CN108503530B - Process for preparing isooctanoic acid - Google Patents
Process for preparing isooctanoic acid Download PDFInfo
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- CN108503530B CN108503530B CN201710112088.XA CN201710112088A CN108503530B CN 108503530 B CN108503530 B CN 108503530B CN 201710112088 A CN201710112088 A CN 201710112088A CN 108503530 B CN108503530 B CN 108503530B
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/295—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with inorganic bases, e.g. by alkali fusion
Abstract
A process method for preparing isooctanoic acid, which belongs to the technical field of fine chemical engineering. The preparation method is characterized by comprising the following preparation steps: carrying out oxidation reaction on isooctanol and sodium hydroxide under the condition of inert atmosphere, wherein the mass ratio of isooctanol to sodium hydroxide is 1: 1.1-1.3, reacting catalyst titanate with the amount of 2-5% of the total mass of isooctanol and sodium hydroxide at the temperature of 220-250 ℃ and the pressure of 0.2-0.40 MPa until no hydrogen is generated, and discharging the pressure; cooling the reaction materials, diluting the reaction materials with water with the mass of 5-10% of the reaction materials, filtering the catalyst, acidifying the filtrate by adopting 30-40% sulfuric acid to maintain the pH value at 2.5-3.5, stirring for 20-30 minutes, and standing for liquid separation to obtain the catalyst. The invention provides a process method for preparing isooctanoic acid, which has the advantages of low production cost, high yield, short reaction time, reasonable utilization of byproducts and continuous industrial scale production.
Description
Technical Field
A process method for preparing isooctanoic acid, which belongs to the technical field of fine chemical engineering.
Background
Isooctanoic acid, academic name 2-ethylhexanoic acid, english name: 2-ethylhexoic acid, molecular weight: 144.21, it is colorless oily liquid, soluble in ether, slightly soluble in ethanol, and has mild odor. It is a fine chemical product and is widely applied in various industries and fields.
At present, the production methods of isooctanoic acid can be roughly divided into two types: one is to produce isooctanoic acid by using isooctaldehyde or isooctenal as raw material; the other method is to produce the isooctanoic acid by using octanol as a raw material, and the first method has the advantages of reasonable use of the raw material, mild reaction conditions and easy large-scale continuous production. However, the first method is suitable for large-scale production with an intermediate product isooctaldehyde, and the isooctanoic acid produced by the method is far from meeting the market demand. Since the aldehyde material is a large chemical industry intermediate and has no commercial product supply, if the large chemical industry is left for producing the isooctanoic acid, only another method for producing the isooctanoic acid by taking octanol as a raw material can be adopted. The process for producing the isooctanoic acid by using the octanol as the raw material has various methods, but has the defects of high production cost, large investment, high raw material and energy consumption, serious equipment corrosion, low product yield, low yield, high public expense, difficulty in forming large-scale production and unsuitability for industrial production.
The preparation method comprises the following steps: 1. potassium permanganate oxidation: isooctanol is prepared by using potassium permanganate as an oxidant in the presence of NaOH. The disadvantages are as follows: poor oxidation catalysis effect, low product yield, long process flow, side reaction, large raw material consumption, certain corrosion of toxic equipment, high cost, low performance index of the product, and no possibility of mass production.
2. Nitric acid oxidation method: the method uses nitric acid as oxidant and ammonium vanadate as catalyst. The disadvantages are as follows: nitric acid has strong corrosivity, high requirements on equipment corrosion resistance and large equipment investment, harmful gas NO is emitted in the reaction process, esterification is easy to generate, carboxylic acid can be obtained only by hydrolysis, and the complexity of the process flow is increased, so that large-scale production is not easy to realize.
3. High pressure dehydrogenation oxidation: isooctanol reacts with sodium hydroxide under high pressure, dehydrogenation and oxidation are carried out to generate 2-ethyl caproate, and then the isooctanol is acidified by sulfuric acid and is made to react with sodium hydroxide to obtain isooctanoic acid. The disadvantages are as follows: the reaction requires reaction at higher temperature and pressure, and has the disadvantages of difficult operation, severe equipment corrosion, strict equipment requirement, increased engineering investment and difficult realization of large-scale production.
4. The normal pressure dehydrogenation oxidation method comprises the following steps: the method is based on a high-pressure dehydrogenation oxidation method, adopts metal oxide as a catalyst, and dehydrolyzes isooctanol and sodium hydroxide under normal pressure to obtain isooctanoic acid. The disadvantages are as follows: the method has the advantages of long process flow, low product yield, difficult catalyst recovery, large raw material and energy consumption, low performance index of the product and no possibility of large-scale production.
5. Catalytic dehydrogenation esterification: and carrying out dehydrogenation reaction on isooctyl alcohol at the reaction temperature of 180-210 ℃ under the catalysis of metal oxide to generate diisooctyl ester. The disadvantages are as follows: the method is used for two processes of esterification and saponification, so that the utilization rate of isooctanol is reduced, meanwhile, the product cost is increased due to the rectification process, and the method is industrially less applied.
6. But also electrolytic oxidation method and ultrasonic wave method, but because of high production cost and low product performance index, the possibility of random modeling production.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art, and provides a process method which has low production cost, high yield, short reaction time, reasonable utilization of byproducts and continuous industrial scale production of isooctanoic acid.
The technical scheme adopted by the invention for solving the technical problems is as follows: the technical method for preparing the isooctanoic acid is characterized by comprising the following preparation steps:
1) carrying out oxidation reaction on isooctanol and sodium hydroxide under the condition of inert atmosphere, wherein the mass ratio of isooctanol to sodium hydroxide is 1: 1.1-1.3, reacting for 30-40 minutes at the temperature of 220-250 ℃ and under the pressure of 0.2-0.40 MPa, and discharging the pressure, wherein the using amount of a catalyst titanate is 2-5% of the total mass of isooctanol and sodium hydroxide;
2) cooling the reaction materials, diluting the reaction materials with water with the mass of 5-10% of the reaction materials, filtering the catalyst, acidifying the filtrate to maintain the pH value at 2.5-3.5, stirring for 20-30 minutes, and standing for liquid separation to obtain the catalyst.
The isooctyl alcohol is oxidized under an inert condition, the reaction conversion is completely carried out for only 30-40 minutes, and the conventional metal oxide catalyst is carried out for 2-3 hours. The titanate belongs to an environment-friendly catalyst, and the catalyst can be quickly decomposed after being washed and diluted by water after reaction, can generate water-insoluble titanic acid, can be recycled, and reduces the production cost.
Preferably, the purity of the isooctyl alcohol and the sodium hydroxide is more than 99 percent, and the mass ratio of the isooctyl alcohol to the sodium hydroxide is 1: 1.2. the reaction rate can be faster by optimizing the reactants and the proportion thereof, and the yield is improved.
Preferably, the catalyst phthalate is tetraisooctyl titanate, and the using amount of the catalyst phthalate is 3% -4% of the total mass of isooctyl alcohol and sodium hydroxide. The inventor finds that the activity of tetraisooctyl titanate in the titanate catalyst is better than that of other catalysts and is stronger than that of the conventional metal oxidant at present, and an active intermediate is formed by virtue of the ligand action of the tetraisooctyl titanate catalyst, so that the reaction rate is accelerated.
Preferably, the temperature of the oxidation reaction is 230-240 ℃, and the pressure is 0.25-0.30 MPa. Preferred reaction conditions can further increase the reaction rate.
Preferably, the using amount of the diluted water is 6-8% of the mass of the reaction materials. The optimal dilution rate can ensure the recovery rate of the catalyst, reduce the cost as much as possible and ensure the recovery efficiency.
The acidification treatment is carried out by adopting 30-40% of sulfuric acid. Preferably, the concentration of the acidized sulfuric acid solution is 35%.
Preferably, the pH value after acidification is 3.
Preferably, the standing and liquid separating step further comprises a water washing step and a reduced pressure dehydration and rectification step. The product obtained by further washing, dewatering and rectifying has high purity.
Compared with the prior art, the technical method for preparing the isooctanoic acid has the beneficial effects that: (1) the isooctyl alcohol is oxidized under an inert condition, the reaction conversion is completely carried out for only 30-40 minutes, and the conventional metal oxide catalyst is carried out for 2-3 hours.
(2) The titanate belongs to an environment-friendly catalyst, and the catalyst can be quickly decomposed after being washed and diluted by water after reaction, can generate water-insoluble titanic acid, can be recycled, and reduces the production cost.
(3) Because the activity of the titanate catalyst is higher, the operation pressure of the reaction kettle in the oxidation process is also lower, the reaction can be quickly finished under the condition of 0.2-0.40 MPa, the pressure is lower than that of the prior art by 2.5-3 MPa, the equipment cost is reduced, and the operation safety coefficient is improved.
(4) The conversion rate is high, the tetraisooctyl titanate catalyst is easy to hydrolyze and decompose isooctanoic acid, can effectively promote the rightward progress of chemical reaction, improves the conversion rate of target products, and can ensure that the conversion rate of isooctanol reaches 99.9 percent.
Detailed Description
The invention is further described in the following with reference to specific embodiments, of which example 1 is the preferred example.
Example 1
Amount of isooctyl alcohol having a purity of 99.5% and sodium hydroxide having a purity of 99.5% in an inert atmosphere condition 1: 1.2, oxidizing, taking tetraisooctyl titanate which accounts for 3.5 percent of the total mass of isooctyl alcohol and sodium hydroxide as a catalyst, reacting at 235 ℃ under the pressure of 0.28MPa until no hydrogen is generated, taking 30 minutes, removing the pressure, cooling the reaction material, diluting with 7 percent of water, and detecting the content of isooctyl alcohol by adopting gas chromatography after full dilution, wherein the detection result is 300 PPM. Filtering the washing solution and the catalyst, acidifying the filtrate by 35% sulfuric acid, keeping the pH value at 3, stirring for 25 min, standing, layering, removing the water layer, washing with water for 3 times, and preferably performing reduced pressure dehydration and rectification to obtain the isooctanoic acid product, wherein the conversion rate of isooctanol reaches 99.9%, and the recovery rate is 109%.
Example 2
Amount of isooctyl alcohol having a purity of 99.3% and sodium hydroxide having a purity of 99.2% in an inert atmosphere condition 1: 1.15, oxidizing, taking tetraisooctyl titanate which accounts for 3 percent of the total mass of isooctyl alcohol and sodium hydroxide as a catalyst, reacting at the temperature of 230 ℃ and the pressure of 0.25MPa until no hydrogen is generated, taking 32 minutes, removing the pressure, cooling the reaction material, diluting the reaction material with 6 percent water, and detecting the content of isooctyl alcohol by adopting gas chromatography after the reaction material is fully diluted, wherein the detection result is 350 PPM. . Filtering the water washing solution and the catalyst, acidifying the filtrate with 33% sulfuric acid while maintaining pH at 3, stirring for 27 min, standing for 3 times, water layer draining, water washing for 3 times, and decompression dewatering and rectifying to obtain isooctanoic acid product with isooctanol converting rate up to 99.9% and recovering rate of 110%.
Example 3
Amount of isooctyl alcohol having a purity of 99.5% and sodium hydroxide having a purity of 99.5% in an inert atmosphere condition 1: 1.25, oxidizing, taking n-butyl titanate which accounts for 4 percent of the total mass of isooctanol and sodium hydroxide as a catalyst, reacting at the temperature of 240 ℃ and the pressure of 0.30MPa until no hydrogen is generated, taking 34 minutes, relieving the pressure, cooling the reaction material, diluting with 8 percent of water, and detecting the content of isooctanol by adopting gas chromatography after full dilution, wherein the detection result is 400 PPM. Filtering the washing solution and the catalyst, acidifying the filtrate by 38% sulfuric acid, keeping the pH value at 3, stirring for 23 min, standing, layering, removing the water layer, washing with water for 3 times, and preferably performing reduced pressure dehydration and rectification to obtain the isooctanoic acid product, wherein the conversion rate of isooctanol reaches 99.9%, and the recovery rate is 111%.
Example 4
Amount of isooctyl alcohol having a purity of 99% and sodium hydroxide having a purity of 99% in an inert atmosphere condition 1: 1.1, oxidizing, taking tetraisopropyl titanate accounting for 2 percent of the total mass of isooctanol and sodium hydroxide as a catalyst, reacting at 220 ℃ under the pressure of 0.2MPa until no hydrogen is generated, taking 38 minutes, removing the pressure, cooling the reaction material, diluting with 5 percent of water, and detecting the content of isooctanol by adopting gas chromatography after full dilution, wherein the detection result is 500 PPM. Filtering the washing solution and the catalyst, acidifying the filtrate by using 30% sulfuric acid, keeping the pH value at 3.5, stirring for 30 minutes, standing for layering, draining a water layer, washing for 3 times, and preferably performing reduced pressure dehydration and rectification to obtain an isooctanoic acid product, wherein the conversion rate of isooctanol reaches 99.3%, and the recovery rate is 113%.
Example 5
Amount of isooctyl alcohol having a purity of 99% and sodium hydroxide having a purity of 99% in an inert atmosphere condition 1: 1.3, oxidizing, taking tetraisooctyl titanate which accounts for 5 percent of the total mass of isooctyl alcohol and sodium hydroxide as a catalyst, reacting at the temperature of 250 ℃ and the pressure of 0.40MPa until no hydrogen is generated, taking 40 minutes, relieving the pressure, cooling the reaction material, diluting the reaction material with 10 percent of water, and detecting the content of isooctyl alcohol by adopting gas chromatography after the reaction material is fully diluted, wherein the detection result is 500 PPM. Filtering the washing solution and the catalyst, acidifying the filtrate by using 40% sulfuric acid, keeping the pH value at 2.5, stirring for 20 minutes, standing for layering, draining a water layer, washing for 3 times, and preferably performing reduced pressure dehydration and rectification to obtain an isooctanoic acid product, wherein the conversion rate of isooctanol reaches 99.7%, and the recovery rate is 114%.
Comparative example 1
Amount of isooctyl alcohol having a purity of 99.5% and sodium hydroxide having a purity of 99.5% in an inert atmosphere condition 1: 1.2, oxidizing, taking vanadium oxide-titanium oxide-potassium sulfate/silicon oxide which accounts for 3.5 percent of the total mass of isooctanol and sodium hydroxide as a catalyst, reacting at 235 ℃ under the pressure of 0.28MPa until no hydrogen is generated, taking 30 minutes, relieving the pressure, cooling the reaction material, diluting with 7 percent of water, and detecting the content of isooctanol by adopting gas chromatography after full dilution, wherein the detection result is 300 PPM. Filtering the washing solution and the catalyst, acidifying the filtrate by 35% sulfuric acid, keeping the pH value at 3, stirring for 25 min, standing, layering, removing the water layer, washing with water for 3 times, and preferably performing reduced pressure dehydration and rectification to obtain the isooctanoic acid product, wherein the conversion rate of isooctanol reaches 97.5%, and the recovery rate is 121%. The isooctanol conversion rate of the comparative example is low, the catalyst recovery rate is high, which shows that the recovered impurity content is high, the reuse rate can be reduced, and the catalyst retreatment increases the process difficulty and the treatment cost.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (9)
1. A process for preparing isooctanoic acid is characterized by comprising the following preparation steps:
1) carrying out oxidation reaction on isooctanol and sodium hydroxide under the condition of inert atmosphere, wherein the mass ratio of isooctanol to sodium hydroxide is 1: 1.1-1.3, reacting for 30-40 minutes at the temperature of 220-250 ℃ and under the pressure of 0.2-0.40 MPa, and discharging the pressure, wherein the using amount of a catalyst titanate is 2-5% of the total mass of isooctanol and sodium hydroxide;
2) cooling the reaction materials, diluting the reaction materials with water with the mass of 5-10% of the reaction materials, filtering the catalyst, acidifying the filtrate to maintain the pH value at 2.5-3.5, stirring for 20-30 minutes, and standing for liquid separation to obtain the catalyst.
2. The process of claim 1, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: the purity of the isooctyl alcohol and the sodium hydroxide is more than 99 percent, and the mass ratio of the isooctyl alcohol to the sodium hydroxide is 1: 1.2.
3. the process of claim 1, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: the catalyst phthalate is tetraisooctyl titanate, and the using amount of the catalyst phthalate is 3-4% of the total mass of isooctyl alcohol and sodium hydroxide.
4. The process of claim 1, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: the temperature of the oxidation reaction is 230-240 ℃, and the pressure is 0.25-0.30 MPa.
5. The process of claim 1, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: the amount of the diluted water is 6-8% of the mass of the reaction materials.
6. The process of claim 1, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: the acidification treatment is carried out by adopting sulfuric acid with the solution concentration of 30-40%.
7. The process of claim 6, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: the concentration of the sulfuric acid solution is 35%.
8. The process of claim 1, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: the pH value after acidification is 3.
9. The process of claim 1, wherein the reaction is carried out in the presence of a catalyst selected from the group consisting of: and the step of washing, decompressing, dehydrating and rectifying is also included after the standing and liquid separation.
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| US6376708B1 (en) * | 2000-04-11 | 2002-04-23 | Monsanto Technology Llc | Process and catalyst for dehydrogenating primary alcohols to make carboxylic acid salts |
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| CN1817845A (en) * | 2006-03-09 | 2006-08-16 | 沈阳市应用技术实验厂 | Production of isooctaacid by composite catalytic method |
| CN101125810A (en) * | 2007-09-26 | 2008-02-20 | 河南庆安化工高科技股份有限公司 | Method for preparing isooctanoic acid |
| CN104945238A (en) * | 2015-06-03 | 2015-09-30 | 郸城县凯杰科技有限公司 | Isocaprylic acid production process |
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