the temperature to be less than 70°C, vacuum degree-0.09 Mpa, reduce pressure distillation to recover the solvent, and the product is obtained. The purity is 99%, and the yield is 96.5%.

[0059] Example 4

[0060] Into a reaction flask, 16g sodium bicarbonate and 190g water, 0.6g sodium bromide, 200ml toluene, 12.5g lauryl alcohol, and 0.106g 4-hydroxy-TEMPO were sequentially added. The pH of the reaction solution was 8-9. The stirring was started and the temperature was lowered to 0-3°C under nitrogen protection. Then 8.25g of 60% calcium hypochlorite solid powder was added in batches for several times (the feeding time was about 15-20min). The temperature was controlled at about 0°C. 5min after the feeding was completed, the sample was taken. After the raw materials were reacted and analyzed, the stirring was stopped and the liquid was separated. The water phase was directly filtered. The filter cake was washed once with 50ml toluene, the liquid was separated, and the organic phase was combined. The filtrate of the water phase could be directly discharged. 0.8mg of butylated hydroxytoluene was added to the organic phase. The temperature was controlled at less than 70°C. The vacuum degree was-0.09Mpa. The solvent was recovered by vacuum distillation to obtain the product. The purity was 98.6% and the yield was 97.6%.

[0061] Example 5:

[0062] Into a reaction flask, 16g sodium bicarbonate and 190g water, 0.6g sodium bromide, 200ml DCE, 12.5g lauryl alcohol, and 0.106g 4-hydroxy-TEMPO were sequentially added. The pH of the reaction solution was 8-9. The stirring was started and the temperature was lowered to 0-3°C under nitrogen protection. Then 6.25g of 60% calcium hypochlorite solid powder was added in batches for several times (the feeding time was about 15-20min). The temperature was controlled at about 0°C. 5min after the feeding was completed, the sample was taken. After the raw materials were reacted and analyzed, the stirring was stopped and the liquid was separated. The water phase was directly filtered. The filter cake was washed once with 50ml DCE, the liquid was separated, and the organic phase was combined. The filtrate of the water phase could be directly discharged. 0.75mg of tert-butyl hydroquinone was added to the organic phase. The temperature was controlled at less than 70°C. The vacuum degree was-0.09Mpa. The solvent was recovered by vacuum distillation to obtain the product. The purity was 98% and the yield was 97%.

[0063] Example 6:

[0064] Into a reaction flask, 16 g of sodium bicarbonate and 190 g of water, 0.6 g of sodium bromide, 200 ml of DCE, 12.5 g of lauryl alcohol, and 0.106 g of 4-hydroxy-TEMPO were sequentially added, the pH of the reaction solution was 8-9, stirring was started, and the temperature was lowered to 0-3°C under nitrogen protection. Then 12.5 g of 60% calcium hypochlorite solid powder was added in batches (the feeding time was about 15-20 min), the temperature was controlled at about 0°C, and 5 min after the feeding was completed, the sample was taken. After the raw materials were completely reacted and the analysis was qualified, the stirring was stopped, and the liquid was separated. The aqueous phase was directly filtered, the filter cake was washed once with 50 ml of DCE, the liquid was separated, and the organic phase was combined. The filtrate of the aqueous phase could be directly discharged. 0.75 mg of tea polyphenol was added to the organic phase, the temperature was controlled at less than 70°C, the vacuum degree was -0.09 MPa, and the solvent was recovered by vacuum distillation, and the product was obtained. The purity was 98%, and the yield was 98%.

[0065] Comparative Example 1

[0066] Into a reaction flask, 16 g of sodium bicarbonate and 190 g of water, 0.6 g of sodium bromide, 200 ml of DCE, 12.5 g of lauryl alcohol, and 0.106 g of 4-hydroxy-TEMPO were sequentially added, the pH of the reaction solution was 8-9, stirring was started, and the temperature was lowered to 0-3°C under nitrogen protection. Then 12.5 g of 60% calcium hypochlorite solid powder was added in batches (the feeding time was about 15-20 min), the temperature was controlled at about 0°C, and 5 min after the feeding was completed, the sample was taken. After the raw materials were completely reacted and the analysis was qualified, the stirring was stopped, and the liquid was separated. The aqueous phase was directly filtered, the filter cake was washed once with 50 ml of DCE, the liquid was separated, and the organic phase was combined. The filtrate of the aqueous phase could be directly discharged. 0.75 mg of tea polyphenol was added to the organic phase, the temperature was controlled at less than 70°C, the vacuum degree was -0.09 MPa, and the solvent was recovered by vacuum distillation, and the product was obtained. The purity was 98%, and the yield was 98%. Figure 2

[0067] Comparative Example 2

[0068] Into a reaction flask, 16 g of sodium bicarbonate and 190 g of water, 0.6 g of sodium bromide, 200 ml of DCE, 12.5 g of lauryl alcohol, and 0.106 g of 4-hydroxy-TEMPO were sequentially added, the pH of the reaction solution was 8-9, stirring was started, and the temperature was lowered to 0-3°C under nitrogen protection. Then 12.5 g of 60% calcium hypochlorite solid powder was added in batches (the feeding time was about 15-20 min), the temperature was controlled at about 0°C, and 5 min after the feeding was completed, the sample was taken. After the raw materials were completely reacted and the analysis was qualified, the stirring was stopped, and the liquid was separated. The aqueous phase was directly filtered, the filter cake was washed once with 50 ml of DCE, the liquid was separated, and the organic phase was combined. The filtrate of the aqueous phase could be directly discharged. 0.75 mg of tea polyphenol was added to the organic phase, the temperature was controlled at less than 70°C, the vacuum degree was -0.09 MPa, and the solvent was recovered by vacuum distillation, and the product was obtained. The purity was 98%, and the yield was 98%. Figure 3 ​The product purity is 85%, and the yield is 80.5%.

[0069] The present comparative example shows that the product yield is low and the impurities are many when the sodium bicarbonate aqueous solution is mixed with calcium hypochlorite and then added dropwise into the reaction. The inventors infer that the pH during the reaction is difficult to maintain at a certain level due to this feeding sequence.

[0070] The present application also carries out related research by changing the solvent and water amount, and the solvent and water amount has certain influence on the reaction yield and purity.

[0071] Comparative Example 3

[0072] 8 g of sodium bicarbonate and 190 g of water, 0.6 g of sodium bromide, 200 ml of DCE, 12.5 g of lauryl alcohol, and 0.106 g of 4-hydroxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 6-7, stirring is started, the temperature is reduced to 0-3°C, and then 8.25 g of 60% calcium hypochlorite solid powder is added in batches for multiple times (the feeding time is about 15-20 min), the temperature is controlled at about 0°C, 5 min after the feeding is completed, the sample is taken until the raw materials are reacted, and the stirring is stopped after the analysis is qualified. The water phase is directly filtered, the filter cake is washed once with 50 ml of DCE, the liquid is separated, and the organic phase is combined. 0.75 mg of tea polyphenol is added into the organic phase, the temperature is controlled to be less than 70°C, the vacuum degree is -0.09 Mpa, the solvent is recovered by vacuum distillation, and the product is obtained. The purity is 85%, and the yield is 80.5%.

[0073] When the pH is less than 7, the reaction impurities are many, resulting in a low yield.

[0074] Comparative Example 4

[0075] 8 g of sodium bicarbonate and 190 g of water, 0.6 g of sodium bromide, 200 ml of DCE, 12.5 g of lauryl alcohol, and 0.106 g of 4-hydroxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 6-7, stirring is started, the temperature is reduced to 0-3°C, and then 8.25 g of 60% calcium hypochlorite solid powder is added in batches for multiple times (the feeding time is about 15-20 min), the temperature is controlled at about 0°C, 5 min after the feeding is completed, the sample is taken until the raw materials are reacted, and the stirring is stopped after the analysis is qualified. The water phase is directly filtered, the filter cake is washed once with 50 ml of DCE, the liquid is separated, and the organic phase is combined. 0.75 mg of tea polyphenol is added into the organic phase, the temperature is controlled to be less than 70°C, the vacuum degree is -0.09 Mpa, the solvent is recovered by vacuum distillation, and the product is obtained. The purity is 85%, and the yield is 80.5%. Figure 4 The purity is 86%, and the yield is 82%.

[0076] When the pH is greater than 10, the reaction impurities are many, resulting in a low yield.

[0077] Comparative Example 5

[0078] Into a reaction bottle, 16 g of sodium bicarbonate and 190 g of water, 0.6 g of sodium bromide, 200 ml of DCE, 12.5 g of lauryl alcohol, and 0.106 g of 4-hydroxy-TEMPO were sequentially added, the pH of the reaction solution was 8-9, stirring was started, the temperature was lowered to 0-3°C, and then 70 g of 6% sodium hypochlorite solution was added dropwise under nitrogen protection (the feeding time was about 15-20 min), the temperature was controlled at about 0°C, and 5 min after the dropwise addition was completed, the sample was taken until the raw material was reacted, and after the analysis was qualified, the stirring was stopped and the liquid was separated. The water phase was directly filtered, the filter cake was washed once with 50 ml of DCE, the liquid was separated, and the organic phase was combined. 0.75 mg of tea polyphenol was added to the organic phase, the temperature was controlled at less than 70°C, the vacuum degree was -0.09 MPa, and the solvent was recovered by vacuum distillation to obtain the product (the results are shown in Figure 5 The purity was 96%, and the yield was 90.6%.

[0079] The reaction impurities were too many when sodium hypochlorite solution was used as the oxidant, resulting in a low yield.

[0080] Comparative Example 6

[0081] Into a reaction bottle, 16 g of sodium bicarbonate and 190 g of water, 0.6 g of sodium bromide, 200 ml of DCE, 12.5 g of lauryl alcohol, and 0.106 g of 4-hydroxy-TEMPO were sequentially added, the pH of the reaction solution was 8-9, stirring was started, the temperature was lowered to 0-3°C, and then 70 g of 6% sodium hypochlorite solution was added dropwise under nitrogen protection (the feeding time was about 15-20 min), the temperature was controlled at about 0°C, and 5 min after the dropwise addition was completed, the sample was taken until the raw material was reacted, and after the analysis was qualified, the stirring was stopped and the liquid was separated. The water phase was directly filtered, the filter cake was washed once with 50 ml of DCE, the liquid was separated, and the organic phase was combined. 0.75 mg of tea polyphenol was added to the organic phase, the temperature was controlled at less than 70°C, the vacuum degree was -0.09 MPa, and the solvent was recovered by vacuum distillation to obtain the product (the results are shown in

[0082] Without adding a stabilizer, the product had a tendency to deteriorate (aldehyde groups were oxidized to carboxylic acid groups), and the yield was low.

[0083] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions described in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for synthesizing lauraldehyde, characterized in that, include: Under the action of a composite catalyst, lauryl alcohol reacts with an oxidant in a solvent to yield lauraldehyde, with the pH of the reaction system ranging from 7.5 to 9.5; wherein, The composite catalyst comprises a metal halide and a TEMPO derivative; the TEMPO derivative is selected from one or more of 4-hydroxy-TEMPO and 4-methoxy-TEMPO; the molar ratio of the metal halide to the TEMPO derivative is 1:(0.01~0.2). The oxidant is hypochlorite; the metal halide is selected from one or more of potassium bromide, sodium bromide, cuprous bromide, potassium iodide, sodium iodide, and cuprous iodide. pH is adjusted using a strong base-weak acid salt.

2. The synthesis method according to claim 1, characterized in that, The pH of the reaction system is 8-9.

3. The synthesis method according to claim 1, characterized in that, The acid salt of a strong base is dissolved in water, and the amount of water added is the amount used to dissolve the acid salt of the strong base.

4. The synthesis method according to claim 3, characterized in that, The amount of water added is the amount used to prepare a saturated strong base-weak acid salt solution.

5. The synthesis method according to claim 1, characterized in that, The strong base weak acid salt is one or more of alkali metal bicarbonate and alkali metal carbonate.

6. The synthesis method according to claim 1, characterized in that, The strong base weak acid salt is selected from one or more of sodium bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate.

7. The synthesis method according to any one of claims 1 to 6, characterized in that, Lauraldehyde was prepared by adding an oxidant in batches to a reaction solution containing a composite catalyst and lauryl alcohol.

8. The synthesis method according to any one of claims 1 to 6, characterized in that, The solvents include organic solvents and water.

9. The synthesis method according to claim 8, characterized in that, The volume ratio of the organic solvent to lauryl alcohol is (10~50):

1.

10. The synthesis method according to claim 8, characterized in that, The volume ratio of the organic solvent to lauryl alcohol is (15~18):

1.

11. The synthesis method according to claim 8, characterized in that, The mass ratio of water to lauryl alcohol is (10~50):

1.

12. The synthesis method according to claim 8, characterized in that, The mass ratio of water to lauryl alcohol is (15~18):

1.

13. The synthesis method according to claim 8, characterized in that, The organic solvent is immiscible with water.

14. The synthesis method according to claim 13, characterized in that, The organic solvent is selected from at least one of dichloromethane, dichloroethane, trichloromethane, and toluene.

15. The synthesis method according to claim 8, characterized in that, The pH of the reaction system is adjusted before adding an oxidant.

16. The synthesis method according to any one of claims 1 to 6, characterized in that, The hypochlorite is selected from metal hypochlorite salts.

17. The synthesis method according to claim 16, characterized in that, The hypochlorite metal salt is at least one of sodium hypochlorite and calcium hypochlorite.

18. The synthesis method according to any one of claims 1 to 6, characterized in that, The hypochlorite is solid calcium hypochlorite.

19. The synthesis method according to claim 18, characterized in that, The calcium hypochlorite solid is 60% calcium hypochlorite powder.

20. The synthesis method according to any one of claims 1 to 6, characterized in that, In the composite catalyst, the molar ratio of metal halide to TEMPO derivative is 1:(0.06~0.15).

21. The synthesis method according to any one of claims 1 to 6, characterized in that, In the composite catalyst, the molar ratio of metal halide to TEMPO derivative is 1:(0.09~0.12).

22. The synthesis method according to any one of claims 1 to 6, characterized in that, In the composite catalyst, the molar ratio of metal halide to TEMPO derivative is 1:(0.1~0.11).

23. The synthesis method according to any one of claims 1 to 6, characterized in that, The molar ratio of lauryl alcohol to metal halide is 1:(0.01~0.5).

24. The synthesis method according to any one of claims 1 to 6, characterized in that, The molar ratio of lauryl alcohol to metal halide is 1:(0.05~0.2).

25. The synthesis method according to any one of claims 1 to 6, characterized in that, The molar ratio of lauryl alcohol to metal halide is 1:(0.06~0.12).

26. The synthesis method according to any one of claims 1 to 6, characterized in that, The molar ratio of lauryl alcohol to metal halide is 1:(0.08~0.1).

27. The synthesis method according to any one of claims 1 to 6, characterized in that, The mass ratio of lauryl alcohol to oxidant is 1:0.5~1.

28. The synthesis method according to any one of claims 1 to 6, characterized in that, The reaction temperature is -1 to 5℃.

29. The synthesis method according to any one of claims 1 to 6, characterized in that, The reaction temperature is 0~5℃.

30. The synthesis method according to any one of claims 1 to 6, characterized in that, The reaction temperature is 0.01~5℃.

31. The synthesis method according to any one of claims 1 to 6, characterized in that, The reaction temperature is 0.01~3℃.

32. The synthesis method according to any one of claims 1 to 6, characterized in that, The reaction time is 0.5~1.5 h.

33. The synthesis method according to any one of claims 1 to 6, characterized in that, The reaction time is 0.5~1.0 h.

34. The synthesis method according to any one of claims 1 to 6, characterized in that, The synthesis method also includes a step of post-processing the reacted materials to obtain lauraldehyde.

35. The synthesis method according to claim 34, characterized in that, Post-processing includes solvent recovery.

36. The synthesis method according to claim 34, characterized in that, The conditions for solvent recovery are controlled temperature below 70℃ and vacuum distillation.

37. The synthesis method according to claim 34, characterized in that, The post-processing also includes the addition of trace amounts of stabilizer.

38. The synthesis method according to claim 34, characterized in that, The stabilizer is at least one of tea polyphenols, tocopherol, butylated hydroxyanisole, dibutylhydroxytoluene, and tert-butylhydroquinone.

39. The synthesis method according to any one of claims 1 to 6, characterized in that, include: Calcium hypochlorite solid was added to a reaction solution containing a composite catalyst and lauryl alcohol at a pH of 8-9, followed by post-treatment to obtain lauryl aldehyde.

40. The synthesis method according to claim 39, characterized in that, The reaction solution contains a solvent, which includes organic solvents and water.

41. The synthesis method according to claim 40, characterized in that, The volume ratio of the organic solvent to lauryl alcohol is (10~50):

1.

42. The synthesis method according to claim 40, characterized in that, The volume ratio of the organic solvent to lauryl alcohol is (15~18):

1.

43. The synthesis method according to claim 40, characterized in that, The mass ratio of water to lauryl alcohol is (10~50):

1.

44. The synthesis method according to claim 41, characterized in that, The mass ratio of water to lauryl alcohol is (15~18):

1.

45. The synthesis method according to claim 40, characterized in that, The organic solvent is immiscible with water.

46. ​​The synthesis method according to claim 40, characterized in that, The organic solvent is selected from at least one of dichloromethane, dichloroethane, trichloromethane, and toluene.

47. The synthesis method according to claim 39, characterized in that, Solid calcium hypochlorite was added in batches.

48. The synthesis method according to claim 39, characterized in that, Post-processing includes solvent recovery and the addition of trace amounts of stabilizer.

49. The synthesis method according to claim 48, characterized in that, The conditions for solvent recovery are controlled temperature below 70℃ and vacuum distillation.

50. The synthesis method according to claim 48, characterized in that, The stabilizer is at least one of tea polyphenols, tocopherol, butylated hydroxyanisole, dibutylhydroxytoluene, and tert-butylhydroquinone.

51. The synthesis method according to claim 48, characterized in that, The mass ratio of lauryl alcohol to the stabilizer is 1:0.00001~0.0001.

52. The synthesis method according to claim 50, characterized in that, The mass ratio of lauryl alcohol to the stabilizer is 1:0.00006~0.00008.

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