Preparation method of furfuryl alcohol
By using a mixture of methyl tert-butyl ether and tetrahydrofuran as solvent in maltol production, Grignard reagent is generated and low-temperature reaction is carried out, the problem of coupling reaction of Grignard reagent is solved, and the yield of furfurfuran is improved and Purity enables more stable product generation.
Patent Information
- Application Number
- CN202411266420.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2025-01-07
AI Technical Summary
During the maltol production process, Grignard reagents are prone to coupling reactions in the traditional furfural method, resulting in a decrease in yield, which in turn affects the production efficiency of furfural alcohol.
Use a mixture of methyl tert-butyl ether and tetrahydrofuran as solvent to form Grignard reagent by nitrogen replacement, and furfural addition and hydrolysis reaction under low temperature conditions to avoid coupling reactions and improve the yield and purity of Grignard reagent .
The yield and purity of Grignard reagent are improved, and the yield and purity of furfurol are improved. The process is safe and controllable, avoiding the generation of by-products caused by high temperatures.
Smart Images
Figure SMS_1 
Figure SMS_2 
Figure SMS_3
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of furfuryl alcohol preparation, and particularly relates to a method for preparing furfuryl alcohol. Background Art
[0002] In the Grignard process of maltol production, the traditional furfural method is adopted. The Grignard reagent reacts with furfural to generate the furfural alcohol intermediate, and then the furfural alcohol is purified by distillation. Therefore, the Grignard reagent needs to be prepared first, and then the furfural and Grignard reagent react to generate the furfural alcohol. In the preparation process of the Grignard reagent, tetrahydrofuran (THF) is usually used as a solvent for preparation. The boiling point of tetrahydrofuran is 66°C. After the initiation is successful, the reaction is exothermic and the reaction temperature is high, which makes the generated Grignard reagent prone to coupling reaction, resulting in a decrease in the yield of the Grignard reagent, and then a decrease in the yield of the generated furfural alcohol. Summary of the invention
[0003] In view of this, the present invention provides a method for preparing furfuryl alcohol capable of controlling product quality.
[0004] The technical solution adopted by the present invention to solve its technical problem is:
[0005] A method for preparing furfuryl alcohol comprises the following steps:
[0006] S1: Put magnesium chips into a solvent, replace the solvent with nitrogen, introduce ethyl chloride / methyl chloride gas after nitrogen replacement to react and generate a Grignard reagent, thereby obtaining a solution containing the Grignard reagent;
[0007] The solvent is methyl tert-butyl ether or a mixture of methyl tert-butyl ether and tetrahydrofuran;
[0008] S2: adding furfural dropwise to the solution containing the Grignard reagent to carry out an addition reaction, and when the temperature does not change, stopping the addition of furfural, and adding soft water dropwise to carry out a hydrolysis reaction, and when the temperature does not change, filtering by suction to obtain a mother liquor;
[0009] S3: The obtained mother liquor is subjected to reduced pressure distillation to obtain furfuryl alcohol.
[0010] Preferably, the mass ratio of the magnesium chips to the solvent is 1:(15-20).
[0011] Preferably, the mass ratio of methyl tert-butyl ether to tetrahydrofuran is (6-1):1.
[0012] Preferably, in the step S1, the ethyl chloride / methyl chloride gas is introduced twice, and the amount of the ethyl chloride / methyl chloride gas introduced in the first time accounts for 1%-3% of the amount of solvent added.
[0013] Preferably, after the first introduction of ethyl chloride / methyl chloride gas is completed, heating is performed, and the heating is stopped after the temperature reaches 40-45° C., and the second introduction of ethyl chloride / methyl chloride gas is performed.
[0014] Preferably, the second addition of ethyl chloride / methyl chloride gas is performed so that the temperature reaches 50-70° C., and when the temperature remains constant, the second addition of ethyl chloride / methyl chloride gas is stopped.
[0015] Preferably, the pressure in step S1 is lower than 0.3 MPa.
[0016] Preferably, the S2 addition reaction and hydrolysis reaction temperature is 25-60°C.
[0017] Preferably, the method further comprises step S4, wherein the liquid distilled out in step S3 is distilled under reduced pressure again and dried to obtain a recovered solvent.
[0018] Preferably, the water content of the recovery solvent is below 1000 pmm.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] The invention provides a method for preparing furfuryl alcohol. The method comprises the following steps: putting magnesium chips into a mixed solution of methyl tert-butyl ether or methyl tert-butyl ether and tetrahydrofuran, replacing the mixture with nitrogen, introducing ethyl chloride / methyl chloride gas after the nitrogen replacement to react and generate a Grignard reagent, thereby obtaining a solution containing the Grignard reagent; dropping furfural into the solution containing the Grignard reagent to perform an addition reaction, stopping the dropping of furfural when the temperature does not change, dropping soft water to perform a hydrolysis reaction, and filtering the mixture when the temperature does not change to obtain a mother liquor; performing reduced pressure distillation on the obtained mother liquor to obtain furfuryl alcohol; in the preparation process of the Grignard reagent, by using methyl tert-butyl ether as a solvent, on the one hand, the prepared Grignard reagent can be dissolved in a solvent containing methyl tert-butyl ether, and the prepared Grignard reagent does not react with the solvent containing methyl tert-butyl ether; on the other hand, the solvent containing methyl tert-butyl ether reduces the initiation temperature of the Grignard reagent, thereby preventing the generated Grignard reagent from having a coupling reaction, thereby improving the yield and purity of the Grignard reagent, and thus improving the yield and purity of the prepared furfuryl alcohol. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is the gas chromatogram of Example 2. DETAILED DESCRIPTION
[0022] The technical solutions and technical effects of the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the present invention.
[0023] A method for preparing furfuryl alcohol comprises the following steps:
[0024] S1: Put magnesium chips into a solvent, replace it with nitrogen, and then introduce ethyl chloride / methyl chloride gas to react to generate a Grignard reagent to obtain a solution containing the Grignard reagent. The reaction equation is as follows:
[0025] The solvent is methyl tert-butyl ether or a mixture of methyl tert-butyl ether and tetrahydrofuran;
[0026] Mg+RCI→RMgCI
[0027] S2: adding furfural dropwise to the solution containing the Grignard reagent to carry out an addition reaction, and when the temperature does not change, stopping the addition of furfural, and adding soft water dropwise to carry out a hydrolysis reaction, and when the temperature does not change, filtering by suction to obtain a mother liquor, the reaction equation is as follows;
[0028]
[0029] S3: The obtained mother liquor is subjected to reduced pressure distillation to obtain furfuryl alcohol.
[0030] Compared with the prior art, the present invention has the following beneficial effects:
[0031] The invention provides a method for preparing furfuryl alcohol. The method comprises the following steps: putting magnesium chips into a mixed solution of methyl tert-butyl ether or methyl tert-butyl ether and tetrahydrofuran, replacing the mixture with nitrogen, introducing ethyl chloride / methyl chloride gas after the nitrogen replacement to react and generate a Grignard reagent, thereby obtaining a solution containing the Grignard reagent; dropping furfural into the solution containing the Grignard reagent to perform an addition reaction, stopping the dropping of furfural when the temperature does not change, dropping soft water to perform a hydrolysis reaction, and filtering the mixture when the temperature does not change to obtain a mother liquor; performing reduced pressure distillation on the obtained mother liquor to obtain furfuryl alcohol; in the preparation process of the Grignard reagent, by using methyl tert-butyl ether as a solvent, on the one hand, the prepared Grignard reagent can be dissolved in a solvent containing methyl tert-butyl ether, and the Grignard reagent does not react with the solvent containing methyl tert-butyl ether; on the other hand, the solvent containing methyl tert-butyl ether reduces the initiation temperature of the Grignard reagent, thereby preventing the generated Grignard reagent from having a coupling reaction, thereby improving the yield and purity of the Grignard reagent, and thus improving the yield and purity of the prepared furfuryl alcohol.
[0032] Furthermore, the mass ratio of the magnesium chips to the solvent is 1:(15-20).
[0033] Furthermore, the mass ratio of methyl tert-butyl ether to tetrahydrofuran is (6-1):1, so that the reaction rate is fast under the condition of low initiation temperature.
[0034] Furthermore, in the step S1, the ethyl chloride / methyl chloride gas is introduced twice, and the amount of the ethyl chloride / methyl chloride gas introduced in the first time accounts for 1%-3% of the amount of solvent added to initiate the Grignard reaction.
[0035] Furthermore, after the first introduction of ethyl chloride / methyl chloride gas is completed, heating is performed, and when the temperature reaches 40-45° C., heating is stopped, and the second introduction of ethyl chloride / methyl chloride gas is performed to carry out the Grignard reaction.
[0036] Furthermore, the second addition of ethyl chloride / methyl chloride gas causes the temperature to reach 50-70° C., and when the temperature remains constant, the second addition of ethyl chloride / methyl chloride gas is stopped to carry out the Grignard reaction, which releases heat by itself, causing the reaction temperature to reach 50-70° C., without the need for an additional heat source, and the reaction is safe.
[0037] Furthermore, in the step S1, the pressure is lower than 0.3 MPa, because the annealing reaction itself releases heat, and the reaction is made safe by controlling the pressure.
[0038] Furthermore, the temperature of the S2 addition reaction and hydrolysis reaction is 25-60°C.
[0039] Furthermore, the method further comprises step S4, wherein the liquid distilled out in step S3 is subjected to reduced pressure distillation and drying again to obtain a recovered solvent. The water treatment process in the solvent recovery process is simple, and the recovered solvent can be used for the reaction in step S1.
[0040] Furthermore, the water content of the recovered solvent is below 1000 pmm, which meets the water requirement of the Grignard reaction.
[0041] The use of the present invention is described by the following examples.
[0042] Embodiment 1:
[0043] Add 24g magnesium chips, 320g MTBE, 64g THF to a 1L autoclave with electric stirring and a thermometer, start stirring, introduce nitrogen into the autoclave twice, introduce 5g chloromethane / chloroethane gas in a closed state, and heat to 40°C. At this time, the rate of increase of the autoclave temperature is accelerated, and the initiation is successful. Continue to introduce 100g chloromethane / chloroethane, and the autoclave pressure is 0.2Mpa until the reaction is completed. The reaction time is 5-6h and the reaction temperature is 50°C. Furfural is added dropwise under stirring, and the autoclave temperature is controlled to 50°C until there is no obvious heat release in the autoclave. Soft water is added dropwise until there is no obvious heat release in the autoclave, the reaction is completed, and suction is filtered. The filtrate is distilled under reduced pressure (-0.08Mpa) to obtain the product furfuryl alcohol, and the solvent is dried and reused for the preparation of Grignard reagent. 105.17g furfuryl alcohol is obtained, with a yield of 96.2%, and the purity is 98.5% measured by gas chromatography.
[0044] Embodiment 2:
[0045] The reaction apparatus and operation method are the same as those in Example 1, except that the amount of MTBE added is 288 g, the amount of THF added is 96 g, the reaction time of the Grignard reaction is 4-5 h, the reaction temperature is about 70 ° C, the kettle temperature is lowered to 50 ° C, and furfural is added dropwise under stirring to obtain 101.5 g of furfuryl alcohol with a yield of 92.8%. The purity measured by gas chromatography is 98.3%. Figure 1 shown.
[0046] Embodiment three:
[0047] The reaction apparatus and operation method are the same as those in Example 1, except that the amount of MTBE added is 192 g, the amount of THF added is 192 g, the reaction time of the Grignard reaction is 2.5 h, the reaction temperature is 75-80 ° C, the kettle temperature is lowered to 50 ° C, and furfural is added dropwise under stirring to obtain 103.69 g of furfuryl alcohol with a yield of 94.84%. The purity measured by gas chromatography is 97.8%.
[0048] Embodiment 4: The reaction apparatus and operation method are the same as those of Embodiment 1, except that 400 g of MTBE is added with 80 g of THF, the reaction time is 6-7 h, the reaction temperature is about 48°C-50°C, and furfural is added dropwise under stirring to obtain 102.01 g of furfuryl alcohol with a yield of 93.31%. The purity is 98.1% as measured by gas chromatography.
[0049] Example 5: The reaction apparatus and operation method are the same as those of Example 1, except that the secondary alkane temperature is controlled at 70°C and the format reaction time is 5-6h. As a result, 100.95g of furfuryl alcohol is obtained with a yield of 92.33% and a purity of 98.4% measured by gas chromatography.
[0050] Embodiment six:
[0051] Add 24g magnesium chips to a 1L autoclave with electric stirring and a thermometer, add 384g MTBE, start stirring, introduce nitrogen replacement twice in the autoclave, introduce 5g chloromethane / chloroethane gas in a closed state, and heat to 40°C. At this time, the rate of increase of the temperature of the autoclave is accelerated, and the initiation is successful. Continue to introduce 100g chloromethane / chloroethane, and the autoclave pressure is 0.2Mpa until the reaction is completed. The reaction time is 12h and the reaction temperature is 40-50°C. The autoclave temperature is 50°C, and furfural is added dropwise under stirring. The autoclave temperature is controlled to 50°C until there is no obvious heat release in the autoclave. Soft water is added dropwise until there is no obvious heat release in the autoclave, the reaction is completed, and suction filtration is performed. The filtrate is subjected to reduced pressure distillation (-0.08Mpa) to obtain the product furfuryl alcohol, and the solvent is reused for Grignard reagent preparation after drying. Furfuryl alcohol 104.78g is obtained, with a yield of 95.8%, and the purity measured by gas chromatography is 98.1%.
[0052] From the above, it can be seen that the experimental results obtained under the experimental conditions of Examples 1 to 6 are shown in Table 1:
[0053] Table 1
[0054]
[0055]
[0056] As shown in Table 1, it can be seen from Examples 1 to 4 and 6 that the more THF is added to the solvent, the faster the reaction rate is. However, after the second addition of methyl chloride / ethyl chloride, the temperature is high, and the Grignard reagent is prone to coupling reaction, resulting in more by-products, thereby reducing the purity of the prepared furfuryl alcohol.
[0057] It can be seen from Example 1 and Example 5 that, under the same amount of solvent added, increasing the temperature has no effect on the reaction time, temperature, and yield and purity of the product.
[0058] If only tetrahydrofuran is used as a solvent to prepare a Grignard reagent and then synthesize furfuryl alcohol, the reaction temperature must be strictly controlled between 25 and 35°C during the addition process and the hydrolysis process, and the product will gradually change from light yellow to black over time, and the corresponding impurities will be significantly increased. However, by using the process of the present invention, the reaction temperature can be controlled between 25 and 60 degrees Celsius during the addition and hydrolysis processes, the controllability is stronger, and the product quality is more stable compared to others.
[0059] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.
Claims
1. A method for preparing furfuryl alcohol, characterized in that: The following steps are involved: S1: Put magnesium chips into a solvent, replace the solvent with nitrogen, introduce ethyl chloride / methyl chloride gas after nitrogen replacement to react and generate a Grignard reagent, thereby obtaining a solution containing the Grignard reagent; The solvent is methyl tert-butyl ether or a mixture of methyl tert-butyl ether and tetrahydrofuran; S2: adding furfural dropwise to the solution containing the Grignard reagent to carry out an addition reaction, and when the temperature does not change, stopping the addition of furfural, and adding soft water dropwise to carry out a hydrolysis reaction, and when the temperature does not change, filtering by suction to obtain a mother liquor; S3: The obtained mother liquor is subjected to reduced pressure distillation to obtain furfuryl alcohol.
2. The method for preparing furfuryl alcohol according to claim 1, characterized in that: The mass ratio of the magnesium chips to the solvent is 1:(15-20).
3. The method for preparing furfuryl alcohol according to claim 1, characterized in that: The mass ratio of the methyl tert-butyl ether to tetrahydrofuran is (6-1):
1.
4. The method for preparing furfuryl alcohol according to claim 1, characterized in that: In the step S1, the ethyl chloride / methyl chloride gas is introduced twice, and the amount of the ethyl chloride / methyl chloride gas introduced in the first time accounts for 1%-3% of the amount of solvent added.
5. The method for preparing furfuryl alcohol as claimed in claim 4, characterized in that: After the first introduction of ethyl chloride / methyl chloride gas is completed, heating is performed, and when the temperature reaches 40-45° C., heating is stopped, and the second introduction of ethyl chloride / methyl chloride gas is performed.
6. The method for preparing furfuryl alcohol according to claim 4 or 5, characterized in that: The second addition of ethyl chloride / methyl chloride gas causes the temperature to reach 50-70° C., and when the temperature remains constant, the second addition of ethyl chloride / methyl chloride gas is stopped.
7. The method for preparing furfuryl alcohol according to claim 1, characterized in that: The pressure in the step S1 is lower than 0.3 MPa.
8. The method for preparing furfuryl alcohol as claimed in claim 1, characterized in that: The temperature of the S2 addition reaction and hydrolysis reaction is 25-60°C.
9. The method for preparing furfuryl alcohol according to claim 1, characterized in that: The method further comprises step S4, wherein the liquid distilled out in step S3 is distilled under reduced pressure again and dried to obtain a recovered solvent.
10. The method for preparing furfuryl alcohol according to claim 9, characterized in that: The water content of the recovery solvent is below 1000 pmm.