Preparation method of 2-hydroxy-benzonitrile

Abstract

The invention discloses a preparation method of 2-hydroxy-benzonitrile, which belongs to the field of organic synthesis and comprises the following steps: adding salicylamide, toluene, a catalyst and magneton into a three-necked flask, introducing condensate water, heating to 110 DEG C, reacting at constant temperature for 3-5 hours while stirring, introducing water generated by the toluene into a water segregator, discharging water from the lower part after standing and layering, and after dehydration is completed, filtering to obtain 2-hydroxy-benzonitrile. Filtering out the catalyst, cooling the residual solution at room temperature, and recrystallizing to obtain 2-hydroxy-benzonitrile; acid and alkaline sites on the surface of the catalyst promote intramolecular dehydration of salicylamide, meanwhile, heteroatom doping effectively changes the electronic structure of the carbon nanotubes, increases the active sites of the catalyst, accelerates the electron transfer ability, and accelerates the intramolecular dehydration rate of salicylamide. The acid-base center coexistence reduces the activation energy of the reaction, so that the catalytic process can be carried out at a lower temperature, and the catalyst is easy to separate and good in cycling stability after the reaction is finished.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis, and particularly relates to a method for preparing salicylonitrile. Background Art

[0002] Aromatic nitriles are a class of organic synthesis intermediates with active properties, among which salicylic nitrile (o-hydroxybenzonitrile) is a fine chemical with important applications in the fields of medicine and pesticides. It is mainly used as an intermediate compound for the pharmaceutical bunitrol and the pesticide fungicide myclobutanil, and has good market prospects. The reaction process and subsequent separation and purification process of salicylic amide dehydration to prepare salicylic nitrile are simple, but the commonly used catalysts such as phosphorus oxychloride and phosgene are highly toxic and difficult to operate industrially. Therefore, the research and development of new and efficient green catalysts and supporting safe and environmentally friendly reaction processes have important theoretical and practical value.

[0003] Currently, the catalysts used for the dehydration of salicylamide to prepare salicylonitrile have achieved the transition from homogeneous to heterogeneous phases, including supported vanadium oxide (CN108863849), supported phosphorus silica gel (US6248917), SO4 2- The salicylamide dehydration process using / Zr(SO4)2 / montmorillonite (CN109433230A) as a heterogeneous catalyst has been reported. Generally, the reaction temperature is above 300°C. The temperature is too high, the reaction energy consumption is large, and there is a problem of poor catalyst cycle stability. Therefore, it is necessary to design a high-stability catalyst with high salicylonitrile selectivity and yield at low temperature. Summary of the invention

[0004] In order to solve the problems of high reaction temperature and poor catalyst cycle stability in the prior art for preparing salicylic nitrile by dehydration of salicylamide, the present invention aims to provide a method for preparing salicylic nitrile.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing salicylic nitrile comprises the following steps:

[0007] The first step is to prepare the following raw materials by weight: 10-20 parts of salicylamide, 40-100 parts of toluene, and 3-7 parts of catalyst;

[0008] The second step is to add the above raw materials and magnetic particles into a three-necked flask equipped with a water separator, pass condensed water, raise the temperature to 110°C, and react at a constant temperature for 3-5 hours under stirring. Toluene brings the generated water into the water separator, and the water is released from the bottom after standing and stratification. After dehydration, filter out the catalyst, and cool the remaining reaction liquid to room temperature until crystals precipitate, filter, and obtain a crude product; the obtained crude product is recrystallized with toluene to obtain salicylonitrile.

[0009] Further, the catalyst is prepared by the following steps:

[0010] S1. Add carbon nanotubes and inorganic acid into water in proportion, perform ultrasonic treatment for 15 min, transfer the solution into a reactor, perform hydrothermal reaction at 180°C for 12 h, filter, wash and dry to obtain modified carbon nanotubes;

[0011] S2. Prepare a mixed aqueous solution of ammonium metavanadate and oxalic acid, heat the mixed aqueous solution to 60°C while stirring to prepare a vanadyl oxalate solution, then add phosphoric acid to obtain a mixed solution, add the mixed solution to the modified carbon nanotubes, and immerse for 4 hours, stirring once every half an hour, put into a 120°C oven to dry for 12 hours, and calcine at 450-650°C in an air atmosphere for 4-6 hours to obtain a VPO-loaded modified carbon nanotube catalyst.

[0012] Furthermore, the inorganic acid is any one of phosphoric acid, boric acid and sulfurous acid.

[0013] Furthermore, the usage ratio of the carbon nanotubes, the inorganic acid and the water is 5-10 g: 1-3 g: 20-50 ml.

[0014] Furthermore, the molar ratio of the ammonium metavanadate, oxalic acid and water is 1:2:80.

[0015] Furthermore, the molar ratio of the added amount of phosphoric acid to ammonium metavanadate is 1-3:1.

[0016] Furthermore, the ratio of the mixed solution to the modified carbon nanotubes is 10-40 ml: 1-6 g.

[0017] Beneficial effects of the present invention:

[0018] In the VPO-loaded modified carbon nanotube catalyst prepared by the present invention, the V element forms active crystal phases such as (VO)2P2O7 and V2O5 by combining with P and O. The VO bonds in these crystal phases affect the acid sites on the catalyst surface. The inorganic acid-modified carbon nanotubes further enhance the acid sites. The electronegativity of the oxygen atom is greater than that of the phosphorus atom. The charge density around the oxygen atom is relatively high, so that the oxygen atom is weakly alkaline to a certain extent. In the catalytic process, the acid sites first combine with the carbonyl oxygen of the amide, and then the alkaline active sites connect with the hydrogen connected to the amino group, which promotes the intramolecular dehydration of salicylic amide to prepare water-like nitrile. The carbon nanotubes are doped and modified with three heteroatoms of P, B and S respectively, which effectively changes the electronic structure of the carbon nanotubes, increases the active sites of the catalyst, enhances the electronic effect between the carrier and the metal vanadium, accelerates the electron transfer ability, accelerates the intramolecular dehydration rate of salicylic amide, and further improves the catalytic performance. The coexistence of the acid and base centers reduces the activation energy of the reaction, so that the catalytic process can be carried out at a lower temperature, and the catalyst is easy to separate after the reaction is completed, and the cycle stability is good. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1

[0021] A method for preparing salicylic nitrile comprises the following steps:

[0022] Step 1: Prepare the following raw materials by weight: 10g salicylamide, 40g toluene, and 3g catalyst;

[0023] The second step is to add the above raw materials and magnetic particles into a three-necked flask equipped with a water separator, pass condensed water, heat up to 110°C at 5°C / min, react at a constant temperature for 4 hours, and maintain a stirring speed of 500rpm. During the reaction, toluene brings out the generated water and enters the water separator. After standing and stratification, water is released from the bottom. After dehydration, the solid catalyst is filtered out, and the remaining reaction liquid is cooled to room temperature until crystals precipitate, and then filtered to separate the crude product; the obtained crude product is recrystallized with toluene to obtain salicylonitrile.

[0024] The catalyst is prepared by the following steps:

[0025] S1. Add 5 g of carbon nanotubes and 1 g of phosphoric acid into 20 ml of water, and after ultrasonic treatment for 15 min, transfer the solution to a reactor, react at 180 °C for 12 h, filter, wash, and dry at 80 °C for 10 h to obtain modified carbon nanotubes;

[0026] S2. 0.05 mol ammonium metavanadate, 0.1 mol oxalic acid and 4 mol water are prepared into a mixed aqueous solution, and the mixed aqueous solution is heated to 60°C at a stirring speed of 200 rpm at 2°C / min to prepare a vanadyl oxalate solution, 0.1 mol phosphoric acid is added to the vanadyl oxalate solution to obtain a mixed solution, 10 ml of the mixed solution is added to 1 g of modified carbon nanotubes, and immersed for 4 hours, stirring once every half an hour, and drying in a 120°C oven for 12 hours, and calcining at 450°C in an air atmosphere for 4 hours to obtain a VPO-loaded modified carbon nanotube catalyst.

[0027] The evaluation results according to gas chromatography analysis are shown in Table 1.

[0028] Example 2

[0029] A method for preparing salicylic nitrile comprises the following steps:

[0030] Step 1: Prepare the following raw materials by weight: 20g salicylamide, 100g toluene, and 7g catalyst;

[0031] The second step is to add the above raw materials and magnetic particles into a three-necked flask equipped with a water separator, pass condensed water, raise the temperature to 110°C at 5°C / min, react at a constant temperature for 5 hours, and maintain a stirring speed of 500rpm. During the reaction, toluene brings out the generated water and enters the water separator. After standing and stratification, water is released from the bottom. After dehydration, the solid catalyst is filtered out, and the remaining reaction liquid is cooled to room temperature until crystals precipitate, and then filtered to separate the crude product; the obtained crude product is recrystallized with toluene to obtain salicylonitrile.

[0032] The catalyst is prepared by the following steps:

[0033] S1. Add 10 g of carbon nanotubes and 3 g of boric acid into 50 ml of water, and after ultrasonic treatment for 15 min, transfer the solution to a reactor, react at 180 °C for 12 h, filter, wash, and dry at 80 °C for 10 h to obtain modified carbon nanotubes;

[0034] S2. 0.05 mol ammonium metavanadate, 0.1 mol oxalic acid and 4 mol water are prepared into a mixed aqueous solution, and the mixed aqueous solution is heated to 60°C at a stirring speed of 200 rpm at 2°C / min to prepare a vanadyl oxalate solution, 0.15 mol boric acid is added to the vanadyl oxalate solution to obtain a mixed solution, 40 ml of the above mixed solution is added to 6 g of modified carbon nanotubes, and immersed for 4 hours, stirring once every half an hour, and drying in a 120°C oven for 12 hours, and calcined at 600°C in an air atmosphere for 6 hours to obtain a VPO-loaded modified carbon nanotube catalyst.

[0035] The evaluation results according to gas chromatography analysis are shown in Table 1.

[0036] Example 3

[0037] A method for preparing salicylic nitrile comprises the following steps:

[0038] Step 1: Prepare the following raw materials by weight: 15g salicylamide, 70g toluene, and 5g catalyst;

[0039] The second step is to add the above raw materials and magnetic particles into a three-necked flask equipped with a water separator, pass condensed water, raise the temperature to 110°C at 5°C / min, react at a constant temperature for 3 hours, and maintain a stirring speed of 500rpm. During the reaction, toluene brings out the generated water and enters the water separator. After standing and stratification, water is released from the bottom. After dehydration, the solid catalyst is filtered out, and the remaining reaction liquid is cooled to room temperature until crystals precipitate, and then filtered to separate the crude product; the obtained crude product is recrystallized with toluene to obtain salicylonitrile.

[0040] The catalyst is prepared by the following steps:

[0041] S1. Add 7.5 g of carbon nanotubes and 2 g of sulfurous acid to 35 ml of water, and after ultrasonic treatment for 15 min, transfer the solution to a reactor, react at 180 ° C for 12 h, filter, wash, and dry at 80 ° C for 10 h to obtain modified carbon nanotubes;

[0042] S2, 0.05 mol ammonium metavanadate, 0.1 mol oxalic acid and 4 mol water are prepared into a mixed aqueous solution, the mixed aqueous solution is heated to 60°C at 2°C / min at a stirring speed of 200 rpm to prepare a vanadyl oxalate solution, 0.05 mol sulfurous acid is added to the vanadyl oxalate solution to obtain a mixed solution, 25 ml of the mixed solution is added to 3.5 g of modified carbon nanotubes, immersed for 4 hours, stirred once every half an hour, placed in a 120°C oven for drying for 12 hours, and calcined at 550°C for 5 hours in an air atmosphere to obtain a VPO-supported modified carbon nanotube catalyst;

[0043] The evaluation results according to gas chromatography analysis are shown in Table 1.

[0044] Example 4

[0045] The preparation method and evaluation conditions of the catalyst are the same as those in Example 1, except that "phosphoric acid" is replaced by "boric acid" during the preparation of the modified carbon nanotubes. The evaluation results are shown in Table 1.

[0046] Example 5

[0047] The preparation method and evaluation conditions of the catalyst are the same as those in Example 1, except that "phosphoric acid" is replaced by "sulfurous acid" during the preparation of the modified carbon nanotubes. The evaluation results are shown in Table 1.

[0048] Example 6

[0049] The preparation method and evaluation conditions of the catalyst were the same as those in Example 1, except that "constant temperature reaction for 4 h" was replaced by "constant temperature reaction for 3 h" during the catalyst evaluation process. The evaluation results are shown in Table 1.

[0050] Example 7

[0051] The preparation method and evaluation conditions of the catalyst were the same as those in Example 1, except that "constant temperature reaction for 4 h" was replaced by "constant temperature reaction for 5 h" during the catalyst evaluation process. The evaluation results are shown in Table 1.

[0052] Example 8

[0053] The preparation method and evaluation conditions of the catalyst were the same as those in Example 1, except that "0.1 mol phosphoric acid" was replaced by "0.05 mol phosphoric acid" during the preparation of VPO-loaded P-modified carbon nanotubes. The evaluation results are shown in Table 1.

[0054] Example 9

[0055] The preparation method and evaluation conditions of the catalyst were the same as those in Example 1, except that "0.1 mol phosphoric acid" was replaced by "1.5 mol phosphoric acid" during the preparation of VPO-loaded P-modified carbon nanotubes. The evaluation results are shown in Table 1.

[0056] Example 10

[0057] The catalyst filtered out in Example 1 was calcined at 450° C. for 2 h in an air atmosphere to remove impurities such as residual reactants, and then reused for a second time. The catalyst evaluation conditions were the same as in Example 1. The evaluation results are shown in Table 1.

[0058] Embodiment 11

[0059] The catalyst recovery method and evaluation conditions are the same as those in Example 10, except that the catalyst is reused for the third time. The evaluation results are shown in Table 1.

[0060] Example 12

[0061] The catalyst recovery method and evaluation conditions are the same as those of Example 10, except that the catalyst is reused for the fourth time. The evaluation results are shown in Table 1.

[0062] Example 13

[0063] The catalyst recovery method and evaluation conditions were the same as those in Example 10, except that the catalyst was reused for the fifth time. The evaluation results are shown in Table 1.

[0064] Comparative Example 1

[0065] The raw material and catalyst preparation process is the same as in Example 1, except that S1 in Example 1 is omitted and the modified carbon nanotubes in S2 are replaced by carbon nanotubes. The evaluation results are shown in Table 1.

[0066] Comparative Example 2

[0067] The raw material and catalyst preparation process is the same as that of Comparative Example 1, except that the carrier "carbon nanotube" is replaced by "silicon dioxide". The evaluation results are shown in Table 1.

[0068] The salicylonitrile obtained in Examples 1 to 14 and Comparative Examples 1 to 2 was subjected to gas chromatography analysis, and the evaluation results are shown in Table 1:

[0069] Table 1

[0070]

[0071]

[0072] It can be seen from Table 1 that the catalyst with carbon nanotubes as the carrier is better than the catalyst with silicon dioxide as the carrier. After the carbon nanotubes are modified with heteroatoms, the conversion rate of salicylamide and the selectivity of salicylonitrile are greatly improved. Compared with B and S, the catalyst prepared by P doping modification has a higher electron transfer efficiency. After 4 hours of constant temperature reaction, the conversion of salicylamide is basically completed, the selectivity of salicylonitrile reaches 95.5%, and the yield reaches 87.3%. In the process of preparing VPO-loaded P-modified carbon nanotubes, too high or too low phosphorus-vanadium molar ratio will affect the acid-base sites on the catalyst surface, thereby affecting the catalytic performance. After five catalytic cycles, the catalytic performance of the catalyst did not decrease significantly. In summary, the VPO-loaded heteroatom-doped modified carbon nanotube acid-base catalyst prepared by the present invention can achieve more efficient dehydration of salicylamide to prepare salicylonitrile at low temperature, and the catalyst is easy to separate and recover after the reaction, and the cycle stability is good.

[0073] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0074] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing salicylic nitrile, characterized in that: The following steps are involved: Salicylamide, toluene, a catalyst and a magnet are added to a three-necked flask equipped with a water separator, condensed water is passed through, the temperature is raised to 110°C, and the reaction is carried out at a constant temperature for 3-5 hours under stirring. The toluene brings the generated water into the water separator, and the water is released from the bottom after standing and stratification. After dehydration, the catalyst is filtered out, and the remaining reaction liquid is cooled to room temperature until crystals precipitate, and filtered to obtain a crude product. The obtained crude product is recrystallized with toluene to obtain salicylonitrile, and the catalyst is a modified carbon nanotube loaded with VPO.

2. The method for preparing salicylic nitrile according to claim 1, characterized in that: VPO-supported modified carbon nanotubes were prepared by the following steps: Ammonium metavanadate and oxalic acid are prepared into a mixed aqueous solution, the mixed aqueous solution is heated to 60°C while stirring to prepare a vanadyl oxalate solution, phosphoric acid is then added to obtain a mixed solution, the mixed solution is added to the modified carbon nanotubes, immersed for 4 hours, stirred every half an hour, placed in a 120°C oven and dried for 12 hours, and calcined at 450-650°C in an air atmosphere for 4-6 hours to obtain a VPO-loaded modified carbon nanotube catalyst.

3. The method for preparing salicylic nitrile according to claim 2, characterized in that: The modified carbon nanotubes are prepared by the following steps: Carbon nanotubes and inorganic acid were added into water, and after ultrasonic treatment for 15 minutes, the solution was transferred into a reactor, and hydrothermally reacted at 180°C for 12 hours, and then filtered, washed and dried to obtain modified carbon nanotubes.

4. The method for preparing salicylic nitrile according to claim 1, characterized in that: The mass ratio of salicylamide, toluene and water is 10-20:40-100:3-7.

5. The method for preparing salicylic nitrile according to claim 2, characterized in that: The molar ratio of ammonium metavanadate, oxalic acid and water is 1:2:

80.

6. The method for preparing salicylic nitrile according to claim 2, characterized in that: The molar ratio of phosphoric acid to ammonium metavanadate added is 1-3:

1.

7. The method for preparing salicylic nitrile according to claim 2, characterized in that: The usage ratio of the mixed liquid to the modified carbon nanotubes is 10-40 ml: 1-6 g.

8. The method for preparing salicylic nitrile according to claim 3, characterized in that: The inorganic acid is any one of phosphoric acid, boric acid and sulfurous acid.

9. The method for preparing salicylic nitrile according to claim 3, characterized in that: The usage ratio of carbon nanotubes, inorganic acid and water is 5-10g:1-3g:20-50ml.

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