Process for the efficient synthesis of salicylonitrile

Abstract

This invention discloses a highly efficient synthesis process for salicylnitrile, belonging to the field of salicylnitrile synthesis technology. The salicylnitrile synthesis process includes the following steps: Step 1, adding salicylamide and a catalyst to a reactor, then adding an acetonitrile aqueous solution, and sealing the reactor; Step 2, heating to 60-70℃, stirring the reaction for 4-8 hours, cooling to room temperature after the reaction, centrifuging to collect the supernatant, removing the solvent by vacuum distillation to obtain crude salicylnitrile. The catalyst is a PdCl2@quaternary ammonium salt modified activated carbon-hydrotalcite composite material, obtained by first modifying the activated carbon-hydrotalcite composite material with quaternary ammonium salt, and then loading PdCl2 onto it. This invention uses salicylamide as a raw material to efficiently dehydrate and synthesize salicylnitrile through the catalytic action of the catalyst. The synthesis conditions are mild, and the catalyst is obtained by loading the active component onto a solid support. Through the synergistic effect of the support and the active component, salicylamide can be efficiently dehydrated, resulting in a high yield of salicylnitrile.

Description

Technical Field

[0001] This invention belongs to the field of salicylaniline synthesis technology, specifically relating to a highly efficient synthesis process for salicylaniline. Background Technology

[0002] Salicylic nitrile is an important organic chemical raw material widely used in the pharmaceutical, pesticide, and fragrance industries. Currently, the synthesis processes of salicylic nitrile, classified by raw materials, mainly include three methods: the salicylaldehyde method, the salicylic acid / methyl salicylate method, and the salicylamide method.

[0003] The salicylaldehyde method uses salicylaldehyde as a raw material, reacting it with hydroxylamine hydrochloride to generate the intermediate salicylaldehyde oxime, which is then converted to salicylate under acidic conditions. This method requires stepwise preparation of salicylate, resulting in a lengthy process and significant wastewater generation. The salicylic acid / methyl salicylate method first generates salicylamide through a reaction, followed by dehydration to produce salicylate. This method uses salicylic acid, a cheaper raw material, significantly reducing raw material costs, but the process is complex and currently not suitable for industrial production. The salicylamide method has a shorter and simpler process than the other two methods, resulting in higher production efficiency. Using salicylamide as a raw material and phosphorus oxychloride, thionyl chloride, or phosgene as a dehydrating agent, salicylamide can be converted to salicylate in one step. However, the dehydrating agents used in this method can easily cause environmental pollution, and it places high demands on production equipment.

[0004] Therefore, the method of preparing salicylnitrile by dehydration of salicylamide using solid catalysts has gradually attracted attention. However, the existing solid catalysts have excessively high reaction temperatures and low yields in practical applications, which cannot meet the requirements of efficient synthesis and hinder the development of green synthesis process of salicylnitrile from salicylamide. Summary of the Invention

[0005] This invention provides a highly efficient synthesis process for salicylnitrile, which can solve the problems of high energy consumption and low yield in the synthesis of salicylnitrile in the prior art.

[0006] The objective of this invention can be achieved through the following technical solutions: A highly efficient synthesis process for salicylnitrile includes the following steps: Step 1: Add salicylamide and catalyst to the reactor, then add acetonitrile aqueous solution, and seal the reactor; Step 2: Heat to 60-70℃ and stir for 4-8 hours. After the reaction is complete, cool to room temperature, centrifuge to collect the supernatant, remove the solvent by vacuum distillation, and obtain crude salicylnitrile.

[0007] The catalyst is a PdCl2@quaternary ammonium salt modified activated carbon hydrotalcite composite material, which is obtained by first modifying the activated carbon hydrotalcite composite material with quaternary ammonium salt and then loading PdCl2.

[0008] In the above scheme, salicylamide is used as a raw material to prepare salicylate via a dehydration reaction under the catalysis of a catalyst. Addressing the problem of inefficient synthesis of salicylate from salicylamide in existing technologies, this invention employs an optimized catalyst for the preparation reaction. The main active component of this catalyst is PdCl2, the support is a quaternary ammonium salt modified activated carbon-hydrotalcite composite material, and acetonitrile is used as the dehydrating agent. Compared with phosgene or phosphorus oxychloride, palladium-catalyzed amide dehydration reaction exhibits extremely high efficiency and excellent compatibility with various functional groups, while also providing milder reaction conditions.

[0009] However, the key to palladium-catalyzed dehydration of amides to nitriles lies in the catalytic activity of palladium. In existing technologies, after loading nano-palladium particles onto a solid support, palladium is difficult to disperse uniformly due to limitations in the loading conditions, and it is prone to agglomeration and loss. This results in insufficient contact between the amide reactants and the catalytically active sites during the amide dehydration reaction, leading to a low yield. The support material of this invention is a quaternary ammonium salt modified activated carbon-hydrotalcite composite material. Activated carbon itself has a large adhesion surface and a complex pore structure, which can provide a platform for the adhesion of catalytically active components and a channel for the diffusion of reactants, thus accelerating the reaction. Hydrotalcite is grown on the surface of activated carbon to form a composite material. The hierarchical structure of hydrotalcite combines with the pore structure of activated carbon to form a surface structure that is more conducive to palladium salt loading. In addition, there are alkaline sites on the hydrotalcite, which help to activate the amide groups of salicylamide and promote amide dehydration. While activated carbon-hydrotalcite composites can achieve a large loading of palladium salts when used as a support material, some palladium will reductively aggregate during the reaction, obscuring active sites. This invention modifies activated carbon-hydrotalcite composites with quaternary ammonium salts. Through electrostatic adsorption, quaternary ammonium salt cations are inserted into the interlayer to achieve organic modification. On the one hand, this promotes the wetting contact of salicylamide on the catalyst surface; on the other hand, the nonpolar chains of quaternary ammonium salts can form steric hindrance on the support surface, preventing the reductive aggregation of palladium salts after loading. In summary, the catalyst provided by this invention, from the perspective of the support, utilizes the combined structure of activated carbon and hydrotalcite to achieve a large loading of catalytically active components, and the quaternary ammonium salt modification hinders aggregation, so that the catalyst maintains high activity during the reaction and promotes the dehydration of amides to nitrile.

[0010] Furthermore, the mass ratio of the catalyst to salicylamide is 1.5-2.5:1.

[0011] Furthermore, the mass ratio of acetonitrile to water in the acetonitrile aqueous solution is 1:1; The ratio of salicylamide to acetonitrile aqueous solution is 0.1-0.2 mol: 1 L.

[0012] Furthermore, the preparation steps of the catalyst are as follows: S1. Immerse activated carbon in concentrated sulfuric acid, stir in a water bath at 80-90℃ for 8-10 hours, let stand, filter, wash until neutral, and dry to obtain activated carbon. S2. Weigh out magnesium nitrate hexahydrate and aluminum nitrate nonahydrate and add them to water to prepare two nitrate solutions; S3. Activated carbon is dispersed in water to form a dispersion. Two nitrate solutions and sodium hydroxide solution prepared in step S2 are added dropwise to the dispersion. After the addition is completed, the pH of the system is controlled to be 9-10. The mixture is stirred for 4-6 hours, allowed to stand and age, filtered, washed with water until neutral, and dried to obtain activated carbon hydrotalcite composite material. S4. Add activated carbon hydrotalcite composite material and benzyltriethylammonium chloride to water and disperse ultrasonically. Heat and stir the reaction for 3-6 hours. After washing, dry to obtain ammonium salt modified activated carbon hydrotalcite composite material. S5. Dissolve palladium chloride in concentrated hydrochloric acid at 60-70℃, and dilute with water to obtain a palladium chloride solution; S6. Disperse the quaternary ammonium salt modified activated carbon hydrotalcite composite material in water, add palladium chloride solution dropwise, stir for 6-12 h, filter, and dry to obtain PdCl2@quaternary ammonium salt modified activated carbon hydrotalcite composite material.

[0013] In the preparation of the above catalyst, activated carbon is first treated with concentrated sulfuric acid to introduce oxygen-containing functional groups, thereby improving hydrophilicity and surface activity. Then, nitrate solution and alkaline solution are added dropwise to the activated carbon, causing hydrotalcite crystals to nucleate and grow in situ on the surface and pores of the activated carbon, forming an activated carbon-hydrotalcite composite structure. Benzyltriethylammonium chloride quaternary ammonium salt cations are embedded in the interlayer to achieve organic modification. PdCl2 is dissolved in concentrated hydrochloric acid to form a solution, which can be loaded onto the support through electrostatic adsorption and coordination.

[0014] Furthermore, the molar ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate is 1-2:1; The ratio of the total mass of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to the mass of activated carbon is 1-3:10.

[0015] Furthermore, the concentration of the sodium hydroxide solution is 0.5-1 mol / L.

[0016] Furthermore, the mass ratio of the benzyltriethylammonium chloride and activated carbon hydrotalcite composite material is 0.2-0.4:1.

[0017] Furthermore, the concentration of the concentrated hydrochloric acid is 36-38 wt%; The molar ratio of palladium chloride to concentrated hydrochloric acid is Pd:HCl = 1:2-5.

[0018] Furthermore, in step S5, the ratio of the total volume of concentrated hydrochloric acid and water to palladium chloride is controlled to be 1L:0.1-0.15mol when diluted with water.

[0019] Further, in step S6, the ratio of the quaternary ammonium salt modified activated carbon hydrotalcite composite material to water is 40-60 g / L; The palladium chloride solution was added dropwise at a mass ratio of palladium chloride to quaternary ammonium salt modified activated carbon hydrotalcite composite material of 2-3:100.

[0020] The beneficial effects of this invention are: (1) This invention uses salicylamide as a raw material to efficiently dehydrate and synthesize salicylnitrile through the catalytic action of a catalyst. During the reaction, salicylamide molecules diffuse from the acetonitrile aqueous solution to the catalyst surface. The quaternary ammonium salt modified organic environment is conducive to the approach of salicylamide. The active component of the catalyst provides Pd 2+ As a Lewis acid, it forms a complex with the carbonyl oxygen of salicylamide, activating the amide functional group and causing it to dehydrate at a lower temperature. At the same time, the basic sites on the hydrotalcite layer promote the dehydration reaction, thus achieving efficient synthesis of salicylnitrile.

[0021] (2) The catalyst of this invention uses activated carbon as the core support. The porous structure provides adsorption sites for the loading of palladium chloride. The composite of hydrotalcite and activated carbon forms a multi-level bonding structure, which is beneficial to the adsorption and fixation of palladium salt. After further modification with quaternary ammonium salt, on the one hand, the hydrophobic alkyl chain helps to enrich salicylamide on the catalyst surface; on the other hand, it can hinder the aggregation of PdCl2, avoid the shielding of active sites, improve catalytic activity, promote the reaction, and increase the yield.

[0022] (3) The synthesis conditions of salicylamide in this invention are mild, and the catalyst is obtained by loading the active component on a solid support. It can be collected and recycled. Through the synergistic effect of the support and the active component, salicylamide can be dehydrated efficiently, avoiding the problem of low yield caused by insufficient active sites or easy deactivation of existing solid catalysts. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 Preparation of catalysts: S1. Weigh out activated carbon and impregnate it in concentrated sulfuric acid. Stir the mixture in a water bath at 85°C for 9 hours. After standing, filter the mixture, wash it until neutral, and dry it to obtain activated carbon.

[0025] S2. Weigh out magnesium nitrate hexahydrate and aluminum nitrate nonahydrate, add them separately to water, and prepare two nitrate solutions with a concentration of 0.1 mol / L.

[0026] S3. Weigh out activated carbon and disperse it in water at a concentration of 20 g / L to form a dispersion. Add the two nitrate solutions and sodium hydroxide solution prepared in step S2 to the dispersion. Control the molar ratio of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to be 1:1, and the ratio of the total mass of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to the mass of activated carbon to be 2:10. After the addition is complete, adjust the pH of the system to 9.5, stir for 5 h, let it stand for 24 h, filter, wash with water until neutral, and dry to obtain activated carbon-hydrotalcite composite material.

[0027] S4. The activated carbon hydrotalcite composite material and benzyltriethylammonium chloride were added to water and ultrasonically dispersed. The mass ratio of benzyltriethylammonium chloride to activated carbon hydrotalcite composite material was 0.3:1. The mixture was heated to 50°C and stirred for 5 hours. After washing and drying, the ammonium salt modified activated carbon hydrotalcite composite material was obtained.

[0028] S5. Dissolve palladium chloride in 36wt% concentrated hydrochloric acid at 65℃, with a molar ratio of Pd:HCl = 1:4. Dilute with water to obtain a palladium chloride solution. The ratio of the total volume of concentrated hydrochloric acid and water to palladium chloride is 1L:0.12mol.

[0029] S6. Disperse the quaternary ammonium salt modified activated carbon hydrotalcite composite material in water at a concentration of 50 g / L, add palladium chloride solution dropwise, with the mass ratio of palladium chloride to quaternary ammonium salt modified activated carbon hydrotalcite composite material being 2.5:100, stir for 8 h, filter, and dry to obtain PdCl2@quaternary ammonium salt modified activated carbon hydrotalcite composite material.

[0030] Synthetic salicylates: Step 1: Add salicylamide and the catalyst prepared in this example to the reactor. The mass ratio of catalyst to salicylamide is 2.0:1. Then add acetonitrile aqueous solution (the mass ratio of acetonitrile to water is 1:1). The ratio of salicylamide to acetonitrile aqueous solution is 0.15 mol:1 L. Seal the reactor.

[0031] Step 2: Heat to 65℃ and stir for 6 hours. After the reaction is complete, cool to room temperature, centrifuge to collect the supernatant, remove the solvent by vacuum distillation, and obtain crude salicylnitrile. The yield of salicylnitrile was 97.6%.

[0032] Example 2 The only difference from Example 1 is that, when preparing the catalyst, the ratio of the total mass of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to the mass of activated carbon is 1:10. Other conditions and steps are the same as in Example 1. The yield of salicylaniline was tested to be 96.6%.

[0033] Example 3 The only difference from Example 1 is that, when preparing the catalyst, the ratio of the total mass of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to the mass of activated carbon is 3:10. Other conditions and steps are the same as in Example 1. The yield of salicylaniline was tested to be 96.9%.

[0034] Example 4 The only difference from Example 1 is that the mass ratio of benzyltriethylammonium chloride and activated carbon-hydrotalcite composite material was 0.2:1 when preparing the catalyst. Other conditions and steps were the same as in Example 1. The yield of salicylnitrile was 96.8%.

[0035] Example 5 The only difference from Example 1 is that the mass ratio of benzyltriethylammonium chloride and activated carbon-hydrotalcite composite material was 0.4:1 when preparing the catalyst. Other conditions and steps were the same as in Example 1. The yield of salicylnitrile was 96.3%.

[0036] Comparative Example 1 The only difference from Example 1 is that the catalyst support is not modified with quaternary ammonium salt.

[0037] Preparation of catalysts: S1. Weigh out activated carbon and impregnate it in concentrated sulfuric acid. Stir the mixture in a water bath at 85°C for 9 hours. After standing, filter the mixture, wash it until neutral, and dry it to obtain activated carbon.

[0038] S2. Weigh out magnesium nitrate hexahydrate and aluminum nitrate nonahydrate, add them separately to water, and prepare two nitrate solutions with a concentration of 0.1 mol / L.

[0039] S3. Weigh out activated carbon and disperse it in water at a concentration of 20 g / L to form a dispersion. Add the two nitrate solutions and sodium hydroxide solution prepared in step S2 to the dispersion. Control the molar ratio of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to be 1:1, and the ratio of the total mass of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to the mass of activated carbon to be 2:10. After the addition is complete, adjust the pH of the system to 9.5, stir for 5 h, let it stand for 24 h, filter, wash with water until neutral, and dry to obtain activated carbon-hydrotalcite composite material.

[0040] S4. Dissolve palladium chloride in 36wt% concentrated hydrochloric acid at 65℃, with a molar ratio of Pd:HCl = 1:4. Dilute with water to obtain a palladium chloride solution. The ratio of the total volume of concentrated hydrochloric acid and water to palladium chloride is 1L:0.12mol.

[0041] S6. Disperse the activated carbon hydrotalcite composite material in water at a concentration of 50 g / L, add palladium chloride solution dropwise, with a mass ratio of palladium chloride to activated carbon hydrotalcite composite material of 2.5:100, stir for 8 h, filter, and dry to obtain PdCl2@activated carbon hydrotalcite composite material.

[0042] Synthetic salicylates: Step 1: Add salicylamide and the catalyst prepared in this comparative example to the reactor. The mass ratio of catalyst to salicylamide is 2.0:1. Then add acetonitrile aqueous solution (the mass ratio of acetonitrile to water is 1:1). The ratio of salicylamide to acetonitrile aqueous solution is 0.15 mol:1 L. Seal the reactor.

[0043] Step 2: Heat to 65℃ and stir for 6 hours. After the reaction is complete, cool to room temperature, centrifuge to collect the supernatant, remove the solvent by vacuum distillation, and obtain crude salicylnitrile. The yield of salicylnitrile was 92.5%.

[0044] Comparative Example 2 The only difference from Example 1 is that the catalyst support does not contain hydrotalcite.

[0045] Preparation of catalysts: S1. Weigh out activated carbon and impregnate it in concentrated sulfuric acid. Stir the mixture in a water bath at 85°C for 9 hours. After standing, filter the mixture, wash it until neutral, and dry it to obtain activated carbon.

[0046] S4. Activated carbon and benzyltriethylammonium chloride are added to water and ultrasonically dispersed. The mass ratio of benzyltriethylammonium chloride to activated carbon is 0.3:1. The mixture is heated to 50°C and stirred for 5 hours. After washing and drying, ammonium salt modified activated carbon material is obtained.

[0047] S5. Dissolve palladium chloride in 36wt% concentrated hydrochloric acid at 65℃, with a molar ratio of Pd:HCl = 1:4. Dilute with water to obtain a palladium chloride solution. The ratio of the total volume of concentrated hydrochloric acid and water to palladium chloride is 1L:0.12mol.

[0048] S6. Disperse the quaternary ammonium salt modified activated carbon material in water at a concentration of 50 g / L, add palladium chloride solution dropwise, with a mass ratio of palladium chloride to quaternary ammonium salt modified activated carbon material of 2.5:100, stir for 8 h, filter, and dry to obtain PdCl2@quaternary ammonium salt modified activated carbon material.

[0049] Synthetic salicylates: Step 1: Add salicylamide and the catalyst prepared in this comparative example to the reactor. The mass ratio of catalyst to salicylamide is 2.0:1. Then add acetonitrile aqueous solution (the mass ratio of acetonitrile to water is 1:1). The ratio of salicylamide to acetonitrile aqueous solution is 0.15 mol:1 L. Seal the reactor.

[0050] Step 2: Heat to 65℃ and stir for 6 hours. After the reaction is complete, cool to room temperature, centrifuge to collect the supernatant, remove the solvent by vacuum distillation, and obtain crude salicylnitrile. The yield of salicylnitrile was 94.3%.

[0051] Comparative Example 3 The only difference from Example 1 is that the catalyst is not modified with quaternary ammonium salt and combined with hydrotalcite.

[0052] Preparation of catalysts: S1. Dissolve palladium chloride in 36wt% concentrated hydrochloric acid at 65℃, with a molar ratio of Pd:HCl = 1:4. Dilute with water to obtain a palladium chloride solution. The ratio of the total volume of concentrated hydrochloric acid and water to palladium chloride is 1L:0.12mol.

[0053] S2. Disperse activated carbon in water at a concentration of 50 g / L, add palladium chloride solution dropwise, with a mass ratio of palladium chloride to activated carbon of 2.5:100, stir for 8 hours, filter, and dry to obtain PdCl2@activated carbon material.

[0054] Synthetic salicylates: Step 1: Add salicylamide and the catalyst prepared in this comparative example to the reactor. The mass ratio of catalyst to salicylamide is 2.0:1. Then add acetonitrile aqueous solution (the mass ratio of acetonitrile to water is 1:1). The ratio of salicylamide to acetonitrile aqueous solution is 0.15 mol:1 L. Seal the reactor.

[0055] Step 2: Heat to 65℃ and stir for 6 hours. After the reaction is complete, cool to room temperature, centrifuge to collect the supernatant, remove the solvent by vacuum distillation, and obtain crude salicylnitrile. The yield of salicylnitrile was 83.7%.

[0056] In summary, the catalyst prepared by this invention can achieve efficient synthesis of salicylnitrile from salicylamide under mild conditions, with a maximum yield of 97.6%.

[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A highly efficient synthesis process for salicylnitrile, characterized in that, Includes the following steps: Step 1: Add salicylamide and catalyst to the reactor, then add acetonitrile aqueous solution, and seal the reactor; Step 2: Heat to 60-70℃, stir and react for 4-8 hours. After the reaction is complete, cool to room temperature, centrifuge to collect the supernatant, remove the solvent by vacuum distillation, and obtain crude salicylnitrile. The catalyst is a PdCl2@quaternary ammonium salt modified activated carbon hydrotalcite composite material, which is obtained by first modifying the activated carbon hydrotalcite composite material with quaternary ammonium salt and then loading PdCl2.

2. The efficient synthesis process of salicylnitrile according to claim 1, characterized in that, The mass ratio of the catalyst to salicylamide is 1.5-2.5:

1.

3. The efficient synthesis process of salicylnitrile according to claim 1, characterized in that, The mass ratio of acetonitrile to water in the acetonitrile aqueous solution is 1:

1. The ratio of salicylamide to acetonitrile aqueous solution is 0.1-0.2 mol: 1 L.

4. The efficient synthesis process of salicylnitrile according to claim 1, characterized in that, The catalyst is prepared in the following steps: S1. Immerse activated carbon in concentrated sulfuric acid, stir in a water bath at 80-90℃ for 8-10 hours, let stand, filter, wash until neutral, and dry to obtain activated carbon. S2. Weigh out magnesium nitrate hexahydrate and aluminum nitrate nonahydrate and add them to water to prepare two nitrate solutions; S3. Activated carbon is dispersed in water to form a dispersion. Two nitrate solutions and sodium hydroxide solution prepared in step S2 are added dropwise to the dispersion. After the addition is completed, the pH of the system is controlled to be 9-10. The mixture is stirred for 4-6 hours, allowed to stand and age, filtered, the water is brought to neutral, and dried to obtain activated carbon-hydrotalcite composite material. S4. Add activated carbon hydrotalcite composite material and benzyltriethylammonium chloride to water and disperse ultrasonically. Heat and stir the reaction for 3-6 hours. After washing and drying, obtain quaternary ammonium salt modified activated carbon hydrotalcite composite material. S5. Dissolve palladium chloride in concentrated hydrochloric acid at 60-70℃, and dilute with water to obtain a palladium chloride solution; S6. Disperse the quaternary ammonium salt modified activated carbon hydrotalcite composite material in water, add palladium chloride solution dropwise, stir for 6-12 h, filter, and dry to obtain PdCl2@quaternary ammonium salt modified activated carbon hydrotalcite composite material.

5. The efficient synthesis process of salicylnitrile according to claim 4, characterized in that, The molar ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate is 1-2:1; The ratio of the total mass of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to the mass of activated carbon is 1-3:

10.

6. The efficient synthesis process of salicylnitrile according to claim 4, characterized in that, The concentration of the sodium hydroxide solution is 0.5-1 mol / L.

7. The efficient synthesis process of salicylnitrile according to claim 4, characterized in that, The mass ratio of the benzyltriethylammonium chloride and activated carbon hydrotalcite composite material is 0.2-0.4:

1.

8. The efficient synthesis process of salicylnitrile according to claim 4, characterized in that, The concentration of the concentrated hydrochloric acid is 36-38 wt%. The molar ratio of palladium chloride to concentrated hydrochloric acid is Pd:HCl = 1:2-5.

9. The efficient synthesis process of salicylnitrile according to claim 4, characterized in that, In step S5, water is added to dilute and control the ratio of the total volume of concentrated hydrochloric acid and water to palladium chloride to 1L:0.1-0.15mol.

10. The efficient synthesis process of salicylnitrile according to claim 4, characterized in that, In step S6, the ratio of the quaternary ammonium salt modified activated carbon hydrotalcite composite material to water is 40-60 g / L; The palladium chloride solution was added dropwise at a mass ratio of palladium chloride to quaternary ammonium salt modified activated carbon hydrotalcite composite material of 2-3:100.