CN103450010B - Method for preparing cyclohexanecarboxylic acid - Google Patents

Abstract

The invention discloses a method for preparing cyclohexanecarboxylic acid, and belongs to the field of synthesis of fine chemicals. The method is characterized by comprising the following steps: pouring a benzoate water solution into a reaction kettle filled with a selective hydrogenation catalyst from a material storage tank to carry out hydrogenation reaction; directly feeding the product to a pickling tower after hydrogenation reaction, wherein the upper oil is cyclohexanecarboxylic acid. By adopting the method, cyclohexanecarboxylic acid with a high additional value is produced by using benzoate; the used catalyst has ultrahigh selectivity and high hydrogenation activity. The method not only is simple to operate and can carry out intermittent reaction and continuous reaction, but also has good economic benefits and an industrial application prospect.

Description

A kind of method for preparing cyclohexyl formic acid

technical field

The invention belongs to the field of fine chemical synthesis and relates to a method for preparing cyclohexylcarboxylic acid.

Background technique

Cyclohexylcarboxylic acid is an important intermediate in organic synthesis. It is a good photocuring agent and can also be used in the synthesis of praziquantel, a new drug for treating schistosomiasis. Its derivatives such as methyl trans-4-isopropylcyclohexylcarboxylate are intermediates in the production of the new drug nateglinide for the treatment of diabetes, so the preparation of cyclohexylcarboxylic acid plays an important role in organic synthesis. It is difficult to prepare cyclohexyl formic acid by selective hydrogenation of benzoic acid under normal conditions, even with a highly active palladium/carbon catalyst, the conversion rate is difficult to reach 100%. In the process of formic acid, not only the carboxyl group of benzoic acid is easily removed by hydrogenation. Moreover, it is difficult to industrialize due to catalyst stability and recovery problems.

With the continuous increase of the amount of cyclohexyl formic acid, the preparation of high-purity cyclohexyl formic acid becomes more and more important. It is crucial for the development of catalysts with good activity, stability and easy recovery in the aqueous phase. Raney nickel not only has a high hydrogenation catalytic activity in water, but also has a magnetic property which is beneficial to the separation of products. Therefore, it is very suitable for the preparation of cyclohexylcarboxylic acid in aqueous phase. There are some deficiencies in the following known technologies:

Now commonly used selective hydrogenation catalyst is palladium/carbon catalyst, and the selective hydrogenation reaction of benzoic acid is carried out in a tank reactor at temperature 160-170oC and pressure 1.2-1.4MPa condition, because palladium/carbon catalyst is a powder catalyst, and The separation of reaction raw materials and products is difficult. For reclaiming noble metal palladium, palladium/carbon catalyst needs to be thoroughly separated from other substances of reaction system, so reactant benzoic acid needs to be thoroughly reacted completely, to reduce follow-up processing steps, but when reactant contacts with palladium/carbon catalyst for a long time Increase side reaction, make the yield of cyclohexylbenzoic acid reduce significantly.

The literature Reactive Polymers, 18 (1992) 1 reported the preparation of platinum-organic carrier catalysts by the method of organic immobilization. In Shi Wenjie, benzoic acid can be reacted to generate hexahydrobenzoic acid, and the conversion rate is close to 100%, but the catalyst is separated. And recovery problems, and the stability of the catalyst is poor, easy to deactivate.

Chinese patent, publication number: CN1406921A, introduces a method for the selective hydrogenation of benzoic acid to produce hexahydrobenzoic acid, which uses a fixed-bed reactor, but the activity of the catalyst is low, the conversion rate is low, and the selectivity to the target product is poor. Separation is more difficult.

Chinese patent, publication number: CN1406666A, introduces a catalyst for the hydrogenation of benzoic acid to produce hexahydrobenzoic acid. The catalyst uses acidic alumina as a carrier and a group VIB or VIII metal as an active component. When it is used in fixed-bed hydrogenation reaction of benzoic acid, not only the yield of hexahydrobenzoic acid produced in the process is low, but also the purity of hexahydrobenzoic acid is low.

Contents of the invention

The invention provides a method for preparing cyclohexyl formic acid. For the purpose of rational utilization of benzoate, there are many disadvantages of benzoic acid, such as poor catalyst stability, difficult recovery, serious environmental pollution, low yield of cyclohexyl formic acid, etc., through constant pressure reaction, pickling and The organic combination of rectification realizes the resource utilization of benzoate and converts it into high value-added chemical cyclohexyl formic acid. In addition, the present invention uses benzoate as a raw material, avoids the occurrence of side reactions during selective hydrogenation, and improves the yield of the target product. The invention improves the conversion rate of the reaction and the selectivity of the cyclohexyl formic acid, prolongs the service life of the catalyst, and obtains the high-value-added and high-purity cyclohexyl formic acid.

Technical scheme of the present invention is as follows:

The raw material of benzoate in the present invention comprises sodium benzoate, potassium benzoate, reaction product of benzoic acid and sodium hydroxide, reaction product of benzoic acid and or potassium hydroxide, or a mixture of two or more as raw materials.

The catalyst used for selective hydrogenation in the present invention is a modified Raney nickel catalyst. The main function of the Raney nickel catalyst is to carry out the hydrogenation saturation of the benzoate aromatic ring. The Raney nickel catalyst first undergoes a dealumination reaction to increase its activity. The dealumination conditions are: reaction temperature 70°C, reaction time 2h, sodium hydroxide aqueous solution concentration 30%, mass ratio of sodium hydroxide aqueous solution to Raney nickel catalyst is 4-10:1. The composition of the Raney nickel catalyst after dealumination is as follows: the content of nickel is 65-80%, the content of molybdenum is 5-10%, and the content of aluminum is 10-25%.

The method is to inject the benzoate aqueous solution from a raw material storage tank into a constant-pressure reactor equipped with a selective hydrogenation catalyst to carry out hydrogenation reaction. The reaction conditions are: hydrogenation reaction temperature 160-240°C, hydrogen pressure 2-6MPa, reaction time 6-10h, benzoate concentration 10-40%, mass ratio of benzoate to catalyst 100:1 ~5. After the hydrogenation reaction, the product directly enters the pickling tower for pickling, and the acid used is concentrated sulfuric acid or concentrated hydrochloric acid. After pickling, the oily cyclohexyl formic acid in the upper layer is rectified in a rectification tower to obtain high-purity cyclohexyl formic acid, and the lower layer of salty wastewater is decontaminated for sewage treatment.

The yield of cyclohexyl formic acid produced by the method of the invention is above 95%.

The constant pressure reaction kettle, pickling tower and rectification of the present invention adopt the mode of intermittent or continuous operation, and the operation is flexible and convenient.

The present invention adopts benzoate aqueous solution as raw material, uses modified Raney nickel as hydrogenation catalyst, carries out hydrogenation reaction in constant pressure reactor, and the product after hydrogenation reaction directly enters pickling tower, and the upper layer oily cyclohexyl formic acid High-purity cyclohexyl formic acid can be obtained by rectification. The invention uses benzoate to produce cyclohexyl formic acid with high added value; the catalyst used has super high selectivity and high hydrogenation activity. This method not only has the advantages of simple operation, can be used for batch reaction in a single tank, but also can be used for continuous reaction in series with multiple tanks, and has good economic benefits and industrial application prospects.

Description of drawings

Accompanying drawing is the technological process schematic diagram of the present invention.

In the figure: 1 raw material storage tank; 2 constant pressure hydrogenation kettle; 3 pickling tower; 4 rectification tower.

detailed description

Specific embodiments of the present invention will be described in detail below in conjunction with technical solutions and accompanying drawings.

Embodiment 1: Raney nickel catalyst carries out dealumination reaction, dealumination condition is: reaction temperature 70 ℃, reaction time 2h, sodium hydroxide aqueous solution concentration 30%, the mass ratio of sodium hydroxide aqueous solution and Raney nickel catalyst is 4: 1. The following table 1 sees the composition of Raney nickel catalyst for dealumination reaction

Embodiment 2: Raney nickel catalyst carries out dealumination reaction, dealumination condition is: reaction temperature 70 ℃, reaction time 2h, sodium hydroxide aqueous solution concentration 30%, the mass ratio of sodium hydroxide aqueous solution and Raney nickel catalyst is 7: 1. The following table 1 sees the composition of Raney nickel catalyst for dealumination reaction

Embodiment 3: Raney nickel catalyst carries out dealumination reaction, dealumination condition is: reaction temperature 70 ℃, reaction time 2h, sodium hydroxide aqueous solution concentration 30%, the mass ratio of sodium hydroxide aqueous solution and Raney nickel catalyst is 10: 1. Table 1 below shows the composition of Raney nickel catalyst for dealumination reaction.

Nickel content/% Molybdenum content/% Aluminum content/%

Embodiment 4: The Raney nickel catalyst modified in Embodiment 3 is used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, sodium benzoate concentration 10%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 5: The Raney nickel catalyst modified in Example 3 was used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, sodium benzoate concentration 20%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 6: The Raney nickel catalyst modified in Example 3 was used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 7: The Raney nickel catalyst modified in Example 3 was used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:1. See Table 2 below for the reaction results.

Example 8: The Raney nickel catalyst modified in Example 3 was used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:5. See Table 2 below for the reaction results.

Example 9: The Raney nickel catalyst modified in Example 3 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, potassium benzoate concentration 40%, mass ratio of potassium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 10: The Raney nickel catalyst modified in Example 1 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, potassium benzoate concentration 40%, mass ratio of potassium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 11: The Raney nickel catalyst modified in Example 2 was used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, potassium benzoate concentration 40%, mass ratio of potassium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 12: The Raney nickel catalyst modified in Example 3 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, concentration of benzoic acid 40%, molar ratio of benzoic acid to sodium hydroxide 0.8, mass ratio of benzoic acid to catalyst 100:3 . See Table 2 below for the reaction results.

Example 13: The Raney nickel catalyst modified in Example 3 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, concentration of benzoic acid 40%, molar ratio of benzoic acid to sodium hydroxide 1.2, mass ratio of benzoic acid to catalyst 100:3 . See Table 2 below for the reaction results.

Example 14: The Raney nickel catalyst modified in Example 3 was used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, concentration of benzoic acid 40%, molar ratio of benzoic acid to potassium hydroxide 0.8, mass ratio of benzoic acid to catalyst 100:3 . See Table 2 below for the reaction results.

Example 15: The Raney nickel catalyst modified in Example 3 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 8h, concentration of benzoic acid 40%, molar ratio of benzoic acid to potassium hydroxide 1.2, mass ratio of benzoic acid to catalyst 100:3 . See Table 2 below for the reaction results.

Example 16: The Raney nickel catalyst modified in Example 3 was used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 160°C, hydrogen pressure 5MPa, reaction time 8h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 17: The Raney nickel catalyst modified in Example 3 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 240°C, hydrogen pressure 5MPa, reaction time 8h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 18: The Raney nickel catalyst modified in Example 3 was used as the selective hydrogenation catalyst in the constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 2MPa, reaction time 8h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 19: The Raney nickel catalyst modified in Example 3 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 4MPa, reaction time 8h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 20: The Raney nickel catalyst modified in Example 3 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 6h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

Example 21: The Raney nickel catalyst modified in Example 3 was used as a selective hydrogenation catalyst in a constant pressure reactor. The reaction conditions are: hydrogenation reaction temperature 180°C, hydrogen pressure 5MPa, reaction time 10h, sodium benzoate concentration 40%, mass ratio of sodium benzoate to catalyst 100:3. See Table 2 below for the reaction results.

As can be seen from Table 2, along with the increase of benzoic acid concentration, conversion rate reduces, but the selectivity to cyclohexyl formic acid is constant; Along with the increase of temperature of reaction, conversion rate increases, but the selectivity to cyclohexyl formic acid declines; The prolongation of the reaction time increases the conversion rate, but the selectivity to cyclohexyl formic acid remains basically unchanged; as the reaction pressure increases, the conversion rate increases, but the selectivity to cyclohexyl formic acid remains basically unchanged; potassium benzoate is higher than sodium benzoate It is easier to select hydrogenation, and when the reaction solution is alkaline, the reaction rate is faster and the selectivity is better.

Example 22: On the basis of Example 6, a stability experiment was carried out, and the following table 3 shows the results of 5 cycles of reactions.

It can be seen from Table 3 that the results of 5 cycles of experiments show that the modified Raney nickel catalyst has good selective hydrogenation activity and shows good stability.

Claims (8)

1. A method for preparing cyclohexyl formic acid is characterized in that: the benzoate aqueous solution is injected into the constant pressure reactor that selects the hydrogenation catalyst and carries out hydrogenation reaction, after the hydrogenation reaction, the product directly enters the pickling tower, and the upper strata The oily cyclohexyl formic acid is rectified in the rectification tower to obtain high-purity cyclohexyl formic acid, and the lower layer of saline wastewater is decontaminated for sewage treatment; the hydrogenation refining catalyst is a modified Raney nickel catalyst, and its composition is: the nickel content is 65-80% , the molybdenum content is 5-10%, and the aluminum content is 10-25%. 2. method according to claim 1, is characterized in that: benzoate comprises sodium benzoate, potassium benzoate. 3. The method according to claim 2, further characterized in that: the concentration of the benzoate is 10-40%, and the mass ratio of the benzoate to the catalyst is 100:1-5. 4. according to the described method of claim 1,2 or 3, it is also characterized in that: the Raney nickel catalyst of described modification obtains in the following way: first carry out dealumination reaction, increase its activity; dealumination condition is : The reaction temperature is 70° C., the reaction time is 2 hours, the concentration of the aqueous sodium hydroxide solution is 30%, and the mass ratio of the aqueous sodium hydroxide solution to the Raney nickel catalyst is 4-10:1. 5. The method according to claim 1, 2 or 3, further characterized in that: the hydrogenation reaction temperature is 160-240° C., the hydrogen pressure is 2-6 MPa, and the reaction time is 6-10 hours. 6 . The method according to claim 4 , further characterized in that: the hydrogenation reaction temperature is 160-240° C., the hydrogen pressure is 2-6 MPa, and the reaction time is 6-10 hours. 7. The method according to claim 5, further characterized in that: single-tank batch reaction or multi-tank series continuous reaction is adopted. 8. The method according to claim 6, further characterized in that: a single-tank batch reaction or a multi-tank continuous reaction in series.