阅读说明：本技术 一种水杨酸异戊酯的制备方法 (Preparation method of isoamyl salicylate ) 是由 郭云峰 桂振友 张静 蔺海政 丰茂英 于 2021-09-16 设计创作，主要内容包括：本发明提供一种制备水杨酸异戊酯的方法。所述方法为水杨酸和异戊醇在SO-(4)～(2-)/TiO-(2)-SiO-(2)超强酸催化剂催化下合成得到水杨酸异戊酯。本发明所用的催化剂在制备过程中,通过加入异丙醇有效调节了Ti盐前体异丙醇钛的水解速率,实现Ti金属在SiO-(2)上的高度分散,提高Ti金属的利用率,此外相比于常规超强酸催化剂,SiO-(2)的掺入既增加了催化剂的B酸位,进一步提高催化剂酸性,又提高了催化剂的稳定性,从而延长其使用寿命。该法所用催化剂可通过过滤即可分离并重复利用,解决了普通有机酸催化剂使用后产生大量废酸和固废的问题,大大降低了三废处理成本。(The invention provides a method for preparing isoamyl salicylate. The method is that salicylic acid and isoamylol are in SO 4 2‑ /TiO 2 ‑SiO 2 The isoamyl salicylate is synthesized under the catalysis of a super acid catalyst. In the preparation process of the catalyst used in the invention, isopropanol is added to effectively adjust the hydrolysis rate of titanium isopropoxide as a Ti salt precursor, so that Ti is realizedMetal on SiO 2 The high dispersion improves the utilization rate of Ti metal, and in addition, compared with the conventional super acidic catalyst, SiO 2 The doping of the catalyst not only increases the B acid position of the catalyst, further improves the acidity of the catalyst, but also improves the stability of the catalyst, thereby prolonging the service life of the catalyst. The catalyst used in the method can be separated and recycled through filtration, the problem that a large amount of waste acid and solid waste are generated after the common organic acid catalyst is used is solved, and the three-waste treatment cost is greatly reduced.)

1. A preparation method of isoamyl salicylate is characterized in that salicylic acid and isoamyl alcohol are added in SO in the method₄ ^2-/TiO₂-SiO₂And (3) esterifying to generate isoamyl salicylate under the catalysis of a super acid catalyst.

2. The method of claim 1, wherein the SO is derived from isoamyl salicylate₄ ^2-/TiO₂-SiO₂The catalyst is prepared by taking a nano activated carbon hard template, titanium isopropoxide, an organic silicon source and a Ti salt hydrolysis inhibitor as raw materials;

preferably, the Ti salt hydrolysis inhibitor is isopropanol.

3. A process for the preparation of isoamyl salicylate according to claim 1 or 2, characterized in that said process comprises the steps of: salicylic acid, isoamyl alcohol and SO₄ ^2-/TiO₂-SiO₂Heating the catalyst for reaction, adding a water separating agent for water separation, washing to be neutral after the reaction is finished, and collecting 150-153 ℃/2KPa fractions by reduced pressure distillation to obtain the isoamyl salicylate.

4. The preparation method of isoamyl salicylate of claim 3, wherein the molar ratio of isoamyl alcohol to salicylic acid is (1.0-4.0):1, preferably (1.5-2.0): 1;

and/or, the SO₄ ^2-/TiO₂-SiO₂The amount of the catalyst is 0.5-3.0 wt%, preferably 1.0-1.5 wt% of the mass of the salicylic acid;

and/or the water-separating agent is preferably cyclohexane, and the amount of the water-separating agent is 2-5 wt% of the mass of the salicylic acid, preferably 3-4 wt%;

and/or the reaction temperature is 100-130 ℃, preferably 105-110 ℃; the reaction time is 1-6h, preferably 2-3 h; the pressure is normal pressure;

and/or, washing with saturated sodium carbonate solution and distilled water.

5. SO (SO)₄ ^2-/TiO₂-SiO₂A process for the preparation of a catalyst for use in the process for the preparation of isoamyl salicylate of any one of claims 1 to 4, characterized in that said catalyst preparation process comprises the steps of:

s1: placing nanometer active carbon in water, adding H₂SO₄Adjusting the pH value of the system to be acidic, adding titanium isopropoxide and organic silicon, adding isopropanol, hydrolyzing and precipitating titanium isopropoxide and a silicon source, and filtering and precipitating to obtain a catalyst precursor;

S2：N₂calcining the catalyst precursor in a calcining furnace, impregnating with sulfuric acid solution, and calcining in an air calcining furnaceAnd obtaining the target catalyst.

6. The method for preparing a catalyst according to claim 5, wherein the concentration of the aqueous activated carbon solution in S1 is 0.02 to 0.08 wt%, preferably 0.04 to 0.06 wt%;

and/or the pH of the S1 system is 2-6, preferably 3-4;

preferably, the added mass of titanium isopropoxide in S1 is TiO₂Calculated) is 10 to 50 times, preferably 20 to 40 times, more preferably 25 to 30 times of the mass of the activated carbon;

and/or the organic silicon source of S1 is methyl orthosilicate and/or ethyl orthosilicate, preferably ethyl orthosilicate;

preferably, the S1 silicone is added in mass (as SiO)₂Calculated as titanium added mass (calculated as TiO)₂From 20 to 80% by weight, preferably from 30 to 60% by weight, more preferably from 40 to 50% by weight, based on) of a solvent;

and/or the isopropanol is added in an amount of titanium isopropoxide added (by TiO) in S1₂Calculated) of 10 to 20 wt.%, preferably 12 to 15 wt.%;

and/or, the hydrolysis temperature of S1 is 30-70 ℃, preferably 40-60 ℃, and more preferably 45-50 ℃; the reaction time is 3 to 10 hours, preferably 5 to 7 hours.

7. The method for preparing the catalyst according to claim 5, wherein the concentration of the sulfuric acid solution in the S2 is 0.5-1.0mol/L, preferably 0.5-0.7mol/L, and the immersion time is 1-3h, preferably 1.5-2.0 h; the liquid-solid ratio of the impregnation is 10-15mL/g, preferably 12-13 mL/g;

and/or the temperature of the nitrogen roasting of S2 is 350-550 ℃, preferably 400-450 ℃, and the time is 3-6h, preferably 4-5 h;

and/or the air roasting temperature of S2 is 500-700 ℃, preferably 550-600 ℃, and the time is 4-8h, preferably 5-6 h.

8. Isoamyl salicylate prepared by the method for preparing isoamyl salicylate described in any one of claims 1 to 4 or by the catalyst obtained by the method for preparing catalyst described in any one of claims 5 to 7.

Technical Field

The invention belongs to the field of organic synthesis, and particularly relates to a preparation method of isoamyl salicylate.

Background

The isoamyl salicylate is also called isoamyl salicylate, is one of important salicylate, is a main agent for blending clover essence, is used as a blending agent and a fragrance fixing agent when the essence is blended, can be well blended with oak moss extract, clary sage oil, geraniol and the like, and has the following structure:

the classical synthesis method of isoamyl salicylate is to heat salicylic acid and isoamyl alcohol in the presence of concentrated sulfuric acid or sodium bisulfate, and the method has the disadvantages that the strong corrosivity of sulfuric acid and sodium bisulfate shortens the service life of equipment, and acidic waste liquid pollutes the environment. Although the sulfuric acid catalyst has high activity, the selectivity is poor, byproducts such as ether and sulfate exist in the reaction mixture, the post-treatment is troublesome, the production cost is high, and the development of the sulfuric acid catalyst is limited to a certain extent.

SO reported by Wangzhonghua (Wangzhonghua, synthesis of isoamyl salicylate, chemical engineering of acetaldehyde acetic acid, 2018,08:08-18.)₄ ^2-/TiO₂The solid acid catalyst is applied to the synthesis of isoamyl salicylate, and compared with the conventional catalyst, the catalyst has better catalytic performance, the catalyst consumption is less, and the product yield reaches 94.6%. Summer rainbow et al (SO)₄ ^2-/TiO₂-M_xO_yPreparation of solid super acid and catalytic synthesis of isoamyl salicylate, industrial catalysis, 2010,18(03):72-76) reports various bimetal-loaded SO₄ ^2-/TiO₂-M_xO_yThe solid acid catalyst can be used for efficiently synthesizing isoamyl salicylate, but the solid acid catalysts are prepared by directly hydrolyzing organic or inorganic metal salt, so that a template agent is not used for pore forming of the catalyst, a corresponding metal salt hydrolysis regulator is not used, the catalyst prepared by the method has fewer pore passages, and metal components are distributedThe catalyst is not uniform, so that the utilization rate of metals is poor, and in addition, the catalyst with all metal components is easy to further cause the collapse of catalyst pore channels when being soaked in sulfuric acid, so that the catalyst pore channels are reduced, the activity of the catalyst is reduced, and the service life of the catalyst is also shortened.

In view of the above, it is necessary to develop a salicylic acid esterification catalyst having higher catalytic activity, which can improve the reaction yield and enhance the catalyst life, and avoid the pollution of waste acid and the like.

Disclosure of Invention

The invention aims to provide a preparation method of isoamyl salicylate. The method adopts SO with rich mesoporous channels and high-efficiency catalytic esterification function₄ ^2-/TiO₂-SiO₂The solid super acidic heterogeneous catalyst is used for catalyzing salicylic acid and isoamyl alcohol to esterify and prepare the isoamyl salicylate. The catalyst used in the invention takes the activated carbon as a hard template, the prepared catalyst has rich mesoporous pore channel structure, the number of metal active sites is obviously increased, the utilization rate of metal components is improved, isoamylol is added in the hydrolysis process of Ti salt, the uncontrollable hydrolysis of the Ti salt under the acidic condition is effectively inhibited, the controllable hydrolysis of the Ti metal and a Si source is improved, the dispersion degree of the Ti metal is improved, and SiO is doped₂Not only the acid center of the B acid of the catalyst is supplemented, but also the stability of the catalyst can be increased, and the service life of the catalyst is prolonged.

The method has the advantages of mild process conditions, short reaction time, easy recycling of the catalyst, high product yield and the like. Under the optimal condition, the reaction conversion rate of salicylic acid and isoamyl alcohol for preparing isoamyl salicylate can reach 99.2 percent, the reaction temperature is reduced to 100 ℃, the reaction time is shortened to 2 hours, and the final product yield reaches more than 99 percent.

In order to achieve the above purpose, the technical scheme provided by the invention is as follows:

preparation method of isoamyl salicylate, wherein methodSalicylic acid and isoamyl alcohol in SO₄ ^2-/TiO₂-SiO₂And (3) esterifying to generate isoamyl salicylate under the catalysis of a super acid catalyst.

In the present invention, the SO₄ ^2-/TiO₂-SiO₂The catalyst is prepared by taking a nano activated carbon hard template, titanium isopropoxide, an organic silicon source and a Ti salt hydrolysis inhibitor as raw materials; preferably, the Ti salt hydrolysis inhibitor is isopropanol. Nano active carbon is used as a hard template, isopropanol is added in the catalyst synthesis process to realize the hydrolysis rate regulation of titanium isopropoxide, and Ti metal in SiO can be realized₂High dispersion of the components.

In the invention, the method comprises the following steps: salicylic acid, isoamyl alcohol and SO₄ ^2-/TiO₂-SiO₂Heating the catalyst for reaction, adding a water separating agent for water separation, washing to be neutral after the reaction is finished, and collecting 150-153 ℃/2KPa fractions by reduced pressure distillation to obtain the isoamyl salicylate.

In the present invention, the molar ratio of isoamyl alcohol to salicylic acid is (1.0-4.0):1, preferably (1.5-2.0): 1.

In the present invention, the SO₄ ^2-/TiO₂-SiO₂The amount of catalyst used is 0.5-3.0 wt%, preferably 1.0-1.5 wt% based on the mass of salicylic acid.

In the present invention, the water-separating agent is preferably cyclohexane, which is used in an amount of 2 to 5 wt%, preferably 3 to 4 wt%, based on the mass of salicylic acid.

In the invention, the reaction temperature is 100-130 ℃, preferably 105-110 ℃; the reaction time is 1-6h, preferably 2-3 h; the pressure is normal pressure.

In the present invention, saturated sodium carbonate solution and distilled water are used for washing.

Another object of the present invention is to provide a SO₄ ^2-/TiO₂-SiO₂A method for preparing the catalyst.

SO (SO)₄ ^2-/TiO₂-SiO₂A preparation method of the catalyst, wherein the catalyst is used in the preparation method of the isoamyl salicylate, and the preparation method of the catalyst comprises the following stepsComprises the following steps:

s1: placing nanometer active carbon in water, adding H₂SO₄Adjusting the pH value of the system to be acidic, adding titanium isopropoxide and organic silicon, adding isopropanol, a titanium source and a silicon source for hydrolysis and precipitation, and filtering the precipitate to obtain a catalyst precursor;

S2：N₂roasting the catalyst precursor in a roasting furnace, soaking the catalyst precursor in sulfuric acid solution, and roasting the catalyst precursor in an air roasting furnace to obtain the target catalyst.

In the invention, the concentration of the activated carbon aqueous solution in S1 is 0.02-0.08 wt%, preferably 0.04-0.06 wt%;

in the present invention, the pH of the S1 system is 2 to 6, preferably 3 to 4.

In the invention, the added mass of the titanium isopropoxide in the S1 is TiO₂Calculated) is 10 to 50 times, preferably 20 to 40 times, more preferably 25 to 30 times of the mass of the activated carbon.

In the invention, the organic silicon source of S1 is methyl orthosilicate and/or ethyl orthosilicate, preferably ethyl orthosilicate; preferably, the S1 silicone is added in mass (as SiO)₂Calculated as titanium added mass (calculated as TiO)₂Calculated) of 20 to 80 wt.%, preferably 30 to 60 wt.%, more preferably 40 to 50 wt.%.

In the invention, the isopropanol adding amount of S1 is the adding mass of titanium isopropoxide (by TiO)₂Calculated) of 10 to 20 wt.%, preferably 12 to 15 wt.%.

In the invention, the hydrolysis temperature of S1 is 30-70 ℃, preferably 40-60 ℃, and more preferably 45-50 ℃; the reaction time is 3 to 10 hours, preferably 5 to 7 hours.

In the invention, the concentration of the sulfuric acid solution in the S2 is 0.5-1.0mol/L, preferably 0.5-0.7mol/L, and the dipping time is 1-3h, preferably 1.5-2.0 h; the liquid-solid ratio of the impregnation is 10-15mL/g, preferably 12-13 mL/g.

In the invention, the nitrogen roasting temperature of S2 is 350-550 ℃, preferably 400-450 ℃, and the time is 3-6h, preferably 4-5 h.

In the invention, the air roasting temperature of S2 is 500-700 ℃, preferably 550-600 ℃, and the time is 4-8h, preferably 5-6 h.

The invention also aims to provide isoamyl salicylate.

The isoamyl salicylate is prepared by the method for preparing the isoamyl salicylate, or is prepared by the catalyst obtained by the catalyst preparation method in a catalytic manner.

SO used in the invention₄ ^2-/TiO₂-SiO₂The mesoporous super acidic catalyst takes the activated carbon as a hard template, and the prepared catalyst has rich mesoporous pore channel structures, so that the number of metal active sites is remarkably increased, and the utilization rate of metal components is improved. In addition, it is generally said that the hydrolysis of organosilicates needs to be carried out in an acidic environment to increase the rate of hydrolysis thereof, but in the process of the invention the hydrolysis is rapid if the titanium isopropoxide is in an acidic environment, whereas uncontrolled hydrolysis of titanium isopropoxide tends to result in aggregation of the Ti component, which is difficult to contact with SiO₂The inventor finds that when isoamyl alcohol is added in the hydrolysis process of titanium isopropoxide (Ti salt containing isoamyl alcohol structure), the uncontrollable hydrolysis of the titanium isopropoxide under the acidic condition can be effectively inhibited, so that Ti metal and SiO are well coordinated₂The mutual action of the Ti and the Si realizes the uniform dispersion of the Ti and the Si, improves the dispersion degree of Ti metal, and is doped with SiO₂Not only the acid center of the B acid of the catalyst is supplemented, but also the stability of the catalyst can be increased, and the service life of the catalyst is prolonged. In addition, the catalyst precursor prepared in the invention needs to be roasted in a nitrogen roasting furnace before being soaked in sulfuric acid, so as to protect the hard template active carbon, and due to the existence of the active carbon, on one hand, the catalyst precursor can still play a role in supporting the carrier pore channel in the roasting process of the carrier precursor, so that the collapse of the pore channel caused by high-temperature sintering is avoided, and on the other hand, the damage of acid corrosion to the mesoporous pore channel structure can be greatly reduced by the hard template active carbon in the subsequent sulfuric acid soaking process.

The invention has the positive effects that:

under the optimal condition, the reaction conversion rate of salicylic acid and isoamyl alcohol for preparing isoamyl salicylate can reach 99.2 percent, the reaction temperature is reduced to 100 ℃, the reaction time is shortened to 2 hours, and the final product yield reaches more than 99 percent. The reaction condition is milder, the reaction efficiency is higher, and the catalyst can be directly recycled, so that the method is more environment-friendly.

Detailed description of the invention

The following examples are not intended to limit the scope of the present invention, and modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is defined in the appended claims.

In the examples, the raw materials used are conventional in the art, and the purity specification used is analytical or chemical purity; raw material source information:

nanometer active carbon, titanium isopropoxide, methyl orthosilicate, ethyl orthosilicate, salicylic acid, isoamyl alcohol, sulfuric acid, isopropanol, sodium carbonate, cyclohexane and Fe (NO)₃)₃All purchased from Shanghai Aladdin Biotechnology, Inc.

The following test methods were used:

the isoamyl salicylate is analyzed by a GC-9800 chromatograph under the following chromatographic conditions: the initial temperature is 100 ℃, the temperature is kept for 2min, the temperature is programmed to 300 ℃ at the speed of 10 ℃/min, and the temperature is kept for 5 min; the temperature of the gasification chamber is 300 ℃, and the temperature of the detection chamber is 300 ℃; FID detection; the sample size was 0.2. mu.l.

Examples1

1) Preparation of SO₄ ^2-/TiO₂-SiO₂Catalyst:

to 500g of deionized water was added 0.25g of nano-activated carbon (0.05 wt%), sulfuric acid was added to adjust the pH to 3, and 26.68g (30 times the mass of the activated carbon) of titanium isopropoxide (as TiO) was added₂Calculated), 10.4g of tetraethoxysilane (calculated as SiO) are added₂Calculated), the addition is titanium (calculated as TiO)₂Calculated as TiO) was added in an amount of 1.13g of isopropanol, based on the mass of titanium₂Calculated by weight percent), adjusting the temperature to 45 ℃, and carrying out hydrolysis reaction for 7 h; then filtering the precipitate obtained by the hydrolysis reaction to obtain a catalyst precursor, and placing the catalyst precursor in N₂Roasting in a roasting furnace at 400 ℃ for 5 hours; then 10g of the calcined product was immersed in 120mL of 0.5mol/L sulfuric acid for 1.5h (solid-to-liquid ratio of 12mL of sulfuric acid/1 g of solid). Finally impregnating the solidFiltering, washing, and calcining in air roaster at 600 deg.C for 6 hr to obtain SO with mesoporous structure₄ ^2-/TiO₂-SiO₂Solid super acidic catalyst.

2) Preparation of isoamyl salicylate:

2000g of isoamyl alcohol and 2089.2g of salicylic acid were added to the reactor, and 31.3g of SO were added₄ ^2-/TiO₂-SiO₂Adding 62.7g of cyclohexane into the catalyst, raising the reaction temperature to 105 ℃, carrying out reflux reaction for 2 hours, adding a saturated sodium carbonate solution and distilled water into the reaction product, washing until the solution becomes neutral, placing the organic phase in a reduced pressure distillation device for reduced pressure distillation, collecting 150-153 ℃/2KPa fraction to obtain isoamyl salicylate, wherein the conversion rate is 99.2 percent, and the yield is 99.1 percent.

3) Catalyst evaluation

The reaction product and the product obtained by rectification are analyzed and then the conversion rate and the yield data obtained by calculation are as follows:

number of times of catalyst application	Conversion rate of reaction/%)	Product yield/%
			10	99.0	98.9
30	98.9	98.8
			50	98.6	98.5

As can be seen from the above table, the catalyst still has excellent catalytic performance after being reused for many times.

Examples2

1) Preparation of SO₄ ^2-/TiO₂-SiO₂Catalyst:

to 500g of deionized water was added 0.10g of nano-activated carbon (0.02 wt%), sulfuric acid was added to adjust the pH to 2, and 3.55g (10 times the mass of the activated carbon) of titanium isopropoxide (as TiO) was added₂Calculated), 0.51g of methyl orthosilicate (in terms of SiO) was added₂Calculated), the addition is titanium (calculated as TiO)₂Calculated as TiO) in an amount of 20 wt.% and 0.1g of isopropanol is added simultaneously in an amount corresponding to the mass of titanium (calculated as TiO)₂Calculated), the temperature is adjusted to 30 ℃, and the hydrolysis reaction is carried out for 3 hours; then filtering the precipitate obtained by the hydrolysis reaction to obtain a catalyst precursor, and placing the catalyst precursor in N₂Roasting in a roasting furnace under the roasting condition of 350 ℃ for 3 hours; then 10g of the calcined product was immersed in 100mL of 1.0mol/L sulfuric acid for 1.0h (solid-to-liquid ratio of 10mL of sulfuric acid/1 g of solid). Finally, filtering and washing the impregnated solid, and then placing the solid in an air roasting furnace for roasting under the roasting condition of 500 ℃ for 8 hours to obtain the SO with the mesoporous structure₄ ^2-/TiO₂-SiO₂Solid super acidic catalyst.

2) Preparation of isoamyl salicylate:

2000g of isoamyl alcohol and 3133.7g of salicylic acid were added to the reactor, followed by 15.7g of SO₄ ^2-/TiO₂-SiO₂Adding 62.7g of cyclohexane into the catalyst, raising the reaction temperature to 100 ℃, carrying out reflux reaction for 1h, adding a saturated sodium carbonate solution and distilled water into a reaction product after the reaction, washing until the solution becomes neutral, finally placing an organic phase in a reduced pressure distillation device for reduced pressure distillation, and collecting 150-DEG C/2 KPa fraction to obtain the isoamyl salicylate. Analyzing the reaction product and the product obtained by rectification and calculating the obtained conversionThe conversion rate was 91.6% and the product yield was 91.5%.

Examples3

1) Preparation of SO₄ ^2-/TiO₂-SiO₂Catalyst:

to 500g of deionized water was added 0.3g of nano activated carbon (0.06 wt%), sulfuric acid was added to adjust the pH to 6, and 21.34g (20 times the mass of the activated carbon) of titanium isopropoxide (as TiO) was added₂Calculated), 6.2g of tetraethoxysilane (calculated as SiO) are added₂Calculated), the addition is titanium (calculated as TiO)₂Calculated as TiO) was added in an amount of 0.78g of isopropanol, based on the mass of titanium₂Calculated), the temperature is adjusted to 70 ℃, and the hydrolysis reaction is carried out for 5 hours; then filtering the precipitate obtained by the hydrolysis reaction to obtain a catalyst precursor, and placing the catalyst precursor in N₂Roasting in a roasting furnace at 550 ℃ for 4 hours; then 10g of the calcined product was immersed in 130mL of 0.9mol/L sulfuric acid for 2.0h (solid-to-liquid ratio of 13mL of sulfuric acid/1 g of solid). Finally, filtering and washing the impregnated solid, and then placing the solid in an air roasting furnace for roasting under the roasting condition of 550 ℃ for 4 hours to obtain the SO with the mesoporous structure₄ ^2-/TiO₂-SiO₂Solid super acidic catalyst.

2) Preparation of isoamyl salicylate:

2000g of isoamyl alcohol and 783.4g of salicylic acid were added to the reactor, followed by 7.8g of SO₄ ^2-/TiO₂-SiO₂Adding 39.2g of cyclohexane into the catalyst, raising the reaction temperature to 130 ℃, carrying out reflux reaction for 5 hours, adding a saturated sodium carbonate solution and distilled water into a reaction product after the reaction, washing until the solution becomes neutral, finally placing an organic phase in a reduced pressure distillation device for reduced pressure distillation, and collecting 150-fold-oil 153 ℃/2KPa fraction to obtain the isoamyl salicylate. The conversion rate calculated after analysis of the reaction product and the product obtained by rectification was 93.2% and the product yield was 93.1%.

Examples4

1) Preparation of SO₄ ^2-/TiO₂-SiO₂Catalyst:

0 was added to 500g of deionized water.4g of nano-active carbon (0.08 wt%), sulfuric acid was added to adjust the pH to 5, and 71.14g (50 times the mass of the active carbon) of titanium isopropoxide (in TiO) was added₂Calculated), 30.4g of tetraethoxysilane (calculated as SiO) are added₂Calculated), the addition is titanium (calculated as TiO)₂Calculated as TiO) was added in an amount of 3.4g of isopropanol, calculated as titanium (in terms of TiO)₂Calculated by weight percent), adjusting the temperature to 40 ℃, and carrying out hydrolysis reaction for 10 hours; then filtering the precipitate obtained by the hydrolysis reaction to obtain a catalyst precursor, and placing the catalyst precursor in N₂Roasting in a roasting furnace under the roasting condition of 450 ℃ for 6 hours; then 10g of the calcined product was immersed in 150mL of 0.7mol/L sulfuric acid for 2.5h (solid-to-liquid ratio of 15mL of sulfuric acid/1 g of solid). Finally, filtering and washing the impregnated solid, and then placing the solid in an air roasting furnace for roasting at 700 ℃ for 5 hours to obtain SO with a mesoporous structure₄ ^2-/TiO₂-SiO₂Solid super acidic catalyst.

2) Preparation of isoamyl salicylate:

2000g of isoamyl alcohol and 1044.6g of salicylic acid were added to the reactor, followed by 20.8g of SO₄ ^2-/TiO₂-SiO₂Adding 31.3g of cyclohexane into the catalyst, raising the reaction temperature to 105 ℃, carrying out reflux reaction for 3h, adding a saturated sodium carbonate solution and distilled water into a reaction product after the reaction, washing until the solution becomes neutral, finally placing an organic phase in a reduced pressure distillation device for reduced pressure distillation, and collecting 150-fold-oil 153 ℃/2KPa fraction to obtain the isoamyl salicylate. The conversion rate calculated after analysis of the reaction product and the product obtained by rectification was 95.2% and the product yield was 95.1%.

Examples5

1) Preparation of SO₄ ^2-/TiO₂-SiO₂Catalyst:

to 500g of deionized water was added 0.15g of nano-activated carbon (0.03 wt%), sulfuric acid was added to adjust the pH to 4, and 21.34g (40 times the mass of the activated carbon) of titanium isopropoxide (as TiO) was added₂Calculated), 16.6g of tetraethoxysilane (calculated as SiO) are added₂Calculated), the addition is titanium (calculated as TiO)₂Calculated by) was added, while 1.2g of isopropyl alcohol was added in an amount ofIs titanium mass (in TiO)₂Calculated), adjusting the temperature to 60 ℃, and carrying out hydrolysis reaction for 8 h; then filtering the precipitate obtained by the hydrolysis reaction to obtain a catalyst precursor, and placing the catalyst precursor in N₂Roasting in a roasting furnace at 500 ℃ for 5 hours; then 10g of the calcined product was immersed in 100mL of 0.8mol/L sulfuric acid for 2.0h (solid-to-liquid ratio of 10mL of sulfuric acid/1 g of solid). Finally, filtering and washing the impregnated solid, and then placing the solid in an air roasting furnace for roasting at 600 ℃ for 7 hours to obtain SO with a mesoporous structure₄ ^2-/TiO₂-SiO₂Solid super acidic catalyst.

2) Preparation of isoamyl salicylate:

2000g of isoamyl alcohol and 1566.9g of salicylic acid were added to the reactor, followed by 47.0g of SO₄ ^2-/TiO₂-SiO₂Adding 62.7g of cyclohexane into the catalyst, raising the reaction temperature to 110 ℃, carrying out reflux reaction for 6h, adding a saturated sodium carbonate solution and distilled water into a reaction product after the reaction, washing until the solution becomes neutral, finally placing an organic phase in a reduced pressure distillation device for reduced pressure distillation, and collecting 150-DEG C/2 KPa fraction to obtain the isoamyl salicylate. The conversion rate calculated after analysis of the reaction product and the product obtained by rectification was 94.7% and the product yield was 94.6%.

Examples6

1) Preparation of SO₄ ^2-/TiO₂-SiO₂Catalyst:

to 500g of deionized water was added 0.10g of nano-activated carbon (0.02 wt%), sulfuric acid was added to adjust the pH to 5, and 8.89g (25 times the mass of the activated carbon) of titanium isopropoxide (as TiO) was added₂Calculated), 4.43g of tetraethoxysilane (calculated as SiO) are added₂Calculated), the addition is titanium (calculated as TiO)₂Calculated as TiO) was added in an amount of 0.38g of isopropanol, based on the mass of titanium₂Calculated by weight percent), adjusting the temperature to 55 ℃, and carrying out hydrolysis reaction for 4 hours; then filtering the precipitate obtained by the hydrolysis reaction to obtain a catalyst precursor, and placing the catalyst precursor in N₂Roasting in a roasting furnace under the roasting condition of 420 ℃ for 3 hours; then 10g of the calcined product was taken and placed in130mL of 0.6mol/L sulfuric acid was immersed for 3.0 hours (solid-to-liquid ratio: 13mL sulfuric acid/1 g solid). Finally, filtering and washing the impregnated solid, and then placing the solid in an air roasting furnace for roasting under the roasting condition of 650 ℃ for 6 hours to obtain SO with a mesoporous structure₄ ^2-/TiO₂-SiO₂Solid super acidic catalyst.

2) Preparation of isoamyl salicylate:

2000g of isoamyl alcohol and 1253.5g of salicylic acid were added to the reactor, followed by 31.3g of SO₄ ^2-/TiO₂-SiO₂Adding 25.07g of cyclohexane into the catalyst, raising the reaction temperature to 120 ℃, carrying out reflux reaction for 4h, adding a saturated sodium carbonate solution and distilled water into a reaction product after the reaction, washing until the solution becomes neutral, finally placing an organic phase in a reduced pressure distillation device for reduced pressure distillation, and collecting 150-DEG C/2 KPa fraction to obtain the isoamyl salicylate. The conversion rate calculated after analysis of the reaction product and the product obtained by rectification was 95.0% and the product yield was 94.9%.

Comparative example1

In contrast to example 1, the only difference is that the SO of example 1 is₄ ^2-/TiO₂-SiO₂Catalyst is changed to equal amount of SO₄ ^2-/TiO₂-Fe₂O₃A catalyst.

SO₄ ^2-/TiO₂-Fe₂O₃Synthesis of the catalyst was synthesized according to the literature reported by Xiarnixian et al (Xiarnixian et al₄ ^2-/TiO₂-M_xO_yThe preparation of solid super acid and the catalytic synthesis performance of isoamyl salicylate, industrial catalysis, 2010,18(03) and 72-76) comprise the following specific operation steps: adding 8.0g of Fe (NO)₃)₃Dissolving the mixture in distilled water, adding concentrated ammonia water, and adjusting the pH value to 9-10 to obtain reddish brown Fe (OH)₃)·H₂O precipitation solution, and simultaneously adding 1.2g of Ti (SO)₄)₂The solution is dripped into the precipitation solution under stirring, is placed for 24 hours, is filtered by suction, and is washed and precipitated until the solution is neutral. Oven drying at 100 deg.C for 24 hr, grinding into powder below 60 meshes, pouring into 0.25mol/L sulfuric acid, soaking for 4 hr, and every 0.Once stirring for 5 h. Suction filtering, drying the precipitate at 110 deg.C for 24 hr, and roasting in muffle furnace at 500 deg.C for 4 hr to obtain composite solid super acidic SO₄ ^2-/TiO₂-Fe₂O₃A catalyst.

The catalyst with the same mass is added for reaction according to the example 1, and the conversion rate and the product yield are calculated to be 74.5% and 74.4% after the analysis of the reaction product and the product obtained by rectification.

Comparative example2

In contrast to example 1, the only difference is that example 1 is used to prepare SO₄ ^2-/TiO₂-SiO₂In the catalyst process, no active template agent is added, and the conversion rate calculated after analyzing the reaction product and the product obtained by rectification is 89.8 percent and the product yield is 89.7 percent.

Comparative example3

In contrast to example 1, the only difference is that example 1 is used to prepare SO₄ ^2-/TiO₂-SiO₂In the catalyst process, isopropanol serving as a hydrolysis regulator is not added, and the conversion rate calculated after analysis of the reaction product and the product obtained by rectification is 85.3% and the product yield is 85.2%.

As can be seen from the comparison between the above examples and comparative examples, the reaction conditions of the scheme of the invention are milder, the reaction efficiency is higher, and the catalyst can be directly recycled, so that the method is more environment-friendly.