CN117720404A

CN117720404A - Synthesis method of lauraldehyde

Info

Publication number: CN117720404A
Application number: CN202311726542.2A
Authority: CN
Inventors: 任川; 赵学庆; 胡海峰; 吴承骏; 毛春晖
Original assignee: Ningxia Yongnong Biological Science Co ltd; YONGNONG BIOSCIENCES CO Ltd
Current assignee: Ningxia Yongnong Biological Science Co ltd; YONGNONG BIOSCIENCES CO Ltd
Priority date: 2023-12-14
Filing date: 2023-12-14
Publication date: 2024-03-19

Abstract

The invention relates to a synthesis method of laurylaldehyde, which relates to the field of chemical synthesis and comprises the following steps: under the action of a composite catalyst, lauryl alcohol reacts with an oxidant in a solvent to obtain lauraldehyde, and the pH value of a reaction system is 7-10; wherein the composite catalyst comprises a metal halide and a TEMPO derivative; the TEMPO derivative is one or more selected from 4-hydroxy-TEMPO and 4-methoxy-TEMPO; the oxidizing agent is hypochlorite. The invention solves the problems of high cost and difficult acquisition of raw materials in the prior art, has mild catalytic reaction conditions, simple post-treatment steps, high reaction yield, high product purity and low production cost, and is suitable for industrial production.

Description

Synthesis method of lauraldehyde

Technical Field

The invention relates to the field of chemical synthesis, in particular to a synthesis method of lauraldehyde.

Background

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as 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.

Laurylaldehyde is also called as dodecanal, colorless transparent oily liquid or lamellar crystal, and lauric acid is generated after oxidation. Naturally occurring in essential oils such as lemon oil, lime oil and rutin oil. Laurylaldehyde has an aldehyde note and a greasy note. Has sweet flower fragrance and orange fragrance. Can be used in small amounts in the floral-type daily-use essence of convallaria, orange flowers, violet, etc. In the edible essence, fruit-flavored essence such as banana, orange, mixed fruits and the like can be prepared. Laurylaldehyde is a raw material of a main intermediate 2-hydroxy-3-dodecyl-1, 4-naphthoquinone of the chloranil, and the synthesis method thereof is reported at home and abroad.

At present, the synthesis methods of laurylaldehyde in the prior literature and patent technical content mainly relate to the following steps: (1) lauryl alcohol oxidation process: the documents (Catalysis Communications (2015), 65,34-40 and Journal of the American Chemical Society (2005), 127 (25), 9251-9254) take lauryl alcohol as a raw material, and in the presence of a ruthenium catalyst, the products are obtained by oxidizing the lauryl alcohol with iodosyl benzene or N-methylmorpholine oxynitride, the raw materials such as the ruthenium catalyst, the iodosyl benzene and the like used in the reaction route have high cost, the used oxidant can generate a large amount of dangerous waste byproducts, the three wastes are greatly increased, and the industrial production is not facilitated. Patent JP2007320899 uses lauryl alcohol as raw material, and the product is obtained by oxidation under the action of tellurium oxide (CAS: 959850-95-4), but the tellurium oxide is difficult to obtain, has no sales in the market, has high synthesis cost, and is not beneficial to industrial production. The reaction of literature (Organic Reactions (Hoboken, NJ, united States) (1990), 39) with cobalt dichloride catalysts, and the oxidation of literature (Monatshefte fuer Chemie (1998), 129 (12), 1305-1308) with metal catalysts such as chromic acid, etc., caused environmental problems due to the difficulty in treating heavy metal catalyst wastewater, and the large amount of three wastes, which are not suitable for industrial production. Documents (Synlett (2010), (7), 1110-1114) and Advanced Synthesis & Catalysis (2006), 348 (9), 1016-1020 refer to sodium bicarbonate, potassium bromide and a catalyst 4- (2-propynyloxy) -TEMPO or CAS1196039-91-4, and the products are obtained by oxidizing with sodium hypochlorite, and the raw materials are cheap and easy to obtain, but the catalyst is difficult to obtain and is not suitable for industrial production.

(2) Lauric acid reduction process: the document (Journal of the Chemical Society (1943), 84-6) uses lauric acid as raw material, under the action of titanium dioxide, formic acid is heated to 200 ℃ for reduction to obtain the product, and the process has high reaction temperature and high requirements on equipment, and is not beneficial to industrial production. Document (Beilstein Journal of Organic Chemistry (2015), 11, 2245-2251) uses lauric acid as a raw material, uses glucose, 5' -ATP and magnesium chloride to perform a reduction reaction under the action of a reducing enzyme to obtain a product, and the cost of the route is high, which is not beneficial to industrialization.

Disclosure of Invention

Object of the Invention

The invention aims to provide a synthesis method of laurylaldehyde, which solves the problems of high cost and difficult acquisition of raw materials in the prior art.

Solution scheme

In order to achieve the aim of the invention, the invention provides a synthesis method of lauraldehyde, which comprises the following steps:

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

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

Further, adding an oxidant into the reaction solution containing the composite catalyst and the lauryl alcohol in batches to prepare the lauraldehyde.

Further, adding oxidant in batches to the reaction liquid (optionally pH 7.5-9.5, optionally pH 8-9) containing the composite catalyst and lauryl alcohol with pH 7-10 to prepare the lauraldehyde.

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

further, the organic solvent is not miscible with water, and optionally, the organic solvent is at least one selected from dichloromethane, dichloroethane, chloroform and toluene.

Optionally, the solvent is used for being added into a reaction liquid containing the composite catalyst and the lauryl alcohol.

Optionally, the pH of the reaction system is adjusted prior to the addition of the oxidizing agent.

Optionally, stirring is performed during the reaction.

Further, the hypochlorite is selected from at least one of metal hypochlorite such as sodium hypochlorite, calcium hypochlorite; optionally, the hypochlorite is a calcium hypochlorite solid, optionally, the calcium hypochlorite solid is 60% calcium hypochlorite powder.

Further, the metal halide is selected from metal iodides and/or metal bromides; optionally, the metal halide is a metal bromide; optionally, the metal halide is selected from one or more of potassium bromide, sodium bromide, cuprous bromide, potassium iodide, sodium iodide, and cuprous iodide; optionally, the metal halide is an alkali metal bromide, optionally, the metal halide is selected from at least one of potassium bromide and sodium bromide.

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

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

Further, the mass ratio of the lauryl alcohol to the oxidant is preferably 1:0.5-1.

Further, the reaction temperature is-1 to 5 ℃, the reaction temperature is 0 to 5 ℃, alternatively 0.01 to 3 ℃.

Further, the reaction time is 0.5 to 1.5 hours, alternatively 0.5 to 1.0 hours.

In the synthesis method, the reaction temperature and the reaction time can be optimized and screened by adopting the conventional parameter conditions in the field.

Further, the synthesis method also comprises the step of post-treating the reacted material to obtain lauraldehyde, and optionally, the post-treatment comprises the recovery of solvent; alternatively, the conditions for recovering the solvent are controlled to a temperature below 70 ℃, and distillation under reduced pressure is performed.

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

A preferred scheme is as follows:

adding calcium hypochlorite solid (optionally added in batches) into a reaction solution containing a composite catalyst and lauryl alcohol and having a pH of 8-9, and performing aftertreatment to obtain lauraldehyde;

adjusting the pH with an alkali metal bicarbonate and/or an alkali metal carbonate, optionally sodium or potassium;

optionally, the solvent comprises an organic solvent and water; optionally, the volume ratio of the organic solvent to the lauryl alcohol is (10-50): 1, optionally (15-18): 1, a step of; optionally, the mass ratio of water to lauryl alcohol is (10-50): 1, optionally (15-18): 1, a step of; optionally, the solvent is used for being added into a reaction liquid containing the composite catalyst and the lauryl alcohol.

Optionally, the organic solvent is not miscible with water, and optionally, the organic solvent is at least one selected from dichloromethane, dichloroethane, chloroform and toluene.

Optionally, in the composite catalyst, the metal halide is an alkali metal bromide, optionally, the alkali metal bromide is sodium bromide and/or potassium bromide.

Optionally, the TEMPO derivative is selected from one or more of 4-hydroxy-TEMPO and 4-methoxy-TEMPO.

Further, the post-treatment includes recovering the solvent and adding a trace amount of stabilizer.

Alternatively, the conditions for recovering the solvent are controlled to a temperature below 70 ℃, and distillation under reduced pressure is performed.

Optionally, the stabilizer is at least one of tea polyphenol, tocopherol, butyl hydroxy anisole, dibutyl hydroxy toluene and tertiary butyl hydroquinone.

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

Advantageous effects

(1) The synthesis method has the advantages of mild catalytic reaction condition, simple post-treatment step, high reaction yield, high product purity and low production cost, and is suitable for industrial production.

(2) The solvent recovered by the invention can be directly used; the Chemical Oxygen Demand (COD) of the wastewater is 20mg/L, and the wastewater can be directly discharged after being directly applied with a part of wastewater. The trace stabilizer is added before distillation to avoid oxidation in the distillation process of the product, so that the product with higher purity is obtained.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings. The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

FIG. 1 shows a high performance liquid spectrum of the product of example 1 of the present invention, with a peak of about 8.342min representing the product lauraldehyde and the other peaks being impurities.

FIG. 2 shows a high performance liquid spectrum of the product of comparative example 1 of the present invention, wherein the peak of about 8.576min represents the product lauraldehyde, and the other peaks are impurities.

FIG. 3 shows a high performance liquid spectrum of the product of comparative example 2 of the present invention, wherein the peak of about 8.533min represents the product lauraldehyde, and the other peaks are impurities.

FIG. 4 shows a high performance liquid spectrum of the product of comparative example 4 of the present invention, with a peak of about 8.537min representing the product lauraldehyde and the other peaks being impurities.

FIG. 5 shows a high performance liquid spectrum of the product of comparative example 5 of the present invention, with a peak of about 8.546min representing the product lauraldehyde and the other peaks being impurities.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or components.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better illustration of the invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In some embodiments, materials, elements, methods, means, etc. well known to those skilled in the art are not described in detail in order to highlight the gist of the present invention.

In the following examples, the starting materials used were essentially commercially available products, wherein 4-hydroxy-TEMPO, 4-methoxy-TEMPO, TEMPO and 60% calcium hypochlorite solids were purchased from microphone.

In the following examples, the filtrate of the separated aqueous phase after filtration can be directly discharged because of its low COD, which meets the direct discharge standard.

Example 1:

16g sodium bicarbonate and 190g water, 0.6g sodium bromide, 200ml Dichloroethane (DCE), 12.5g lauryl alcohol and 0.106g 4-hydroxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 8-9, stirring is started, the temperature is reduced to 0-3 ℃, under the protection of nitrogen, then 8.25g 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 ℃, sampling can be carried out for 5min after the feeding is finished, and stirring and liquid separation are stopped after the raw materials are reacted and analyzed to be qualified. The separated aqueous phase is directly filtered, the filter cake is washed once with 50ml of DCE, the separated organic phases are combined, and the filtrate after the aqueous phase filtration can be directly discharged. And adding 0.75mg tea polyphenols into the organic phase, controlling temperature to be less than 70deg.C, vacuum degree to be-0.09 Mpa, and distilling under reduced pressure to recover solvent to obtain the final product (the result of sampling test is shown in figure 1). Purity 99%, yield 98%.

Example 2

10g of sodium carbonate, 190g of water, 0.69g of potassium bromide, 200ml of DCE,12.5g of lauryl alcohol and 0.106g of 4-hydroxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 8-9, stirring is started, the temperature is reduced to 0-3 ℃, under the protection of nitrogen, then 8.25g of 60% calcium hypochlorite solid powder (the feeding time is about 15-20 min) is added in batches for multiple times, the temperature is controlled at about 0 ℃, sampling can be performed after 5min after the feeding is finished, and stirring is stopped after the raw materials are reacted and are analyzed to be qualified, and liquid separation is performed. The aqueous phase after separation was directly filtered, the filter cake was washed once with 50ml DCE, the organic phases were combined, and the filtrate after filtration of the aqueous phase was directly discharged. And adding 0.75mg of tocopherol into the organic phase, controlling the temperature to be less than 70 ℃, distilling under reduced pressure to recover the solvent under the vacuum degree of-0.09 Mpa, and obtaining the product. Purity 99%, yield 97%.

Example 3

16g sodium bicarbonate, 190g water, 0.6g sodium bromide, 200ml Dichloromethane (DCM), 12.5g lauryl alcohol and 0.115g 4-methoxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 8-9, stirring is started, the temperature is reduced to 0-3 ℃, under the protection of nitrogen, then 8.25g 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 ℃, sampling can be carried out after 5min after feeding is finished, and stirring and liquid separation are stopped after the raw materials are reacted and are analyzed to be qualified. The aqueous phase after separation was directly filtered, the filter cake was washed once with 50ml DCM, the organic phases were combined and the filtrate after aqueous phase filtration was directly discharged. And adding 0.75mg of butyl hydroxy anisole into the organic phase, controlling the temperature to be less than 70 ℃, and distilling under reduced pressure to recover the solvent under the vacuum degree of-0.09 Mpa to obtain the product. Purity 99%, yield 96.5%.

Example 4

Adding 16g of sodium bicarbonate, 190g of water, 0.6g of sodium bromide, 200ml of toluene, 12.5g of lauryl alcohol and 0.106g of 4-hydroxy-TEMPO into a reaction bottle in sequence, starting stirring, cooling to 0-3 ℃ under the protection of nitrogen, adding 8.25g of 60% calcium hypochlorite solid powder (the charging time is about 15-20 min) in batches for multiple times, controlling the temperature to be about 0 ℃, sampling for 5min after charging, stopping stirring until the raw materials react completely and are analyzed to be qualified, and separating the liquid. The aqueous phase is directly filtered, the filter cake is washed once with 50ml of toluene, the organic phases are combined, and the filtrate after the aqueous phase filtration can be directly discharged. And adding 0.8mg of dibutyl hydroxy toluene into the organic phase, controlling the temperature to be less than 70 ℃, and distilling under reduced pressure to recover the solvent under the vacuum degree of-0.09 Mpa to obtain the product. Purity 98.6% and yield 97.6%.

Example 5:

16g of sodium bicarbonate, 190g of water, 0.6g of sodium bromide, 200ml of DCE,12.5g of lauryl alcohol and 0.106g of 4-hydroxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 8-9, stirring is started, the temperature is reduced to 0-3 ℃, under the protection of nitrogen, then 6.25g of 60% calcium hypochlorite solid powder (the feeding time is about 15-20 min) is added in batches for multiple times, the temperature is controlled at about 0 ℃, sampling can be performed for 5min after the feeding is finished, and stirring and liquid separation are stopped after the raw materials are reacted and analyzed to be qualified. The separated aqueous phase is directly filtered, the filter cake is washed once with 50ml of DCE, the separated organic phases are combined, and the filtrate after the aqueous phase filtration can be directly discharged. And adding 0.75mg of tertiary butyl hydroquinone into the organic phase, controlling the temperature to be less than 70 ℃, distilling under reduced pressure to recover the solvent under the vacuum degree of-0.09 Mpa, and obtaining the product. Purity 98% and yield 97%.

Example 6:

16g sodium bicarbonate, 190g water, 0.6g sodium bromide, 200ml DCE,12.5g lauryl alcohol and 0.106g 4-hydroxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 8-9, stirring is started, the temperature is reduced to 0-3 ℃,12.5g 60% calcium hypochlorite solid powder (the feeding time is about 15-20 min) is added in batches for multiple times under the protection of nitrogen, the temperature is controlled at about 0 ℃, sampling can be performed for 5min after the feeding is finished, and stirring and liquid separation are stopped after the raw materials are reacted and analyzed to be qualified. The separated aqueous phase is directly filtered, the filter cake is washed once with 50ml of DCE, the separated organic phases are combined, and the filtrate after the aqueous phase filtration can be directly discharged. And adding 0.75mg tea polyphenols into the organic phase, controlling temperature to be less than 70deg.C, vacuum degree to be-0.09 Mpa, and distilling under reduced pressure to recover solvent. Purity 98% and yield 98%.

Comparative example 1

16g of sodium bicarbonate, 190g of water, 0.6g of sodium bromide, 200ml of DCE,12.5g of lauryl alcohol and 0.106g of TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 8-9, stirring is started, the temperature is reduced to 0-3 ℃, under the protection of nitrogen, then 8.25g of 60% calcium hypochlorite solid powder (the feeding time is about 15-20 min) is added in batches for multiple times, the temperature is controlled to about 0 ℃, the time is 5min after the dripping is finished, and the mixture can be sampled until the raw materials react, and stirring and liquid separation are stopped after the analysis is qualified. The aqueous phase was filtered directly, the filter cake was washed once with 50ml DCE, the fractions were separated and the organic phases were combined. And adding 0.75mg tea polyphenols into the organic phase, controlling temperature to be less than 70deg.C, vacuum degree to be-0.09 Mpa, and distilling under reduced pressure to recover solvent to obtain the final product (result is shown in figure 2). Purity 81%, yield 78.2% and a lot of by-products.

Comparative example 2

Adding 0.6g sodium bromide, 200ml DCE,12.5g lauryl alcohol and 0.106g 4-hydroxy-TEMPO into a reaction bottle in sequence, starting stirring, cooling to 0-3 ℃, dropwise adding a mixed solution (the feeding time is about 15-20 min) prepared from 16g sodium bicarbonate, 190g water and 8.25g 60% calcium hypochlorite solid under the protection of nitrogen, controlling the temperature at about 0 ℃, and sampling until the raw materials react, and stopping stirring and liquid separation after analysis is qualified. The aqueous phase was filtered directly, the filter cake was washed once with 50ml of DCM, the fractions were separated and the organic phases were combined. And adding 0.75mg tea polyphenols into the organic phase, controlling temperature to be less than 70deg.C, vacuum degree to be-0.09 Mpa, and distilling under reduced pressure to recover solvent to obtain the final product with a spectrum shown in figure 3, product purity of 85% and yield of 80.5%.

This comparative example illustrates that the drop addition reaction after mixing the aqueous sodium bicarbonate solution with calcium hypochlorite gives a lower product yield and a higher impurity content, and the inventors concluded that it is likely that this addition sequence would be relevant to maintain the pH at a level where the reaction is difficult.

The invention also carries out related researches by changing the dosage of the solvent and the water, and the dosage of the solvent and the water has certain influence on the reaction yield and the purity.

Comparative example 3

8g of sodium bicarbonate, 190g of water, 0.6g of sodium bromide, 200ml of DCE,12.5g of lauryl alcohol and 0.106g 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 ℃, under the protection of nitrogen, then 8.25g of 60% calcium hypochlorite solid powder (the feeding time is about 15-20 min) is added in batches for multiple times, the temperature is controlled at about 0 ℃, 5min after the feeding is finished, and the stirring and liquid separation are stopped after the raw materials are analyzed to be qualified after the sampling is finished. The aqueous phase was filtered directly, the filter cake was washed once with 50ml DCE, the fractions were separated and the organic phases were combined. And adding 0.75mg tea polyphenols into the organic phase, controlling temperature to be less than 70deg.C, vacuum degree to be-0.09 Mpa, and distilling under reduced pressure to recover solvent. Purity 85%, yield 80.5%.

At a pH of less than 7, the reaction impurities are more abundant, resulting in lower yields.

Comparative example 4

18.5g of sodium carbonate and 190g of water, 0.6g of sodium bromide, 200ml of DCE,12.5g of lauryl alcohol and 0.115g of 4-methoxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 10-11, stirring is started, the temperature is reduced to 0 ℃ to 3 ℃ under the protection of nitrogen, then 8.25g of 60% calcium hypochlorite solid powder (the feeding time is about 15-20 min) is added in batches for multiple times, the temperature is controlled at about 0 ℃, the time is 5min after the feeding is finished, and the mixture can be sampled until the raw materials are reacted, and the stirring and the liquid separation are stopped after the analysis is qualified. The aqueous phase was filtered directly, the filter cake was washed once with 50ml DCE, the fractions were separated and the organic phases were combined. And adding 0.75mg tea polyphenols into the organic phase, controlling temperature to be less than 70deg.C, vacuum degree to be-0.09 Mpa, and distilling under reduced pressure to recover solvent to obtain the final product (result is shown in figure 4). Purity 86%, yield 82%.

At a pH greater than 10, the reaction impurities are more abundant, resulting in lower yields.

Comparative example 5

16g of sodium bicarbonate, 190g of water, 0.6g of sodium bromide, 200ml of DCE,12.5g of lauryl alcohol and 0.106g of 4-hydroxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 8-9, stirring is started, the temperature is reduced to 0-3 ℃ under the protection of nitrogen, 70g of 6% sodium hypochlorite solution (the feeding time is about 15-20 min) is dropwise added, the temperature is controlled to be about 0 ℃, the time is 5min after the dropwise addition, and the mixture can be sampled until the raw materials react, and stirring and liquid separation are stopped after the analysis is qualified. The aqueous phase was filtered directly, the filter cake was washed once with 50ml DCE, the fractions were separated and the organic phases were combined. And adding 0.75mg tea polyphenols into the organic phase, controlling temperature to be less than 70deg.C, vacuum degree to be-0.09 Mpa, and distilling under reduced pressure to recover solvent to obtain the final product (result is shown in figure 5). Purity 96%, yield 90.6%.

Sodium hypochlorite solution is used as an oxidant, and the reaction impurities are more, so that the yield is lower.

Comparative example 6

16g of sodium bicarbonate, 190g of water, 0.6g of sodium bromide, 200ml of DCE,12.5g of lauryl alcohol and 0.106g of 4-hydroxy-TEMPO are sequentially added into a reaction bottle, the pH of the reaction solution is 8-9, stirring is started, the temperature is reduced to 0-3 ℃, 8.25g of 60% calcium hypochlorite solid powder is added in batches under the protection of nitrogen, the temperature is controlled to be about 0 ℃, the addition is completed for about 15-20min, and after the dripping is completed, sampling can be performed until the raw materials react, and stirring and liquid separation are stopped after the analysis is qualified. The aqueous phase was filtered directly, the filter cake was washed once with 50ml DCE, the fractions were separated and the organic phases were combined. Controlling the temperature to be less than 70 ℃, distilling under reduced pressure to recover the solvent, and obtaining the product. The purity of the product is 96 percent and the yield is 92.6 percent.

Without the addition of a stabilizer, the product has a deterioration tendency (aldehyde groups are oxidized into carboxylic acid groups), and the yield is low.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing lauraldehyde, comprising the steps of:

under the action of a composite catalyst, lauryl alcohol reacts with an oxidant in a solvent to obtain lauraldehyde, and the pH value of a reaction system is 7-10; wherein,

the composite catalyst comprises metal halide and TEMPO derivative; the TEMPO derivative is one or more selected from 4-hydroxy-TEMPO and 4-methoxy-TEMPO;

the oxidizing agent is hypochlorite.

2. The synthesis according to claim 1, wherein the pH in the reaction system is 7.5 to 9.5, optionally 8 to 9;

3. The synthesis method according to claim 1 or 2, wherein the lauraldehyde is prepared by adding an oxidizing agent to a reaction solution containing a composite catalyst and laurinol in batches;

optionally, the solvent comprises an organic solvent and water; optionally, the volume ratio of the organic solvent to the lauryl alcohol is (10-50): 1, optionally (15-18): 1, a step of; optionally, the mass ratio of water to lauryl alcohol is (10-50): 1, optionally (15-18): 1, a step of; optionally, the organic solvent is not mutually soluble with water, and optionally, the organic solvent is at least one selected from dichloromethane, dichloroethane, chloroform and toluene; optionally, the solvent is used for being added into a reaction liquid containing the composite catalyst and lauryl alcohol;

4. A method of synthesis according to any of claims 1 to 3, wherein the hypochlorite is selected from metal hypochlorite salts; optionally, the metal hypochlorite is at least one of sodium hypochlorite and calcium hypochlorite; optionally, the hypochlorite is a calcium hypochlorite solid; optionally, the calcium hypochlorite solid is 60% calcium hypochlorite powder;

optionally, the metal halide is selected from metal iodides and/or metal bromides; optionally, the metal halide is a metal bromide; optionally, the metal halide is selected from one or more of potassium bromide, sodium bromide, cuprous bromide, potassium iodide, sodium iodide, and cuprous iodide; optionally, the metal halide is an alkali metal bromide, optionally, the metal halide is selected from at least one of potassium bromide and sodium bromide.

5. The synthetic method according to any one of claims 1 to 4, wherein the molar ratio of metal halide and TEMPO derivative in the composite catalyst is 1: (0.01 to 0.2), optionally 1: (0.06-0.15), optionally 1: (0.09-0.12), optionally 1: (0.95-0.12), optionally 1: (0.1 to 0.11);

and/or the molar ratio of lauryl alcohol to metal halide is 1: (0.01 to 0.5), optionally 1: (0.05 to 0.2), optionally 1: (0.06-0.12), optionally 1: (0.08-0.1);

and/or the mass ratio of the lauryl alcohol to the oxidant is preferably 1:0.5-1;

and/or the reaction temperature is-1 to 5 ℃, the reaction temperature is 0 to 5 ℃, alternatively 0.01 to 3 ℃;

and/or the reaction time is 0.5 to 1.5 hours, alternatively 0.5 to 1.0 hours.

6. The method of any one of claims 1 to 5, further comprising the step of post-treating the reacted material to provide lauraldehyde, optionally post-treating comprising recovering solvent; alternatively, the conditions for recovering the solvent are controlled to a temperature below 70 ℃, and distillation under reduced pressure is performed.

7. The method of claim 6, wherein the post-treatment further comprises adding a trace amount of a stabilizer, optionally at least one of tea polyphenols, tocopherols, butylated hydroxyanisole, dibutylhydroxytoluene, tertiary butylhydroquinone.

8. The synthetic method according to any one of claims 1 to 7, comprising:

adding calcium hypochlorite solid into a reaction solution containing a composite catalyst and lauryl alcohol and having the pH of 8-9, and performing aftertreatment to obtain lauraldehyde;

optionally, adjusting the pH with an alkali metal bicarbonate and/or an alkali metal carbonate; optionally, the alkali metal is sodium or potassium;

optionally, the metal halide is an alkali metal bromide, optionally, the alkali metal bromide is sodium bromide and/or potassium bromide;

9. The synthetic method of claim 8 wherein the solvent comprises an organic solvent and water; optionally, the volume ratio of the organic solvent to the lauryl alcohol is (10-50): 1, optionally (15-18): 1, a step of; optionally, the mass ratio of the water to the lauryl alcohol is (10-50): 1, optionally (15-18): 1, a step of;

optionally, the organic solvent is not mutually soluble with water, and optionally, the organic solvent is at least one selected from dichloromethane, dichloroethane, chloroform and toluene;

optionally, the solvent is used for being added into a reaction liquid containing the composite catalyst and lauryl alcohol;

and/or, calcium hypochlorite solids are added in portions.

10. The synthetic method of claim 8 or 9, wherein the post-treatment comprises recovering the solvent and adding a trace amount of stabilizer;

alternatively, the conditions for recovering the solvent are controlled to be lower than 70 ℃, and reduced pressure distillation is performed;

optionally, the stabilizer is at least one of tea polyphenol, tocopherol, butyl hydroxy anisole, dibutyl hydroxy toluene and tertiary butyl hydroquinone;

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