Method for producing furan-2-carbaldehyde

Abstract

FIELD: chemical synthesis.SUBSTANCE: method for producing furan-2-carbaldehyde of general formula 1 using ultrasound. The method involves mixing pentose-containing raw materials with a catalyst in an amount of 0.1-15% of the raw material's mass, after which the resulting mass is subjected to ultrasound treatment at a frequency of 40 kHz for 5-180 minutes. The treated mixture is then heated for 5-180 minutes to a temperature of 80-280 ° C, filtered with separation of the filtrate, which is neutralized with a carbonate base or a carbonate salt soluble in water, followed by the addition of sodium chloride in an amount of 10 g per 100 ml of solution. The resulting solution is extracted with ethyl acetate and the low-boiling fraction is distilled off. In this case, lignocellulosic biomass, pre-crushed to a particle size of 0.1 mm to 1.0 cm, is used as a pentose-containing raw material, and an aqueous solution of sulfuric acid with a concentration of 5-12% is used as a catalyst.EFFECT: proposed method allows for increasing the yield of the target compound and reducing the synthesis time.1 cl, 3 ex

Description

[0001] The invention relates to a method for producing furan-2-carbaldehyde of general formula 1 from biomass using ultrasound

[0002] .

[0003] Furfural is a valuable reagent used in the production of plastics and polymers (furfural acetone monomers), in petrochemistry as a solvent for the separation of dienes, in agriculture for plant protection as a starting component for growth regulators, in medicine for the creation of antibacterial agents, and in the production of solvents.

[0004] Several methods for obtaining furan-2-carbaldehyde of formula 1 from lignocellulosic biomass using ultrasound have been described in the literature to date.

[0005] The primary source of furan-2-carbaldehyde, also known as furfural and furfural, is plant fibers rich in pentose sugars. These include sawdust from deciduous and coniferous trees, as well as other lignocellulosic waste from Group 4 wood processing (dust, wood chips, bark), sunflower husks, other plant husks, oilcake, rice husks, straw, corn cobs and stalks, and the like.

[0006] The first method for producing furfural using ultrasound is based on the use of nitric acid as a catalyst [S.A. Bizzi, D. Santos. Furfural production from lignocellulosic biomass by ultrasound-assisted acid hydrolysis / / Ultrasonics - chemistry. - 2019. - No. 51. - pp. 332-339]. The source of pentoses in this method was rice husk, sugarcane straw, yerba mate waste, grass and wood waste. This method uses reaction time intervals from 30 to 120 min, an ultrasound frequency of 20 kHz and an amplitude of 20 to 70%. The yield of furfural by weight of absolute dry raw materials ranged from 3.64 to 7.24% (1).

[0007]

[0008] The disadvantage of this method is the low yield of the target product.

[0009] The prototype of the invention is a method for producing furan-2-carbaldehyde in a two-stage process, including the interaction of a pentose solution with an extractant consisting of benzene, ethyl acetate and a chlorinated hydrocarbon with a boiling point lower than the boiling point of formic acid (chloroform, trichloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane), in the presence of a catalyst, which is a mixture of acetic and formic acids, which are formed during the reaction [Bo Dechen; Wang Yanfeng; Zhang Long; Gao Jingshan; Zhang Shengzhong - China Petroleum and Chemical Company, 2015,

[0010] https: / / worldwide.espacenet.com / patent / search / family / 053074984 / publication / CN104557811A?q=CN104557811A] (2)

[0011]

[0012] and subsequent ultrasonic treatment at a frequency of 10 to 300 kHz, ultrasonic power of 0.1 to 500 W / L, pressure of 2 to 10 MPa, temperature of 150 to 280°C, and reaction time of 0.1 to 2 hours. The extractant is introduced directly into the reaction chamber along with the pentose solution and is heavier (the lower layer). The yields of the target product range from 38.7% to 85.3%.

[0013] A disadvantage of this method is the presence of a multi-component extractant, which complicates the separation of furfural from the solvent mixture and hinders the extractant regeneration process due to the large difference in the boiling points of the components and the formation of azeotropes. This method also completely omits the acid neutralization step, which can lead to partial polymerization and a decrease in the yield of furan-2-carbaldehyde.

[0014] The objective of the invention is to improve the method for producing furan-2-carbaldehyde 1.

[0015] The technical result of the invention is a reduction in the synthesis time, an increase in the yield of the target product, while ensuring the environmental friendliness of the synthesis.

[0016] The technical result of the proposed invention is achieved by the fact that the method for obtaining furan-2-carbaldehyde of general formula 1

[0017] ,

[0018] including mixing pentose-containing raw materials with a catalyst taken in an amount of 0.1-15% of the mass of the raw materials, after which the resulting mass is subjected to ultrasound treatment at a frequency of 40 kHz for 5-180 minutes, then the treated mixture is heated for 5-180 minutes to a temperature of 80-280 ° C, filtered with separation of the filtrate, which is neutralized with a carbonate base or a carbonate salt soluble in water, followed by the addition of sodium chloride in an amount of 10 g per 100 ml of solution, the resulting solution is extracted with ethyl acetate with distillation of the low-boiling fraction, while lignocellulosic biomass, pre-crushed to a particle size of 0.1 mm to 1.0 cm, is used as a pentose-containing raw material, and an aqueous solution of sulfuric acid with a concentration of 5-12% is used as a catalyst.

[0019] The common features of the proposed method and prototype are:

[0020] - using ultrasound to increase the yield of the target product;

[0021] - using a catalyst;

[0022] - use of pentose-containing raw materials;

[0023] - use of extractant.

[0024] Distinctive features are:

[0025] - use of an aqueous solution of catalyst mixed with biomass;

[0026] - using sulfuric acid as a catalyst;

[0027] - the presence of a neutralization stage;

[0028] - adding inorganic salts to improve the transition of furan-2-carbaldehyde from the aqueous phase to the organic phase;

[0029] - using ethyl acetate as an organic solvent.

[0030] Reducing the synthesis time, increasing the yield of the target product,

[0031] Ensuring the environmental friendliness of the synthesis is achieved due to the fact that:

[0032] - the raw material used is lignocellulosic biomass, pre-crushed to a particle size of 0.1 mm to 1 cm, which is mixed with a catalyst - sulfuric acid, taken in an amount of 0.1-15% of the mass of the raw material;

[0033] - the resulting mass is treated with ultrasound at a frequency of 40 kHz for 5-180 minutes, followed by heating for 5-180 minutes to a temperature of 80-280°C;

[0034] carry out timely neutralization of the resulting filtrate with a carbonate base or a carbonate salt soluble in water, followed by the addition of sodium chloride in an amount of 10 g per 100 ml of solution;

[0035] To isolate furan-2-carbaldehyde from an aqueous medium, extraction is carried out with ethyl acetate, which has an optimal boiling point, is capable of selectively dissolving the target product or derivatives closest in structure (5-methylfurfural), and is also easily separated during the purification process.

[0036] Thus, the combination of the claimed features allows achieving the desired technical result.

[0037] Example 1. Obtaining furan-2-carbaldehyde using ultrasound and an aqueous solution of sulfuric acid with a concentration of 12% from sunflower husk.

[0038] Pre-crushed sunflower husks (50 g) and 800 ml of an aqueous solution of H2SO4 (12% by weight) were placed in a 2000 ml round-bottomed flask.

[0039] While mechanically stirring, the solution is irradiated with an ultrasonic reactor at 40 kHz for 30 minutes. The resulting mixture is then heated for 120 minutes. Afterward, the solution is filtered, neutralized with calcium carbonate, and sodium chloride is added at a rate of 10 g per 100 ml of solution. The resulting mixture is extracted with ethyl acetate, after which the lower-boiling fraction is distilled off. The resulting liquid product is pale yellow. The yield relative to the pentose content in dry matter is 87.7%.

[0040] Example 2. Obtaining furan-2-carbaldehyde using ultrasound and an aqueous solution of sulfuric acid with a concentration of 9% from sunflower husk.

[0041] Pre-crushed sunflower husks (50 g) and 600 ml of an aqueous solution of H2SO4 (9% by weight) were placed in a 1000 ml round-bottomed flask.

[0042] While mechanically stirring, the solution is irradiated with an ultrasonic reactor at 40 kHz for 20 minutes. The resulting mixture is then heated for 90 minutes. Afterward, the solution is filtered, neutralized with calcium carbonate, and sodium chloride is added at a rate of 10 g per 100 ml of solution. The resulting mixture is extracted with ethyl acetate, after which the lower-boiling fraction is distilled off. The resulting liquid product is pale yellow. The yield relative to the pentose content in dry matter is 88.1%.

[0043] Example 3. Obtaining furan-2-carbaldehyde using ultrasound and an aqueous solution of sulfuric acid with a concentration of 5% from sunflower husk.

[0044] Pre-crushed sunflower husks (50 g) and 700 ml of an aqueous solution of H2SO4 (5% by weight) were placed in a 2000 ml round-bottomed flask.

[0045] While mechanically stirring, the solution is irradiated with an ultrasonic reactor at 40 kHz for 45 minutes. The resulting mixture is then heated for 120 minutes. Afterward, the solution is filtered, neutralized with calcium hydroxide, and sodium chloride is added at a rate of 10 g per 100 ml of solution. The resulting mixture is extracted with ethyl acetate, after which the lower-boiling fraction is distilled off. The resulting liquid product is pale yellow. The yield relative to the pentose content in dry weight is 62.3%.

[0046] As can be seen from the specific examples provided, the yields of furan-2-carbaldehyde 1 using ethyl acetate as the organic solvent and intermediate neutralization of the aqueous medium are no lower or higher than those achieved using the methods described in the prior art. Furthermore, each subsequent reaction utilized ethyl acetate purified from the previous reaction, demonstrating the environmentally friendly and cost-effective nature of the process.

[0047] Based on the above, it can be concluded that the proposed technical solution is new, has distinctive features and can be scaled up for the industrial production of furan-2-carbaldehyde.

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