CN114956994B - A kind of preparation method of salicylate - Google Patents

Abstract

The application relates to a preparation method of salicylate, which belongs to the technical field of chemical industry, and comprises the following steps: s1: mixing and stirring methyl salicylate, alcohol and a catalyst uniformly, and reacting for 5-10 h at the temperature of 130-190 ℃; wherein, the mol ratio of the methyl salicylate to the alcohol is 1: (1.7-2.0); the catalyst adopts an Sn-Rh-La-Mg-Na-K/dolomite catalyst, and the dosage of the Sn-Rh-La-Mg-Na-K/dolomite catalyst is 0.1-0.5% of the total mass of methyl salicylate and alcohol; s2: and (3) filtering the obtained product in the step (S1) to remove the catalyst, washing with water, then carrying out reduced pressure distillation under the pressure of 0.93-1.8 kPa, and collecting fractions to obtain the product. The preparation method has the advantages of simple process, higher product yield, higher purity and good product fragrance.

Description

A kind of preparation method of salicylate

Technical field

The present application relates to the field of chemical engineering, and in particular to a preparation method of salicylate.

Background technique

Salicylic acid is a fat-soluble organic acid that exists in nature in willow bark, white pearl leaves and sweet birch trees. It is an important fine chemical raw material. Salicylate, synthesized from salicylic acid as raw material, is widely used in the fragrance industry and daily chemical industry. It is an important class of fine chemical products.

Generally, the synthesis of salicylate mainly uses the esterification method, which is obtained by heating esterification reaction of salicylic acid and alcohol under the catalysis of sulfuric acid. However, salicylic acid is prone to side reactions during the reaction, leading to oxidation, discoloration or odor, and it is difficult to recover salicylic acid once it deteriorates. Therefore, in industry, the transesterification method is usually used to synthesize salicylate, that is, methyl salicylate and other alcohols except methanol are used to generate new salicylate under the catalytic heating of a catalyst. The inventor found that the conversion rate of the current process of synthesizing salicylate through transesterification needs to be improved.

Contents of the invention

In order to simplify the process, increase the yield of the product, and make the product have a better aroma, this application provides a preparation method of salicylate.

The preparation method of salicylate provided by this application adopts the following technical solution:

A preparation method of salicylate, comprising the following steps:

S1: Mix methyl salicylate, alcohol and catalyst evenly and react at 130~190℃ for 5~10h;

Wherein, the molar ratio of methyl salicylate and alcohol is 1: (1.7~2.0); the catalyst adopts Sn-Rh-La-Mg-Na-K/dolomite catalyst, Sn-Rh-La-Mg -The dosage of Na-K/dolomite catalyst is 0.1~0.5% of the total mass of methyl salicylate and alcohol;

S2: Filter the result of step S1 to remove the catalyst, wash with water, and then distill under reduced pressure under a pressure of 0.93 to 1.8 kPa, collect fractions, and obtain the product.

By adopting the above technical solution, this application carries out a transesterification reaction between methyl salicylate and alcohol within a specific molar ratio range under the catalysis of a specific catalyst, and controls the temperature and time of the transesterification reaction process to be within a specific range. , making the transesterification reaction between methyl salicylate and alcohol more thorough, promoting the reaction to proceed in the forward direction, and improving the conversion rate of methyl salicylate.

This application controls the molar ratio range of methyl salicylate and alcohol. Since the transesterification reaction is a reversible reaction, according to Le Chatelier's principle, the added amount of alcohol is higher than that of methyl salicylate within a certain range, which can promote transesterification. The reaction proceeds in the forward direction, increasing the conversion rate of methyl salicylate. However, if the amount of alcohol added is higher than the range of this application, it will increase the time for recovery of alcohol by vacuum distillation, which may cause side reactions, and part of the methyl salicylate will be azeotropically taken away during vacuum distillation of alcohol. Therefore, increasing the amount of alcohol added will correspondingly increase the amount of methyl salicylate that azeotropes with the alcohol, resulting in a reduction in the conversion rate of methyl salicylate, thereby reducing the yield.

At the same time, this application controls the reaction temperature of the transesterification reaction process within a specific range, which is much higher than the boiling point of methanol, so that methanol is evaporated, reducing the products produced by the reaction, making the reaction proceed in the forward direction, and improving the efficiency of salicylic acid. Conversion rate of acid methyl ester. However, if the reaction temperature is too high, not only will it not increase the conversion rate of methyl salicylate, it will also cause an oxidation reaction of phenolic hydroxyl groups, affecting the quality of the product.

This application controls the reaction time of the transesterification reaction process within a specific range, allowing methyl salicylate and alcohol to fully react, making the reaction more thorough, reducing the residual amount of methyl salicylate, and improving the purity of the product. Continuously increasing the reaction time will not increase the conversion rate of methyl salicylate, but will increase the production cost.

This application uses Sn-Rh-La-Mg-Na-K/dolomite as the catalyst for the transesterification reaction, and controls the addition amount of the catalyst within a specific range to fully catalyze the transesterification reaction and make the transesterification The reaction is more thorough and the conversion rate of methyl salicylate is improved. If the added amount of the catalyst is lower than this range, the contact between the catalyst and the material is too little, which affects the reaction speed; but if the added amount of the catalyst is higher than this range, agglomeration will easily occur, but the surface area in contact with the material will be reduced, making it impossible to react. To improve the conversion rate, it will also increase production costs.

At the same time, Sn-Rh-La-Mg-Na-K/dolomite is a solid alkaline catalyst with high catalytic activity, and there are a large number of flakes on the surface of the Sn-Rh-La-Mg-Na-K/dolomite solid alkali catalyst. The ravines formed by the accumulation of substances can promote full contact between the Sn-Rh-La-Mg-Na-K/dolomite solid alkali catalyst and the reactants, thereby increasing the conversion rate of the transesterification reaction. At the same time, the Sn-Rh-La-Mg-Na-K/dolomite solid alkali catalyst has excellent reusability and is easy to separate from the product. It can still maintain high catalytic activity after multiple uses, reducing production costs and meeting the requirements. meet the requirements of green production. At the same time, the Sn-Rh-La-Mg-Na-K/dolomite solid alkali catalyst has little effect on the aroma of salicylate.

In summary, the salicylate produced by the preparation method of the present application has a higher yield and higher purity, and the salicylate produced has a good aroma.

Preferably, the alcohol in step S1 is benzyl alcohol; the reaction temperature of methyl salicylate and benzyl alcohol is 160~190°C, and the reaction time is 6~8h; and in step S2, the reaction temperature is 0.93~0.95kPa. Collect the 170~175°C fraction under pressure to obtain benzyl salicylate.

By adopting the above technical solution, this application uses benzyl alcohol and methyl salicylate to carry out transesterification reaction at a specific reaction temperature and reaction time, and collects benzyl salicylate and water under reduced pressure and fractionation within specific pressure conditions and temperature conditions. Benzyl Cylate has a sweet aroma and is often used as a fixative in cosmetics and soap flavors. Appropriate reaction conditions promote the forward progress of the reaction, make the transesterification reaction proceed more fully, increase the conversion rate of methyl salicylate, and thereby increase the yield and purity of benzyl salicylate.

Preferably, the alcohol in step S1 is isooctyl alcohol; the reaction temperature of methyl salicylate and isooctyl alcohol is 130~150°C, and the reaction time is 5~9h; and in step S2, the reaction temperature is 1.0~ Collect the fraction at 174~178°C under a pressure of 1.2kPa to obtain isooctyl salicylate.

By adopting the above technical solution, this application uses isooctyl alcohol and methyl salicylate to carry out transesterification reaction at a specific reaction temperature and reaction time, and collects isooctyl salicylate by vacuum fractionation within specific pressure conditions and temperature conditions. , Isooctyl salicylate has a good fragrance and is a commonly used fine chemical raw material. Appropriate reaction conditions promote the forward progress of the reaction, make the transesterification reaction proceed more fully, increase the conversion rate of methyl salicylate, and thereby increase the yield and purity of isooctyl salicylate.

Preferably, n-hexanol is used as the alcohol in step S1; the reaction temperature of methyl salicylate and n-hexanol is 140~190°C, and the reaction time is 6~10h; and in step S2, the reaction temperature is 1.6~1.8kPa. Collect the 167~168°C fraction under pressure to obtain hexyl salicylate.

By adopting the above technical solution, this application uses n-hexanol and methyl salicylate to carry out transesterification reaction at a specific reaction temperature and reaction time, and collects hexyl salicylate and water under reduced pressure and fractionation under specific pressure conditions and temperature conditions. Hexyl Cylate has a floral and fruity aroma, accompanied by a soft and sweet herbal fragrance. It is a commonly used fixative for cosmetic fragrances. Appropriate reaction conditions promote the forward progress of the reaction, make the transesterification reaction proceed more fully, increase the conversion rate of methyl salicylate, and thereby increase the yield and purity of hexyl salicylate.

Preferably, the Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

Dip the dolomite powder in the mixed solution of Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , K ⁺ for 2~5h, dry it, and then calcine it at 500~600℃ for 1~2h , obtain Sn-Rh-La-Mg-Na-K/dolomite catalyst.

By adopting the above technical solution, this application uses an impregnation method to load Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , and K ⁺ ions onto dolomite powder. Dolomite powder is mainly composed of calcium carbonate and magnesium carbonate. After dolomite powder is calcined at high temperature, Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , and K ⁺ ions are loaded onto the dolomite powder, which can reduce the The crystal grain size of calcium oxide in dolomite powder. Smaller calcium oxide particles are conducive to full contact between the active ingredients of the catalyst and the reactants, which improves the conversion rate of methyl salicylate.

Moreover, after Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , and K ⁺ ions are loaded onto the dolomite powder, the specific surface area of the Sn-Rh-La-Mg-Na-K/dolomite catalyst is reduced. and average pore diameter, which improves the mesoporous performance, enhances the mass transfer of the transesterification reaction, improves the catalytic performance of the catalyst, thereby increasing the conversion rate of methyl salicylate.

At the same time, this application controls the immersion time of dolomite powder in the mixed solution of Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , K ⁺ as well as the calcination temperature and calcination time within a specific range, so that each The ions are fully loaded onto the surface of dolomite powder, which improves the alkali strength and catalytic activity of the Sn-Rh-La-Mg-Na-K/dolomite catalyst, thereby increasing the conversion rate of methyl salicylate.

Preferably, the ion molar concentrations of Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , and K ⁺ in the mixed solution are 0.65~0.70mol/L, 0.02~0.04mol/L, and 0.05 respectively. ~0.06mol/L, 0.45~0.55mol/L, 0.22~0.26mol/L and 0.32~0.36mol/L.

By adopting the above technical solution, this application strictly controls the molar concentration of Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , and K ⁺ in the mixed solution within a specific range, so that each metal ion can It is better attached to the dolomite powder, so that the Sn-Rh-La-Mg-Na-K/dolomite catalyst has higher alkali strength, higher catalytic activity, excellent reusability, and easy separation from the product. It can still maintain high catalytic activity after repeated use, reducing production costs and meeting the requirements of green production.

Preferably, the drying conditions are drying at a temperature of 80 to 90°C for 1 to 2 hours.

By adopting the above technical solution, this application dries the mixed solution under a specific temperature range to remove moisture, which reduces the possibility of moisture interfering with subsequent calcination and improves the quality of Sn-Rh-La-Mg-Na-K/dolomite. The base strength and catalytic activity of the catalyst improve the conversion rate of methyl salicylate.

Preferably, in step S1, N ₂ is passed in for protection during the reaction.

By adopting the above technical solution, this application introduces N ₂ to protect the reaction during the transesterification reaction, which can eliminate oxygen in the reaction system and reduce the possibility of thermal oxidative degradation caused by the presence of oxygen at high temperatures. At the same time, the presence of N ₂ can increase the pressure in the system, promote the reaction to proceed in the forward direction, and increase the conversion rate of methyl salicylate.

Preferably, in step S1, fractions at 64 to 70°C are continuously fractionated during the reaction.

By adopting the above technical solution, this application continuously fractionates the 64~70°C fraction during the transesterification reaction, so that the methanol produced in the transesterification reaction is continuously fractionated out of the reaction system, and the amount of methanol generated by the reaction is continuously reduced. Promote the reaction to proceed in the forward direction and increase the conversion rate of methyl salicylate.

Preferably, in step S2, the number of water washings is 2 to 3 times.

By adopting the above technical solution, this application washes the filtered product a certain number of times, so that unreacted substances on the surface of the product are fully removed, impurities are reduced, and the purity of other salicylic acid esters generated by the transesterification reaction is improved.

To sum up, this application includes at least one of the following beneficial technical effects:

1. The preparation method of the present application results in a high conversion rate of methyl salicylate, thereby resulting in a higher yield of the prepared salicylate and a higher purity of the product;

2. The catalyst in the preparation method of the present application has high catalytic activity, is easy to separate from the raw materials, can be recycled repeatedly, and can still maintain high catalytic activity after repeated use without affecting the aroma of the prepared salicylate;

3. The preparation method of salicylate in the present application has simple steps, mild reaction conditions, low production cost, and is suitable for large-scale industrial production.

Detailed ways

The present application will be further described in detail below in conjunction with examples.

In the following examples and comparative examples:

Methyl salicylate was purchased from Beijing Beida Zhengyuan Technology Co., Ltd.;

Benzyl alcohol was purchased from Shandong Yiweian Chemical Technology Co., Ltd.;

Isooctanol was purchased from Jinan Rongguang Chemical Co., Ltd.;

n-hexanol was purchased from Jinan Yunuo Chemical Co., Ltd.;

SnCl ₂ was purchased from Henan Hongju Chemical Products Co., Ltd.;

Rh(NO ₃ ) ₃ was purchased from Shanghai Jiuyi New Material Technology Co., Ltd.;

La(NO ₃ ) ₃ was purchased from Hubei Xingheng Technology Co., Ltd.;

Mg(NO ₃ ) ₂ was purchased from Shanxi Wencheng Chemical Co., Ltd.;

NaCl and KCl were purchased from Jinan Kunfeng Chemical Co., Ltd.

Example 1

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 183.6kg benzyl alcohol (1700mol) and 0.3356kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, pass in N ₂ for protection, and set at 160 The reaction is carried out for 6 hours at a temperature of ℃, and the fractions at 64~70℃ are continuously fractionated during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water twice, and then collect the 170~175°C fraction under a pressure of 0.93kPa to obtain benzyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.65mol/L, 0.02mol/L, and 0.05mol/L respectively. , 0.45mol/L, 0.22mol/L, 0.32mol/L mixed solution for 2h, then dried at 80℃ for 1h, and then calcined at 500℃ for 1h to obtain Sn-Rh-La- Mg-Na-K/dolomite catalyst.

Example 2

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 199.8kg benzyl alcohol (1850mol) and 1.0554kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, pass in N ₂ for protection, and set at 175 The reaction was carried out for 7 hours at a temperature of ℃, and the fractions at 64~70℃ were continuously fractionated during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water twice, and then collect the 170~175°C fraction under a pressure of 0.94kPa to obtain benzyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.675mol/L, 0.03mol/L, and 0.055mol/L respectively. , 0.5mol/L, 0.24mol/L, 0.34mol/L mixed solution for 3.5h, then dried at 85℃ for 1.5h, and then calcined at 550℃ for 1.5h to obtain Sn-Rh -La-Mg-Na-K/dolomite catalyst.

Example 3

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 216kg benzyl alcohol (2000mol) and 1.84kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, pass in N ₂ for protection, and heat at 190°C The reaction was carried out for 8 hours at a temperature of 64°C, and the fractions at 64~70°C were continuously fractionated during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water three times, and then collect the 170~175°C fraction under a pressure of 0.95kPa to obtain benzyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.7mol/L, 0.04mol/L, and 0.06mol/L respectively. , 0.55mol/L, 0.26mol/L, 0.36mol/L mixed solution for 5h, then dried at 90℃ for 2h, and then calcined at 600℃ for 2h to obtain Sn-Rh-La- Mg-Na-K/dolomite catalyst.

Example 4

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 221kg isooctyl alcohol (1700mol) and 0.373kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, pass in N ₂ for protection, and set at 130 React for 5 hours at a temperature of ℃, and continuously fractionate fractions of 64~70℃ during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water twice, and then collect the fraction at 174~178°C under a pressure of 1.0kPa to obtain isooctyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.65mol/L, 0.02mol/L, and 0.05mol/L respectively. , 0.45mol/L, 0.22mol/L, 0.32mol/L mixed solution for 2h, then dried at 80℃ for 1h, and then calcined at 500℃ for 1h to obtain Sn-Rh-La- Mg-Na-K/dolomite catalyst.

Example 5

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 240.5kg isooctyl alcohol (1850mol) and 1.1775kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, and pass in N ₂ for protection. React for 7 hours at a temperature of 140°C, and continuously fractionate fractions at 64~70°C during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water three times, and then collect the fraction at 174~178°C under a pressure of 1.1kPa to obtain isooctyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.675mol/L, 0.03mol/L, and 0.055mol/L respectively. , 0.5mol/L, 0.24mol/L, 0.34mol/L mixed solution for 3.5h, then dried at 85℃ for 1.5h, and then calcined at 550℃ for 1.5h to obtain Sn-Rh -La-Mg-Na-K/dolomite catalyst.

Example 6

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 260kg isooctyl alcohol (2000mol) and 2.06kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, pass in N ₂ for protection, and set at 150 The reaction was carried out for 9 hours at a temperature of ℃, and the fractions at 64~70℃ were continuously fractionated during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water three times, and then collect the fraction at 174~178°C under a pressure of 1.2kPa to obtain isooctyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.7mol/L, 0.04mol/L, and 0.06mol/L respectively. , 0.55mol/L, 0.26mol/L, 0.36mol/L mixed solution for 5h, then dried at 90℃ for 2h, and then calcined at 600℃ for 2h to obtain Sn-Rh-La- Mg-Na-K/dolomite catalyst.

Example 7

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 173.4kg n-hexanol (1700mol) and 0.3254kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, pass in N ₂ for protection, and set at 140 The reaction is carried out for 6 hours at a temperature of ℃, and the fractions at 64~70℃ are continuously fractionated during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water twice, and then collect the fraction at 167~168°C under a pressure of 1.6kPa to obtain hexyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.65mol/L, 0.02mol/L, and 0.05mol/L respectively. , 0.45mol/L, 0.22mol/L, 0.32mol/L mixed solution for 2h, then dried at 80℃ for 1h, and then calcined at 500℃ for 1h to obtain Sn-Rh-La- Mg-Na-K/dolomite catalyst.

Example 8

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 188.7kg n-hexanol (1850mol) and 1.0221kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, pass in N ₂ for protection, and set at 165 The reaction was carried out for 8 hours at a temperature of ℃, and the fractions at 64~70℃ were continuously fractionated during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water three times, and then collect the fraction at 167~168°C under a pressure of 1.7kPa to obtain hexyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.675mol/L, 0.03mol/L, and 0.055mol/L respectively. , 0.5mol/L, 0.24mol/L, 0.34mol/L mixed solution for 3.5h, then dried at 85℃ for 1.5h, and then calcined at 550℃ for 1.5h to obtain Sn-Rh -La-Mg-Na-K/dolomite catalyst.

Example 9

A preparation method of salicylate, comprising the following steps:

S1: Mix 152kg methyl salicylate (1000mol), 204kg n-hexanol (2000mol) and 0.712kg Sn-Rh-La-Mg-Na-K/dolomite catalyst, stir evenly, pass in N ₂ for protection, and heat at 190°C React at a temperature of 10 hours, and continuously fractionate the 64~70°C fraction during the reaction process;

S2: Filter the result of step S1 to remove the catalyst, wash with water three times, and then collect the 167~168°C fraction under a pressure of 1.8kPa to obtain hexyl salicylate;

The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method:

The molar concentrations of dolomite powder in SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mg(NO ₃ ) ₂ , NaCl, and KCl are 0.7mol/L, 0.04mol/L, and 0.06mol/L respectively. , 0.55mol/L, 0.26mol/L, 0.36mol/L mixed solution for 5h, then dried at 90℃ for 2h, and then calcined at 600℃ for 2h to obtain Sn-Rh-La- Mg-Na-K/dolomite catalyst.

Example 10

A method for preparing salicylate is different from Example 2 in that the catalyst used is a catalyst that has been recycled 5 times under the conditions of Example 2.

Example 11

A method for preparing salicylate is different from Example 5 in that the catalyst used is a catalyst that has been recycled 7 times under the conditions of Example 5.

Example 12

A method for preparing salicylate is different from Example 8 in that the catalyst used is a catalyst that has been recycled 10 times under the conditions of Example 8.

Comparative example 1

The difference from Example 2 is that in step S1, concentrated sulfuric acid is used instead of Sn-Rh-La-Mg-Na-K/dolomite catalyst.

Comparative example 2

The difference from Example 5 is that in step S1, concentrated sulfuric acid is used instead of the Sn-Rh-La-Mg-Na-K/dolomite catalyst, and the rest are the same.

Comparative example 3

The difference from Example 8 is that in step S1, concentrated sulfuric acid is used instead of the Sn-Rh-La-Mg-Na-K/dolomite catalyst, and the rest are the same.

Comparative example 4

The difference from Example 2 is that: in the Sn-Rh-La-Mg-Na-K/dolomite catalyst, dolomite powder is mixed with SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Immerse in a mixed solution with molar concentrations of Mg(NO ₃ ) ₂ , NaCl, and KCl of 0.35mol/L, 0.09mol/L, 0.03mol/L, 0.6mol/L, 0.2mol/L, and 0.4mol/L respectively.

Comparative example 5

The difference from Example 5 is that: in the Sn-Rh-La-Mg-Na-K/dolomite catalyst, dolomite powder is mixed with SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Immerse in a mixed solution with molar concentrations of Mg(NO ₃ ) ₂ , NaCl, and KCl of 0.8mol/L, 0.01mol/L, 0.12mol/L, 0.3mol/L, 0.3mol/L, and 0.9mol/L respectively.

Comparative example 6

The difference from Example 8 is that: in the Sn-Rh-La-Mg-Na-K/dolomite catalyst, dolomite powder is mixed with SnCl ₂ , Rh(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Immerse in a mixed solution with molar concentrations of Mg(NO ₃ ) ₂ , NaCl, and KCl being 0.4mol/L, 0.13mol/L, 0.02mol/L, 0.7mol/L, 0.1mol/L, and 0.5mol/L respectively.

Comparative example 7

The difference from Example 2 is that benzyl alcohol is 800 mol (86.4kg), and the rest are the same.

Comparative example 8

The difference from Example 5 is that isooctyl alcohol is 900 mol (117kg), and the rest are the same.

Comparative example 9

The difference from Example 8 is that: n-hexanol is 2500 mol (255kg), and the rest are the same.

Comparative example 10

The difference from Example 2 is that the Sn-Rh-La-Mg-Na-K/dolomite catalyst is 0.15kg, and the rest are the same.

Comparative example 11

The difference from Example 5 is that: the Sn-Rh-La-Mg-Na-K/dolomite catalyst is 2.78kg, and the rest are the same.

Comparative example 12

The difference from Example 8 is that the Sn-Rh-La-Mg-Na-K/dolomite catalyst is 0.14kg, and the rest are the same.

Performance testing

Detect and calculate the yield and purity of the salicylate prepared by the preparation methods of Examples 1 to 12 and Comparative Examples 1 to 12.

Table 1

project Product quantity (kg) Product yield (%) purity(%) Example 1 217.28 90.3 99.5 Example 2 218.42 89.8 99.7 Example 3 216.60 88.0 99.6 Example 4 239.00 91.6 99.4 Example 5 239.75 90.9 99.5 Example 6 238.50 87.4 99.4 Example 7 211.12 89.1 99.5 Example 8 212.68 90.8 99.7 Example 9 211.57 91.3 99.4 Example 10 215.00 87.3 99.6 Example 11 235.25 88.1 99.9 Example 12 208.01 87.7 99.1 Comparative example 1 197.45 76.6 97.5 Comparative example 2 214.75 75.9 97.8 Comparative example 3 191.59 76.3 97.1 Comparative example 4 199.50 77.5 99.2 Comparative example 5 219.75 72.9 99.5 Comparative example 6 189.59 70.4 99.4 Comparative example 7 191.29 73.9 99.1 Comparative example 8 209.00 69.6 99.2 Comparative example 9 189.14 78.2 98.9 Comparative example 10 187.19 72.1 99.1 Comparative example 11 208.00 73.2 99.3 Comparative example 12 176.71 79.6 99.4

As can be seen from Table 1, the yields of benzyl salicylate, isooctyl salicylate and hexyl salicylate prepared in Examples 1 to 9 of the present application are above 87%, and the purity is above 99.4%, and The product has a good aroma, indicating that the yield of salicylate prepared by the preparation method of Examples 1 to 9 of the present application is relatively high, the transesterification reaction proceeds relatively thoroughly, and the conversion rate of methyl salicylate is relatively high.

The yields of the products in Examples 10 to 12 are 87.3%, 88.1% and 87.7% respectively, which are slightly different from the corresponding Examples 2, 5 and 8 respectively, indicating that the catalyst of the present application can still maintain a high yield after repeated use. Excellent catalytic performance and can be recycled and reused.

The yields of the products in Comparative Examples 1 to 3 are respectively lower than those in Example 2, Example 5 and Example 8, indicating that the catalyst of the present application has higher alkali strength and higher catalytic activity, and can improve the conversion of methyl salicylate. rate, thereby increasing the yield of the product.

The yields of the products in Comparative Examples 4 to 6 are respectively lower than those in Example 2, Example 5 and Example 8, indicating that the molar concentration of each ion in the Sn-Rh-La-Mg-Na-K/dolomite catalyst is lower or higher. Within the scope of this application, the conversion rate of methyl salicylate will be reduced, thereby reducing the yield.

The yields of the products in Comparative Examples 7 to 9 are respectively lower than those in Example 2, Example 5 and Example 8, indicating that the molar ratio of methyl salicylate to alcohol is lower or higher than the range of the present application, which will reduce the salicylic acid content. The conversion rate of methyl ester, thereby reducing the yield of salicylate.

The yields of the products in Comparative Examples 10 to 12 are respectively lower than those of Example 2, Example 5 and Example 8, indicating that the addition amount of Sn-Rh-La-Mg-Na-K/dolomite catalyst is lower or higher than that of the present application. The range will reduce the conversion rate of methyl salicylate, thereby reducing the yield of salicylate.

The examples of this specific implementation mode are all preferred embodiments of the present application and do not limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application shall be covered by within the protection scope of this application.

Claims (8)

1. A preparation method of salicylate, characterized in that the method includes the following steps: S1: Mix methyl salicylate, alcohol and catalyst evenly and react at 130~190℃ for 5~10h; Wherein, the molar ratio of methyl salicylate and alcohol is 1: (1.7~2.0); the catalyst adopts Sn-Rh-La-Mg-Na-K/dolomite catalyst, Sn-Rh-La-Mg -The dosage of Na-K/dolomite catalyst is 0.1~0.5% of the total mass of methyl salicylate and alcohol; S2: Filter the result of step S1 to remove the catalyst, wash with water, and then distill under reduced pressure under a pressure of 0.93~1.8kPa, collect the fractions, and obtain the product; The Sn-Rh-La-Mg-Na-K/dolomite catalyst is prepared by the following method: Dip the dolomite powder in the mixed solution of Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , K ⁺ for 2~5h, dry it, and then calcine it at 500~600℃ for 1~2h , obtain Sn-Rh-La-Mg-Na-K/dolomite catalyst; The ion molar concentrations of Sn ²⁺ , Rh ³⁺ , La ³⁺ , Mg ²⁺ , Na ⁺ , and K ⁺ in the mixed solution are 0.65~0.70mol/L, 0.02~0.04mol/L, and 0.05~0.06mol respectively. /L, 0.45~0.55mol/L, 0.22~0.26mol/L and 0.32~0.36mol/L. 2. The preparation method of salicylate according to claim 1, characterized in that: the alcohol in step S1 adopts benzyl alcohol; the reaction temperature of methyl salicylate and benzyl alcohol is 160~190°C. , the reaction time is 6~8h; and in step S2, the fraction at 170~175°C is collected under a pressure of 0.93~0.95kPa to obtain benzyl salicylate. 3. the preparation method of a kind of salicylate according to claim 1, is characterized in that: the alcohol in described step S1 adopts isooctyl alcohol; the reaction temperature of methyl salicylate and isooctyl alcohol is 130 ~ 150°C, the reaction time is 5~9h; and in step S2, the fraction at 174~178°C is collected under a pressure of 1.0~1.2kPa to obtain isooctyl salicylate. 4. The preparation method of a kind of salicylate according to claim 1, characterized in that: the alcohol in the step S1 adopts n-hexanol; the reaction temperature of methyl salicylate and n-hexanol is 140~190°C. , the reaction time is 6~10h; and in the step S2, the fraction at 167~168°C is collected under a pressure of 1.6~1.8kPa to obtain hexyl salicylate. 5. The preparation method of a kind of salicylate according to claim 1, characterized in that: in the preparation method of Sn-Rh-La-Mg-Na-K/dolomite catalyst, the drying conditions are Dry at 80~90℃ for 1~2h. 6. The preparation method of a salicylate according to any one of claims 1 to 4, characterized in that: in step S1, N ₂ is passed in for protection during the reaction. 7. The preparation method of salicylate according to any one of claims 1 to 4, characterized in that in step S1, fractions of 64 to 70°C are continuously fractionated during the reaction process. 8. The preparation method of salicylate according to any one of claims 1 to 4, characterized in that in step S2, the number of water washings is 2 to 3 times.