JP2014043443A - Method of manufacturing lactic acids by using indium compound, tin compound and salts containing fluorine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alternative method of efficiently manufacturing lactic acids from carbohydrate-containing raw materials.SOLUTION: In a method of manufacturing lactic acids, carbohydrate-containing raw materials containing an indium compound, a tin compound and salts containing fluorine, and further, if required, one or several compounds selected from perfluoro alkylsulfonate of group 3 (including lanthanoid series), group 4, group 13 and group 15 in the periodic table, boric acid, organic boric acid and formaldehyde, and a derivative thereof are heat treated in a solvent containing water and/or alcohol.

Description

  The present invention relates to a method for producing lactic acids from a carbohydrate-containing raw material using a combination of an indium compound and a tin compound and a salt containing fluorine as a catalyst.

  In addition to the indium compound, the tin compound, and the salt containing fluorine, the present invention further includes groups 3 (including lanthanoids), groups 4, 13 and 15 of the periodic table. The present invention relates to a method for producing lactic acids from a carbohydrate-containing raw material by using, as a catalyst, one or more compounds selected from perfluoroalkyl sulfonate, boric acid, organic boric acid, and formaldehyde and derivatives thereof.

  At present, a method for producing lactic acid that is industrially used is based on lactic acid fermentation of saccharides (see Patent Document 1). However, in order to use cellulose as a raw material for lactic acid fermentation by this method, it is necessary to go through a saccharification step using an acid or an enzyme. In general, the method for producing lactic acid by fermentation has a slow reaction rate, requires a huge fermenter, and has a problem that the energy consumption for purification becomes large because the concentration of lactic acid produced is low. In addition, lactic acid fermentation is performed while neutralizing with a base because the fermentation efficiency of lactic acid bacteria decreases as the pH of the solution decreases as the fermentation progresses. Accordingly, lactate is produced by this lactic acid fermentation method, and treatment with acid is performed to liberate lactic acid from lactate, and treatment of neutralized salt resulting therefrom is a major problem in the process. Yes.

  As a method for producing lactic acid that does not depend on a biological method, a chemical method in which a carbohydrate is hydrothermally treated in the presence of an alkali is known. For example, when saccharides (see Non-Patent Documents 1 and 2), cellulose (see Patent Documents 2 and 3), or organic waste (see Non-Patent Document 4) are treated by this method, reaction conditions of high temperature and high pressure are performed. Lactic acid is produced by isomerization of some of the carbohydrates decomposed in However, in this method, lactic acid reacts with the alkali added as a catalyst to form a lactate, so that in order to separate lactic acid as an acid, it is necessary to add some inorganic acid to the reaction solution to make it acidic. There is a problem that the alkali and the inorganic acid are consumed stoichiometrically.

  As a chemical production method of lactic acid without using an alkali, there has been reported a method of converting starch, oligosaccharide or monosaccharide into a lactic acid ester by reacting with alcohol using a metal halide as a catalyst (Patent Literature). 3). However, as a result of investigations by the present inventors, the cellulose-based raw material could not be decomposed at a temperature lower than 200 ° C., and formation of lactic acid or lactic acid ester was not recognized.

  In addition, an example in which a cellulose-based raw material is directly converted to lactic acid by a chemical reaction without using an alkali has been reported, but this is very high temperature and high pressure (temperature 350 ° C. or more and less than 400 ° C., pressure 20 MPa or more and 35 MPa). ), The energy consumption is large, and the yield of lactic acid is insufficient (see Patent Document 4).

  In addition, as a report of producing lactic acid from cellulose-based raw materials in one step, examples using Group 3 metal salts as catalysts (see Patent Documents 5 and 6) and examples using rare earth metal oxides as catalysts (Patent Document 7). Have been reported). In these methods, there is a demand for a production method in which the lactic acid yield is high only under relatively low raw material concentration conditions and the lactic acid yield is good at practically higher raw material concentrations.

  In addition, the present inventors have previously reported a method for producing lactic acids from cellulose-based raw materials using various metal compounds such as indium compounds, tin-containing compounds, and rhenium compounds as catalysts (patents). Document 8-11). In these methods, it is possible to obtain lactic acids with a relatively high yield as compared with conventional production methods, but in the field, the production can still obtain lactic acids with a higher yield. The law is sought.

JP-A-6-31886 JP-A-2005-232116 JP 2004-359660 A JP 2004-323403 A JP 2008-120996 A JP 2009-263242 A JP 2009-263241 A JP 2011-213637 A JP 2011-225513 A JP 2012-097007 A JP2012-097010A

Byung Y. Y. and Montgomery R.M. , Carbohydrate Research, Vol. 280 (1996) p. 27-45 Byung Y. Y. and Montgomery R.M. , Carbohydrate Research, Vol. 280 (1996) p. 47-57 Niemelae K.M. and Sjoestroem E. et al. , Biomass, 11 (1986) p. 215-221 Armando T. Q. et al. , Journal of Hazardous Materials, B93 (2002)

  An object of the present invention is to provide an alternative method for efficiently producing lactic acids from a carbohydrate-containing raw material.

  As a result of intensive studies to solve the above problems, the present inventors have efficiently used lactic acids from a carbohydrate-containing raw material by using a combination of an indium compound and a tin compound and a fluorine-containing salt as a catalyst. It was found that it can be manufactured.

  In addition to the indium compound, the tin compound, and the salt containing fluorine, the inventors further include Group 3 (including the lanthanoid group), Group 4, Group 13, and 15 of the periodic table. Lactic acid can be efficiently produced from carbohydrate-containing raw materials by using as a catalyst a combination of one or more compounds selected from perfluoroalkyl sulfonates, boric acid, organic boric acid, and formaldehyde and derivatives thereof I found out that I can do it.

That is, the present invention includes the following.
[1] A method for producing lactic acid, comprising subjecting a carbohydrate-containing raw material to heat treatment in a solvent containing water and / or alcohol containing an indium compound and a tin compound, and a salt containing fluorine.
[2] The method according to [1], wherein the fluorine-containing salt is at least one salt selected from the group consisting of tetrafluoroborate and fluoride salts.
[3] The method according to [1] or [2], wherein the tin compound is at least one compound selected from the group consisting of tin and organotin halides and tin and organotin perfluoroalkylsulfonates. .
[4] The method of [3], wherein the perfluoroalkyl sulfonate is trifluoromethane sulfonate.
[5] The method according to any one of [1] to [4], wherein the indium compound is a halide.
[6] The method of [3] or [5], wherein the halide is chloride.
[7] The method according to any one of [1] to [6], wherein the carbohydrate-containing raw material contains cellulose.
[8] The solvent is further at least one selected from the group consisting of perfluoroalkyl sulfonates of Group 3 (including lanthanoid groups), Group 4, Group 13, and Group 15 of the Periodic Table The method according to any one of [1] to [7], comprising a salt of a seed.
[9] The method according to [8], wherein the perfluoroalkyl sulfonate is trifluoromethane sulfonate.
[10] The method according to any one of [1] to [9], wherein the solvent further contains boric acid and / or organic boric acid.
[11] The method according to any one of [1] to [10], wherein the solvent further contains formaldehyde and / or a derivative thereof.

  In the method of the present invention, lactic acid can be produced from a carbohydrate-containing raw material in a very high yield as compared with the prior art.

  Hereinafter, the present invention will be described in detail.

  In the present invention, a lactic acid compound is obtained by heat-treating a carbohydrate-containing raw material in the presence of an indium compound and a tin compound that function as a catalyst and a salt containing fluorine in a solvent containing water and / or alcohol. Can be obtained as a reaction product.

  In the present invention, in addition to the indium compound, the tin compound, and the salt containing fluorine, which function as a catalyst in a solvent containing water and / or alcohol, the third group of the periodic table (the lanthanoid group) is added. Carbohydrates in the presence of one or more compounds selected from Group 4, Group 13, Group 15 and Group 15 perfluoroalkyl sulfonates, boric acid, organic boric acid, and formaldehyde and derivatives thereof By heat-treating the containing raw material, lactic acids can be obtained as a reaction product.

  In the present invention, “lactic acid” means lactic acid and / or lactic acid ester. The lactic acid ester is not particularly limited, but is preferably methyl lactate.

  When cellulose is used as a starting material, the production reaction of lactic acid or lactic acid ester from carbohydrate generally proceeds as follows.

  Cellulose is solvolyzed in alcohol or water under high temperature and pressure to produce saccharides. Under this reaction condition, the produced saccharide is further decomposed to be converted into a low molecular compound, or conversely polymerized into a carbonaceous polymer compound. The decomposition reaction includes dehydration reaction and retroaldolization. In the dehydration reaction, 5-methoxymethylfurfural is produced, and in retroaldolization, glycolaldehyde (dicarbon sugar), dihydroxyacetone or glyceraldehyde (tricarbon sugar), and erythritol (tetracarbon sugar) are produced. Among these, tricarbon sugar can be converted into lactic acid by isomerization. Furthermore, lactic acid is converted into a lactic acid ester by a dehydration condensation reaction with alcohol.

  The carbohydrate-containing raw material that can be used as the raw material in the method of the present invention may be any raw material containing carbohydrate. Without limitation, the carbohydrate-containing material can be any carbohydrate such as a monosaccharide, oligosaccharide (2-9 linked monosaccharides), or polysaccharide (10 or more monosaccharides bonded), or It may be a biological material containing it. Although it does not limit as a polysaccharide, A cellulose is preferable. Carbohydrate-containing raw materials include, for example, carbohydrates containing hexoses such as cellulose, holocellulose, cellobiose, starch (for example, soluble starch), maltose, glucose, mannose, fructose, galactose, and growth, hemicellulose, xylose, arabinose, etc. It may be a hemicellulose-based material containing carbon sugar, or at least one of them, for example, a lignocellulosic material. Although a carbohydrate containing raw material is not specifically limited, For example, the biomass material containing the above carbohydrates (for example, cellulose etc.) may be sufficient. Examples of carbohydrate-containing raw materials include lignocellulosic biomass materials including agricultural waste such as waste paper, sawn timber, wheat straw, corn stover, corn cob, and corn ears, and food waste containing sugars such as starch and glucose Etc. The carbohydrate-containing raw material used in the method of the present invention preferably contains water in addition to a carbohydrate such as cellulose.

  The solvent containing water and / or alcohol used in the method of the present invention is a solution containing water or alcohol, or both. This solvent may be water or alcohol alone, a mixed solution of water and alcohol, or a solution in which other components such as other organic solvents are mixed. As water, distilled water, ion exchange water, industrial water, or the like can be used. Although it does not specifically limit as alcohol, A C1-C8 aliphatic alcohol is preferable. For example, methanol, ethanol, propanol, isopropanol, 1-butanol, 2-butanol, ethylene glycol and the like can be mentioned. Hydrous alcohol can also be suitably used as a solvent in the present invention. One or two or more alcohols may be contained in the solvent. In the method of the present invention, when producing lactic acid, water is used as a solvent, and when producing a lactic acid ester, a solvent containing alcohol may be used.

  In the present invention, the “indium compound” may be in the form of halide (fluoride, chloride, bromide, and iodide), acetylacetone compound, alkoxide compound, carboxylate, phosphate, sulfate, nitrate, and the like. , Preferably a halide, particularly preferably a chloride. Examples of indium compounds that can be used in the present invention include indium (III) bromide, indium (III) chloride, indium (III) iodide, indium (III) chloride tetrahydrate, and the like.

  In one reaction system, as the indium compound, one type of compound selected from the above may be used, or two or more types may be used in combination.

In the present invention, the “tin compound” includes tin or organotin. “Organic tin” refers to tin (Sn) to which one or more organic substituents (hydrocarbon groups) are bonded. Although it does not specifically limit as a substituent couple | bonded on the tin atom of the organotin which can be used by this invention, For example, n-butyl group, t-butyl group, n-hexyl group, n-octyl group etc. are mentioned. Tin compounds may be in the form of halides (fluorides, chlorides, bromides, and iodides), acetylacetone compounds, alkoxide compounds, carboxylates, phosphates, sulfates, nitrates, etc., preferably halides is there. Examples of the tin compound that can be used in the present invention include tin (II) chloride and dibutyltin dichloride. The “tin compound” includes perfluoroalkyl sulfonates of tin or organotin. The perfluoroalkyl sulfonate of tin or organotin may be a tin (II) salt or a tin (IV) salt. The “perfluoroalkyl sulfonate” is not particularly limited, and examples thereof include trifluoromethane sulfonate, pentafluoromethane sulfonate, heptafluoropropane sulfonate, and nonafluorobutane sulfonate. In the present invention, a more preferred perfluoroalkyl sulfonate is trifluoromethane sulfonate (common name: triflate). As the perfluoroalkyl sulfonate of tin, for example, tin (II) trifluoromethanesulfonate (Sn (OTf) ₂ ) (Tf represents a trifluoromethylsulfonyl group CF ₃ SO ₂ —, the same applies hereinafter). It can be preferably used. As the perfluoroalkylsulfonate of organotin, for example, dibutyltin (II) trifluoromethanesulfonate can be used particularly preferably.

  In one reaction system, one type of compound selected from the above may be used as the tin compound, or two or more types may be used in combination.

  In the present invention, “a salt containing fluorine” means a salt containing a fluorine atom, and examples thereof include fluoride salts, fluoroborates, fluorosilicates, fluorophosphates, fluorotitanates and the like. Tetrafluoroborate is preferable. The cation in the salt is not particularly limited, and alkali metal salts such as lithium salt, sodium salt and potassium salt, alkaline earth metal salts, other typical metal salts, transition metal salts, ammonium salts, phosphonium salts, carbonium salts and the like. It may be in a form, preferably an alkali metal salt or an ammonium salt. Examples of the “fluorine-containing salt” include sodium fluoride, tetrabutylammonium tetrafluoroborate, sodium tetrafluoroborate, disodium hexafluorosilicate, disodium hexafluorotitanate, trisodium hexafluoroaluminate and the like.

  Further, in the present invention, perfluoroalkyl sulfonates belonging to Group 3 (including lanthanoid group), Group 4, Group 13, and Group 15 of the Periodic Table can be used as a catalyst. “Perfluoroalkyl sulfonates of Group 3 (including lanthanoids), Group 4, Group 13, and Group 15 of the periodic table” include Group 3 (Lantanoids) of the Periodic Table. Group 4), Group 13, Group 13 and Group 15 trifluoromethanesulfonate, pentafluoromethanesulfonate, heptafluoropropanesulfonate, nonafluorobutanesulfonate and the like. In the present invention, these perfluoroalkyl sulfonates are more preferably trifluoromethane sulfonate (common name: triflate). Examples of the “group 3 (including lanthanoid group), group 4, group 13 and group 15 perfluoroalkylsulfonates of the periodic table” that can be used in the present invention include scandium, yttrium, Examples include hafnium, aluminum, indium, bismuth, cerium, thulium, ytterbium, and samarium trifluoromethanesulfonate.

  In one reaction system, group 3 (including lanthanoid group), group 4, group 13, and group 15 perfluoroalkylsulfonates of the periodic table are selected from the above. A compound may be used and may be used in combination of 2 or more types.

  In the present invention, boric acid and / or organic boric acid can be used as a catalyst. “Organic boric acid” refers to boric acid to which one or more organic substituents (hydrocarbon groups) are bonded. The substituent bonded to boric acid of the organic boric acid that can be used in the present invention is not particularly limited, and examples thereof include an isobutyl group, an n-butyl group, a t-butyl group, an n-hexyl group, and an n-octyl group. For example, isobutyl boronic acid can be used.

  In one reaction system, boric acid and / or organic boric acid may use one kind of compound selected from the above, or may use two or more kinds in combination.

  In the present invention, formaldehyde and / or a derivative thereof can further be used as a catalyst. Examples of formaldehyde derivatives include paraformaldehyde, trioxane, and ethylal.

  In one reaction system, one type of compound selected from the above may be used as formaldehyde and / or its derivative, or two or more types may be used in combination.

  In the method of the present invention, the amount of the solvent containing water and / or alcohol with respect to the carbohydrate-containing raw material can be appropriately selected by those skilled in the art and is not particularly limited. : Solvent = 1: 1 to 1: 1000, preferably 1: 5 to 1: 100.

  The total amount (usage amount) of the indium compound and the tin compound to be contained in the solvent containing water and / or alcohol can be determined based on the number of moles of monosaccharides contained in the carbohydrate-containing raw material. An amount corresponding to 0.001 to 1.0 mol, preferably 0.005 mol to 0.1 mol, for example 0.01 to 0.05 mol in terms of mass ratio per mol of monosaccharide residues in the carbohydrate-containing raw material can be used (particularly, It is not limited to these). If the amount used is too small, the decomposition of cellulose is difficult to proceed, and if it is too large, the yield of lactic acid or lactic acid ester decreases due to side reactions, which is not preferable.

  Further, the total amount (usage amount) of the fluorine-containing salt contained in the solvent containing water and / or alcohol is 0.000 with respect to 1.0 mol of the total amount (usage amount) of the indium compound and the tin compound. An amount corresponding to 1 to 10.0 mol, preferably 0.1 mol to 5.0 mol, for example, 0.1 to 2.5 mol can be used (not particularly limited thereto).

  In addition, perfluoroalkyl sulfonates of Group 3 (including lanthanoid group), Group 4, Group 13, and Group 15 of the Periodic Table to be contained in a solvent containing water and / or alcohol The total amount (used amount) is 0.1 to 10.0 mol, preferably 0.1 to 5.0 mol, for example 0.1 to 0.1 mol with respect to the total amount (used amount) of the indium compound and tin compound. An amount corresponding to 2.5 mol can be used (not particularly limited thereto).

  Moreover, the total amount (usage amount) of boric acid and / or organic boric acid contained in the solvent containing water and / or alcohol is 1.0 mol with respect to the total amount (usage amount) of the indium compound and tin compound. An amount corresponding to 10.0 to 300.0 mol, preferably 50.0 mol to 200.0 mol, for example, 50.0 mol to 100.0 mol can be used (but is not particularly limited thereto).

  Further, the total amount (use amount) of formaldehyde and / or a derivative thereof contained in the solvent containing water and / or alcohol is 10 with respect to 1.0 mol of the total amount (use amount) of the indium compound and the tin compound. An amount corresponding to 0.0 to 300.0 mol, preferably 50.0 mol to 200.0 mol, for example, 50.0 mol to 100.0 mol can be used (but is not particularly limited thereto).

  In the method of the present invention, a carbohydrate-containing raw material is heat-treated in a solvent containing water and / or alcohol in the presence of an indium compound and a tin compound that function as a catalyst and a salt containing fluorine. Alternatively, in addition to an indium compound, a tin compound, and a salt containing fluorine, which function as a catalyst in a solvent containing water and / or alcohol, group 3 (including the lanthanoid group) of the periodic table, Carbohydrates in the presence of one or more compounds selected from Group 4, Group 13 and Group 15 perfluoroalkyl sulfonates, boric acid, organic boric acid, and formaldehyde and / or derivatives thereof Heat the raw material. The conditions for the heat treatment can be appropriately adjusted depending on the type of saccharide or alcohol contained in the raw material, but are preferably 100 ° C to 300 ° C, more preferably 120 ° C to 250 ° C, and preferably 150 ° C to 200 ° C. Can be used for

  In the method of the present invention, the heat treatment is preferably performed in the absence of oxygen. In order to make the oxygen non-existing condition, it is preferable to fill the reaction vessel with an inert gas before the heat treatment and purge (exclude) the air. Although the kind of inert gas is not specifically limited, For example, nitrogen gas, argon gas, carbon dioxide gas etc. are mentioned as an example.

  The heat treatment of the present invention is also preferably performed under pressure. The reaction pressure is preferably at least atmospheric pressure, preferably 0.3 MPa to 20 MPa, and more preferably 0.4 MPa to 10 MPa.

  Although the reaction in the solvent containing water and / or alcohol in the method of the present invention is not limited, for example, it is preferably carried out in an autoclave. Another preferred reaction form is a continuous flow reaction method (continuous method). The reaction liquid in which the raw material / solvent / catalyst is mixed can be continuously supplied to a reactor controlled at a predetermined temperature and pressure, and allowed to stay in the reactor for a predetermined time for reaction.

  In the method of the present invention, for example, an electromagnetic stirring autoclave is mixed with an indium compound and a tin compound, a salt containing fluorine, and, if necessary, a group 3 (including a lanthanoid group), a group 4 of the periodic table, One or more compounds selected from Group 13 and Group 15 perfluoroalkyl sulfonates, boric acid, organic boric acid, and formaldehyde and derivatives thereof, and a solvent containing water and / or alcohol After charging and purging air with an inert gas, the reaction may be performed for a predetermined time by heating to the heating temperature. The heating time can be appropriately adjusted and is not particularly limited, but may be 30 minutes to 20 hours after reaching the heating temperature, and preferably 1 hour to 10 hours. In the method of the present invention, a relatively short processing time is required as compared with the conventional method. After a predetermined heating time has elapsed, heating may be stopped and allowed to cool to room temperature. After cooling to room temperature, the reaction product is removed from the autoclave.

  In the method of the present invention using a continuous flow reaction method, a carbohydrate-containing raw material, a solvent containing water and / or alcohol, an indium compound and a tin compound, a salt containing fluorine, and if necessary, a periodic table One or more selected from group 3 (including lanthanoid groups), group 4, group 13 and group 15 perfluoroalkyl sulfonates, boric acid, organic boric acid, and formaldehyde and its derivatives What is necessary is just to supply the reaction liquid which mixed several compounds continuously to the reactor controlled by the predetermined heating temperature and pressure, and to make it stay in a reactor for predetermined heating time, and to make it react. After the heating time has elapsed, heating may be stopped and allowed to cool to room temperature. After cooling to room temperature, the reaction product is removed from the reactor.

  By the above method, lactic acids can be produced in high yield. When the carbohydrate-containing material contains a monosaccharide such as fructose, when an indium compound and a tin compound are combined with a salt containing fluorine and used as a catalyst, lactic acids can be efficiently produced from those sugars. By using these combinations of catalysts, lactic acids can be converted to 60% or more, for example 63% to 70%, based on the number of moles produced per monosaccharide in the carbohydrate-containing feedstock, It can be obtained in a very high yield.

  When the carbohydrate-containing raw material contains a polysaccharide such as cellulose, an indium compound and a tin compound (particularly perfluoroalkyl sulfonate of tin or organotin) and a fluorine-containing salt are used in combination as a catalyst. Thus, the polysaccharide can be efficiently solvolyzed to obtain a saccharide, and lactic acid can be produced from the saccharide. For example, by this method, lactic acids can be obtained in a yield of 40% or more based on the number of moles produced per glucose residue in the carbohydrate-containing raw material. Further, when the carbohydrate-containing raw material contains a polysaccharide such as cellulose, in addition to the indium compound tin compound (particularly perfluoroalkyl sulfonate of tin or organotin), the salt containing fluorine, the third of the periodic table One or more compounds selected from perfluoroalkyl sulfonates of groups (including lanthanoid groups), groups 4, 13 and 15, boric acid, organic boric acid, and formaldehyde and derivatives thereof Can be used as a catalyst to produce lactic acids from the saccharides more efficiently.

  It is also preferable to separate lactic acids from the reaction solution obtained as described above. This separation can be performed by an organic acid separation method known to those skilled in the art, such as liquid chromatography.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the technical scope of the present invention is not limited to these examples.

[1] Production of lactic acid from fructose or cellulose using an indium compound, a tin compound, and a salt containing fluorine (Example 1)
In a 50 ml stainless steel pressure reactor (made by Nitto Koatsu), indium (III) chloride tetrahydrate (0.05 mmol) and dibutyltin dichloride (0.025 mmol) as metal compounds, and tetrabutylammonium as a salt Tetrafluoroborate (0.05 mmol), fructose (2.5 mmol) as a raw material carbohydrate, methanol 20 mL as a solvent, and a stirring bar were added, and the lid was closed. After the air in the autoclave was purged with nitrogen gas and pressurized to 0.5 MPa, the autoclave was heated to 160 ° C. using an electric furnace while stirring the mixture with a magnetic stirrer. Thereafter, stirring was continued for 10 hours while maintaining the temperature at 160 ° C., and then the autoclave was allowed to cool at room temperature. After cooling, the reaction solution was taken out from the autoclave, and the products in the solution were quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below. Each yield is a percentage (%) of the number of moles (mol) of the product with respect to the number of moles of lactic acid (lactic acid / fructose = 5 mmol / 2.5 mmol) theoretically generated from D-fructose as a raw material. Expressed in

(Example 2)
The reaction was conducted in the same manner as in Example 1 except that tin (II) chloride (0.01 mmol) was used instead of dibutyltin dichloride (0.025 mmol), and the product in the solution was quantitatively analyzed by liquid chromatography. did. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Example 3)
The reaction was conducted in the same manner as in Example 2 except that sodium tetrafluoroborate (0.05 mmol) was used instead of tetrabutylammonium tetrafluoroborate (0.05 mmol), and the product in the solution was obtained by liquid chromatography. Quantitative analysis was performed. The yield of lactic acids in the analysis results is shown in Table 1 below.

Example 4
The reaction was conducted in the same manner as in Example 2 except that sodium fluoride (0.05 mmol) was used instead of tetrabutylammonium tetrafluoroborate (0.05 mmol), and the product in the solution was quantified by liquid chromatography. analyzed. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Example 5)
In place of dibutyltin dichloride (0.025 mmol), dibutyltin (II) trifluoromethanesulfonate (0.01 mmol) and tetrabutylammonium tetrafluoroborate (0.05 mmol) in place of sodium tetrafluoroborate (0. The reaction was carried out in the same manner as in Example 1 except that 02 mmol) was used, and the product in the solution was quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Comparative Example 1)
The reaction was carried out in the same manner as in Example 3 except that indium (III) chloride tetrahydrate (0.05 mmol) and sodium tetrafluoroborate (0.05 mmol) were used and tin (II) chloride was not used. The product in solution was quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Comparative Example 2)
The reaction was carried out in the same manner as in Example 3 except that tin (II) chloride (0.01 mmol) and sodium tetrafluoroborate (0.01 mmol) were used and indium (III) chloride tetrahydrate was not used. The product in solution was quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Comparative Example 3)
The reaction was conducted in the same manner as in Example 2 except that sodium chloride (0.05 mmol) was used instead of tetrabutylammonium tetrafluoroborate (0.05 mmol), and the product in the solution was quantitatively analyzed by liquid chromatography. did. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Example 6)
Indium (III) chloride tetrahydrate (0.05 mmol) as a metal compound and dibutyltin (II) trifluoromethanesulfonate (0.025 mmol), sodium tetrafluoroborate (0.02 mmol) as a salt, and cellulose ( The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was 200 ° C., and the product in the solution was quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below. Each yield is a percentage of the number of moles (mol) of the product with respect to the number of moles of lactic acid theoretically produced from the raw material cellulose (lactic acid / glucose unit in cellulose = 5 mmol / 2.5 mmol) ( %).

(Example 7)
The reaction was performed in the same manner as in Example 6 except that the reaction time was 20 hours, and the product in the solution was quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Comparative Example 4)
Same as Example 6 except that indium (III) chloride tetrahydrate (0.05 mmol) and sodium tetrafluoroborate (0.02 mmol) were used and dibutyltin (II) trifluoromethanesulfonate was not used. The product in the solution was quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Comparative Example 5)
Same as Example 6 except that dibutyltin (II) trifluoromethanesulfonate (0.025 mmol) and sodium tetrafluoroborate (0.02 mmol) were used and no indium (III) chloride tetrahydrate was used. The product in the solution was quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below.

(Comparative Example 6)
The reaction was performed in the same manner as in Example 6 except that sodium chloride (0.02 mmol) was used instead of sodium tetrafluoroborate (0.02 mmol), and the product in the solution was quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 1 below.

(result)
As shown in the results of Example 1-5 and Comparative Example 1-3 in Table 1, by using a combination of an indium compound, a tin compound, and a salt containing fluorine as a catalyst, 63% of lactic acid is obtained from fructose. It was possible to obtain a very high yield exceeding. Moreover, as shown in the results of Examples 6 and 7 and Comparative Example 4-6 in Table 1, by using a combination of an indium compound, a tin compound, and a fluorine-containing salt as a catalyst, 42 lactic acids can be obtained from cellulose. % With very high yields.

  From these results, it is possible to produce lactic acids at a very high yield from carbohydrate-containing raw materials containing monosaccharides and / or polysaccharides by using a combination of an indium compound, a tin compound, and a salt containing fluorine as a catalyst. Became clear.

[2] Production of lactic acid from cellulose using indium compound, tin compound, fluorine-containing salt, and various perfluoroalkyl sulfonates (Examples 8 to 20)
In a 50 ml stainless steel pressure reactor (made by Nitto Koatsu), indium (III) chloride tetrahydrate as metal compound A, dibutyltin trifluoromethanesulfonate (II) as metal compound B, and perfluoro as metal compound C An alkyl sulfonate and sodium tetrafluoroborate as a salt are added in the formulation shown in Table 2 below, and cellulose (corresponding to 2.5 mmol as glucose unit) as a raw material carbohydrate, methanol 20 mL as a solvent, a stir bar And the lid was closed. The air in the autoclave was purged with nitrogen gas and pressurized to 0.5 MPa, and then the autoclave was heated to 200 ° C. using an electric furnace while stirring the mixture with a magnetic stirrer. Thereafter, stirring was continued for 10 hours while maintaining at 200 ° C., and then the autoclave was allowed to cool at room temperature. After cooling, the reaction solution was taken out from the autoclave, and the products in the solution were quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 2 below. Each yield is a percentage of the number of moles (mol) of the product with respect to the number of moles of lactic acid theoretically produced from the raw material cellulose (lactic acid / glucose unit in cellulose = 5 mmol / 2.5 mmol) ( %).

(result)
By using a combination of an indium compound, a tin compound, a perfluoroalkyl sulfonate, and a salt containing fluorine as a catalyst, lactic acids could be obtained at a higher yield than cellulose. In particular, by using any triflate selected from aluminum, ytterbium, and samarium as a perfluoroalkyl sulfonate as a catalyst, methyl lactate can be obtained in a very high yield exceeding 40% from cellulose. It was.

[3] Production of lactic acid from cellulose using indium compound, tin compound, fluorine-containing salt, various perfluoroalkyl sulfonates, and boric acid (Examples 21 to 33)
Indium (III) chloride tetrahydrate as the metal compound A, dibutyltin (II) trifluoromethanesulfonate as the metal compound B, perfluoroalkyl sulfonate as the metal compound C, and sodium tetrafluoroborate as the salt are described later. After adding boric acid (2.50 mmol) and pressurizing to 3.5 MPa, the reaction is performed in the same manner as in [2] above, and the product in the solution is subjected to liquid chromatography. Quantitative analysis was performed by chromatography. The yield of lactic acid in the analysis results is shown in Table 3 below.

(result)
As is clear from the results in Table 2, in addition to the indium compound, tin compound, perfluoroalkyl sulfonate, and fluorine-containing salt, boric acid is used as a catalyst in combination with lactic acids from cellulose. Could be obtained in high yield. In particular, as a perfluoroalkyl sulfonate, 40% of methyl lactate is obtained from cellulose by using any triflate selected from aluminum, cerium, scandium, thulium, ytterbium, hafnium, yttrium, bismuth, and samarium as a catalyst. Can be obtained in very high yields exceeding.

[4] Production of lactic acid from cellulose using indium compound, tin compound, fluorine-containing salt, perfluoroalkyl sulfonate, and organic boric acid (Example 34)
The reaction was performed in the same manner as in [Example 29] except that isobutylboronic acid (2.50 mmol) was used instead of boric acid (2.50 mmol), and the product in the solution was quantitatively analyzed by liquid chromatography. did. The yield of lactic acid in the analysis results is shown in Table 4 below.

(result)
As is clear from the results of Example 29 in Table 3, methyl lactate was obtained in a very high yield (54%) than cellulose by using isobutyl boronic acid instead of boric acid.

[5] Production of lactic acid from cellulose using a derivative of indium compound, tin compound, fluorine-containing salt, perfluoroalkyl sulfonate, and formaldehyde (Examples 35 to 37)
Indium (III) chloride tetrahydrate as metal compound A, dibutyltin (II) trifluoromethanesulfonate as metal compound B, samarium triflate as metal compound C (perfluoroalkyl sulfonate), and sodium tetrafluoroborate as salt In addition, formaldehyde derivatives were added in the formulations shown in Table 5 below, and the reaction was carried out in the same manner as in [Example 16] above, and the products in the solution were quantitatively analyzed by liquid chromatography. The yield of lactic acids in the analysis results is shown in Table 5 below.

(result)
As apparent from comparison with the results of Example 16 in Table 2, in addition to the indium compound, tin compound, perfluoroalkyl sulfonate, and the salt containing fluorine, a derivative of formaldehyde is used in combination as a catalyst. It was possible to obtain methyl lactate in a very high yield exceeding 50% from cellulose.

[6] Production of lactic acid from cellulose using derivatives of indium compound, tin compound, fluorine-containing salt, various perfluoroalkyl sulfonates, boric acid, and formaldehyde (Examples 38 to 41)
Indium (III) chloride tetrahydrate as metal compound A, dibutyltin (II) trifluoromethanesulfonate as metal compound B, samarium triflate or thulium triflate as metal compound C (perfluoroalkyl sulfonate), sodium tetrafluoro as salt Borates, boric acid, and derivatives of formaldehyde were added in the formulations shown in Tables 6 and 7 below, respectively, and the reaction was carried out in the same manner as in the above [Examples 24 and 29], and the products in the solution were Quantitative analysis was performed by liquid chromatography. The yield of lactic acid in the analysis results is shown in Table 6 below.

(result)
As apparent from comparison with the results of Examples 24 and 39 in Table 3, in addition to indium compound, tin compound, perfluoroalkyl sulfonate, salt containing fluorine, and boric acid, formaldehyde or a derivative thereof is combined. As a catalyst, methyl lactate was obtained in a very high yield exceeding 57% from cellulose.

  From the above results, in addition to the indium compound, the tin compound, and the salt containing fluorine, the group 3 (including the lanthanoid group), group 4, group 13, and group 15 of the periodic table By using as a catalyst a combination of one or more compounds selected from perfluoroalkyl sulfonates, boric acid, organic boric acid and formaldehyde or derivatives thereof, a much higher yield than carbohydrate-containing raw materials containing polysaccharides It became clear that lactic acid (especially methyl lactate) can be manufactured by this.

  The method of the present invention provides a novel catalytic reaction system that efficiently converts biomass containing saccharides such as monosaccharides and polysaccharides into lactic acids. Use of the method of the present invention enables efficient production of lactic acids using biomass containing carbohydrates. By using the method of the present invention, for example, lactic acids can be produced in a very high yield compared to the prior art while suppressing the formation of by-products in one step from a saccharide in a carbohydrate-containing raw material by a chemical reaction. It becomes possible to do.

Claims (11)

  A method for producing lactic acid, comprising subjecting a carbohydrate-containing raw material to a heat treatment in a solvent containing water and / or alcohol containing an indium compound and a tin compound, and a salt containing fluorine.   The method of claim 1, wherein the fluorine-containing salt is at least one salt selected from the group consisting of tetrafluoroborate and fluoride salts.   The method according to claim 1 or 2, wherein the tin compound is at least one compound selected from the group consisting of tin and organotin halides and tin and organotin perfluoroalkylsulfonates.   The method according to claim 3, wherein the perfluoroalkyl sulfonate is trifluoromethane sulfonate.   The method according to claim 1, wherein the indium compound is a halide.   6. A process according to claim 3 or 5, wherein the halide is chloride.   The method according to any one of claims 1 to 6, wherein the carbohydrate-containing raw material comprises cellulose.   The solvent further includes at least one salt selected from the group consisting of group 3 (including lanthanoid group), group 4, group 13, and group 15 perfluoroalkyl sulfonates of the periodic table The method according to claim 1, comprising:   The method of claim 8, wherein the perfluoroalkyl sulfonate is trifluoromethane sulfonate.   The method according to claim 1, wherein the solvent further comprises boric acid and / or organic boric acid.   The method according to any one of claims 1 to 10, wherein the solvent further comprises formaldehyde and / or a derivative thereof.