阅读说明：本技术 一种制备糠酸的方法 (Method for preparing furoic acid ) 是由 孟祥福 于 2019-10-18 设计创作，主要内容包括：本发明涉及一种制备糠酸的方法,具体公开了使糠醛温度低于20℃,在搅拌的条件下按照糠醛：碱性试剂＝1～5:0.5～4的物质的量比滴加碱性试剂,滴加完毕后继续搅拌0.3-2h；向混合物中加水至溶液透明,用溶剂萃取后得到糠酸溶液,蒸馏回收溶剂；将得到的糠酸溶液至少一次用酸调节pH至2～3并过滤,得到粗品；将得到的粗品洗涤、干燥后得到产品糠酸。本发明的技术方案通过控制体系温度和酸化用酸量,避免了糠醛自聚或酯化,解决了现有技术中产品颜色深的问题,无需经过复杂的后处理如重结晶等步骤,即可获得颜色较浅的产品,缩短了生产时间、提升了生产效率；产品质量稳定、收率高；采用了两次酸化的处理方式,使产品纯度和收率有效提高。(The invention relates to a method for preparing furoic acid, and particularly discloses a method for preparing furoic acid by mixing furfural, wherein the furfural temperature is lower than 20 ℃, and the furfural: dropwise adding the alkaline reagent according to the mass ratio of 1-5: 0.5-4, and continuously stirring for 0.3-2h after dropwise adding is finished; adding water into the mixture until the solution is transparent, extracting with a solvent to obtain a furoic acid solution, and distilling to recover the solvent; adjusting the pH value of the obtained furoic acid solution to 2-3 with acid at least once, and filtering to obtain a crude product; and washing and drying the obtained crude product to obtain the product furoic acid. According to the technical scheme, by controlling the system temperature and the amount of acid for acidification, the self-polymerization or esterification of furfural is avoided, the problem of dark product color in the prior art is solved, and a product with lighter color can be obtained without complicated post-treatment such as recrystallization and the like, so that the production time is shortened, and the production efficiency is improved; the product quality is stable and the yield is high; the treatment mode of twice acidification is adopted, so that the purity and the yield of the product are effectively improved.)

1. A process for the preparation of furoic acid comprising the steps of:

1) the furfural temperature is lower than 20 ℃, and the furfural: dropwise adding the alkaline reagent according to the mass ratio of 1-5: 0.5-4, and continuously stirring for 0.3-2h after dropwise adding is finished;

2) adding water into the mixture obtained in the step 1) until the solution is transparent, extracting with a solvent to obtain a furoic acid solution, and distilling to recover the solvent;

3) adjusting the pH of the furoic acid solution obtained in the step 2) to 2-3 with acid at least once, and filtering to obtain a crude product;

4) washing and drying the crude product obtained in the step 3) to obtain the product furoic acid.

2. The process for producing furoic acid according to claim 1, wherein the furfural temperature in step 1) is lower than 15 ℃.

3. The process for producing furoic acid according to claim 2, wherein the furfural temperature in step 1) is lower than 12 ℃.

4. The method for preparing furoic acid according to claim 1, wherein the alkaline agent in step 1) is an aqueous solution of an inorganic base with a mass fraction of less than 50%.

5. The method for preparing furoic acid according to claim 4, wherein said inorganic base is KOH or NaOH.

6. The method for producing furoic acid according to claim 1, wherein the rate of dropping the alkali agent in the step 1) is 0.4 to 0.6 ml/min; preferably 0.4 ml/min.

7. The method for producing furoic acid according to claim 1, wherein in step 1), the furfural: the mass ratio of the alkaline agent was 1: 0.8.

8. The process for producing furoic acid according to claim 1, wherein stirring is continued for 0.5h after completion of the dropwise addition in step 1).

9. The method for preparing furoic acid according to claim 1, wherein the solvent for extracting furoic acid in step 2) is any one of benzene, chloroform or a mixture of both.

10. The method for preparing furoic acid according to claim 1, wherein the acid in step 3) is 6mol/L hydrochloric acid, the pH is adjusted to 2-3 with the acid, and the number of filtration is 2.

Technical Field

The invention belongs to the field of organic synthesis, and particularly relates to a method for preparing furoic acid.

Background

Furoic acid, white monoclinic rhombohedral crystal, melting point of 123-; as plasticizers, thermosetting resins, etc. in the plastics industry; as a preservative in the food industry; it can also be used as coating additive, medicine and intermediate of perfume.

At present, the technology for producing the furoic acid in China mainly takes furfural as a raw material, and the furfural α -carbon has no hydrogen, so that the furoic acid is prepared by disproportionation or oxidation, wherein the reaction equation is as follows:

the patent application with the application number of CN201811610709.8 discloses a method for preparing furoic acid by oxidizing furfural, but the method mainly uses a compound nano metal oxide catalyst and has the reaction temperature of 35-45 ℃, and the method has the inconvenience that the use of the compound nano technical oxide catalyst causes higher production cost, the catalyst needs to be recovered, dried, cooled and ground, the method is inconvenient for large-scale industrial production, the time consumption in the post-treatment process is longer, and crystal growth is required for 12 hours and ice water leaching is required.

The traditional process has the problems of low overall product yield and high production cost. Therefore, a new reaction method is desired, which can solve the above problems, and at the same time, improve the product yield, reduce the production cost, and simplify the post-treatment operation.

Disclosure of Invention

The invention provides a method for preparing furoic acid by a high-yield disproportionation method, aiming at the problems of low overall product yield, high production cost, complex post-treatment operation and the like caused by the disproportionation method in the production process of furoic acid.

In order to achieve the technical purpose, the invention provides the following technical scheme: a process for the preparation of furoic acid comprising the steps of:

a process for the preparation of furoic acid comprising the steps of:

1) the furfural temperature is lower than 20 ℃, and the furfural: dropwise adding the alkaline reagent according to the mass ratio of 1-5: 0.5-4, and continuously stirring for 0.3-2h after dropwise adding is finished;

2) adding water into the mixture obtained in the step 1) until the solution is transparent, extracting with a solvent to obtain a furoic acid solution, and distilling to recover the solvent;

3) adjusting the pH of the furoic acid solution obtained in the step 2) to 2-3 with acid at least once, and filtering to obtain a crude product;

4) washing and drying the crude product obtained in the step 3) to obtain a product furoic acid;

further, the temperature of the furfural in the step 1) is lower than 15 ℃;

further, the temperature of the furfural in the step 1) is lower than 12 ℃;

further, in the step 1), the alkaline reagent is an inorganic alkaline water solution with the mass fraction of less than 50%;

further, the inorganic base is KOH or NaOH;

further, the speed of dripping the alkaline reagent in the step 1) is 0.4-0.6 ml/min; preferably 0.4 ml/min;

further, furfural in step 1): the mass ratio of the alkaline reagent is 1: 0.8;

further, after the dropwise adding in the step 1) is finished, continuously stirring for 0.5 h;

further, the solvent for extracting the furoic acid in the step 2) is any one of benzene and chloroform or a mixture of the benzene and the chloroform;

further, the acid in the step 3) is 6mol/L hydrochloric acid, the pH is adjusted to 2-3 by the acid, and the filtering times are 2 times.

Due to the adoption of the technology, compared with the prior art, the invention has the remarkable advantages that:

1) by controlling the system temperature and the acid consumption for acidification, the self-polymerization or esterification of furfural is avoided, the problem of dark product color in the prior art is solved, and a product with lighter color can be obtained without complicated post-treatment such as recrystallization and other steps, so that the production time is shortened, and the production efficiency is improved;

2) the product has stable quality and high yield under the condition of simplifying the post-reaction treatment process, is suitable for industrial production, and overcomes the defects in the existing furoic acid preparation process;

3) the treatment mode of twice acidification is adopted, so that the furfuryl acid is reduced from being separated out in batches by directly contacting with acid, the purity and yield of the product are effectively improved, and the total yield of the product reaches more than 93 percent;

4) the organic solvent produced in the production process can be recycled, and the inorganic salt in the wastewater is mainly ammonium chloride and sodium chloride, so that the treatment difficulty is greatly reduced, and the requirements of the current green chemical industry are met.

Detailed Description

In order to make the technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to specific examples, but the scope of the present invention is not limited thereby.