KR102176738B1 - Process for Preparing Furan-2,5-diakylcarboxylate - Google Patents

Abstract

The present invention includes the steps of: (i) performing an oxidation reaction of reacting furfural of Formula II with alcohol in the presence of a catalyst to obtain a compound of Formula III; (ii) brominating the compound of Formula III with N-bromosuccinimide (NBS) to obtain a compound of Formula IV; And (iii) reacting the compound of formula IV with alcohol and carbon monoxide in the presence of a catalyst, a ligand and a base to induce alkoxy carbonylation. It provides a method for producing a boxylate (FDAC).

Description

Method for producing furan-2,5-dialkylcarboxylate {Process for Preparing Furan-2,5-diakylcarboxylate}

The present invention relates to a method for producing 2,5-furandialkylcarboxylate from easily supplied and inexpensive raw materials in high yield.

Furan-2,5-dialkylcarboxylate (FDAC) is a biomass-derived compound having the structure of the following formula (I), and is structurally related to terephthalic acid, which is a raw material for polyester. Is similar to Therefore, FDAC is being evaluated as an eco-friendly monomer that can replace terephthalic acid in plastic products in which terephthalic acid is used as a raw material.

[Formula I]

In the above formula, R is C ₁ -C ₆ alkyl.

A representative example of FDAC of the above structure is furan-2,5-dimethylcarboxylate (FDMC, R=CH ₃ ), and the FDMC is as shown in Scheme 1 below, bio 2,5-furandicarboxylic acid by oxidizing 5-hydroxymethylfurfural (HMF), known as a platform molecule derived from biomass, in the presence of oxygen. , FDCA), and it is known that the FDCA can be prepared by reacting with methanol (CH ₃ OH).

[Scheme 1]

Also, see ChemSusChem 2008 , 1, 75-78] discloses a method of preparing FDMC by continuously esterifying HMF by reacting with methanol in the presence of oxygen, as shown in Scheme 2 below. Specifically, the document discloses that HMF, methanol, Au/TiO ₂ as a catalyst and sodium methoxide as a base are added to an autoclave reactor, and then aerobic oxidation is performed under oxygen pressure at room temperature. The aldehyde group of is oxidized faster than the hydroxymethyl group to produce 5-hydroxymethyl methylfuroate (HMMF). After that, if the temperature of the reactor is increased to 130° C., the hydroxymethyl group is It is described that it is further oxidized to produce methyl 5-formyl-2-furoate (MFF), and the oxidation reaction is continued to finally obtain FDMC.

[Scheme 2]

However, all of the above methods use HMF, which is a hexasaccharide, as a starting material, and since HMF is produced in a liquid state using fructose (C ₆ H ₁₂ O ₆ ) corresponding to an edible crop, it is difficult to separate and purify it. However, there is a limit to mass production. In addition, since the oxidation reaction of HMF uses pure oxygen or air, there is a high risk of explosion during a high temperature and high pressure reaction.

In particular, the oxidation reaction of HMF in Reaction Scheme 2 is carried out in the presence of a base while using a somewhat expensive Au/TiO ₂ catalyst, so the method of preparing 2,5-furandialkylcarboxylate under more economical and mild conditions is Is required.

Therefore, the present invention is to solve the above problems in the production of 2,5-furandialkylcarboxylate (FDAC), one object of the present invention is a novel method that can more economically produce a high yield of FDAC To provide a way.

The present invention relates to a method for preparing 2,5-furandialkylcarboxylate (FDAC) of the following formula (I), wherein the method of the present invention is

(i) performing an oxidation reaction of reacting furfural of Formula II with alcohol in the presence of a catalyst to obtain a compound of Formula III;

(ii) brominating the compound of Formula III with N-bromosuccinimide (NBS) to obtain a compound of Formula IV; And

(iii) reacting the compound of Formula IV with alcohol and carbon monoxide in the presence of a catalyst, a ligand, and a base to induce alkoxycarbonylation.

[Formula II]

[Formula III]

[Formula IV]

[Formula I]

In the above formula, R is C ₁ -C ₆ alkyl.

In addition, the manufacturing method of the present invention may further include an extraction process of the compound of Formula IV in step (ii).

According to the production method of the present invention, an alkyl 2-furoate of formula III obtained by using perfural of formula II, which is easy to obtain and can be mass produced as a starting material, is oxidized and then brominated with cheap NBS, Through a series of processes for performing the nilation, it is possible to more economically produce a high yield of 2,5-furandialkylcarboxylate (FDAC).

Hereinafter, terms or words used in the present specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor appropriately defines the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that it can be done.

The present invention relates to a method for preparing 2,5-furandialkylcarboxylate (FDAC) of Formula I, and the method for preparing the present invention is detailed step by step with reference to Scheme 3 below. Explain clearly.

[Scheme 3]

In the above formula, R is C ₁ -C ₆ alkyl.

As used herein, C ₁ -C ₆ alkyl refers to a straight-chain or branched monovalent hydrocarbon having 1 to 6 carbon atoms, for example methyl, ethyl, n-propyl, i-propyl, n- Butyl, i-butyl, t-butyl, n-pentyl, n-hexyl, and the like may be included.

First step : Generation of compound of formula III by oxidation reaction

In the first step of the preparation method of the present invention, furfural of formula II is used as a starting material, and an oxidation reaction in which it reacts with alcohol (ROH) in the presence of a catalyst is carried out to obtain alkyl 2 of formula III. -To obtain the furoate (alkyl 2-furoate).

The furfural of Formula II used as the starting material is made from xylose (C ₅ H ₁₀ O ₅ ) obtained by decomposing it into a single molecule by treating the lignocellulosic biomass of non-edible crops. It is a typical biomass-derived pentose compound prepared by dehydrating under acidic conditions.

These furfurals are manufactured in the form of white solids and are commercialized and mass-produced in China as they are easily separated and purified. Therefore, when furfural is used as a starting material for FDAC manufacturing, it is easier to obtain than HMF manufactured using edible crops as a raw material, and is advantageous in terms of separation and purification, thus contributing to economically manufacturing FDAC.

An alcohol is used for the oxidation of the furfural of Formula II, and the alcohol may be methanol, ethanol, isopropanol, butanol, pentanol, hexanol, or a mixture of two or more thereof. These alcohols may be used in an amount of 1 to 50 L, specifically 5 to 20 L, based on 1 mole of furfural of Formula II.

As a catalyst for the oxidation reaction, Au-HAP (hydroxyapatite) may be used. The Au-HAP is cheaper in HAP, which is a support material, and is more economical than a catalyst such as Au-TiO ₂ used in the oxidation reaction of HMC according to the conventional method of Scheme 2. The amount of the catalyst is not particularly limited as long as it is a level capable of accelerating the reaction.

The oxidation reaction is carried out in a high-pressure reactor under conditions of air pressure of 100 to 400 psi, specifically 200 to 400 psi, and more specifically 200 to 300 psi, and under such pressure conditions, the oxidation reaction can be performed without an explosion reaction. .

Further, the oxidation reaction may be performed at a temperature of 80 to 120°C, specifically 90 to 100°C for 0.5 to 12 hours, specifically 0.5 to 10 hours, and more specifically 0.5 to 5 hours.

As described above, the oxidation reaction according to the present invention can obtain the alkyl 2-furoate of Formula III with high yield and high selectivity even under relatively mild conditions compared to the oxidation reaction of HMC according to the conventional method of Scheme 2.

Second stage : Generation of compound of formula IV by bromination

In the second step of the preparation method of the present invention, the compound of Formula III is brominated with N-bromosuccinimide (NBS) to obtain an alkyl 5-bromo-2-furoate (alkyl 5- bromo-2-furoate) is obtained.

The NBS used for bromination is an inexpensive brominating agent, and is advantageous in that it can safely perform the bromination process than directly using dangerous and intractable bromine, and can be recycled and used later.

The NBS may be used in an amount of 0.5 to 2 moles, specifically 0.5 to 1.6 moles, based on 1 mole of the compound of Formula III.

The bromination reaction is carried out using a solvent, and acetonitrile, N-methyl-2-pyrrolidone (NMP), and the like may be used as the solvent.

According to an embodiment of the present invention, in the second step reaction, the compound of Formula III and NBS are dissolved in a solvent to prepare a solution, and a solution of the compound of Formula III is added to the reactor, and then the solution of NBS is It may proceed in a dropwise manner, and at this time, the solution of NBS may be added at once, or may be added sequentially over several times. Alternatively, the second step reaction may proceed by dissolving the compound of Formula III and NBS in a solvent at once.

The reaction temperature of the bromination reaction may be 20 to 70°C, specifically 30 to 60°C, and the reaction time may be 2 to 6 hours, specifically 3 to 5 hours.

The manufacturing method of the present invention may include an extraction process to increase the purity of the compound of formula IV obtained from the bromination. The extraction process may be performed in an extraction method using ether.

Step 3 : Generation of compounds of formula I by alkoxycarbonylation

In the third step of the manufacturing method of the present invention, the compound of Formula IV is reacted with alcohol (ROH) and carbon monoxide (CO) in the presence of a catalyst such as palladium acetate (Pd(OAc) ₂ ) in a high-pressure reactor to alkoxycarbonylation. (alkoxycarbonylation) was induced to obtain the target compound, 2,5-furandialkylcarboxylate (FDAC) of formula (I).

The alcohol may be methanol, ethanol, isopropanol, butanol, pentanol, hexanol, or a mixture of two or more thereof.

Carbon monoxide (CO) used in this step is a highly reactive compound because it can act as a σ-donor and a π-acceptor.

For example, when methanol is used as the alcohol in this step, the compound of formula IV (MBF) reacts with the catalyst to produce Pd ^II (Br) (MF) by oxidative addition, and then by CO The resulting Pd ^II (Br)(MF)(CO) complex is produced, and then Pd ^II (Br)(CO-MF) is produced through migration of CO. In the Pd ^II (OMe) (CO-MF) complex produced by dissociation of methanol protons under basic conditions, HBr is produced as a compound of Formula I and a by-product through reductive elimination of OMe and CO-MF ligands.

At this time, for the alkoxycarbonylation of the compound of Formula IV, the alcohol may be used in an amount of 3 to 15 L, specifically 5 to 10 L, based on 1 mole of the compound of Formula IV.

In addition, CO may be used in an amount that maintains a pressure in the reactor of 800 to 1200 psi, or 900 to 1000 psi, particularly 1000 psi.

Palladium acetate (Pd(OAc) ₂ ), the catalyst used for the alkoxycarbonylation, is used so that the molar ratio of the compound of Formula IV and the catalyst is 50:1 to 500:1, specifically 100:1 to 300:1. I can.

The catalyst may be used with a ligand, examples of the ligand include Xantphos, di(1-adamantyl)-n-butylphosphine (Di(1-adamantyl)-n-butylphosphine, cataCXium ^® A ), and the like, in particular, when Xantphos is used as a ligand, the alkoxycarbonylation reaction can be more efficiently promoted.

The catalyst and the ligand may be used in a molar ratio of 1:1 to 1:3, specifically 1:2 to 1:3, and in particular, a molar ratio of 1:3 is advantageous in terms of selectivity and yield of the target compound. .

In addition, the alkoxycarbonylation is preferably carried out in the presence of a base. Examples of the base include alkyl imidazole such as 1-methyl imidazole, alkyl amine such as cyclohexylamine, hexylamine, metal methoxide such as sodium methoxide, Alternatively, KOH may be used, and in particular, 1-methyl imidazole is preferred. These bases may be used such that the molar ratio of the compound of formula IV as a reactant and the base is 1:1 to 1:2.

As described above, the catalyst and ligand may be used not only in the form of simple mixing, but also may be used in the form of a metal compound by combining them. That is, a catalyst and a ligand are added to a solvent such as methanol or acetone in the presence of a base, reacted at room temperature for a certain period of time under stirring, and then dried to obtain a metal compound, which can be used for an alkoxycarbonylation reaction. When using such a catalyst and a ligand in combination, it is advantageous in terms of reducing the ratio of the ligand used compared to the case of simple mixing. According to an embodiment of the present invention, when the catalyst and the ligand are complexed, the catalyst, the ligand, and the base may be used in a molar ratio of 1:2:2.

Meanwhile, the alkoxycarbonylation may be carried out in a high-pressure reactor at a temperature of 90 to 110°C, specifically 100 to 110°C for 4 to 15 hours, or 5 to 7 hours.

As described above, after bromination of alkyl 2-furoate of formula III obtained by oxidizing perfural of formula II, which is readily available, with NBS, a series of alkoxycarbonylation is performed using CO having excellent reactivity. According to the manufacturing method of the present invention performing the process, it is possible to more economically manufacture the FDAC of high yield.

FDAC thus prepared can be used as an eco-friendly monomer that can replace terephthalic acid in the fields of polymers, fine chemicals, pharmaceuticals and agrochemicals. For example, biodegradable polymers such as polyethylene furanoate (PEF) can be used. It can be usefully used in manufacturing.

Hereinafter, examples will be described in detail to aid understanding of the present invention. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention should not be construed as being limited to the following examples. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

Example One:

Step 1: methyl 2- Furoate (methyl 2- furoate , MF) (compound of formula III)

In a 100 mL high-pressure stainless steel reactor equipped with a magnetic stirrer and electric heater, furfural of formula II (0.19 g, 2 mmol, furfural (185914), Sigma-Aldrich), methanol (20 ml) and Au (1.0%) HAP catalyst (0.39g) was added. Thereafter, 80 psi of oxygen was purged to evacuate the atmosphere three times from the reaction mixture. Subsequently, the stirring speed of the reactor was set to 650 rpm, heated to 100° C., and reacted for 3 hours under 300 psi of air pressure. After completion of the reaction, the product was cooled to room temperature, filtered and dried to obtain the target compound (MF) of Formula III. At this time, the conversion rate C _F (%) of the perfural (F) used as a raw material and the yield Y _MF (%) of the obtained target product (MF) were calculated according to Equations 1 and 2 below. As a result, it was confirmed that C _F was 99.6% and Y _MF was 98.0%.

[Equation 1]

Conversion rate (%) = [(number of moles of raw material reaction)/(number of moles of input raw material)] ⅹ100

[Equation 2]

Yield (%) = [(number of moles of actual target product)/(number of moles of theoretical target product)] ⅹ100

Step 2: methyl 5- Bromo -2- Furoate (methyl 5-bromo-2- furoate , MBF) (compound of formula IV)

Obtained by dissolving the compound of formula III (MF) (10 mmol) obtained in step 1 in a 100 mL glass reactor equipped with a magnetic stirrer and an electric heater in acetonitrile (CH ₃ CN, 15 ml) After the solution (0.67M) was added, a solution (1.07M) obtained by dissolving NBS (N-bromosuccinimide, 16 mmol) in acetonitrile (CH ₃ CN, 15ml) was slowly added thereto over 20 minutes. . Then, the reactor was reacted for 3 hours while maintaining the stirring speed (500 rpm) and temperature (45° C.).

Next, the reaction solution was mixed with ether in a ratio of 1:4 (v/v), and a 0.6% by mass aqueous sodium carbonate solution was added thereto in an amount of 20 times the volume of the mixture. After stirring for 2 hours, the upper layer corresponding to the ether layer was separated. This extraction process was repeated three times. The extracted solution was dried over anhydrous sodium sulfate (1 g) to remove water, thereby obtaining a solid product.

In order to increase the purity of the obtained solid product, 30 ml of hexane was added and dissolved per 1 g of the solid product, filtered, and then hexane was evaporated to obtain a pure compound of Formula IV as a target product. At this time, the conversion rate C _MF (%) of the compound of formula III (MF) and the yield Y _MBF (%) of the compound of formula IV (MBF) were calculated in the same manner as in Step 1. As a result, it was confirmed that C _MF was 96.1% and Y _MBF was 83.5%.

Step 3: Furan -2,5- Dimethylcarboxylate ( furan -2,5- dimethylcarboxylate , FDMC) (compound of formula I)

The compound of formula IV (3 mmol) and methanol (30 ml) obtained in step 2 were added to a 100 mL high-pressure stainless steel reactor equipped with a magnetic stirrer and an electric heater. Here, Pd(OAc) ₂ (0.03 mmol) as a catalyst, xantphos (0.09 mmol) as a ligand, and 1-methylimidazole (3 mmol) as a base were mixed and added (Formula IV The molar ratio of compound, catalyst, ligand and base of 100:1:3:100). Thereafter, 80 psi of carbon monoxide (CO) was purged to exhaust the atmosphere from the reaction mixture three times. Subsequently, the stirring speed of the reactor was set to 750 rpm, heated to 100° C., and then pressurized to a pressure of 1000 psi by injecting CO, and reacted for 5 hours. After completion of the reaction, the product was cooled to room temperature, filtered and dried to obtain the target compound of formula I (FDMC). At this time, the conversion rate C _MBF (%) of the compound of formula IV (MBF) and the yield Y _FDMC (%) of the compound of formula I (FDMC) were calculated in the same manner as in Step 1. As a result, it was confirmed that C _MBF was 94.1% and Y _FDMC was 94.1%.

Examples 2 to 7:

The same procedure as in Example 1 was carried out, but the reaction conditions (change of reaction time) shown in Table 1 were applied in Step 1, and the results are shown in Table 1.

Au (1.0%) HAP catalyst content (g) Reaction time
(h) Reaction temperature
(℃) Reaction pressure
(Air, psi) Results of the compound of formula III C _F (%) Y _MF (%) Example 1 0.39 3 100 300 99.6 98.0 Example 2 0.39 0.5 100 300 75.0 74.4 Example 3 0.39 One 100 300 834 83.2 Example 4 0.39 1.5 100 300 87.2 85.9 Example 5 0.39 2 100 300 90.5 90.2 Example 6 0.39 2.5 100 300 97.6 97.6 Example 7 0.36 5 100 300 99.8 98.8

Example 8 to 10:

The same procedure as in Example 1 was performed, but the reaction conditions (changes in the content of reactants and catalysts) shown in Table 2 were applied in step 1, and the results are shown in Table 2.

Perfural
(mmol) Au (1.0%) HAP catalyst content (g) Results of the compound of formula III C _F (%) Y _MF (%) Example 1 2 0.39 99.6 98.0 Example 8 1.8 0.35 97.1 96.5 Example 9 1.6 0.32 96.8 95.9 Example 10 1.4 0.27 94.9 94.4

Example 11 to 14:

The same procedure as in Example 1 was performed, but the reaction conditions (changes in reaction temperature and reaction pressure) shown in Table 3 were applied in Step 1, and the results are shown in Table 3.

Au (1.0%) HAP catalyst content (g) Reaction time
(h) Reaction temperature
(℃) Reaction pressure
(Air, psi) Results of the compound of formula III C _F (%) Y _MF (%) Example 1 0.39 3 100 300 99.6 98.0 Example 11 0.39 3 80 300 83.9 82.4 Example 12 0.39 3 120 300 99.7 99.2 Example 13 0.39 3 100 200 96.6 94.2 Example 14 0.39 3 100 400 99.6 98.7

Examples 15-17:

The same procedure as in Example 1 was carried out, but the reaction conditions (concentration of reactants) shown in Table 4 were applied in Step 2, and the results are shown in Table 4. As can be seen in Table 4, when the concentration of the compound of formula III (MF) used in step 2 is 0.67 M (Example 1), the conversion rate of the reactant (C _MF ) and the target compound of formula IV It exhibited an excellent effect on both the yield (Y _MBF) of (MBF). On the other hand, in the case of Example 17, as the reactant and NBS were dissolved and reacted at once, a side reaction occurred and the yield was considered to have decreased.

Concentration of a solution in which the compound of formula III (10 mmol) is dissolved (M)
(Solvent consumption) Concentration of solution in which NBS (1.6 mmol) is dissolved (M)
(Solvent consumption) Results of the compound of formula IV C _MF (%) Y _MBF (%) Example 1 0.67M
(CH ₃ CN 15ml) 1.07M
(CH ₃ CN 15ml) 96.1 83.5 Example 15 2M (CH ₃ CN 5ml) 0.64
CH ₃ CN 25ml) 97.0 77.4 Example 16 0.5M (CH ₃ CN 20ml) 1.6M
(CH ₃ CN 10ml) 98.4 76.7 Example 17 Dissolve 10 mmol of the compound of formula III and 1.6 mmol of NBS in 30 ml of CH ₃ CN at once. 100 63.1

Example 18 to 20:

The same procedure as in Example 1 was carried out, but the reaction conditions (change of base type) shown in Table 5 were applied in Step 3, and the results are shown in Table 5. As can be seen in Table 5, the conversion rate (C _MBF ) of the compound of formula IV (MBF) as the reaction product of Example 1 using 1-methyl imidazole as the base and the yield of the compound of formula I (FDMC) as the target product ( Y _FDMC ) showed excellent effects in all.

base Results of obtaining the compound of formula I (FDMC) according to the base type in step 3 C _MBF (%) Y _FDMC (%) Example 1 1-methyl imidazole 94.1 94.1 Example 18 Cyclohexylamine 90.8 90.2 Example 19 Hexylamine 85.4 82.9 Example 20 KOH 97.5 62.6 Example 21 Sodium methoxide 100 81.3

Example 22:

The same procedure as in Example 1 was performed, but the reaction conditions (change of ligand type) shown in Table 6 were applied in Step 3, and the results are shown in Table 6. As can be seen in Table 6, in Example 1 using Xantphos as a ligand, both the conversion rate of the compound of formula IV (MBF) (C _MBF ) and the yield of the compound of formula I (FDMC) (Y _FDMC ) Showed an excellent effect.

Ligand The result of obtaining the compound of formula I (FDMC) according to the kind of ligand in step 3 C _MBF (%) Y _FDMC (%) Example 1 Xantphos 94.1 94.1 Example 22 cataCXium A 86.9 65.3

cataCXium A

Xantphos

cataCXium A

Example 23 to 24:

The same procedure as in Example 1 was carried out, but in step 3, the reaction conditions (changes in the amount of catalyst and ligand used) shown in Table 7 were applied, and the results are shown in Table 7. As can be seen in Table 7, Example 1 and Example 21 in which the catalyst and the ligand were used in a molar ratio of 1:3 were the conversion ratio of the compound of formula IV (MBF) (C _MBF ) and the compound of formula I (FDMC) It showed excellent effects in both the yield (Y _FDMC ).

catalyst Ligand Catalyst: Ligand
(Molar ratio) The result of obtaining the compound of formula I (FDMC) according to the molar ratio of the catalyst and the ligand in step 3 C _MBF (%) Y _FDMC (%) Example 1 0.03mmol 0.09mmol 1:3 94.1 94.1 Example 23 0.03mmol 0.06mmol 1:2 91.4 91.2 Example 24 0.03mmol 0.03mmol 1:1 81.1 74.1

Example 25 to 28:

The same procedure as in Example 23 was performed, but the reaction conditions (change of reaction time) shown in Table 8 were applied in Step 3, and the results are shown in Table 8.

Reaction time(h) Results of obtaining the compound of formula I (FDMC) according to the reaction time in step 3 C _MBF (%) Y _FDMC (%) Example 23 5 91.4 91.2 Example 25 3 65.6 51.1 Example 26 4 91.5 82.2 Example 27 7 100 98.4 Example 28 15 100 98.3

Example 28:

The same procedure as in Example 23 was carried out, but the reaction conditions (change of reaction temperature) shown in Table 9 were applied in step 3, and the results are shown in Table 9. As can be seen in Table 9, when the reaction temperature is 100°C under the same conditions (Example 23), the conversion rate of the compound of formula IV (MBF) (C _MBF ) and the yield of the compound of formula I (FDMC) (Y _FDMC ) showed excellent effects in all.

Reaction temperature(℃) Results of obtaining the compound of formula I (FDMC) according to the reaction temperature in step 3 C _MBF (%) Y _FDMC (%) Example 21 100 91.4 91.2 Example 29 110 86.7 76.5

Example 30 to 31

The same procedure as in Example 23 was performed, but the reaction conditions (change of reaction pressure) shown in Table 10 were applied in Step 3, and the results are shown in Table 10. As can be seen in Table 10, when the reaction pressure is CO 1000psi under the same conditions (Example 23), the conversion rate of the compound of formula IV (MBF) (C _MBF ) and the yield of the compound of formula I (FDMC) (Y _FDMC ) showed excellent effects in all.

Reaction pressure
(CO, psi) Results of obtaining the compound of formula I (FDMC) according to the reaction pressure in step 3 C _MBF (%) Y _FDMC (%) Example 21 1000 91.4 91.2 Example 30 800 92.0 78.2 Example 31 1100 72.1 60.8 Example 32 1200 62.8 52.1

Example 33:

The same procedure as in Example 1 was performed, but the reaction conditions (changes in the amount of reactants and catalyst used) shown in Table 11 were applied in Step 3, and the results are shown in Table 11. As can be seen in Table 11, when the reactant and the catalyst were used in a molar ratio of 100:1 under the same conditions (Example 1), the conversion of the compound of formula IV (MBF) (C _MBF ) and the compound of formula I ( FDMC) showed excellent effects in both the yield (Y _FDMC ).

Reactant
(Compound of formula IV) catalyst
(Pd(OAc) ₂₎ Molar ratio of reactants to catalyst The result of obtaining the compound of formula I (FDMC) according to the ratio of reactants and catalyst in step 3 C _MBF (%) Y _FDMC (%) Example 1 3 mmol 0.03 mmol 100 94.1 94.1 Example 33 3 mmol 0.06 mmol 200 88.5 88.5

Example 34:

The same procedure as in Example 1 was carried out, but in step 3, the catalyst Pd(OAc) ₂ and the ligand xantphos were combined in a high-pressure stainless steel reactor into which the compound of formula IV (3 mmol) and methanol (30 ml) were added. Then, it was prepared and added in the form of a metal compound. Specifically, the metal compound was added Pd(OAc) ₂ (0.5 mmol) and xantphos (1 mmol) to methanol (30 ml) in the presence of 1-methylimidazole (1 mmol), After stirring at room temperature for 2 days, the product was filtered, washed and dried under vacuum to obtain a light green powder. As such, the results according to the use of the metal compound are shown in Table 12.

Example 35:

The same procedure as in Example 34 was performed, except that Pd(OAc) ₂ (1 mmol) and xantphos (1 mmol) were added to acetone (30 ml) without the use of a base when preparing a metal compound, and 5 at room temperature. After stirring for an hour, the product was filtered, washed and dried under vacuum to give an orange powder. As such, the results according to the use of the metal compound are shown in Table 12.

As can be seen in Table 12, in the presence of 1-methylimidazole as a base, Pd(OAc) ₂ as a catalyst and Xantphos as a ligand were reacted at a molar ratio of 1:2 Compared to the complex of (Pd(Xantphos) ₂ ) formed by dropping of the acetate attached to the catalyst (Example 34), the catalyst Pd(OAc) ₂ and the ligand Xantphos were 1:1 in the absence of a base. The complex of (Pd(OAc) ₂ Xantphos) obtained by reacting at a molar ratio (Example 35) exhibited a high activity corresponding to that of Example 1 using a catalyst in the form of a mixture. Therefore, Example 35 is also advantageous in that the content of the ligand Xantphos can be reduced.

Combination form of catalyst and ligand Molar ratio of reactants to catalyst The result of obtaining the compound of formula I (FDMC) according to the ratio of reactants and catalyst in step 3 C _MBF (%) Y _FDMC (%) Example 1 mixture 100 94.1 94.1 Example 34 Metal compound (Pd(Xantphos) ₂ ) 100 81.1 73.4 Example 35 Metal compound (Pd(OAc) ₂ Xantphos) 100 91.2 91.0

Example 36 to 38:

The same procedure as in Example 1 was performed, but in step 3, instead of methanol, an alcohol shown in Table 13 was used to prepare a compound of Formula I (FDAC) to which various alkyl groups were applied.

Alcohol The result of obtaining the compound of formula I (FDAC) according to the ratio of reactants and catalyst in step 3 C _MBF (%) Y _FDAC (%) Example 1 Methanol 94.1 94.1 Example 36 ethanol 90.2 89.8 Example 37 iso-propanol 80.4 76.2 Example 38 Butanol 84.2 83.7

Comparative example One:

In Comparative Example 1, FDMC was prepared using 5-hydroxymethylfurfural (HMF), which is a hexasaccharide, as a starting material.

Specifically, HMF 0.2513g (2 mmol), methanol (20 ml) and Au (1.0%)/TiO ₂ catalyst were added to a 100 mL high-pressure stainless steel reactor equipped with a magnetic stirrer and an electric heater. It was charged so that the molar ratio of HMF/Au was 100, and then, air of 0.5 MPa was purged into the reactor to exhaust the atmosphere from the reaction mixture three times. Subsequently, the air pressure of the reactor was pressurized to 2.4 MPa, the stirring speed was 650 rpm, heated to 130 °C, the reaction temperature was maintained at 130 °C for 6 hours, and the reaction air pressure, which is the final pressure (Pair) of air entering the reactor. FDMC was prepared while maintaining at 2.4 MPa using a gas reservoir equipped with a back pressure regulator and pressure transducer. Upon completion of the reaction, the resulting mixture was cooled at room temperature and a certain amount of methanol was added. The solid catalyst and product were separated by filtration.

According to Comparative Example 1, HMF used as a starting material was converted to 5-hydroxymethylmethylfuroate (HMMF) as an intermediate, and the HMMF was gradually converted to methyl 5-formyl-2-furoate (MFF ), the MFF was converted to FDMC through subsequent oxidation spots.

Table 14 below shows the conversion rate of HMF used as a starting material, and the yield of HMMF as an intermediate and FDMC as a final target product.

catalyst C _HMF (%) Y _HMMF (%) Y _FDMC (%) Comparative Example 1 Au/TiO ₂ 98.9 36.1 26.5

As can be seen in Table 13, according to the method of producing FDMC by using HMF as a hexasaccharide as a starting material and Au/TiO ₂ as a catalyst and performing a continuous oxidation reaction, the yield of FDMC as the final target is very low. It can be seen that.

Claims (17)

(i) performing an oxidation reaction of reacting furfural of Formula II with alcohol in the presence of a catalyst to obtain a compound of Formula III;
(ii) brominating the compound of Formula III with N-bromosuccinimide (NBS) to obtain a compound of Formula IV; And
(iii) reacting the compound of Formula IV with alcohol and carbon monoxide in the presence of a catalyst, a ligand and a base to induce alkoxycarbonylation,
The ligand is Xantphos,
The alkoxycarbonylation reaction of step (iii) is carried out for 4 to 15 hours at a carbon monoxide (CO) pressure of 800 to 1200 psi and a temperature of 90 to 110°C,
Method for preparing 2,5-furandialkylcarboxylate (FDAC) of the following formula (I):
[Formula II]

[Formula III]

[Formula IV]

[Formula I]

In the above formula, R is C ₁ -C ₆ alkyl. The method of claim 1,
In the step (ii), the method further comprises an extraction process of the compound of formula IV. The method of claim 1,
The catalyst in step (i) is Au-HAP (hydroxyapatite). The method of claim 1,
The oxidation reaction of step (i) is a manufacturing method that is carried out for 0.5 to 12 hours at an air pressure of 100 to 400 psi and a temperature of 80 to 120 °C. The method of claim 1,
In the bromination reaction of step (ii), the NBS is used in an amount of 0.5 to 2 moles based on 1 mole of the compound of Formula III. The method of claim 1,
The bromination reaction of step (ii) is carried out at 20 to 70°C for 2 to 6 hours. The method of claim 1,
In the step (iii), the catalyst is palladium acetate (Pd(OAC) ₂ ). The method of claim 1,
In the step (iii), the base is an alkylamine, an alkylimidazole, or a mixture thereof. The method of claim 1,
In the step (iii), the catalyst and xantphos are used in the form of a mixture or a composite metal compound. The method of claim 1,
In the step (iii), the molar ratio of the compound of Formula IV and the catalyst is 50:1 to 500:1. The method of claim 10,
In the step (iii), the molar ratio of the compound of Formula IV and the catalyst is 100:1 to 300:1. The method of claim 1,
In the step (iii), the molar ratio of the catalyst and xantphos is 1:1 to 1:3. The method of claim 1,
In the step (iii), the molar ratio of the compound of Formula IV and the base is 1:1 to 1:2. delete The method of claim 1,
The alcohol used in step (i) and step (ii) is methanol, ethanol, isopropanol, butanol, pentanol, hexanol, or a mixture of two or more thereof. The method of claim 1,
In the step (i), the alcohol is used in an amount of 1 to 50 L based on 1 mole of the compound of formula II. The method of claim 1,
In the step (i), the alcohol is used in an amount of 3 to 15 L based on 1 mole of the compound of formula IV.