A method for synthesizing vanillin

Abstract

The present invention belongs to the technical field of spice synthesis, and specifically relates to a method for synthesizing vanillin. The synthesis method comprises the following steps: using 4-vinyl-2-methoxyphenol as a raw material, under an inert atmosphere, irradiating light to excite 2-chloro-4-nitropyridine, and under the synergistic action of the excited 2-chloro-4-nitropyridine and trifluoroethanol, an oxidation reaction occurs to obtain vanillin. The synthesis process of the present invention does not require metal catalysts, flammable and explosive reagents, and high-temperature reaction conditions, and the reaction process is safe.

Description

Technical Field

[0001] The present invention belongs to the technical field of spice synthesis, and particularly relates to a method for synthesizing vanillin. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the understanding of the overall background of the present invention, and it is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Vanillin (CAS: 121 - 33 - 5), also known as vanilla powder, vanillin, vanilla extract, etc., is an important spice extracted from the vanilla beans of the Rutaceae family. It is one of the synthetic spices with the largest production volume and is an important raw material for formulating chocolate, chewing gum, pastry, and tobacco flavors. It naturally exists in vanilla bean pods, as well as clove oil, oak moss oil, and benzoin resin. It is widely used in the food, cosmetics, and pharmaceutical fields. Currently, the synthesis methods of vanillin mainly include extraction from natural vanilla, chemical synthesis, and biosynthesis, etc.

[0004] Although the traditional chemical synthesis methods are mature, they are often accompanied by problems such as complex reaction steps, low yields, and harsh reaction conditions. To improve the production efficiency of vanillin and reduce production costs, developing new synthetic routes has important economic and social significance. Summary of the Invention

[0005] To solve the deficiencies of the prior art, the purpose of the present invention is to provide a method for synthesizing vanillin. The synthesis method of the present invention does not require a metal catalyst, flammable and explosive reagents, and high - temperature reaction conditions during the synthesis process. The reaction process is safe and has the advantages of simple and efficient steps, mild reaction conditions, and high product yield.

[0006] To achieve the above - mentioned purpose, the technical solution of the present invention is as follows:

[0007] A method for synthesizing vanillin, using 4 - vinyl - 2 - methoxyphenol as a raw material, under an inert atmosphere condition, adding trifluoroethanol and 2 - chloro - 4 - nitropyridine, and performing light irradiation to carry out an oxidation reaction to obtain vanillin.

[0008] The present invention has found through research that under an inert atmosphere condition, by performing light irradiation, 2 - chloro - 4 - nitropyridine is excited. Under the synergistic action of the excited - state 2 - chloro - 4 - nitropyridine and trifluoroethanol, 4 - vinyl - 2 - methoxyphenol can undergo an oxidation reaction to obtain vanillin. The reaction formula is as follows:

[0009]

[0010] In some embodiments, the oxidation reaction is carried out in a solvent. The solvent can make the substances mix evenly and increase the reaction rate.

[0011] Specifically, the solvent is chloroform, dichloroethane or dichloromethane. Research shows that the solvent affects the yield of vanillin. When the solvent is chloroform, the yield of vanillin is higher.

[0012] In some embodiments, the molar ratio of 4-vinyl-2-methoxyphenol, trifluoroethanol and 2-chloro-4-nitropyridine is 1:(1~2.0):(1~2.0). Research shows that under this condition, the yield of vanillin is higher.

[0013] In some embodiments, the reaction temperature is 20~30 °C and the time is 8~15 h.

[0014] In some embodiments, the light wavelength is 380~440 nm. Research shows that the light wavelength also affects the yield of vanillin. When the light wavelength is 395~405 nm, the yield of vanillin is higher.

[0015] The inert atmosphere described in the present invention refers to a gas atmosphere formed by an inert gas such as nitrogen or helium, argon, xenon, etc. In some embodiments, the inert atmosphere is a nitrogen atmosphere. Using nitrogen to form an inert atmosphere can further reduce costs.

[0016] In some embodiments, after the oxidation reaction, the solvent is removed by vacuum distillation, and then an organic solvent and water are added for extraction and liquid separation. After the organic layer is vacuum distilled to remove the solvent, column chromatography is carried out. Using this purification method is beneficial to obtaining vanillin with higher purity.

[0017] The beneficial effects obtained by one or more of the above technical solutions of the present invention are as follows:

[0018] The present invention uses 4-vinyl-2-methoxyphenol as a raw material, and under the action of 2-chloro-4-nitropyridine in the excited state, an oxidation reaction occurs to obtain vanillin. Through the optimization of the synthesis method, the reaction yield can reach 88%. The synthesis process does not require metal catalysts, flammable and explosive reagents, and high-temperature reaction conditions, and the reaction process is green and safe. Specific Embodiments

[0019] In order to enable those skilled in the art to more clearly understand the technical solutions of the present invention, the technical solutions of the present invention will be described in detail below with specific embodiments.

[0020] Example 1

[0021]

[0022] Add 4-vinyl-2-methoxyphenol (0.45 g, 3 mmol), 2-chloro-4-nitropyridine (0.62 g, 3.9 mmol) and trifluoroethanol (0.39 g, 3.9 mmol) into a 10 mL reaction flask. Under a nitrogen atmosphere, add 5 mL of chloroform. Under the condition of 25 °C, irradiate and stir with a 400 nm wavelength LED lamp for 12 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. Dilute with 20 mL of dichloromethane, add 10 mL of deionized water for extraction and liquid separation. Distill off the solvent from the extracted organic layer under reduced pressure. The crude product is separated by column chromatography to obtain 0.4 g of the product, with a total yield of 88%.

[0023] The proton nuclear magnetic resonance spectrum of the obtained vanillin is as follows: 1 H NMR (500 MHz, CDCl 3 ): δ= 9.84 (s, 1H), 7.47–7.40 (m, 2H), 7.06 (d, J = 8.5 Hz, 1H), 6.20 (s, 1H,) 3.99 (s, 3H).

[0024] Example 2

[0025]

[0026] Add 4-vinyl-2-methoxyphenol (0.45 g, 3 mmol), 2-chloro-4-nitropyridine (0.62 g, 3.9 mmol) and trifluoroethanol (0.39 g, 3.9 mmol) into a 10 mL reaction flask. Under a nitrogen atmosphere, add 5 mL of dichloroethane. Under the condition of 25 °C, irradiate and stir with a 400 nm wavelength LED lamp for 12 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. Dilute with 20 mL of dichloroethane, add 10 mL of deionized water for extraction and liquid separation. Distill off the solvent from the extracted organic layer under reduced pressure. The crude product is separated by column chromatography to obtain 0.37 g of the product, with a total yield of 81%.

[0027] Example 3

[0028]

[0029] Add 4-vinyl-2-methoxyphenol (0.45 g, 3 mmol), 2-chloro-4-nitropyridine (0.62 g, 3.9 mmol) and trifluoroethanol (0.39 g, 3.9 mmol) to a 10 mL reaction flask. Under a nitrogen atmosphere, add 5 mL of chloroform. Stir and irradiate with a 420 nm wavelength LED lamp at 25 °C for 12 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. Dilute with 20 mL of dichloromethane, add 10 mL of deionized water for extraction and liquid separation. Distill off the solvent from the extracted organic layer under reduced pressure. The crude product is separated by column chromatography to obtain 0.34 g of the product, with an overall yield of 75%.

[0030] Example 4

[0031]

[0032] Add 4-vinyl-2-methoxyphenol (0.45 g, 3 mmol), 2-chloro-4-nitropyridine (0.71 g, 4.5 mmol) and trifluoroethanol (0.39 g, 3.9 mmol) to a 10 mL reaction flask. Under a nitrogen atmosphere, add 5 mL of chloroform. Stir and irradiate with a 400 nm wavelength LED lamp at 25 °C for 12 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. Dilute with 20 mL of dichloromethane, add 10 mL of deionized water for extraction and liquid separation. Distill off the solvent from the extracted organic layer under reduced pressure. The crude product is separated by column chromatography to obtain 0.39 g of the product, with an overall yield of 86%.

[0033] Example 5

[0034]

[0035] Add 4-vinyl-2-methoxyphenol (0.45 g, 3 mmol), 2-chloro-4-nitropyridine (0.47 g, 3.0 mmol) and trifluoroethanol (0.30 g, 3 mmol) to a 10 mL reaction flask. Under a nitrogen atmosphere, add 5 mL of chloroform. Stir and irradiate with a 400 nm wavelength LED lamp at 25 °C for 12 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. Dilute with 20 mL of dichloromethane, add 10 mL of deionized water for extraction and liquid separation. Distill off the solvent from the extracted organic layer under reduced pressure. The crude product is separated by column chromatography to obtain 0.32 g of the product, with an overall yield of 70%.

[0036] Example 6

[0037]

[0038] Add 4-vinyl-2-methoxyphenol (0.45 g, 3 mmol), 2-chloro-4-nitropyridine (0.95 g, 6.0 mmol) and trifluoroethanol (0.60 g, 6 mmol) into a 10 mL reaction flask. Under a nitrogen atmosphere, add 5 mL of chloroform. Stir and irradiate with a 400 nm wavelength LED lamp at 25 °C for 12 h. After the reaction is completed, remove the solvent by distillation under reduced pressure. Dilute with 20 mL of dichloromethane, add 10 mL of deionized water for extraction and liquid separation. Distill off the solvent from the extracted organic layer under reduced pressure. The crude product is separated by column chromatography to obtain 0.38 g of the product, with a total yield of 84%.

[0039] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for synthesizing vanillin, characterized in that: Using 4-vinyl-2-methoxyphenol as a raw material, trifluoroethanol and 2-chloro-4-nitropyridine are added under an inert atmosphere, and light is irradiated to produce vanillin by oxidation reaction; The oxidation reaction is carried out in a solvent; The solvent is chloroform, dichloroethane or dichloromethane; The reaction temperature is 20-30 °C and the reaction time is 8-15 h; The wavelength of light is 380-440 nm; The molar ratio of 4-vinyl-2-methoxyphenol, trifluoroethanol and 2-chloro-4-nitropyridine is 1:(1~2.0):(1~2.0).

2. The method for synthesizing vanillin according to claim 1, characterized in that: The solvent is chloroform.

3. The method for synthesizing vanillin according to claim 1, characterized in that: The wavelength of light is 395~405 nm.

4. The method for synthesizing vanillin according to claim 1, characterized in that: The inert atmosphere is a nitrogen atmosphere.

5. The method for synthesizing vanillin according to claim 1, characterized in that: After the oxidation reaction, the solvent is distilled off under reduced pressure, and then an organic solvent and water are added to perform extraction and separation. After the solvent is distilled off under reduced pressure in the organic layer, column chromatography is performed.

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