A method for synthesizing methyl benzoate

Abstract

The application discloses a kind of synthesis methods of methyl benzoate, belong to organic synthesis technical field.The application uses benzoic acid, methanol and trichloroisocyanuric acid as raw material, adds trace amount of triphenylphosphine initiator in continuous photochemical tubular reactor and is reacted to prepare methyl benzoate.The synthesis method of the application is mild, efficient and energy-saving, avoids the energy consumption and environmental pollution generated in traditional production method such as heating, alkali washing / washing, and the whole process is environmentally friendly;Synthesis process is simple, low in cost, avoids the problems of complex preparation and high cost caused by the use of special catalyst, easy to industrial production;The yield of synthetic product is high;The continuous flow light reaction method can reduce energy consumption, improve raw material utilization rate and effectively avoid resource waste.The product obtained by the synthesis method of the application has more pure and correct aroma, and does not need to be aged.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and specifically relates to a method for synthesizing methyl benzoate. Background Technology

[0002] Methyl benzoate is an important fragrance, solvent, and organic synthesis intermediate, and its application value has attracted much attention in the chemical industry. Currently, the synthesis methods for methyl benzoate include: the concentrated sulfuric acid catalytic method (De Oliveira, CS, et al. Synthesis, molecular properties prediction, and anti-staphylococcal activity of N-acylhydrazones and new 1,3,4-oxadiazole derivatives. Molecules, 2012, 17:5095-5107; Martínez R, et al. Synthesis and antitubercular activity of new N-[5-(4-chlorophenyl)-1,3,4-oxadiazol-2-yl]-(nitroheteroaryl)carboxamides. Heterocyclic Communications, 2019, 25: 52-59), which is simple, low-cost, and industrially mature, but suffers from strong equipment corrosion, difficult waste acid treatment, numerous side reactions, and non-recoverable catalyst; and the p-toluenesulfonic acid catalytic method (Gianni J, et al. Silver triflate / p-TSA co-catalyzed synthesis of 3-substituted isocoumarins from 2-alkynylbenzoates. Organic & Biomolecular Chemistry, 2018, 16: 3213-3219) has low equipment corrosion and few side reactions, but the catalyst is difficult to recover and acidic wastewater is still generated; ionic liquid catalysis (CN107915626A) has low corrosion, recoverable catalyst, continuous operation, and low waste, but the ionic liquid catalyst is difficult to separate and has high cost; solid acid catalysis (Yu X, et al. Synthesis of a series of methyl benzoates through esterification with a Zr / Ti solid acid catalyst. Catalysts, 2023, 13, 915) is non-corrosive, easy to separate and recover, reusable, produces less wastewater, and reduces energy consumption, but the catalyst preparation is complex and costly; microwave-assisted synthesis (Umrigar V, et al.)Cleaner production of methyl benzoate using solid heterogenous catalyst via electromagnetic waves as an energy source. Journal of The Institution of Engineers (India): Series E, 2020, 101: 109-114. The reaction is fast, yields high, and simple to operate, but requires specialized microwave equipment and still produces acid catalyst corrosion and acidic wastewater. Biocatalysis (Leszczak JP, Tran-Minh C. Optimized enzymatic synthesis of methyl benzoate in organic medium. Operating conditions and impact of different factors on kinetics. Biotechnology and Bioengineering, 1998, 60: 356-361; Murfitt LM, et al. Purification and characterization of S-adenosyl-L-methionine: benzoic acid carboxyl methyltransferase, the enzyme responsibility for biosynthesis of the volatile ester methyl benzoate in flowers of Antirrhinum majus. Archives of Biochemistry and (Biophysics, 2000, 382:145-151) This method exhibits high reactivity and mild reaction conditions, but the enzyme catalyst is prone to deactivation, resulting in low yield and difficulty in industrial scale-up. CN121824250A discloses a one-pot photocatalytic oxidative esterification method for synthesizing methyl benzoate, monosubstituted methyl benzoate, and dimethyl 2,5-furandicarboxylate. However, the preparation of the cobalt phthalocyanine / B / P co-doped g-C3N4Z-type heterojunction photocatalyst is complex and costly. Since methyl benzoate itself is not expensive, there is an urgent need for a method to synthesize methyl benzoate that features mild reaction conditions, simple process, low energy consumption, low cost, high yield, pure aroma of the product, environmental friendliness, and ease of industrial production. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for synthesizing methyl benzoate. This invention uses benzoic acid, methanol, and trichloroisocyanuric acid as raw materials, with a trace amount of triphenylphosphine added as an initiator to carry out the reaction in a photoreactor. The possible reaction mechanism is that under light irradiation, trichloroisocyanuric acid combines with the trace amount of triphenylphosphine to produce chloride (Cl). - ), of which chloride ions (Cl) in chlorides - It promotes the formation of the corresponding acyl chloride (RCOCl) from benzoic acid, which then reacts with methanol to form methyl benzoate.

[0004] The present invention adopts the following technical solution: This invention provides a method for synthesizing methyl benzoate, comprising the following steps: S1. Dissolve benzoic acid, triphenylphosphine, and trichloroisocyanuric acid in a methanol solution, and stir the reaction mixture. S2. The solution is pumped into a continuous photochemical tubular reactor and continuously circulated within the reactor. The reaction is detected by gas chromatography. After the reaction is complete, the reaction solution is released and cooled. S3. First, filter out the solid produced after cooling, then remove methanol under normal pressure, and finally distill under reduced pressure to obtain methyl benzoate product.

[0005] Preferably, in step S1, the molar ratio of benzoic acid, triphenylphosphine, and trichloroisocyanuric acid is 100:1:100.

[0006] Preferably, in step S1, the volume of methanol is 100 mL.

[0007] Preferably, in step S1, the stirring time is 30 minutes.

[0008] Preferably, in step S2, the wavelength of the light in the reactor is 360-560 nm.

[0009] Preferably, in step S2, the temperature is lowered to 0°C.

[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. The synthesis method of the present invention is mild, efficient and energy-saving, avoiding the energy consumption and environmental pollution caused by heating, alkaline washing / water washing and other processes in traditional production methods. The whole process is environmentally friendly.

[0011] 2. The synthesis process of this invention is simple and low-cost, avoiding the problems of complex preparation and high cost caused by the use of special catalysts, and is easy to industrialize.

[0012] 3. The synthesis method of the present invention has a high product yield (up to 94%).

[0013] 4. This invention uses a continuous photoreaction method, which has low energy consumption, high raw material utilization, and effectively avoids resource waste.

[0014] 5. Compared with products obtained by traditional heating synthesis methods, the products obtained by the synthesis method of this invention have a purer aroma and do not require aging treatment. Detailed Implementation

[0015] To make the present invention more apparent and understandable, preferred embodiments are described in detail below.

[0016] This invention provides a method for synthesizing methyl benzoate, using benzoic acid, methanol, and trichloroisocyanuric acid as raw materials, and adding a trace amount of triphenylphosphine initiator in a continuous photochemical tubular reactor to produce methyl benzoate. The synthesis method of this invention is mild, highly efficient, and energy-saving, avoiding the energy consumption and environmental pollution caused by heating, alkaline washing / water washing, etc., in traditional production methods. The entire process is environmentally friendly. The synthesis process is simple and low-cost, avoiding the problems of complex preparation and high cost caused by using special catalysts, and is easy to industrialize. The yield of the synthesized product is high. The continuous photochemical reaction method has low energy consumption, high raw material utilization, and effectively avoids resource waste. The product obtained by the synthesis method of this invention has a purer aroma and does not require aging treatment.

[0017] Example 1 This invention provides a method for synthesizing methyl benzoate, comprising the following steps: S1. Benzoic acid (10.5 g, 86 mmol, 100 eq.), triphenylphosphine (0.226 g, 0.86 mmol, 1 eq.) and trichloroisocyanuric acid (20 g, 86 mmol, 100 eq.) were dissolved in 100 mL of methanol solution, and the reaction mixture was stirred for 30 minutes. S2. The solution is pumped into a continuous photochemical tubular reactor and continuously circulated in the reactor under a light wavelength of 360 nm. The reaction is detected by gas chromatography. After the reaction is completed, the reaction solution is released and cooled to 0°C. S3. First, filter out the solid produced after cooling, then remove methanol under normal pressure, and distill under reduced pressure to obtain 6.79g of methyl benzoate product, with a yield of 58%.

[0018] Example 2 This invention provides a method for synthesizing methyl benzoate, comprising the following steps: S1. Benzoic acid (10.5 g, 86 mmol, 100 eq.), triphenylphosphine (0.226 g, 0.86 mmol, 1 eq.) and trichloroisocyanuric acid (20 g, 86 mmol, 100 eq.) were dissolved in 100 mL of methanol solution, and the reaction mixture was stirred for 30 minutes. S2. The solution is pumped into a continuous photochemical tubular reactor and continuously circulated in the reactor at a wavelength of 390 nm. The reaction is detected by gas chromatography. After the reaction is completed, the reaction solution is released and cooled to 0°C. S3. First, filter out the solid produced after cooling, then remove methanol under normal pressure, and distill under reduced pressure to obtain 11g of methyl benzoate product, with a yield of 94%.

[0019] Example 3 This invention provides a method for synthesizing methyl benzoate, comprising the following steps: S1. Benzoic acid (10.5 g, 86 mmol, 100 eq.), triphenylphosphine (0.226 g, 0.86 mmol, 1 eq.) and trichloroisocyanuric acid (20 g, 86 mmol, 100 eq.) were dissolved in 100 mL of methanol solution, and the reaction mixture was stirred for 30 minutes. S2. The solution is pumped into a continuous photochemical tubular reactor and continuously circulated in the reactor under a light wavelength of 450 nm. The reaction is detected by gas chromatography. After the reaction is completed, the reaction solution is released and cooled to 0°C. S3. First, filter out the solid produced after cooling, then remove methanol under normal pressure, and distill under reduced pressure to obtain 5.03g of methyl benzoate product, with a yield of 43%.

[0020] Example 4 This invention provides a method for synthesizing methyl benzoate, comprising the following steps: S1. Benzoic acid (10.5 g, 86 mmol, 100 eq.), triphenylphosphine (0.226 g, 0.86 mmol, 1 eq.) and trichloroisocyanuric acid (20 g, 86 mmol, 100 eq.) were dissolved in 100 mL of methanol solution, and the reaction mixture was stirred for 30 minutes. S2. The solution is pumped into a continuous photochemical tubular reactor and continuously circulated in the reactor under a light wavelength of 560 nm. The reaction is detected by gas chromatography. After the reaction is completed, the reaction solution is released and cooled to 0°C. S3. First, filter out the solid produced after cooling, then remove methanol under normal pressure, and distill under reduced pressure to obtain 1.76g of methyl benzoate product, with a yield of 15%.

[0021] Aroma evaluation was conducted on the products obtained by the synthesis method of this invention and those obtained by traditional heating methods. It was found that the product obtained by the synthesis method of this invention has a purer aroma and does not require further aging. Products obtained by traditional heating methods have varying degrees of burnt smell when freshly steamed, and this burnt smell only diminishes after a period of aging.

[0022] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for synthesizing methyl benzoate, characterized in that, Includes the following steps: Step S1: Dissolve benzoic acid, triphenylphosphine, and trichloroisocyanuric acid in a methanol solution and stir the reaction mixture; Step S2: The solution is pumped into a continuous photochemical tubular reactor and continuously circulated within the reactor. The reaction is detected by gas chromatography. After the reaction is complete, the reaction solution is discharged and cooled. Step S3: First, filter out the solid produced after cooling, then remove methanol under normal pressure, and finally distill under reduced pressure to obtain methyl benzoate product.

2. The method for synthesizing methyl benzoate as described in claim 1, characterized in that, In step S1, the molar ratio of benzoic acid, triphenylphosphine, and trichloroisocyanuric acid is 100:1:

100.

3. The method for synthesizing methyl benzoate as described in claim 1, characterized in that, In step S1, the volume of methanol is 100 mL.

4. The method for synthesizing methyl benzoate as described in claim 1, characterized in that, In step S1, the stirring time is 30 minutes.

5. The method for synthesizing methyl benzoate as described in claim 1, characterized in that, In step S2, the wavelength of the light in the reactor is 360-560nm.

6. The method for synthesizing methyl benzoate according to claim 1, characterized in that, In step S2, the temperature is lowered to 0°C.