Method for preparing phenylacetonitrile based on a continuous flow dynamic microreactor

Abstract

The application discloses a method for preparing phenylacetonitrile based on a continuous flow dynamic microreactor. By regulating the flow rates of the two-phase reactants of benzyl chloride and sodium cyanide containing a phase transfer catalyst, the residence time of the reaction is regulated. Meanwhile, the flow rate ratio of the two-phase reactants is dynamically adjusted according to the real-time feedback of the yield of phenylacetonitrile, so that the fine control of the cyanation reaction is realized. The microreactor of the application is built-in with magnetic stirring. On the one hand, the microdroplets with excellent dispersibility are formed, which has excellent process intensification effect on the cyanation reaction, greatly improves the phase transfer catalytic efficiency, and makes the yield of phenylacetonitrile increase to more than 97%, and the reaction time is reduced to 30 minutes. The space-time yield is increased from 460 g / (m 3 ·min) of the tank process to 13000 g / (m 3 ·min), which is increased by about 30 times. On the other hand, the sodium chloride particles can be continuously broken, avoiding the blockage of the microchannel caused by the deposition and aggregation of sodium chloride particles, solving the problem that the ordinary microchannel reactor cannot cope with the high solid content system, and ensuring the long-period stable operation.

Description

Technical Field

[0001] This invention relates to a technology in the field of chemical pharmaceuticals, specifically a method for preparing the pharmaceutical intermediate phenylacetonitrile based on a continuous flow dynamic microreactor. Background Technology

[0002] Phenylacetonitrile is an important chemical intermediate, mainly used in the synthesis of high-end chemicals such as pharmaceuticals, pesticides, dyes, and fragrances. Phenylacetonitrile is a key raw material for the production of phenylacetic acid, which is an important intermediate in the synthesis of antibiotics such as cephalosporins and penicillins. Currently, among the various methods for synthesizing phenylacetonitrile, the nucleophilic substitution reaction between benzyl chloride and sodium cyanide is the most widely used method. Benzyl chloride and sodium cyanide are inexpensive and readily available raw materials. At the same time, the reaction conditions are relatively mild (50-100℃), requiring no additional high pressure or special equipment. This reaction has high yield and good selectivity, making it suitable for large-scale production. These reasons make this method the preferred choice for industrial synthesis of phenylacetonitrile.

[0003] Phenylacetonitrile is mainly produced by the reaction of benzyl chloride and sodium cyanide in the presence of a phase-transfer catalyst. The reaction route is as follows: .

[0004] The cyanation reaction between benzyl chloride (oil phase) and an aqueous sodium cyanide solution (aqueous phase) is a typical oil-water two-phase reaction. Cyanide ions interact with a phase-transfer catalyst, transferring from the aqueous phase to the oil phase to react with benzyl chloride, synthesizing phenylacetonitrile while simultaneously generating a large amount of sodium chloride. Therefore, a larger specific phase interface area results in more thorough contact between the two phases, faster mass transfer, more uniform concentration distribution, and improved reaction rate and selectivity. The specific phase interface area is a key controlling factor for the reaction rate of this two-phase reaction. The aqueous phase, rich in sodium chloride, easily reaches saturation, leading to the precipitation of a large number of sodium chloride particles. In traditional batch processes, a small specific phase interface area results in slow mass and heat transfer rates, leading to a long cyanation reaction cycle, typically exceeding 8 hours. Furthermore, the long reaction time also poses significant safety risks, such as overheating and potential personnel exposure to cyanide. Moreover, the hydrogen on the benzyl carbon is highly reactive, making dimerization of phenylacetonitrile and benzyl chloride difficult to avoid during the reaction. Therefore, process control is crucial for improving yield and process stability. How to enhance mass transfer efficiency by actively constructing multiphase flow patterns, accurately control reaction residence time based on "spatiotemporal transformation," and precisely control temperature and pressure have become key issues that urgently need to be addressed. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a method for preparing phenylacetonitrile based on continuous flow dynamic microreaction technology, which addresses the shortcomings of existing batch-process preparation of phenylacetonitrile, such as long reaction time, low overall yield, and safety hazards.

[0006] This invention is achieved through the following technical solution: A method for preparing phenylacetonitrile based on a continuous flow dynamic microreactor, the method comprising the following steps: injecting benzyl chloride and a sodium cyanide solution containing a phase transfer catalyst into the continuous flow dynamic microreactor for a cyanation reaction, maintaining the reaction temperature at 40-80℃ and the reaction residence time at 5-40 min, until a phenylacetonitrile solution is generated; wherein the flow rate of the sodium cyanide is 0.16-1.24 ml / min, and the flow rate of the benzyl chloride is 0.10-0.77 ml / min; the phase transfer catalyst is tetrabutylammonium bromide or didodecyldimethylammonium bromide, the content of which is 1-5 wt% of benzyl chloride.

[0007] In one embodiment of the present invention, the continuous flow dynamic microreactor is a micro plate reactor containing a magnetic stirrer inside, the reactor is made of titanium alloy, and the magnetic stirrer speed is greater than or equal to 1200 rpm.

[0008] In one embodiment of the present invention, the reaction temperature is 50-80°C.

[0009] In one embodiment of the present invention, the reaction temperature is controlled by a constant temperature water bath or a constant temperature oil bath.

[0010] In one embodiment of the present invention, the reaction residence time is 5-30 min.

[0011] In one embodiment of the present invention, the flow rate ratio of the sodium cyanide solution to the benzyl chloride solution is 1:2 to 5:1.

[0012] In one embodiment of the present invention, the flow rate ratio of the sodium cyanide solution to the benzyl chloride solution is 1:2 to 1.75:1.

[0013] In one embodiment of the present invention, the phase transfer catalyst is tetrabutylammonium bromide, the content of which is 3-5 wt% of benzyl chloride.

[0014] In one embodiment of the present invention, the sodium cyanide content in the sodium cyanide solution containing the phase transfer catalyst is 30 wt%.

[0015] In one embodiment of the present invention, the benzyl chloride is pure benzyl chloride with a content greater than 99.5%, without the addition of any additives.

[0016] Compared with the prior art, this application has the following significant technical advantages: (1) The present invention uses a continuous flow dynamic microreactor to synthesize phenylacetonitrile. By screening phase transfer catalysts, the flow rate, reaction temperature and reaction residence time of the two-phase reactants of sodium cyanide and benzyl chloride are controlled. At the same time, the flow rate ratio of the two-phase reactants is dynamically adjusted according to the real-time feedback of the phenylacetonitrile yield, which significantly improves the cyanation reaction efficiency of phenylacetonitrile. The reaction time is greatly shortened from more than 8 hours in the traditional batch reactor to within 30 minutes, the total yield is increased to more than 97%, and the selectivity is greater than 98%.

[0017] (2) The continuous flow dynamic microreactor of the present invention has a magnetic stirrer built into a micro reaction tank, thereby actively forming a high specific surface area and strong shear flow field in the microreactor, realizing instantaneous renewal and molecular-level mixing of the liquid-liquid two-phase interface, rapidly breaking up sodium chloride particles to form a uniformly dispersed suspension, significantly suppressing the violent exothermic reaction caused by excessively high local concentration of cyanide, effectively avoiding serious blockage caused by the deposition or aggregation of sodium chloride particles, and ensuring the continuous and stable operation of the high solid content system.

[0018] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of the embodiments of this application are described below. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0020] Figure 1 A schematic diagram of the structure of a dynamic microreactor for synthesizing phenylacetonitrile according to an embodiment of this application is shown.

[0021] In the diagram, 1 is the cover plate; 101 is the benzyl chloride inlet; 102 is the sodium cyanide inlet; 103 is the outlet; 104 is the cover plate connection hole; 2 is the reaction chamber module; 201 is the micro-reaction groove; 202 is the flow channel; 203 is the sealing groove; 204 is the reaction chamber module connection hole; and 3 is the sealing ring. Detailed Implementation

[0022] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0023] To keep the drawings concise, only the parts relevant to the invention are shown schematically, and they do not represent the actual structure of the device. Furthermore, for ease of understanding, some drawings show only one or a few components with the same structure or function. In this document, "a few" includes both "two" and "more than two".

[0024] In this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a mechanical connection, or a physical or electrical connection between different components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of description and simplification of operation, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0026] Figure 1 This is a schematic diagram of the structure of a dynamic microreactor for synthesizing phenylacetonitrile according to an embodiment of this application. Figure 1 As shown, the dynamic microreactor is a miniature plate reactor made of titanium alloy, which consists of a cover plate 1, a reaction chamber module 2, and a sealing ring 3. The cover plate 1 is provided with a benzyl chloride inlet 101, a sodium cyanide inlet 102, and an outlet 103. The benzyl chloride inlet 101 and the sodium cyanide inlet 102 are used to inject benzyl chloride and a sodium cyanide solution containing a phase transfer catalyst into the reactor under heating conditions to carry out the cyanidation reaction. The phenylacetonitrile and sodium chloride generated by the reaction are discharged from the dynamic microreactor through the outlet 103.

[0027] The reaction chamber module 2 is equipped with multiple micro-reaction troughs 201 connected in series. The total effective reaction volume of the microreactor is 10 mL, and the connecting pipelines are made of PFA material. The multiple micro-reaction troughs 201 are connected to each other through flow channels 202, and the reaction troughs are also connected to the feed inlet through flow channels 202.

[0028] To ensure the airtightness of the microreactor, the reaction chamber module 2 is also provided with an annular sealing groove 203, with an embedded sealing ring 3. The material of the sealing ring 3 is preferably resistant to cyanide corrosion. The cover plate 1 is provided with several connection holes 104, which correspond one-to-one with the connection holes 204 provided on the reaction chamber module 2. The cover plate 1 and the reaction chamber module 2 are fastened together with bolts through the connection holes 104 and 204 to form a closed microfluidic system.

[0029] In the actual synthesis process, benzyl chloride and sodium cyanide solution containing a phase transfer catalyst are injected through inlets 101 and 102 and then enter the micro-reaction tank 201 via channel 202 for cyanidation reaction. The reaction flow rate and residence time have a significant impact on the reaction performance. Generally, the lower the flow rate, the longer the residence time, and the higher the reaction yield. However, excessively low flow rates can lead to excessively long residence times, easily causing local overheating and side reactions. Furthermore, in microreactors, the fluid is usually in a laminar flow state, and mixing mainly relies on slow molecular diffusion, which is not conducive to improving mass transfer efficiency or rapid dissipation of reaction heat. Therefore, in the continuous flow dynamic microreactor of this invention, each micro-tank contains a magnetic stir bar (not shown in the figure). By driving the built-in micro-magnetic bar to rotate, local turbulence and shear force are generated, ensuring continuous renewal of the reaction interface and achieving high mixing efficiency at low flow rates. Simultaneously, enhanced stirring rapidly homogenizes the reaction heat and reactant concentration, effectively improving product selectivity and yield.

[0030] The cyanidation reaction between benzyl chloride and sodium cyanide produces a large amount of sodium chloride particles as a byproduct. Therefore, when synthesizing phenylacetonitrile using a conventional microchannel reactor, these sodium chloride particles continuously settle or aggregate at the bottom of the micro-reaction tank 201 and the flow channel 202, causing severe blockage. In the dynamic microreactor of this invention, magnetic stirring generates high fluid shear, continuously breaking up the sodium chloride particles to form a well-dispersed suspension, maintaining the homogeneity of the reaction system and effectively preventing solid particles from directly settling or agglomerating to form larger particles and causing blockage. After the reaction is complete, the reaction liquid containing phenylacetonitrile and sodium chloride continuously flows out through outlet 103 into subsequent processing stages, ultimately yielding a high-purity phenylacetonitrile product with a yield exceeding 97% and a selectivity exceeding 99.1%.

[0031] Examples 1-7 Prepare a pure benzyl chloride liquid with a purity greater than 99.5%, the concentration of which is determined by gas chromatography. Add a phase transfer catalyst to a 30 wt% sodium cyanide aqueous solution and mix thoroughly. The amount of phase transfer catalyst added is such that the phase transfer catalyst in the reaction system is 3 wt% of the benzyl chloride. Maintain the reaction temperature at 80℃ using a constant temperature water bath. Turn on the magnetic stirrer and rotate the magnetic stir bar at 1200 rpm. Simultaneously start two injection pumps, injecting benzyl chloride and the sodium cyanide solution containing the phase transfer catalyst at flow rates of 0.38 mL / min and 0.62 mL / min respectively. The reaction solution resides in the micro-cylinder for 10 min, obtaining a mixture of phenylacetonitrile and sodium chloride particles. Under the magnetic stirring of the micro-cylinder, the sodium chloride particles are continuously broken down, forming a well-dispersed sodium chloride-phenylacetonitrile suspension, preventing particle sedimentation or aggregation and the formation of large particles that block the channels. The sodium chloride-phenylacetonitrile suspension was discharged through the outlet, and the yield of phenylacetonitrile was determined by gas chromatography.

[0032] The results of Examples 1-7 are shown in Table 1.

[0033] Table 1 .

[0034] As shown in Table 1, the preferred phase transfer catalysts in this invention are TBAB and DDAB, with TBAB being the most preferred. Under the same reaction time, the cyanation reaction of benzyl chloride showed higher yields with TBAB and DDAB, reaching 52.5% and 46.6% respectively, significantly higher than other catalysts. TBAB possesses high phase transfer efficiency, good water solubility, and thermal stability, effectively promoting the migration of cyanide ions from the aqueous phase to the organic phase at 80°C, significantly enhancing interfacial reaction kinetics. Although DDAB has a slightly lower yield, its double-long-chain structure endows it with stronger interfacial adsorption capacity, exhibiting a superior anti-clogging synergistic effect in reaction systems with high solid content. Both catalysts can achieve efficient mixing of the two-phase reaction liquid at low flow rates under magnetic shearing, while avoiding clogging caused by sodium chloride particle sedimentation, ensuring the long-term stable operation of the dynamic microreactor.

[0035] Examples 8-12 This set of examples is similar to Examples 1-7 in the first set, except that the reaction residence time is extended to 30 min, and TBAB is selected as the phase transfer catalyst, with its content set to 0, 1 wt%, 2 wt%, 3 wt%, and 5 wt%, respectively. The conversion rate of benzyl chloride and the yield of phenylacetonitrile are determined by gas chromatography.

[0036] The results of Examples 8-12 are shown in Table 2.

[0037] Table 2 .

[0038] As shown in Table 2, the cyanation reaction rate increases significantly with increasing catalyst mass fraction. When the catalyst mass fraction increases to 5 wt%, the conversion rate of benzyl chloride reaches 99% and the yield reaches 97.2% within 30 min. With decreasing catalyst content, the cyanation reaction rate decreases significantly. The reaction yield drops from 97.2% at 5 wt% to 58% at 1 wt%. A sodium cyanide solution with a content of 0 wt% hardly undergoes any cyanation reaction. Sodium cyanide solutions with phase transfer catalyst contents of 2 wt% and 3 wt% show reaction yields of 76% and 97%, respectively.

[0039] Examples 13-17 Examples 13-17 in the third group are similar to Examples 8-12 in the second group, except that a constant temperature oil bath is used to control the temperature at 40, 50, 60, 70, and 80°C, respectively. The content of the phase transfer catalyst TBAB is set to 3 wt%.

[0040] The results of Examples 13-17 are shown in Table 3.

[0041] Table 3 .

[0042] As shown in Table 3, the conversion rate of benzyl chloride increases with increasing reaction temperature. The yield of phenylacetonitrile reaches its maximum value of 97.0% at a reaction temperature of 80℃ and a residence time of 30 min. At a reaction temperature of 40℃, the cyanidation reaction hardly occurs, and the yield can be considered 0%. In experiments targeting reaction selectivity, the selectivity remains relatively stable within the reaction temperature range of 50℃-80℃, consistently between 98% and 99%, effectively achieving the technical objectives of this invention.

[0043] To verify the synergistic effect of reaction temperature and catalyst dosage on the cyanidation reaction, the inventors also conducted Examples 13', 14', and 15', increasing the catalyst dosage in these three examples to 5 wt%. The yields of the three examples increased to 72%, 85%, and 92%, respectively, while the reaction selectivity remained above 99%. This demonstrates that within a lower temperature range, increasing the catalyst dosage can improve interfacial reactivity, thereby increasing the reaction rate and yield. According to the technical solution of the present invention, the technical effects required by the present invention can be achieved within a reaction temperature range of 40℃-80℃.

[0044] Examples 18-24 Examples 18-24 in the fourth group are similar to Examples 1-7 in the first group, except that the flow rates of benzyl chloride and sodium cyanide solution containing a phase transfer catalyst are controlled in the fourth group, so that the reaction residence time of each example is controlled at 5, 10, 15, 20, 25, 30, and 40 min, respectively. TBAB is selected as the phase transfer catalyst, and its content is set to 3 wt%.

[0045] The results of Examples 18-24 are shown in Table 4.

[0046] Table 4 .

[0047] As shown in Table 4, as the flow rate decreases, the reaction residence time increases, and the reaction yield also increases slowly. When the flow rate of sodium cyanide solution is 0.21 mL / min and the flow rate of benzyl chloride is 0.13 mL / min, the reaction residence time reaches 30 min, at which point the phenylacetonitrile yield reaches its highest value of 97%.

[0048] When the flow rate of sodium cyanide solution decreased to 0.16 mL / min and the flow rate of benzyl chloride was 0.10 mL / min, the reaction residence time increased to 40 min. At this point, the content of phenylacetonitrile began to decrease, and the yield reached 95%. Excessive residence time led to side reactions in the system. When the flow rate of sodium cyanide solution was further adjusted to 0.10 mL / min and the flow rate of benzyl chloride to 0.06 mL / min, the color of the reaction solution changed from dark yellow to black, beginning to affect the subsequent separation process. This indicates that the reaction system had exceeded its optimal window, and the tar formation of byproducts intensified, not only decreasing the yield but also causing coking in the equipment and a significant increase in purification difficulty.

[0049] On the other hand, when the flow rate of sodium cyanide solution is set to 2.50 mL / min and the flow rate of benzyl chloride is set to 1.60 mL / min, the reaction residence time is too short, less than 3 min, resulting in a low yield and lacking process economy. Therefore, it is necessary to set the flow rate of sodium cyanide solution in the range of 0.16 mL / min to 1.24 mL / min and the flow rate of benzyl chloride in the range of 0.10 mL / min to 0.77 mL / min.

[0050] Example 5 Examples 25-31 in the fifth group are similar to examples 18-24 in the fourth group, except that the flow rate ratio of sodium cyanide to benzyl chloride in the fifth group is controlled at 1:3, 1:2, 1:1, 1.67:1, 1.75:1, 3:1, and 5:1, respectively. The reaction residence time is 30 min.

[0051] The results of Examples 25-31 are shown in Table 5.

[0052] Table 5 .

[0053] As shown in Table 5, the flow rate ratio of sodium cyanide to benzyl chloride is one of the key factors affecting the yield of phenylacetonitrile. With increasing flow rate ratio, the yield of phenylacetonitrile shows a significant increasing trend. When the flow rate ratio is greater than 1:1, the yield of phenylacetonitrile rapidly increases to over 90%, reaching a maximum of 97%. Since the cyanation reaction of benzyl chloride is a second-order reaction, the conversion rate of benzyl chloride gradually increases with the increasing flow rate ratio, while a decrease in the flow rate ratio leads to a decrease in the reaction rate. When the flow rate ratio of sodium cyanide to benzyl chloride is less than 1:2, the rate of sodium cyanide reaction is significantly slower in the later stages, and the final yield of phenylacetonitrile drops below 50%.

[0054] Therefore, based on the technical solution of this invention, the flow rate ratio of sodium cyanide to benzyl chloride can be dynamically adjusted according to the phenylacetonitrile yield feedback to maintain the stability of the two-phase flow pattern. Experiments have shown that controlling the flow rate ratio within the range of 1:2 to 5:1, preferably within the range of 1:2 to 1.75:1, can form highly monodisperse microdroplets, effectively increasing the interfacial area between the two phases, significantly improving the reaction rate, and ensuring the achievement of the phenylacetonitrile yield.

[0055] Application Examples When using traditional industrial reactors such as batch reactors for the cyanation reaction of sodium cyanide and benzyl chloride, the reaction yield typically reaches 95% after 8 hours. In contrast, the continuous flow dynamic microreactor of this invention allows for precise control of the cyanation reaction by regulating the flow rates of the two reactants, thereby controlling the reaction residence time. Furthermore, the flow rate ratio of the two reactants is dynamically adjusted based on real-time feedback of the phenylacetonitrile reaction yield, enabling refined control of the cyanation reaction. In addition, the microreactor incorporates magnetic stirring, which forms highly dispersed microdroplets, significantly enhancing the process of benzyl chloride cyanation and greatly improving phase transfer catalytic efficiency. This further enhances mass and heat transfer, increasing the phenylacetonitrile yield to over 97% and reducing the reaction time to within 30 minutes. The space-time yield is significantly improved compared to 460 g / (m³) in batch reactors. 3 •min) increased to 13000g / (m 3 The efficiency is increased by approximately 30 times (min). Furthermore, the continuous flow dynamic microreactor with built-in magnetic stirring in this invention can continuously break up sodium chloride particles generated during the cyanidation reaction, preventing the deposition and aggregation of sodium chloride particles in the phenylacetonitrile solution that could cause microchannel blockage. This solves the problem that ordinary microchannel reactors cannot handle high-solids-content systems, ensuring long-term stable operation.

[0056] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A method for preparing phenylacetonitrile based on a continuous flow dynamic microreactor, characterized in that: The method includes the following steps: injecting benzyl chloride and a sodium cyanide solution containing a phase transfer catalyst into the continuous flow dynamic microreactor for cyanation reaction, maintaining the reaction temperature at 40℃-80℃, and the reaction residence time at 5-40 min, until a phenylacetonitrile solution is generated; wherein, the flow rate of sodium cyanide is 0.16-1.24 ml / min, and the flow rate of benzyl chloride is 0.10-0.77 ml / min; the phase transfer catalyst is tetrabutylammonium bromide or didodecyldimethylammonium bromide, and its content is 1-5 wt% of benzyl chloride.

2. The method according to claim 1, characterized in that: The continuous flow dynamic microreactor is a micro plate reactor with an internal magnetic stirrer. The reactor is made of titanium alloy, and the magnetic stirrer speed is greater than or equal to 1200 rpm.

3. The method according to claim 1, characterized in that: The reaction temperature is 50℃-80℃.

4. The method according to claim 1, characterized in that: The reaction temperature is controlled by a constant temperature water bath or a constant temperature oil bath.

5. The method according to claim 1, characterized in that: The reaction residence time is 5-30 min.

6. The method according to claim 1, characterized in that: The flow rate ratio of the sodium cyanide solution to the benzyl chloride solution is 1:2 to 5:

1.

7. The method according to claim 6, characterized in that: The flow rate ratio of the sodium cyanide solution to the benzyl chloride solution is 1:2 to 1.75:

1.

8. The method according to claim 1, characterized in that: The phase transfer catalyst is tetrabutylammonium bromide, and its content is 3-5 wt% of benzyl chloride.

9. The method according to claim 1, characterized in that: The sodium cyanide solution containing the phase transfer catalyst has a sodium cyanide content of 30 wt%.

10. The method according to claim 1, characterized in that: The benzyl chloride in question is pure benzyl chloride with a purity greater than 99.5%, without any additives.

Images