CN103058962B - Method for preparing 2,5-furan methylene glycol dialkyl ether by furfuryl alcohol - Google Patents

Abstract

The invention relates to a method for preparing 2,5-furandimethanol dialkyl ether from furfuryl alcohol. Specifically, furfuryl alcohol is prepared from renewable biomass such as corncobs as a raw material. Under the action of an acidic catalyst, it reacts with formaldehyde gram reaction, the generated 2,5-furandimethanol is etherified to prepare 2,5-furandimethanol dialkyl ether. The preparation method of the invention adopts industrially produced furfuryl alcohol to replace expensive 5-hydroxymethylfurfural as a raw material, has mild reaction conditions, low cost and high yield, and has high industrial application prospects.

Description

A kind of method of preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol

technical field

The invention relates to a method for preparing 2,5-furandimethanol dialkyl ether from furfuryl alcohol. Specifically, furfuryl alcohol is prepared from renewable biomass such as corncobs as a raw material. Under the action of an acidic catalyst, it reacts with formaldehyde gram reaction, the generated 2,5-furandimethanol is etherified to prepare 2,5-furandimethanol dialkyl ether.

Background technique

Since entering the 21st century, the sources of chemicals and fuels have become more and more diversified, and the proportion of chemicals and fuels based on petroleum is gradually decreasing. The development of new energy and new materials has become a hot topic in the field of scientific research. Among them, biomass is regarded as an ideal source of raw materials because of its abundant reserves, wide range of sources and renewability.

Furanylmethanol dialkyl ether is a new type of diesel additive, which can significantly increase the cetane number of diesel. The traditional synthesis method of 2,5-furandimethanol dialkyl ether is to use 5-hydroxymethylfurfural (HMF) as the substrate, and it is produced after selective hydrogenation and etherification. For example, Gruter et al reported in the patent (EP2008/007423) that 5-hydroxymethylfurfural or 5-alkoxymethylfurfural can be converted into furandimethanol dialkyl in the presence of a hydrogenation catalyst and an acidic catalyst ether. However, due to the high production cost of HMF, since the 1980s, HMF has not yet been industrialized. The efficient conversion and utilization of HMF has become one of the difficulties in scientific research, which has led to the development of 2,5-furan di The production and application of a series of disubstituted furan derivatives such as methanol dialkyl ether have been greatly restricted. In addition, the inventors of the present application have also developed a method for preparing furandimethanol dialkyl ether using sugar as raw material, specifically see CN102442982A, wherein glucose, fructose, starch, etc. are used as raw materials in the simultaneous presence of hydrogenation catalyst and acid catalyst The condition conversion obtains furandimethanol dialkyl ether, but conversion rate is still not ideal enough.

It is worth noting that polypentose contained in renewable biomass such as corncobs is used as raw material, after hydrolysis into pentose, further dehydration to prepare furfural and selective hydrogenation of furfural to prepare furfuryl alcohol. The process is very mature and has now been realized. Industrialized production and application, using cheap furfuryl alcohol as raw material to prepare 2,5-furan methanol dialkyl ether, avoiding the use of expensive HMF, reducing production costs, and having higher feasibility and commercial value.

Contents of the invention

The object of the present invention is to provide a kind of method of preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol, described method is represented by following reaction formula 1 and comprises the following steps:

Reaction 1

1) In the presence of an organic solvent or water and an acidic catalyst, furfuryl alcohol undergoes a Friedel-Crafts reaction with a solution containing formaldehyde to generate 2,5-furandimethanol;

2) In the presence of an acidic catalyst, the obtained 2,5-furandimethanol is etherified with alcohol to generate 2,5-furandimethanol dialkyl ether.

in,

In step 1), the molar ratio of raw material furfuryl alcohol to formaldehyde in the solution containing formaldehyde is 0.001-1, preferably 0.05-0.5; the molar ratio of acidic catalyst to furfuryl alcohol is 0.01-0.16, preferably 0.01-0.1; the reaction temperature It is 25°C to 125°C; the reaction time is 1min to 48h, preferably 10h to 48h. Unoptimized reaction conditions will speed up the reaction rate of side reactions, resulting in a significant decrease in the yield of 2,5-furandimethanol, or even failure to obtain the target product, so it is very important to properly adjust the above reaction parameters. For example, when the molar ratio of raw material furfuryl alcohol and formaldehyde is small, that is, when the amount of raw material furfuryl alcohol is small, the amount of acidic catalyst can be appropriately increased within the above range; Do it as fully as possible.

The reaction system in step 1) can be a single-phase system or a two-phase system, and the solvent in the single-phase system can be: water, methanol, ethanol, ether, tetrahydrofuran, 1-butanol, 2-butanol, ethyl acetate Ester, methyl isobutyl ketone or acetone, preferably water, ethanol, ether or tetrahydrofuran, more preferably water or tetrahydrofuran; one-phase solvent in two-phase system can be water, methanol or ethanol, preferably water; One phase can be diethyl ether, THF, 1-butanol, 2-butanol, ethyl acetate or methyl isobutyl ketone which is immiscible with the first phase, preferably ethyl acetate or methyl isobutyl base ketones.

The formaldehyde-containing solution can be an industrial-grade 35-40% formaldehyde solution, or a formaldehyde solution obtained by directly depolymerizing paraformaldehyde in an organic solvent, or a formaldehyde solution obtained by depolymerizing paraformaldehyde into an organic solvent. formaldehyde solution. The organic solvent used to obtain the formaldehyde solution is methanol, ethanol, tetrahydrofuran, ethyl acetate or acetone.

In step 2), the mass ratio of 2,5-furandimethanol to alcohol is 0.01-0.5; the molar ratio of acid catalyst to 2,5-furandimethanol is 0.01-0.16, preferably 0.01-0.1; the reaction temperature is 25°C~125°C; the reaction time is 1min~48h, preferably 10h~48h. The alcohol used is selected from C ₁ -C ₈ alkyl alcohols, preferably C ₁ -C ₆ alkyl alcohols, most preferably methanol, ethanol, propanol or isopropanol.

The acidic catalysts used in step 1) and step 2) can be the same or different, and can be protic acid or Lewis acid. The protic acid is selected from sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, oxalic acid and fluorosulfonic acid, preferably hydrochloric acid or acetic acid; the Lewis acid is selected from aluminum chloride, ferric chloride, boron trifluoride, pentachloride Triflates of niobium and lanthanides, preferably aluminum chloride.

The method for preparing 2,5-furandimethanol dialkyl ether from furfuryl alcohol of the present invention can be carried out by a one-step method or a two-step method.

In the one-step method, raw materials such as furfuryl alcohol, formaldehyde-containing solution, acid catalyst, alcohol and other reactants can be added into the reactor for reaction to prepare 2,5-furandimethanol dialkyl ether.

In the two-step method, step 1) and step 2) can be performed separately.

The 2,5-furan dimethanol dialkyl ether prepared by the preparation method of the present invention can be 2,5-furan dimethanol dimethyl ether, 2,5-furan dimethanol diethyl ether, 2,5-furan dimethanol Dimethanol di-n-propyl ether or 2,5-furandimethanol diisopropyl ether, etc.

Beneficial effect

The preparation method of the invention adopts industrially produced furfuryl alcohol to replace expensive 5-hydroxymethylfurfural as a raw material, has mild reaction conditions, low cost and high yield, and has high industrial application prospects.

Detailed ways

Reagents and experimental instruments:

The reagents used in the examples of the present invention are analytically pure. Furfuryl alcohol was purchased from Shanghai Puzhen Biotechnology Co., Ltd.; hydrochloric acid was purchased from Laiyang Dongfang Chemical Co., Ltd.; aluminum chloride was purchased from Aladdin (China) Co., Ltd.; the rest of the reagents were purchased from Sinopharm Chemical Reagent Co., Ltd.

ZNCL-S digital display magnetic stirring oil bath, Shanghai Yuezhong Instrument Equipment Co., Ltd.; electronic analysis balance, Beijing Sartorius Instrument System Co., Ltd.; gas chromatography system (Varian-450; ion flame detector; DB-FFAP column) ; High performance liquid chromatography system (Waters 1525 pump; Agilent SB-C18 column; Waters 2998 photodiode array detector).

Preparation of 2,5-furandimethanol dialkyl ether by two-step method

Example 1: Preparation of 2,5-furandimethanol in aqueous formaldehyde solution

Add 5mL of acetic acid to 50mL of 37% formaldehyde aqueous solution, mix evenly, add 5mL of furfuryl alcohol, react in an oil bath with magnetic stirring at 60°C for 20h, cool to room temperature, and analyze with high performance liquid chromatography (HPLC). The conversion rate and selectivity of 2,5-furandimethanol were 63% and 49%, respectively. Formaldehyde aqueous solution and unreacted furfuryl alcohol were distilled off under reduced pressure at 80°C to obtain brownish yellow crude 2,5-furandimethanol liquid.

Example 2: Preparation of 2,5-furandimethanol in tetrahydrofuran

The formaldehyde generated by the depolymerization of paraformaldehyde was absorbed and dissolved in tetrahydrofuran to make a tetrahydrofuran solution of formaldehyde, and the mass fraction of formaldehyde was 40% according to gas chromatography. Take 50mL of this solution and add 5mL acetic acid, mix well and add 5mL furfuryl alcohol, react in an oil bath with magnetic stirring at 60°C for 20h, cool to room temperature, analyze by gas chromatography (GC), the conversion rate of furfuryl alcohol and 2,5 The selectivities of -furandimethanol were 59% and 82%, respectively. Formaldehyde, tetrahydrofuran and unreacted furfuryl alcohol were distilled off under reduced pressure at 80°C to obtain brownish-yellow crude 2,5-furandimethanol liquid.

Example 3: Preparation of 2,5-furandimethanol in a two-phase system

Add 0.5g of aluminum chloride to 50mL of 37% formaldehyde solution, mix well, then add 50mL of methyl isobutyl ketone (MIBK) and 5mL of furfuryl alcohol in turn, react in an oil bath with magnetic stirring at 35°C for 30h, cool After reaching room temperature, analysis by HPLC showed that the conversion rate of furfuryl alcohol and the selectivity of 2,5-furandimethanol were 73% and 77% respectively. Formaldehyde solution, MIBK and unreacted furfuryl alcohol were distilled off under reduced pressure at 80°C to obtain brown-yellow Crude 2,5-furandimethanol liquid.

Example 4: Preparation of 2,5-furandimethanol dimethyl ether from 2,5-furandimethanol

Take 3 g of 2,5-furandimethanol prepared in Example 1, dissolve it in 30 mL of methanol, then add 30 microliters of hydrochloric acid, react in an oil bath with magnetic stirring at 35°C for 20 h, cool to room temperature, and use GC Analysis showed that the conversion rate of 2,5-furandimethanol and the selectivity of 2,5-furandimethanol dimethyl ether were 87% and 54%, respectively.

Example 5: Preparation of 2,5-furandimethanol diethyl ether from 2,5-furandimethanol

Take 3 g of 2,5-furandimethanol prepared in Example 1, dissolve it in 30 mL of ethanol, then add 30 microliters of hydrochloric acid, react in an oil bath with magnetic stirring at 35°C for 20 h, cool to room temperature, and use GC Analysis showed that the conversion rate of 2,5-furandimethanol and the selectivity of 2,5-furandimethanol dimethyl ether were 80% and 52%, respectively.

Example 6: Preparation of 2,5-furandimethanol di-n-propyl ether from 2,5-furandimethanol

Take 3 g of 2,5-furandimethanol prepared in Example 1, dissolve it in 30 mL of n-propanol, then add 30 microliters of hydrochloric acid, react in an oil bath with magnetic stirring at 35°C for 25 hours, and cool to room temperature. By GC analysis, the conversion rate of 2,5-furandimethanol and the selectivity of 2,5-furandimethanol dimethyl ether were 82% and 49%, respectively.

One-step preparation of 2,5-furandimethanol dialkyl ether

Example 7: One-step preparation of 2,5-furandimethanol dimethyl ether in formaldehyde methanol solution

The formaldehyde generated by the depolymerization of paraformaldehyde was absorbed and dissolved in methanol to make a methanol solution of formaldehyde, and the mass fraction of formaldehyde was 40% according to gas chromatography analysis. Take 50mL of this solution and add 5mL of acetic acid, mix well and add 5mL of furfuryl alcohol, react in an oil bath with magnetic stirring at 60°C for 20h, after cooling to room temperature, use gas chromatography to analyze the conversion rate of furfuryl alcohol and 2,5-furan Dimethanol dimethyl ether selectivities were 61% and 71%, respectively.

Example 8: One-step preparation of 2,5-furandimethanol diethyl ether in formaldehyde ethanol solution

The formaldehyde generated by the depolymerization of paraformaldehyde was absorbed and dissolved in ethanol to make a formaldehyde ethanol solution, and the mass fraction of formaldehyde was 40% according to gas chromatography analysis. Take 50mL of this solution and add 5mL of acetic acid, mix well and add 5mL of furfuryl alcohol, react in an oil bath with magnetic stirring at 60°C for 20h, after cooling to room temperature, use gas chromatography to analyze the conversion rate of furfuryl alcohol and 2,5-furan Dimethanol dimethyl ether selectivities were 59% and 68%.

Example 9: One-step preparation of 2,5-furandimethanol di-n-propyl ether in formaldehyde n-propanol solution

The formaldehyde generated by the depolymerization of paraformaldehyde was absorbed and dissolved in n-propanol to prepare formaldehyde in n-propanol solution, and the mass fraction of formaldehyde was 40% according to gas chromatography. Take 50mL of this solution and add 5mL acetic acid, mix well and add 5mL furfuryl alcohol, react in an oil bath with magnetic stirring at 60°C for 25h, after cooling to room temperature, use gas chromatography to analyze the conversion rate of furfuryl alcohol and 2,5-furan Dimethanol dimethyl ether selectivities were 62% and 66%.

It can be seen from the above examples that the conversion rate of furfuryl alcohol and the selectivity of 2,5-furandimethanol dialkyl ether by the method of the present invention are higher than those of the prior art. At the same time, because the preparation method of the present invention starts from furfuryl alcohol as the starting reactant, it is more economical and more suitable for industrial production.

Above embodiment is only enumerated as the example of embodiment of the present invention, does not constitute any restriction to the present invention, and those skilled in the art can understand that the modification in the scope of not departing from the spirit and design of the present invention all falls into the protection of the present invention. scope.

Claims (16)

1. a method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol, is characterized in that, described method comprises the following steps: 1) In the presence of an organic solvent or water and an acidic catalyst, furfuryl alcohol reacts with a formaldehyde-containing solution to generate 2,5-furandimethanol; 2) In the presence of an acidic catalyst, the obtained 2,5-furandimethanol is etherified with alcohol to generate 2,5-furandimethanol dialkyl ether, The 2,5-furan dimethanol dialkyl ether is 2,5-furan dimethanol dimethyl ether, 2,5-furan dimethanol diethyl ether, 2,5-furan dimethanol di-n-propyl Ether or 2,5-furandimethanol diisopropyl ether; The acid catalysts used in the step 1) and step 2) are the same or different, and are selected from protonic acids or Lewis acids; the protonic acids are selected from sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, oxalic acid and fluorosulfonic acid; The Lewis acid is selected from the group consisting of aluminum chloride, ferric chloride, boron trifluoride, niobium pentachloride and triflate salts of lanthanides. 2. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 1, is characterized in that, in step 1), the mol ratio of furfuryl alcohol and the formaldehyde in the solution containing formaldehyde is 0.001 ~1. 3. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 2, is characterized in that, in step 1), the mol ratio of furfuryl alcohol and the formaldehyde in the solution containing formaldehyde is 0.05 ~0.5. 4. The method for preparing 2,5-furandimethanol dialkyl ether from furfuryl alcohol according to claim 1, characterized in that, in step 1), the molar ratio of the acidic catalyst to furfuryl alcohol is 0.01 to 0.16. 5. The method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 4, characterized in that, in step 1), the molar ratio of the acidic catalyst to furfuryl alcohol is 0.01 to 0.1. 6. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 1, is characterized in that, in step 1), reaction temperature is 25 ℃～125 ℃; Reaction time is 1min～ 48h. 7. The method for preparing 2,5-furandimethanol dialkyl ether from furfuryl alcohol according to claim 6, characterized in that the reaction time in step 1) is 10h to 48h. 8. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 1, is characterized in that, the reaction system of described step 1) is single-phase system or two-phase system, in single-phase The solvents in the system are: water, methanol, ethanol, ether, tetrahydrofuran, 1-butanol, 2-butanol, ethyl acetate, methyl isobutyl ketone or acetone; the one-phase solvent in the two-phase system is water , methanol or ethanol; the other phase is a solvent immiscible with the first phase in diethyl ether, tetrahydrofuran, 1-butanol, 2-butanol, ethyl acetate or methyl isobutyl ketone. 9. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 8, is characterized in that, the reaction system of described step 1) is single-phase system or two-phase system, in single-phase The solvent in the system is: water, ethanol, ether or tetrahydrofuran; in the two-phase system, one phase solvent is water; the other phase is ethyl acetate or methyl isobutyl ketone. 10. The method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 9, characterized in that the solvent in the single-phase system is water or tetrahydrofuran. 11. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 1, is characterized in that, the solution containing formaldehyde described in the step 1) is selected from industrial grade 35～40% Aqueous formaldehyde solution, or the formaldehyde solution obtained by directly depolymerizing paraformaldehyde in an organic solvent, or the formaldehyde solution obtained by passing the formaldehyde generated by depolymerization of paraformaldehyde into an organic solvent; the organic solvent used to obtain the formaldehyde solution is Methanol, ethanol, tetrahydrofuran, ethyl acetate or acetone. 12. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 1, is characterized in that, described step 2) in the mass ratio of 2,5-furandimethanol and alcohol is 0.01 ～0.5; the molar ratio of acid catalyst to 2,5-furandimethanol is 0.01～0.16; the reaction temperature is 25℃～125℃; the reaction time is 1min～48h; the alcohol used is an alkane selected from C ₁ -C ₈ base alcohol. 13. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 12, is characterized in that, described step 2) in acidic catalyst and the mol ratio of 2,5-furandimethanol is 0.01～0.1; the reaction time is 10h～48h; the alcohol used is C ₁ -C ₆ alkyl alcohol. 14. the method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 13, is characterized in that, the alcohol used in described step 2) is methyl alcohol, ethanol, propanol or isopropanol . 15. The method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 1, characterized in that, the protic acid is hydrochloric acid or acetic acid; the Lewis acid is aluminum chloride. 16. The method for preparing 2,5-furandimethanol dialkyl ether by furfuryl alcohol according to claim 1, characterized in that, the step 1) and step 2) are carried out by one-step method or two-step method.