Method for preparing sugars that are at least partially acetal protected.

Abstract

The present invention relates to a process for preparing an at least partially acetal-protected sugar, comprising the step of reacting a sugar or sugar derivative selected from the group consisting of aldopentoses, aldohexoses, aldopentosides and aldohexosides with an aldehyde or aldehyde source in the presence of a heterogeneous acidic catalyst to form an at least partially acetal-protected sugar selected from the group consisting of compounds of formula (I), (II), (III), (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI) and (XII): In the formula, R1, R1', R2, R2', R3, R3', R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 and R 12 and R and R′, R and R′, R and R′, and R 12 and R 12 are identical or different from one another; and Y is hydrogen or a straight, branched, or cyclic hydrocarbon moiety having 1 to 20 carbon atoms; Z is a linear, branched, or cyclic hydrocarbon moiety having 0 to 12 carbon atoms, optionally substituted with 1 to 4 C1-C4 alkyl groups, or 1 to 4 halogen atoms, or a benzyl group; and E is -COOH, -CH(COOH)2, -COOR 19 , -CH(COOR 20 )(COOR 21 ), -CHO, -CH(CHO)2, -C2H3, -CH(C2H3)2, -CHCHR 22 , -CHCR 23 R 24 , -C2H, -C2R 25 , -N3, -NH2, -CH(NH2)2, -NHR 26 , -CH(NHR 27 )(NHR 28 ), -NR 29 R 30 , -CH(NR 31 R 32 )(NR 33 R 34 ), -OH, -OR35 , or -CH(R 36 OH)(R 37 OH); and R 19 , R 20 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R 29 , R 30 , R 31 , R 32 , R 33 , R 34 and R 35 are C1 to C 20 is alkyl; and R 20 and R 21 , R 23 and R 24 , R 27 and R 28 , R 29 and R 30 , R 31 and R 32 , and R 33 and R 34 are identical to or different from one another; and R 36 and R 37 are, independently of one another, absent or straight-chain or branched C1-C 12 is a hydrocarbon chain; and R 13 , R 14 , R 15 , R 16 , R 17 and R 18 are each independently hydrogen or a straight-chain, branched-chain, or cyclic hydrocarbon moiety having 1 to 20 carbon atoms. JPEG2025536078000039.jpg83102

Description

[Technical Field]

[0001] The present invention relates to a method for preparing sugars that are at least partially acetal-protected. [Background technology]

[0002] In recent years, the gradual depletion of fossil fuel resources, increasing global energy consumption, and environmental problems have driven the development of new materials and technologies that utilize renewable biological resources such as biomass and food waste. One of the cutting-edge topics in this field is the development of bio-based chemicals, which are considered more environmentally friendly alternatives to petroleum-derived chemicals. Essentially, bio-based chemicals often do not result in a net increase in carbon dioxide in the atmosphere when their lifespan ends, thus ensuring less environmental damage.

[0003] International Publication No. 2022 / 223480 discloses acetal-protected xylose, i.e., diformyl xylose (DFX) and its derivatives, as environmentally friendly polar aprotic solvents. Example 1 demonstrates a synthesis route from commercially available D-xylose and paraformaldehyde using a homogeneous acidic catalyst (H2SO4) that must be added dropwise, thus avoiding sugar degradation.

[0004] International Publication No. 2021 / 074211 discloses a method for producing polymerizable monomers from renewable resources such as biomass. It shows that glyoxylic acid-protected xylose can be produced in the presence of a homogeneous acidic catalyst. This glyoxylic acid-protected xylose can be used in polymer synthesis.

[0005] Y.M.Questell-Santiago, R.Zambrano-Varela, M.Talebi Amiri, and J.S.Luterbacher, Nat. Chem. 2018, 10, 1222-1228, disclose that DFX can be directly synthesized from D-xylose using 1,4-dioxane as a solvent and n-hexane as an extraction solvent in the presence of a 37 wt% aqueous solution of formaldehyde and a 37 wt% aqueous solution of HCl.

[0006] All methods require the continuous addition and neutralization of a homogeneous acid system, which is undesirable for large-scale treatments due to additional costs and waste management. [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention was to provide a simpler method for preparing acetal-protected sugars in high yield using an expandable method. [Means for solving the problem]

[0008] This problem is solved by the method described in claim 1. More preferred embodiments are the subject of dependent claims 2 to 15.

[0009] It has been found that at least partially acetal-protected sugars can be prepared by a method comprising the step of reacting a sugar or sugar derivative selected from the group consisting of aldopentoses, aldohexoses, aldopentosides, and aldohexosides with an aldehyde or aldehyde source in the presence of a heterogeneous acidic catalyst to form a sugar at least partially acetal-protected, selected from the group consisting of compounds of the following formulas I, II, III, IV, V, VI, VII, VIII, IX, X, XI, and XII.

[0010] [ka] [Chemical] [Chemical]

[0011] In the formula, R1, R1’, R2, R2’, R3, R3’, R4, R5, R6, R7, R8, R9, R 30 , 21 , 20 , R 11 , R 12 and R 12 ’ are Y or Z-E, and R1 and R1’, R2 and R2’, R3 and R3’, and R 12 and R 12 ’ are the same as or different from each other, Y is hydrogen or a linear, branched, or cyclic hydrocarbon moiety having 1 to 20 carbon atoms, Z is a linear, branched, or cyclic hydrocarbon moiety having 0 to 12 carbon atoms, which may be substituted with 1 to 4 C1-C4 alkyl groups, or 1 to 4 halogen atoms, or a benzyl group, and E is -COOH, -CH(COOH)2, -COOR 19 , -CH(COOR 20 )(COOR 21 ), -CHO, -CH(CHO)2, -C2H3, -CH(C2H3)2, -CHCHR 22 , -CHCR 23 R 24 , -C2H, -C2R 25 , -N3, -NH2, -CH(NH2)2, -NHR 26 , -CH(NHR 27 )(NHR 28 ), -NR 29 R 30 , -CH(NR 31 R 32 )(NR 33 R 34 ), -OH, -OR 35 , or -CH(R 36 OH)(R 37 OH), and, R 19 , R 20 , R 21 , R22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R 29 , R 30 , R 31 , R 32 , R 33 , R 34 and R 35 These are C1~C, which are independent of each other. 20 It is alkyl, and R 20 and R 21 , R 23 and R 24 , R 27 and R 28 , R 29 and R 30 , R 31 and R 32 , and R 33 and R 34 They are either identical or different from each other, and R 36 and R 37 These are independent of each other, either nonexistent or linear or branched C1-C1 chains. 12 It is a hydrocarbon chain, and R 13 , R 14 , R 15 , R 16 , R 17 and R 18 These are linear, branched, or cyclic hydrocarbon portions, each independently containing hydrogen or 1 to 20 carbon atoms.

[0012] The use of heterogeneous acid catalysts reduces the need for continuous addition and neutralization of homogeneous acids. These catalysts can be easily recycled, for example, by filtration, which is advantageous from both an economic and environmental perspective. Furthermore, these catalysts can be used as packing material in continuous flow reactors for large-scale production. They also improve the yield and selectivity of acetal-protected sugars compared to conventional homogeneous catalyst systems such as HCl or H2SO4.

[0013] Furthermore, despite the high reactivity of aldehydes to undesirable aldol condensation, oxidation, autopolymerization, and geminal diol formation during the reaction, it is possible to obtain compounds of formulas I-XII in the presence of heterogeneous catalysts. Moreover, the aldehyde-specific hydrate formation allows for control of the rate and selectivity of sugar protection by adjusting the water content in the reaction system.

[0014] The selectivity for acetal-protected sugars can be further enhanced by the various pore sizes and affinity of heterogeneous catalysts to reactants and products. Selectivity for small products can be enhanced by heterogeneous catalysts with small pores, for example, by enhancing the selective formation of compounds of formulas IV-XI compared to compounds of formulas I, II, III, and XII, or by enhancing the selection of bulkier R groups (R1, R1', R2, R2', R3, R3', R4, R5, R6, R7, R8, R9, R). 10 , R 11 , R 12 and R 12 Smaller R groups (R1, R1', R2, R2', R3, R3', R4, R5, R6, R7, R8, R9, R) than the group selected from '. 10 , R 11 , R 12 and R 12 The selective formation of compounds of formulas I to XII having a group selected from ' can be enhanced. Conversely, the selectivity for larger products can be enhanced by heterogeneous catalysts with large pores, for example, the selective formation of compounds of formulas I, II, III, and XII can be enhanced more than that of compounds of formulas IV to XI, or the selective formation of compounds of formulas I to XII having a bulkier R group can be enhanced more than that of a smaller R group. Similarly, selectivity can be adjusted by the affinity between the aldehyde and the heterogeneous catalyst. A high affinity between the aldehyde and the heterogeneous catalyst results in higher selectivity for the formation of compounds of formulas I, II, III, and XII than that of compounds of formulas IV to XI. A low affinity between the aldehyde and the heterogeneous catalyst results in higher selectivity for the formation of compounds of formulas IV to XI than that of compounds of formulas I, II, III, and XII.

[0015] Some of the compounds produced by the method according to the present invention can be used as environmentally friendly polar aprotic solvents. Some of these compounds that can be used as these types of solvents perform comparably to or better than conventional fossil-based analogues. Furthermore, they have many other applications. For example, these compounds can be used as foundational molecules for the production of many other bio-based products, and therefore, the efficient production of these compounds is important. For example, DFX can be a starting compound for producing xylitol, a food additive. Partially acetal-protected sugars having long-chain hydrocarbon aldehydes such as alkyl or alkenyl aldehydes can also be used as bio-based surfactants. Fully protected sugars having esters, carboxyls, or hydroxyls in the corresponding R groups can be used as building blocks for polymer production.

[0016] Within the scope of the present invention, the term "aldopentose" means a pentose having an aldehyde functional group as its terminal carbon atom, preferably selected from the group consisting of D-ribose, L-ribose, D-arabinose, L-arabinose, D-xylose, L-xylose, D-lyxose, and L-lyxose. Due to sugar tautomerism, this aldopentose can be used in a linear pyranose or furanose conformation or a mixture thereof.

[0017] Within the scope of the present invention, the term "aldohexose" means a hexose having an aldehyde functional group as its terminal carbon atom, and is preferably selected from the group consisting of D-allose, L-allose, D-altrose, L-altrose, D-glucose, L-glucose, D-mannose, L-mannose, D-growth, L-growth, D-idose, L-idose, D-galactose, L-galactose, D-talose, and L-talose. Due to sugar tautomerism, this aldohexose can be used in a linear pyranose or furanose conformation or a mixture thereof.

[0018] Within the scope of the present invention, the term "aldopentoside" means a pentose as defined above, in which a functional group selected from the group consisting of a linear, branched, or cyclic hydrocarbon moiety having 1 to 20 carbon atoms, preferably a C1 to C4 alkyl group, is bonded to the oxygen atom at position 1 of the aldopentose by a glycosidic bond; therefore, it means 1-O-alkylaldopentose. This is preferably selected from the group consisting of 1-O-alkyl-D-ribose, 1-O-alkyl-L-ribose, 1-O-alkyl-D-arabinose, 1-O-alkyl-L-arabinose, 1-O-alkyl-D-xylose, 1-O-alkyl-L-xylose, 1-O-alkyl-D-lyxose and 1-O-alkyl-L-lyxose, and the alkyl group is preferably selected from the group consisting of methyl, ethyl, propyl and butyl, and most preferably methyl. Most preferably, the aldopentoside is 1-O-methyl-D-xylose. Due to the tautomerization of the sugar, this alkylaldopentose can be used in linear pyranose or furanose conformations, or in mixtures thereof. Due to the further protection of the hydroxyl group at position 1 of the sugar, this starting material can lead to the easier production of unilateral acetal monomers containing a free hydroxyl group. This can result in bifunctional monomers (such as hydroxy acids when glyoxylic acid is used).

[0019] Within the scope of the present invention, the term "aldohexoside" means a hexose as defined above, in which a functional group selected from the group consisting of a linear, branched, or cyclic hydrocarbon moiety having 1 to 20 carbon atoms, preferably a C1 to C4 alkyl group, is bonded to the oxygen atom at position 1 of the aldohexose by a glycosidic bond, and therefore means a 1-O-alkylaldohexose. This is preferably selected from the group consisting of 1-O-alkyl-D-allose, 1-O-alkyl-L-allose, 1-O-alkyl-D-altrose, 1-O-alkyl-L-altrose, 1-O-alkyl-D-glucose, 1-O-alkyl-L-glucose, 1-O-alkyl-D-glucose, 1-O-alkyl-L-glucose, 1-O-alkyl-D-idose, 1-O-alkyl-L-idose, 1-O-alkyl-D-galactose, 1-O-alkyl-L-galactose, 1-O-alkyl-D-talose and 1-O-alkyl-L-talose, and the alkyl group is preferably selected from the group consisting of methyl, ethyl, propyl and butyl, and most preferably methyl. Most preferably, the aldhexoside is 1-O-methyl-D-glucose. Due to the tautomerization of the sugar, this alkylaldohexose can be used in linear pyranose or furanose conformations, or in mixtures thereof. Due to further protection of the hydroxyl group at position 1 of the sugar, this starting material yields a more stable product without free -OH groups, which may be useful for producing linear polymers.

[0020] The term "at least partially acetal-protected sugar" means a sugar or sugar derivative selected from the group consisting of aldopentoses, aldohexoses, aldopentosides, and aldohexosides, wherein the aldopentose, aldohexose, aldopentoside, or aldohexoside is partially protected with an aldehyde, i.e., only two hydroxyl groups combine with one aldehyde to form one cyclic acetal (thus forming compounds of formula IV, V, VI, VII, VIII, IX, X, or XI), or the aldopentose, aldohexose, aldopentoside, or aldohexoside is fully protected, i.e., four hydroxyl groups combine with two aldehydes to form two corresponding cyclic acetals (thus forming compounds of formula I, II, III, or XII).

[0021] Aldehydes are organic compounds containing the group -CHO, and aldehyde sources are polymers or oligomeric compounds that can produce aldehydes under reaction conditions. The term aldehyde also encompasses the geminal diol of the corresponding aldehyde, i.e., aldehyde hydrate. [Modes for carrying out the invention]

[0022] One embodiment of the present invention is a set of formulas I, II, III and XII Regarding the preparation of fully protected compounds selected from the group consisting of the following compounds:

[0023] [ka]

[0024] In one embodiment of the present invention, R 13 , R 14 , R 15 , R 16 and R 17 is hydrogen, and as a result, it gives a compound selected from the group consisting of compounds of formulas IVa, VIa, VIIIa, Xa and XIa that is at least partially protected:

[0025]

Chem.

[0026] In one embodiment of the present invention, R 13 、R 14 、R 15 、R 16 and R 17 are linear, branched, or cyclic hydrocarbon moieties having 1 to 20 carbon atoms, preferably 1 to 6 carbon atoms, most preferably methyl, ethyl, propyl and butyl, ideally methyl, resulting in at least partially protected compounds selected from the group consisting of Formulas IVb, VIb, VIIIb, VIIb, Xb, XIb and XII:

[0027]

Chem.

Chem.

[0028] In one embodiment of the present invention, R1, R1’, R2, R2’, R3, R3’, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 and R 12 ’ are Y, and Y is hydrogen.

[0029] In a further embodiment of the present invention, R1, R1’, R2, R2’, R3, R3’, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 and R 12 ’ are Y, and are linear or branched C1-C 20 alkyl, linear or branched C2-C 20 alkenyl, a cycloaliphatic ring or an aromatic system, preferably C6-C 20It is selected from the group consisting of alkyl and combinations thereof.

[0030] The term "linear or branched C1-C 20 alkyl" refers to a linear or branched hydrocarbon group containing 1 to 20 carbon atoms. Examples of "alkyl" as used herein include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl.

[0031] The term "linear or branched C2-C 20 alkenyl" refers to a linear or branched hydrocarbon group containing 2 to 20 carbon atoms and having at least one carbon-carbon double bond. Examples of "alkenyl" as used herein include vinyl (ethenyl), propenyl, 2-methyl-1-propenyl, 1-butenyl, 2-butenyl, and isobutenyl.

[0032] The term "cycloaliphatic ring or aromatic system" refers to an aliphatic or aromatic ring system having 3 to 10, preferably 5 to 8 carbon atoms.

[0033] In one embodiment of the present invention, R1, R1', R2, R2', R3, R3', R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 and R 12 ' are Z-E, where Z is a linear, branched, or cyclic hydrocarbon moiety having 0 to 12 carbon atoms, which may be substituted with 1 to 4 C1-C4 alkyl groups, or 1 to 4 halogen atoms, or a benzyl group, and E is -COOH, -CH(COOH)2, -COOR 19 ,-CH(COOR 20 )(COOR 21 ), -CHO, -CH(CHO)2, -C2H3, -CH(C2H3)2, -CHCHR 22 , -CHCR 23 R 24 -C2H, -C2R 25 , -N3, -NH2, -CH(NH2)2, -NHR 26 ,-CH(NHR 27 )(NHR 28 ), -NR 29 R 30 -CH(NR 31 R 32 )(NR 33 R 34 ), -OH, -OR 35 , or -CH(R 36 OH)(R 37 OH) and, R 19 , R 20 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R 29 , R 30 , R 31 , R 32 , R 33 , R 34 and R 35 These are C1~C, which are independent of each other. 20 It is alkyl, and R 20 and R 21 , R 23 and R 24 , R 27 and R 28 , R 29 and R 30 , R 31 and R 32 , and R 33 and R 34 They are either identical or different from each other, and R 36 and R 37These are independent of each other, either nonexistent or linear or branched C1-C1 chains. 12 It is a hydrocarbon chain, and R 13 , R 14 , R 15 , R 16 , R 17 and R 18 These are linear, branched, or cyclic hydrocarbon portions, each independently containing hydrogen or 1 to 20 carbon atoms.

[0034] According to embodiments of the present invention, in compounds of formulas I, II, III, IV (IVa and IVb), V, VI (VIa and VIb), VII, VIII (VIIIa and VIIIb), IX, X (Xa and Xb), XI (XIa and XIb), and XII, ZE is preferably, -(CH2) m COOH;-C6H4COOH, where this aromatic ring may be substituted with 1-4 C1-C4 alkyl groups or 1-4 halogen atoms;-C6H 10 COOH, where this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups;-(CH2) m CH(COOH)2; -(CH2) m COOR 19 ;-C6H4COOR 19 Here, this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 COOR 19 Here, this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) m (COOR 20 )(COOR 21 );-C6H4CH(COOR 20 )(COOR 21 ) where this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 CH(COOR20 )(COOR 21 ) where this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) m CHO;-C6H4CHO, where the aromatic ring may be substituted with 1-4 C1-C4 alkyl groups or 1-4 halogen atoms;-C6H 10 CHO, where the aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups or 1 to 4 halogen atoms;-(CH2) m CH(CHO)2; -(CH2) m C2H3;-C6H4C2H3, where this aromatic ring may be substituted with 1-4 C1-C4 alkyl groups or 1-4 halogen atoms;-C6H 10 C2H3, where this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups;-(CH2) m CH(C2H3)2; -(CH2) m CHCHR 22 ;-C6H4CHCHR 22 Here, this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 CHCHR 22 Here, this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) m CHCR 23 R 24 ;-C6H4CHCR 23 R 24 Here, this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 CHCR 23 R 24 Here, this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) mC2H;-C6H4C2H, where this aromatic ring may be substituted with 1-4 C1-C4 alkyl groups or 1-4 halogen atoms;-C6H 10 A C2H ring, where this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) m C2R 25 ;-C6H4C2R 25 Here, this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 C2R 25 Here, this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups;

[0035] -(CH2) m N3;-C6H4N3, where this aromatic ring may be substituted with 1-4 C1-C4 alkyl groups or 1-4 halogen atoms;-C6H 10 N3, where this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) m NH2;-C6H4NH2, where this aromatic ring may be substituted with 1-4 C1-C4 alkyl groups or 1-4 halogen atoms;-C6H 10 NH2, where this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups;-(CH2) m CH(NH2)2; -(CH2) m NHR 26 ;-C6H4NHR 26 Here, this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 NHR 26 Here, this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) m NR 29 R 30 ;-C6H4NR29 R 30 Here, this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 NR 29 R 30 Here, this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) m CH(NR 31 R 32 )(NR 33 R 34 );-C6H4CH(NR 31 R 32 )(NR 33 R 34 ) where this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 CH(NR 31 R 32 )(NR 33 R 34 ) where this aliphatic ring may be substituted with 1 to 4 C1-C4 alkyl groups; -(CH2) m OH;-C6H4OH, where this aromatic ring may be substituted with 1-4 C1-C4 alkyl groups or 1-4 halogen atoms;-C6H 10 An OH group, where this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -(CH2) m Ure 35 ;-C6H4OR 35 Here, this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms;-C6H 10 Ure 35 Here, this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; -CH(R 36 OH)(R 37 OH);-C6H4CH(R 36 OH)(R 37OH) where this aromatic ring may be substituted with 1 to 4 C1 to C4 alkyl groups or 1 to 4 halogen atoms; or -C6H 10 CH(R 36 OH)(R 37 OH) where this aliphatic ring may be substituted with 1 to 10 C1-C4 alkyl groups; R 19 , R 20 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R 29 , R 30 , R 31 , R 32 , R 33 , R 34 and R 35 These are C1~C, which are independent of each other. 20 It is alkyl, and R 20 and R 21 , R 23 and R 24 , R 27 and R 28 , R 29 and R 30 , R 31 and R 32 , and R 33 and R 34 These are either identical or different from each other, preferably methyl, ethyl, propyl, and butyl, and R 36 and R 37 These are either nonexistent (e.g., -CH(OH)2 or -CH(OH)CH2OH) or C1-C1 in a straight or branched chain. 12 The hydrocarbon chain is preferably methylene, ethylene, propylene, or butylene.

[0036] m is an integer from 0 to 12, and more specifically, an integer from 0 to 4.

[0037] Within the scope of the present invention, the term "heterogeneous acidic catalyst" means that the acidic catalyst is in a solid phase and the reactants are in a liquid phase. Preferably, the acidic catalyst is a Brønsted acidic catalyst, and more preferably an anhydrous Brønsted acidic catalyst. More specifically, this may be a heterogeneous acidic material and / or optionally a Brønsted acidic catalyst, which may be incorporated into a solid carrier, for example, a resin bead, a membrane, porous carbon particles, a zeolite material, and other solid carriers, incorporated on these solid carriers, or covalently bonded to these solid carriers. The solid carrier may be a material comprising, for example, carbon, silicon dioxide, titanium dioxide, zirconium oxide, aluminum oxide, or any combination thereof.

[0038] Brønsted acids can donate protons and are known to those skilled in the art. The Brønsted acid may be, for example, a hydroxyl group crosslinking a zeolite, or a resin functionalized with a Brønsted acid moiety. Examples of such Brønsted acids that can be used to functionalize a resin are preferably selected from the group consisting of sulfuric acid, phosphoric acid, and methanesulfonic acid or mixtures thereof.

[0039] Preferably, the Brønsted acid catalyst is selected from the group consisting of the following: a. Acidic zeolite, b. Acid-doped zeolite, c. Resins functionalized with acidic moieties, d. Oxides functionalized at the acidic site, e. Acidic oxides, f. Heteropoly acids and their derivatives

[0040] As used herein, the term “acid-moisture functionalized resin” refers to a resin or polymer synthesized from an organic polymer substrate that acts as a medium for ion exchange. The organic polymer substrate is, for example, a sulfonated polystyrene-divinylbenzene or sulfonated tetrafluoroethylene-based fluoropolymer-copolymer, resulting in a strongly acidic cation-exchange resin or polymer. Non-limiting examples include Amberlyst®-15, Amberlyst®-36, Amberlyst®-XNIOIO, Amberlite® (e.g., Amberlite® IRC120), Dowex® D 2030, Nafion® NR50, and Nafion® SAC13.

[0041] The term "oxygenated oxide with acidic moieties" refers to materials obtained by functionalizing oxides such as zirconia, alumina, or silica, for example, through sulfation or sulfonation. Such solid acidic metal oxides may optionally be supported on a carrier material.

[0042] The term "acid oxide" refers to metal oxides that have Brønsted acidity, such as niobia or alumina.

[0043] As used herein, the term “zeolite” refers to both natural and synthetic porous, crystalline silicate materials (including aluminosilicates, borosilicates, and aluminoborosilicates) having a distinct crystalline structure determined by X-ray diffraction. Zeolites include a system of channels which may be interconnected with other channel systems or cavities, such as side pockets or cages. This channel system may be three-dimensional, two-dimensional, or one-dimensional. Zeolites include SiO4 and XO4 tetrahedra, where X may be Al (aluminum) or B (boron). Zeolites may include combinations of AlO4 and BO4 tetrahedra. In one embodiment, X is Al, and the zeolite does not include BO4 tetrahedra. The SiO4 and XO4 tetrahedra are linked at their corners via a common oxygen atom. The "Atlas of Zeolite Framework Types (C Baerlocher, LB McCusker, DH Olson, 6th edition, Elsevier, Amsterdam, 2007)," along with its web-based version (http: / / www.iza-structure.org / databases / ), provides an overview of topological and structural details of zeolite frameworks, including the types of ring structures present in zeolites and the channel dimensions defined by each ring type. Verified synthesis methods and good laboratory practices for zeolite synthesis can be found in "Verified synthesis of Zeolitic materials," 2nd edition, 2001. Various verified synthesis methods, including those for BO tetrahedra, are available. For example, the synthesis and characterization of boron-based zeolites with MFI topology are described by Cichocki and Parasiewicz-Kaczmarska (Zeolites, 1990, 10, 577-582).

[0044] Suitable zeolites for use in the method according to the present invention may include the following: - A zeolite having at least two, preferably two or three, uninterconnected parallel channel systems, at least one of which comprises channels of eight-membered rings or more; and having a Si / X2 ratio of the backbone of at least 4 as measured by NMR; or - A zeolite having at least two, preferably two or three, interconnected non-parallel channel systems, wherein at least one of these channel systems comprises channels with 10 or more membered rings; and the Si / X2 ratio of the skeleton is at least 4 as measured by NMR; or - A zeolite comprising three interconnected non-parallel channel systems, of which at least two are composed of channels with 10 or more member rings; and having a Si / X2 ratio of the backbone of at least 4 as measured by NMR; Here, each X is either Al or B.

[0045] As used herein, the term "channel system" means a system of parallel or non-parallel and crystallographically equivalent channels, where the channel is an 8-membered ring channel or larger, for example, a 10-membered ring channel or a 12-membered ring channel. Thus, as used herein, the term "channel" means an 8-membered ring or more-membered ring channel that is part of a system of parallel or non-parallel and crystallographically equivalent channels.

[0046] Zeolites suitable for use in the method of the present invention include channels with 10 or more member rings, for example, 12-membered ring channels (12MR) or larger channels. The ring sizes of each known zeolite framework type are provided in "Atlas of Zeolite Framework Types" (C Baerlocher, LB McCusker, DH Olson, 6th edition, Elsevier, Amsterdam, 2007), which is incorporated herein by reference.

[0047] As used herein, the term “eight-membered ring channel” or “8MR” refers to a channel containing an unobstructed eight-membered ring, where the eight-membered ring defines the minimum diameter of the channel. The eight-membered ring comprises eight T atoms and eight alternative oxygen atoms (forming the ring), where each T is Si, Al, or B. As used herein, the term “ten-membered ring channel” or “10MR” refers to a channel containing an unobstructed ten-membered ring, where the ten-membered ring defines the minimum diameter of the channel. The ten-membered ring comprises ten T atoms and ten alternative oxygen atoms (forming the ring), where each T is Si, Al, or B. As used herein, the term “twelve-membered ring” or “12MR” refers to a channel containing an unobstructed twelve-membered ring, where the twelve-membered ring defines the minimum diameter of the channel. A 12-membered ring comprises 12 T atoms and 12 alternative oxygen atoms (forming the ring), where each T is Si, Al, or B. As used herein, the term “10-membered ring or more-membered ring channel” refers to a 10-membered ring channel or a channel larger than that, and therefore includes, for example, both 10-membered ring channels and 12-membered ring channels.

[0048] The Si / X2 ratio of the framework can be determined by nuclear magnetic resonance (NMR) measurement, more specifically, 29 Si-NMR and 27This can be determined via Al-NMR. In a preferred embodiment, the B skeleton is absent, and the Si / X2 ratio is equal to the Si / Al2 ratio. The Si / Al2 ratio can be determined by NMR as described by Klinowski (Ann. Rev. Mater. Sci. 1988, 18, 189-218); or as described by G. Engelhardt and D. Michel ("High-Resolution Solid-State NMR of Silicates and Zeolites," John Wiley & Sons, Chichester 1987, xiv, p. 485). The Si / B2 ratio can be determined by NMR as discussed by D. Trong On et al. ("Studies in Surface Science and Catalysis," 1995, 97, 535-541; Journal of Catalysis, November 1995, Volume 157, Issue 1, pp. 235-243).

[0049] Zeolites are thermally stable catalysts and, therefore, can be regenerated by calcination, in contrast to classical thermally unstable ion exchange resins such as Amberlyst®-15.

[0050] As used herein, the term "heteropoly acid" refers to compounds including: - A metal selected from the group consisting of tungsten, molybdenum, and vanadium. - Elements from the p-block of the periodic table, such as silicon, phosphorus, or arsenic. - Oxygen, and - Hydrogen.

[0051] Preferably, the heteropoly acid is selected from the group consisting of phosphotungstic acid, silicotungstic acid, arcentungstic acid, phosphomolybdic acid, silicomolybdic acid, arcenmolybdic acid, phosphovanadic acid, silicovanadic acid, and arcenvanadic acid. In another preferred embodiment, the heteropoly acid derivatives are produced by general derivatization techniques to solidify / immobilize them, particularly including their salts and immobilized forms on a solid support or resin beads.

[0052] In one embodiment of the present invention, the method includes the step of contacting an aldopentose or aldohexose and an aldehyde or aldehyde source with an acidic zeolite, wherein the zeolite includes: - A zeolite having at least two, preferably two or three, uninterconnected parallel channel systems, at least one of which comprises channels of eight-membered rings or more; and having a Si / X2 ratio of the backbone of at least 4 as measured by NMR; or - A zeolite having at least two, preferably two or three, interconnected non-parallel channel systems, wherein at least one of these channel systems comprises channels with 10 or more membered rings; and the Si / X2 ratio of the skeleton is at least 4 as measured by NMR; or - A zeolite comprising three interconnected non-parallel channel systems, of which at least two are composed of channels with 10 or more member rings; and having a Si / X2 ratio of the backbone of at least 4 as measured by NMR; Here, each X is either Al or B.

[0053] A zeolite containing three interconnected non-parallel channel systems, wherein at least two of these channel systems consist of channels with 10 or more membered rings, and the Si / X2 ratio of the framework is at least 4 as measured by NMR, yields excellent results.

[0054] The term "channel system" preferably refers to a system of parallel, crystallographically equivalent channels, where the channels are 8-membered ring channels or larger.

[0055] Good results were obtained using zeolites containing at least two interconnected non-parallel channel systems (2D or 3D microporous structures). Therefore, the zeolites used in the methods described herein include 2D or 3D microporous structures, more specifically, interconnected 2D or 3D microporous structures.

[0056] Good results were also obtained with zeolites containing at least one channel with 10 or more member rings.

[0057] Accordingly, in certain embodiments, zeolites for use in the method herein may include those having a Si / X2 ratio of at least 4 in the framework, for example, those having a Si / Al2 ratio of at least 4 in the framework, wherein the zeolite further comprises at least two, preferably two or three, uninterconnected parallel channel systems, at least one of which comprises a channel of eight-membered rings or more. Examples of such zeolites are, but are not limited to, zeolites having a mordenite (MOR) topology.

[0058] In certain embodiments, the zeolite for use in the method described herein may include one in which the Si / X2 ratio of the skeleton is at least 4, for example, one in which the Si / Al2 ratio of the skeleton is at least 4; wherein the zeolite further comprises at least two interconnected non-parallel channel systems, at least one of which comprises a channel having 10 or more member rings, i.e., at least one of which comprises a channel having 10 or more member rings, and at least one other channel system comprises a channel having 8 or more member rings.

[0059] In certain embodiments, zeolites for use in the method herein may include those having a Si / X2 ratio of at least 4 in the framework, for example, those having a Si / Al2 ratio of at least 4 in the framework; where the zeolite further comprises three interconnected non-parallel channel systems, at least two of which comprises channels of 10-membered rings or more, i.e., at least two of which comprises channels of 10-membered rings or more, and the other channel system comprises channels of 8-membered rings or more. Examples of such zeolites include, but are not limited to, zeolites having topologies selected from the group including BEA, FAU, and MEL.

[0060] In certain embodiments, the zeolite comprises at least two uninterconnected parallel channel systems, at least one of which comprises channels of eight-membered rings or more; wherein the zeolite further comprises a Si / X2 ratio of at least 4 of the framework, more specifically, at least 4, for example, at least 15, for example, at least 20, for example, at least 25, for example, at least 30, for example, at least 35, for example, at least 40, for example, less This includes ratios of at least 50, for example, at least 60, for example, at least 70, for example, at least 80, for example, at least 90, or for example, at least 100, or for example, at least 110, or for example, at least 120, or for example, at least 130, or for example, at least 140, or for example, at least 150, or for example, at least 160, or for example, at least 170, or for example, at least 180, or for example, at least 190, or for example, at least 200.

[0061] In certain embodiments, the zeolite comprises at least two, preferably two or three, interconnected non-parallel channel systems, at least one of which comprises channels of 10-membered rings or more; wherein the zeolite further comprises a Si / X2 ratio of at least 4 in its framework, more specifically, at least 8, for example, at least 10, for example, at least 15, for example, at least 20, for example, at least 25, for example, at least 30, for example, at least 35, for example, at least This includes ratios of 40, for example, at least 50, for example, at least 60, for example, at least 70, for example, at least 80, for example, at least 90, or for example, at least 100, or for example, at least 110, or for example, at least 120, or for example, at least 130, or for example, at least 140, or for example, at least 150, or for example, at least 160, or for example, at least 170, or for example, at least 180, or for example, at least 190, or for example, at least 200.

[0062] In certain embodiments, the zeolite comprises three interconnected non-parallel channel systems, at least two of which comprise channels of 10-membered rings or more; wherein the zeolite further comprises a Si / X2 ratio of at least 4 in its framework, more specifically, at least 8, for example, a ratio of at least 10, for example, a ratio of at least 15, for example, a ratio of at least 20, for example, a ratio of at least 25, for example, a ratio of at least 30, for example, a ratio of at least 35, for example, a ratio of at least 40, for example, a small This includes ratios of at least 50, for example, at least 60, for example, at least 70, for example, at least 80, for example, at least 90, or for example, at least 100, or for example, at least 110, or for example, at least 120, or for example, at least 130, or for example, at least 140, or for example, at least 150, or for example, at least 160, or for example, at least 170, or for example, at least 180, or for example, at least 190, or for example, at least 200.

[0063] In most embodiments, the conversion of the protected sugar to a fully acetal-protected product increases as the Si / X2 ratio increases, preferably as the Si / X2 ratio increases. In some embodiments, it has been observed that at high Si / X2 ratios, the yield of the partially protected sugar may decrease as the Si / X2 ratio increases further. While we do not wish to be bound by theory, this is thought to be related to the small amount of acidic sites in zeolites with high Si / X2 ratios and, nevertheless, the higher Brønsted acidity. Therefore, in certain embodiments, the zeolite has a Si / X2 ratio of less than 280 for the skeleton. In further embodiments, the zeolite has a Si / X2 ratio of less than 150 for the skeleton. Preferably, the zeolite has a Si / X2 ratio of less than 280 for the skeleton. In further embodiments, the zeolite has a Si / X2 ratio of less than 200 for the skeleton.

[0064] The zeolite used in the methods described herein may include AlO4 tetrahedra, BO4 tetrahedra, or both. Thus, in some embodiments, X2 is (Al2 + B2). Therefore, for a given zeolite, substituting the Al skeleton with B keeps the Si / X2 skeleton ratio the same, and vice versa. However, in certain embodiments, the zeolite is assumed to contain no BO4 tetrahedra or only a small amount (e.g., an Al / B ratio of 100 or more). Thus, in certain embodiments, X2 may be Al2.

[0065] The Si / X2 ratios referred to herein are molar ratios determined by NMR unless otherwise specified. Those skilled in the art will understand that the Si / X2 ratios referred to herein are equal to the SiO2 / X2O3 molar ratio [where X2O3 is (Al2O3 and / or B2O3)]. Furthermore, those skilled in the art will understand that the Si / X molar ratio is obtained by dividing the Si / X2 ratio by 2, where X is (Al and / or B).

[0066] Preferably, the channels defined by the zeolite topology are large enough to allow the protected sugar to reach, but small enough to prevent significant formation and / or diffusion of by-products. Thus, in certain embodiments, the zeolite comprises only channels having a maximum ring size of 18, preferably a maximum of 14, for example, a maximum of 12.

[0067] In preferred embodiments, zeolites suitable for use in the method herein include topologies selected from the group comprising BEA, FAU, and MEL. These zeolites yield a large amount of final product. In specific embodiments, one or more zeolites include topologies selected from the group comprising MOR. In specific embodiments, one or more zeolites include zeolites having a FAU or BEA topology that provides excellent results.

[0068] In certain embodiments, the zeolite includes channels having an average (equivalent) diameter of at least 5 Å. More specifically, the zeolite may include five or more non-parallel channels having an average diameter of at least 5 Å. The channel diameters can be theoretically determined via information about the zeolite framework type or via X-ray diffraction (XRD) measurements, as is known to those skilled in the art. Preferably, the zeolite includes two or more non-parallel, interconnected channels having an average (equivalent) diameter of 5–13.0 Å, more preferably 5–11 Å. Preferably, diameters for a suitable topology are obtained from the international standard literature: Atlas of Zeolite structures or the corresponding online database found at http: / / www.iza-structure.org / databases / mentioned above. The (equivalent) diameter of the channel can also be measured experimentally via N2 adsorption, as discussed, for example, by Groen et al. (Microporous and Mesoporous Materials 2003, 60, 1-17), Storck et al. (Applied Catalysis A: General 1998, 174, 137-146), and Rouquerol et al. (Rouquerol F, Rouquerol J and Sing K, Adsorption by powders and porous solids: principles, methodology and applications, Academic Press, London, 1999).

[0069] In some embodiments, the zeolite may further contain mesopores. The presence of mesopores can increase the ease with which the sugar to be protected can reach both pores (micropores and mesopores), and therefore can further increase the reaction rate. However, it is also conceivable that the zeolite may not contain mesopores.

[0070] As used herein, the term "mesopore" refers to pores in zeolite crystals having an average diameter of 2.0 nm to 50 nm. For pore shapes that deviate from cylindrical shapes, the above diameter range for mesopores refers to equivalent cylindrical pores. The average diameter of mesopores can be determined by gas adsorption techniques such as N2 adsorption.

[0071] One or more zeolites can be used as is, for example, in powder form. In certain embodiments, one or more zeolites can be formulated into a catalyst by combining them with other substances that provide additional shape, hardness, or catalytic activity, resulting in a finished catalyst product. Materials that can be blended with zeolites can be a variety of inert or catalytically active substances, or a variety of binder materials. These materials include compositions such as kaolin and other clays, phosphates, alumina or alumina sol, titania, metal oxides, such as zirconia, quartz, silica or silica sol, metal silicates, and mixtures thereof. These components are effective in increasing the density of the catalyst and increasing the strength of the formulated catalyst.

[0072] The catalyst can be formulated into pellets, spheres, extruded into other shapes, or formed into spray-dried particles.

[0073] In some embodiments, one or more zeolites intended for use in the methods described herein can be subjected to (post-synthesis) treatment to increase the Si / Al2 skeleton ratio. Methods for increasing the Si / Al2 ratio of zeolites are known in the art and include dealuminization of the skeleton by (hydro) heat treatment, extraction of the skeleton aluminum by acid, and substitution of the skeleton aluminum with silicon by reaction with silicon halides or hexafluorosilicates. Exemplary methods of dealuminization are described by Remy et al. (J. Phys. Chem. 1996, 100, 12440-12447). Zeolites intended for use in the methods described herein are preferably Brønsted acid zeolites, i.e., zeolites having proton-donating sites in their pores. The Brønsted acid density can be directly derived from the Si / Al2 ratio when all Al T-sites are balanced with acidic protons (as opposed to cations), as is known to those skilled in the art.

[0074] Zeolites for use in the processes described herein may be obtained in an acidic form (acidic H-type zeolite or acidic H-form zeolite), or (partially) H + It can be exchanged with cations other than cations. In some embodiments, acidic H-type zeolite can be used as is. In some other embodiments, the zeolite for use in the processes described herein can be treated (post-synthesis) to increase the Brønsted acid density. The Brønsted acid moiety in the zeolite can be readily generated by aqueous ion exchange with an ammonium salt, followed by thermal decomposition of ammonium ions inside the zeolite. Alternatively, the acidic moiety can be a polyvalent metal cation (Mg 2+ Ca 2+ , La 3+ It can be produced by aqueous ion exchange with a salt of (or mixed rare earth cations, etc.), followed by thermal dehydration (J. Weitkamp, ​​Solid State Ionics 2000, 131, 175-188).

[0075] The zeolite catalysts described herein may be regenerated and reused in this method. Therefore, certain embodiments of the methods described herein may include a step of regenerating the zeolite catalyst. Regeneration of the zeolite catalyst can be carried out by washing or calcination. Preferably, regeneration of the zeolite catalyst is carried out by calcination at a temperature of, for example, at least 150°C. In certain embodiments, the calcination temperature is at least 200°C, for example at least 300°C, for example at least 400°C, for example at least 450°C, for example about 550°C.

[0076] The zeolites described above may contain, but are not limited to, various dopants such as gallium, tin, or rare earth metals. Dopants can provide better catalytic stability or a higher conversion rate of sugars to desired fully or partially protected products.

[0077] Examples of commercially available zeolites suitable for use in the processes described herein include, but are not limited to, beta polymorph A-type (BEA topology), Y-type zeolites (FAU topology), and mordenite.

[0078] [Table 1-1]

[0079] Preferably, the acidic zeolite catalyst is selected from the group consisting of zeolite Y (SiO2:Al2O3=5.2:1), zeolite Y (SiO2:Al2O3=12:1), zeolite Y (SiO2:Al2O3=30:1), zeolite Y (SiO2:Al2O3=60:1), zeolite Y (SiO2:Al2O3=80:1), zeolite β (SiO2:Al2O3=25:1), zeolite β (SiO2:Al2O3=38:1), zeolite β (SiO2:Al2O3=150:1), and mordenite (SiO2:Al2O3=19:1).

[0080] Preferably, the aldehydes used in the method according to the present invention are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, isovaleraldehyde, hexanal, heptanal, octanal, nonanal, decanal, dodecanal, tetradecanal, hexadecanal, octadecanal, crotonaldehyde, glyoxal, malonate dialdehyde, succinate dialdehyde, glutaraldehyde, adipic acid dialdehyde, 2-hydroxyadipic acid dialdehyde, pimelic acid dialdehyde, The following can be selected from the group consisting of suberic acid dialdehyde, azelaic acid dialdehyde, sebacate acid dialdehyde, maleic acid aldehyde, fumaric acid aldehyde, phthalaldehyde, isophthalaldehyde, terephthalaldehyde, and 1,4-diformylcyclohexane, glyoxylic acid, glyoxylic acid monohydrate, formylacetic acid, terephthalaldehyde, and succinic acid semialdehyde. Preferably, the following can be selected from the group consisting of formaldehyde, acetaldehyde, dodecanal, glyoxylic acid, glyoxylic acid monohydrate, and glutaraldehyde.

[0081] Alternatively, the aldehyde source is selected from the group consisting of paraformaldehyde, 1,3,5-trioxane, polyoxymethylene, and metaldehyde. These polymers or oligomeric compounds form the corresponding aldehydes under reaction conditions.

[0082] Therefore, aldehydes may be gases, liquids, or solids, and may exist as solutions or as pure compounds. For example, formaldehyde can be provided as a gas, a formaldehyde solution (e.g., formalin), paraformaldehyde, or as 1,3,5-trioxane, polyoxymethylene (POM).

[0083] In one embodiment of the present invention, R1 and R1', R2 and R2', R3 and R3' and R 12 and R 12These compounds are identical. They can be obtained using the same aldehyde, resulting in a simpler synthesis procedure.

[0084] Another embodiment of the present invention includes R1 and R1', R2 and R2', R3 and R3' and R 12 and R 12 These are different from each other. For example, in the first step, in the presence of a heterogeneous acidic catalyst, the sugar to be protected reacts with a first aldehyde (i.e., dodecanal), and one side of the sugar is protected. Then, in the second step, in the presence of a heterogeneous acidic catalyst, this partially protected sugar reacts with a different aldehyde (e.g., glyoxylic acid) to obtain a fully protected sugar.

[0085] In one embodiment of the present invention, the protected sugar is an aldopentose that gives rise to compounds of formulas I, IV, V, IX, X, and XI: [ka] In the formula, R1, R1', R4, R5, R9, R 10 and R 11 This is the same definition as above.

[0086] The following are exemplary reactions for obtaining compounds of formulas I, IV, V, IX, X, or XI in the presence of a heterogeneous acidic catalyst:

[0087] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5] [Table 1-6]

[0088] Aldopentoses can be selected from the group consisting of D-ribose, L-ribose, D-arabinose, L-arabinose, D-xylose, L-xylose, D-lyxose, and L-lyxose, most preferably selected from the group consisting of D-arabinose and D-xylose, and ideally selected from D-xylose. The stereochemistry of aldopentoses is known to those skilled in the art.

[0089] In one embodiment of the present invention, the protected sugar is an aldopentoside that yields a partially protected sugar selected from compounds of formula IVb, Xb, or XIb: [ka] In the formula, R4, R 10 and R 11 It has the same definition as above, and R 13 , R 16 and R 17 These are linear, branched, or cyclic hydrocarbon portions having hydrogen or 1 to 20 carbon atoms, and are preferably methyl, ethyl, propyl, or butyl.

[0090] The following are exemplary reactions for obtaining compounds of formula IVb, Xb, or XIb in the presence of a heterogeneous acidic catalyst:

[0091] [Table 1-7] [Table 1-8] [Table 1-9]

[0092] In another embodiment of the present invention, the protected sugar is an aldohexose that gives rise to compounds of formulas II, III, VIa, VII, and VIIIa: [ka] In the formula, R2, R2', R3, R3', R6, R7, and R8 have the same definitions as above.

[0093] The aldohexose is preferably selected from the group consisting of D-allose, L-allose, D-altrose, L-altrose, D-glucose, L-glucose, D-mannose, L-mannose, D-growth, L-growth, D-idose, L-idose, D-galactose, L-galactose, D-talose, and L-talose, and most preferably selected from D-glucose. The stereochemistry of aldohexoses is known to those skilled in the art.

[0094] The following are exemplary reactions for obtaining compounds of formulas II, III, VIa, VII, and VIIIa in the presence of a heterogeneous acidic catalyst:

[0095] [Table 1-10] [Table 1-11] [Table 1-12] [Table 1-13]

[0096] In one embodiment of the present invention, the protected sugar is an aldohexoside that yields at least a partially protected sugar selected from compounds of formulas VIb, VIIIb, and XII: [ka] In the formula, R6, R8, R 12 and R 12 ' has the same definition as above, and R 14 , R 15 and R 18These are linear, branched, or cyclic hydrocarbon portions having hydrogen or 1 to 20 carbon atoms, and are preferably methyl, ethyl, or propyl.

[0097] The following are exemplary reactions for obtaining compounds of formulas VIb, VIIIb, and VII in the presence of a heterogeneous acidic catalyst:

[0098] [Table 1-14] [Table 1-15] [Table 1-16]

[0099] Preferably, the catalyst has a pore structure as described above for the zeolite detailed above. The selectivity of the pore shape of heterogeneous catalysts allows for the adjustment of product selectivity and avoids a common problem in homogeneous catalytic systems: namely, sugar molecules and their ring systems with many OH groups tend to form many by-products, thus avoiding the common problem of difficulty in obtaining high selectivity for a single desired product.

[0100] For compounds of formulas I, II, III, or XII, there are no restrictions on pore size, as long as the pore size allows the reactants to reach the Brønsted acid moiety and the fully acetal-protected sugar to diffuse. Furthermore, the pore size should be large enough to allow the product to detach from the catalyst after the reaction. If high selectivity for a partially protected sugar is preferred, the pore size should be larger than the desired partially protected sugar size, but smaller than the fully protected alternative product. The exact pore size depends on the type of sugar and aldehyde used in the reaction. Those skilled in the art can predict the range of pore sizes used in these cases. Aldopentoses, aldopentosides, aldohexoses, and aldohexosides that are unprotected or partially protected solely due to steric reasons can reach the catalytic active site through the pores and then leave the pores; therefore, such catalysts can produce compounds of formulas IV (IVa and IVb), V, VI (VIa and VIb), VII, VIII (VIIa and VIIb), IX, X (Xa and Xb), and XI (XIa and XIb). However, to obtain higher yields, catalysts containing mesopores with an average diameter of 2 nm to 50 nm are preferred, with pore diameters of 0.7 nm or greater preferred for aldohexose and aldohexoside protection, and pore diameters of 0.5 nm or greater preferred for aldopentose and aldopentoside protection.

[0101] In one embodiment of the present invention, the reaction is carried out in an organic solvent. Therefore, a sugar selected from the group consisting of aldopentoses, aldohexoses, aldopentosides, and aldohexosides, and an aldehyde or aldehyde source can be reacted in either a batch reactor or a continuous reactor, preferably a flow reactor, in the presence of the heterogeneous Brønsted acid catalyst and the organic solvent. The heterogeneous Brønsted acid catalyst used is preferably essentially insoluble in the organic solvent. Unless the catalyst is already confined inside the reactor, for example in a basket or column packing, after the reaction, the catalyst can be removed, for example by filtration, and recycled and returned to the reactor. The remaining reaction mixture can be concentrated by evaporating the solvent. The final product can be obtained from the concentrate by crystallization. Preferably, the organic solvent is selected from the group consisting of dimethyl isosorbide, cyclic ethers, particularly 1,4-dioxane, 2-methyltetrahydrofuran, sulfolane, sulfone, aliphatic acid, particularly acetic acid, alkylpyrrolidone, cyclic carbonate, cyclic ester, particularly γ-valerolactone, γ-butyrolactone, acetonitrile, dialkyl ethers, particularly CPME (cyclopentyl methyl ether) and diethyl ether, cyclic ether, and glycol monoethers and glycol diethers.

[0102] The solvent can be removed while simultaneously enabling a high conversion rate of the protected sugar. This solvent system is particularly preferred for aldehydes with long chains (e.g., decanal).

[0103] In another embodiment, the reaction is carried out in aqueous solution. Thus, a sugar selected from the group consisting of aldopentoses, aldohexoses, aldopentosides, and aldohexosides, and an aldehyde or aldehyde source can be reacted in either a batch reactor or a continuous reactor, preferably a flow reactor, in the presence of the heterogeneous Brønsted acid catalyst and water. The heterogeneous Brønsted acid catalyst used is essentially insoluble in water. Unless the catalyst is already confined inside the reactor, for example in a basket or column packing, after the reaction the catalyst can be separated and recycled, for example by filtration and / or centrifugation. The remaining liquid can be extracted with a solvent (e.g., hexane, DCM (dichloromethane), diethyl ether, ethyl acetate, or CPME (cyclopentyl methyl ether)) to remove the product. The extracting solvent can then be removed by evaporation to separate the product. Alternatively, the extract layer containing the product can be concentrated, and the product can be gradually crystallized in the concentrate. The extracted aqueous phase contains unreacted reactants, namely sugars, aldehydes, and intermediates. This extracted aqueous phase can be concentrated and recycled back into the reactor to improve the overall yield. For environmental reasons, aqueous solutions are particularly preferred as the solvent system.

[0104] In one embodiment of the present invention, the reaction is carried out in a two-phase solvent system to achieve in-situ separation of the product from the reaction mixture and to improve the product yield by shifting the reaction equilibrium. Specifically, the extractant phase is added to a batch reactor together with the reaction mixture and a heterogeneous acidic catalyst. In a continuous flow reactor, the extractant can be added in a parallel, cross-flow, or counter-flow manner. Preferably, the two-phase solvent system is selected from the group consisting of dialkyl ether / water (e.g., CPME / water, dialkyl ether / water), anisole / water, dialkyl ketone / water (e.g., methyl isobutyl ketone / water), and toluene / water, preferably selected from CPME / water and toluene / water, and most preferably selected from CPME / water. The reaction takes place in the aqueous phase, and the product is extracted into the organic phase during the reaction. For stability reasons, two-phase solvent systems selected from the group consisting of dialkyl ether / water and dialkyl ketone / water are more suitable for aldehydes that have no side chains or short side chains, such as formaldehyde and acetaldehyde. The extractant phase containing the product is concentrated to crystallize the product. The remaining product in the aqueous phase can be removed by further extraction with a solvent (e.g., ethyl acetate or CPME), and this product can also be crystallized after evaporation of the extractant. The extracted aqueous phase can be concentrated and reused as described above.

[0105] Preferably, the reaction is carried out at a temperature of 50–160°C, most preferably 80–140°C. In organic solvents, the reaction temperature is typically 80–130°C, in two-phase solvent systems 120–140°C, and preferably 120–150°C in aqueous solutions. The reaction time is determined by the degree of transformation achieved.

[0106] The amount of heterogeneous acidic catalyst used is based on the amount of sugar to be protected. For alternative and preferred continuous operation modes, the relative amount of catalyst is adjusted for the reactor size and the flow of aldopentose or aldohexose. In this case, it will be understood that determining the appropriate relative amount based on numerical values ​​for batch operation modes is within the scope of the normal skill of the chemist or chemical technician manufacturing the product.

[0107] The method according to the present invention is convenient to carry out in a normal environment, but it can also be carried out under an inert gas atmosphere, preferably gaseous nitrogen, helium, or argon. [Examples]

[0108] Examples 1-5 below are based on the production of DFX (diformylxylose) using formaldehyde. The same principle can be applied to other aldehydes to produce different types of fully or partially protected xyloses, in particular dipropylxylose, di-n-butylxylose, diisobutylxylose, didodecylxylose, and the like.

[0109] Example 1 : D-xylose (2 g, 13.3 mmol, 1.0 equivalent), paraformaldehyde (2 g, 66.7 mmol formaldehyde, 5.0 equivalents), and H-form Y-type zeolite (SiO2:Al2O3=80:1, 2 g) were added to 2-Me-THF (32 mL) in a 50 mL round-bottom flask. The mixture was then heated at 120°C for 6 hours with stirring. The resulting solution was cooled to room temperature (approximately 23-25°C), filtered through a nylon membrane filter, and concentrated under vacuum using a rotary evaporator at a bath temperature of 45°C. HPLC analysis showed a DFX yield of 82.3% from D-xylose. The concentrated residue crystallized at 4-5°C.

[0110] Using the same method, other catalysts can also be used. Table 1 shows various DFX yields using different catalysts. These reactions were carried out using 0.25 g of D-xylose, and all other chemicals were scaled down relatively from the above example. The reactions were carried out in a 10 mL glass reactor.

[0111]

Table 1-17

[0112] Example 2 : D-xylose (0.1 g, 0.67 mmol, 1.0 equivalent), paraformaldehyde (0.1 g, 3.34 mmol, 5 equivalents) and ZrO2 / SO4 2- (self-synthesized, 50 mg) was added to 2-Me-THF (2 mL) in a 10 mL glass reactor. Then, this mixture was heated at 110 °C for 9 hours while stirring. The resulting solution was cooled to room temperature (about 23 - 25 °C), filtered through a nylon membrane filter, and diluted 10-fold with distilled water. HPLC measurement showed a 79% DFX yield from D-xylose.

[0113] Using the same method, other groups of acidic catalysts (e.g., Amberlite®, sulfated ZrO2, heteropolyacid, niobia oxide) can also be used (Table 2).

[0114] [[ID=​​​​​​​​​D-xylose (0.1 g, 0.67 mmol, 1.0 equivalent), 37% aqueous formalin solution (0.5 ml, 10.3 equivalents), and β-type zeolite (SiO2:Al2O3=25:1, 0.1 g) were added to GVL (γ-valerolactone, 5 mL) in a 10 mL glass reactor. The mixture was then heated at 140 °C for 2 hours with stirring. The resulting solution was cooled to room temperature (approximately 23-25 ​​°C), filtered through a nylon membrane filter, and GVL was removed by distillation under reduced pressure (10 mbar) at 80 °C. HPLC analysis showed a 76% DFX yield from D-xylose. The concentrated residue crystallized at 4-5 °C.

[0116] Other catalysts and solvents can also be used using this same method. Table 3 shows the various DFX yields when other catalysts are used.

[0117] [Table 3]

[0118] Example 4 : D-xylose (8 g, 53.3 mmol, 1.0 equivalent), 37% aqueous formalin solution (40 mL, 10.3 equivalents), and Y-type zeolite (SiO2:Al2O3=80:1, 1.6 g) were mixed in a 60 mL glass reactor. The mixture was then heated at 140 °C for 6 hours with stirring. HPLC analysis showed a 57.6% DFX yield from the D-xylose. The resulting solution was cooled to room temperature (approximately 23-25 ​​°C) and filtered through a nylon membrane filter. The filtrate was extracted four times in a separatory funnel with 10 mL of ethyl acetate or cyclopentyl methyl ether. The resulting organic phase was concentrated under reduced pressure (0.02 mbar) at 45 °C to obtain a DFX-rich solution. The DFX in the solution was then crystallized at 4-5 °C or room temperature.

[0119] Other catalysts can also be used using this same method. Table 4 shows the various DFX yields when other catalysts are used.

[0120] [Table 4]

[0121] Example 5 : D-xylose (0.3 g, 2 mmol, 1.0 equivalent), 37 wt% formalin aqueous solution (1.5 mL, 10.3 equivalents), and Y-type zeolite (SiO2:Al2O3=80:1, 0.2 g) were mixed in a 10 mL glass reactor. Cyclopentyl methyl ether (CPME; 4.5 mL, 3 volume equivalents) was added to the aqueous phase. The mixture was then heated at 140 °C for 4 hours with stirring. HPLC measurements showed a DFX yield of 50.4% in the organic cyclopentyl methyl ether phase and 18.4% in the aqueous phase. The solution was cooled to room temperature (approximately 23-25 ​​°C). The aqueous and organic phases were separated and filtered through a nylon membrane filter. The organic phase was distilled under reduced pressure (0.02 mbar) at 45 °C to obtain a concentrate. The aqueous filtrate was extracted three times in a separatory funnel with 1.5 mL of ethyl acetate or cyclopentyl methyl ether. The extractant phase was distilled under reduced pressure (0.02 mbar) at 45°C to obtain a concentrate. The two concentrates were combined and then crystallized at 4-5°C to obtain DFX as white crystals.

[0122] Other extraction solvents such as anisole, methyl isobutyl ketone (MIBK), dibutyl ether, and toluene can be used in various amounts in the same manner (Table 5).

[0123] [Table 5]

[0124] Example 6 : D-Xylose (0.25 g, 1.67 mmol, 1.0 equivalent), dodecanal (0.75 mL, 2 equivalents), and Y-type zeolite (SiO2:Al2O3 = 30:1, 0.1 g) were added to dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated at 65 °C for 5 hours with stirring. The resulting solution was cooled to room temperature (about 23 - 25 °C), filtered through a nylon membrane filter, and dioxane was removed by rotary evaporator in a 45 °C water bath. GC-FID measurement showed a 66.2% yield of MDX (3,5-O-dodecylidene-xylose), a 7.2% yield of MDX (1,2-O-dodecylidene-xylose), and a 3.9% yield of DDX (diddodecylidene-xylose) from D-xylose. Similar reactions using other heterogeneous catalysts are summarized in the following table (MDX and DDX yields and xylose conversion using various heterogeneous catalysts in Example 6).

[0125]

Table 6

[0126] Example 7 : Glyoxylic acid monohydrate (0.29 g, 2 equivalents) was added to 1,4-dioxane (5 mL). The mixture was pre-dried with 0.6 g of 4A molecular sieves to remove water. In a 10 mL glass reactor, this dried mixture was combined with Amberlyst® 15 (0.125 g), and MDX (0.5 g, 1.6 mmol, 1 equivalent, isolated from Example 6) was added. The mixture was then heated at 80 °C for 4 hours with stirring. The resulting solution was cooled to room temperature (about 23 - 25 °C), filtered through a nylon membrane filter, and dioxane was removed by rotary evaporator in a 45 °C water bath. GC-FID measurement showed a 59.4% yield of GMAX (1,2-O-glyoxylic acid-3,5-O-dodecylidene-xylose).

[0127] Example 8 : D-xylose (5.0 g, 33 mmol, 1.0 equivalent), glyoxylic acid monohydrate (7.66 g, 2.5 equivalents), and sulfonating resin (Dowex® r 50wx8, hydrogenated form, 200-400 mesh, 1.5 g) were added to sulfolane (20 mL) in a 100 mL round-bottom flask. This mixture was heated under reduced pressure (40 mbar) at 90 °C for 5 hours while stirring by rotating the flask. The resulting solution was cooled to room temperature (approximately 23-25 ​​°C) and filtered through a nylon membrane filter to remove the Dowex® catalyst. The yield of xylose diglycylate (DGAX), measured by HPLC and based on xylose loading, was 77%.

[0128] Example 9 : D-xylose (0.25 g, 1.67 mmol, 1.0 equivalent), various aldehydes (2 equivalents), and Y-type zeolite (SiO2:Al2O3=80:1, 0.25 g) were added to 1,4-dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated at 65°C for 5 hours with stirring. The resulting solution was cooled to room temperature (approximately 23-25°C), filtered through a nylon membrane filter, and the dioxane was removed using a rotary evaporator in a 45°C water bath.

[0129] For comparison, D-xylose (0.25 g, 1.67 mmol, 1.0 equivalent), various aldehydes (2 equivalents), and H2SO4 (5.3 μL) were added to dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated at 65°C for 5 hours with stirring. The resulting solution was cooled to room temperature (approximately 23-25°C), filtered through a nylon membrane filter, and the dioxane was removed using a rotary evaporator in a 45°C water bath.

[0130] For each type of aldehyde, the yields of various products measured by GC-FID from heterogeneous and homogeneous reactions are compared in pairs in the table below (yields of products IVa, Va, Xa, XIa, and I, and xylose conversion rates, using various aldehydes in Example 9).

[0131] [Table 7]

[0132] Example 10 : L-arabinose (0.25 g, 1.67 mmol, 1.0 equivalent), dodecanal (0.75 mL, 2 equivalents), and Y-type zeolite (SiO2:Al2O3=30:1, 0.25 g) were added to 1,4-dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated at 65°C for 5 hours with stirring. The resulting solution was cooled to room temperature (approximately 23-25°C), filtered through a nylon membrane filter, and 1,4-dioxane was removed using a rotary evaporator in a 45°C water bath. GC-FID analysis showed 77.3% partially protected arabinose and 12.7% fully protected arabinose.

[0133] Example 11 : D-glucose (0.3 g, 1.67 mmol, 1.0 equivalent), dodecanal (1.85 mL, 5 equivalents), and Y-type zeolite (SiO2:Al2O3=30:1, 0.25 g) were added to 1,4-dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated at 80°C for 5 hours with stirring. The resulting solution was cooled to room temperature (approximately 23-25°C), filtered through a nylon membrane filter, and 1,4-dioxane was removed using a rotary evaporator in a 45°C water bath. GC-FID measurements showed a yield of 58.0% partially protected glucose and a yield of 34.3% fully protected glucose. The inventions disclosed herein include the following embodiments: [1] A method for preparing at least partially acetal-protected sugars, comprising the step of reacting a sugar or sugar derivative selected from the group consisting of aldopentoses, aldohexoses, aldopentosides and aldohexosides with an aldehyde or aldehyde source in the presence of a heterogeneous acidic catalyst to form at least partially acetal-protected sugars selected from the group consisting of compounds of formulas I, II, III, IV, V, VI, VII, VIII, IX, X, XI and XII: [ka] [ka] [ka] In the formula, R 1 、R 1 ’、R 2 、R 2 ’、R 3 、R 3 ’、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 、R 11 、R 12 and R 12 ' is Y or ZE, and R 1 and R 1 ’、R 2 and R 2 ’、R 3 and R 3 ', and R 12 and R 12 ' are either identical or different from each other, Y is hydrogen, or a linear, branched, or cyclic hydrocarbon portion having 1 to 20 carbon atoms. Z is a linear, branched, or cyclic hydrocarbon moiety having 0 to 12 carbon atoms, and 1 to 4 C 1 ~C 4 It may be substituted with an alkyl group, or 1 to 4 halogen atoms, or a benzyl group, and E is -COOH, -CH(COOH) 2 ,-COOR 19 ,-CH(COOR 20 )(COOR 21 ), -CHO, -CH(CHO) 2 、-C 2 H 3 , -CH(C 2 H 3 ) 2 ,-CHCHR 22 -CHCR 23 R 24 、-C 2 H, -C 2 R 25 、-N 3 , -NH 2 , -CH(NH 2 ) 2 , -NHR 26 ,-CH(NHR 27 )(NHR 28 ), -NR 29 R30 -CH(NR 31 R 32 )(NR 33 R 34 ), -OH, -OR 35 , or -CH(R 36 OH)(R 37 OH) and, R 19 、R 20 、R 21 、R 22 、R 23 、R 24 、R 25 、R 26 、R 27 、R 28 、R 29 、R 30 、R 31 、R 32 、R 33 、R 34 and R 35 C 1 ~C 20 It is alkyl, and R 20 and R 21 、R 23 and R 24 、R 27 and R 28 、R 29 and R 30 、R 31 and R 32 , and R33 and R 34 They are either identical or different from each other, and R 36 and R 37 These are C's that are independent of each other, either nonexistent or linear or branched. 1 ~C 12 It is a hydrocarbon chain, and R 13 、R 14 、R 15 、R 16 、R 17 and R 18 These are linear, branched, or cyclic hydrocarbon portions, each independently containing hydrogen or 1 to 20 carbon atoms. [2] The heterogeneous acidic catalyst is a Brønsted acidic catalyst, preferably selected from the group consisting of the following, according to the method in [1] above: a. Acidic zeolite, b. Acid-doped zeolite, c. Resins functionalized with acidic moieties, d. Oxides functionalized at the acidic site, e. Acidic oxides, f. Heteropoly acids and their derivatives [3] The method according to [2] above, wherein the heterogeneous Brønsted acid catalyst is an acid zeolite, and preferably comprises the following: - A system comprising at least two, preferably two or three, uninterconnected parallel channel systems, wherein at least one of the channel systems consists of channels with eight or more member rings; and the Si / X of the framework as measured by NMR. 2 Zeolite with a ratio of at least 4; or - A system comprising at least two, preferably two or three, interconnected non-parallel channel systems, wherein at least one of the channel systems is composed of channels with 10 or more member rings; and the Si / X of the framework as measured by NMR. 2 Zeolite with a ratio of at least 4; or - A system comprising three interconnected non-parallel channel systems, wherein at least two of the channel systems consist of channels with 10 or more member rings; and the Si / X ratio of the framework is measured by NMR. 2 Zeolite with a ratio of at least 4; Here, each X is either Al or B. [4] The aldehydes include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, isovaleraldehyde, hexanal, heptanal, octanal, nonanal, decanal, dodecanal, tetradecanal, hexadecanal, octadecanal, crotonaldehyde, glyoxal, malonate dialdehyde, succinate dialdehyde, glutaraldehyde, adipic acid dialdehyde, 2-hydroxyadipic acid dialdehyde, pimelic acid dialdehyde, s The method according to any one of the above [1] to [3], wherein the method is selected from the group consisting of beric acid dialdehyde, azelaic acid dialdehyde, sebacate acid dialdehyde, maleic acid aldehyde, fumaric acid aldehyde, phthalaldehyde, isophthalaldehyde, terephthalaldehyde, 1,4-diformylcyclohexane, glyoxylic acid, glyoxylic acid monohydrate, formylacetic acid, and succinic acid semialdehyde, preferably formaldehyde, acetaldehyde, dodecanal, glyoxylic acid, glyoxylic acid monohydrate, and glutaraldehyde. [5] The method according to any one of [1] to [3] above, wherein the aldehyde source is selected from the group consisting of paraformaldehyde, 1,3,5-trioxane, polyoxymethylene, and metaldehyde. [6]R 13 、R 14 、R 15 、R 16 、R 17 and R 18 The method according to any one of the above [1] to [5], wherein the element is hydrogen, methyl, or ethyl, preferably hydrogen. [7] The method according to any one of the above [1] to [6], wherein the sugar is an aldopentose. [8] The method according to any one of the above [1] to [7], wherein the sugar is arabinose or xylose, preferably D-xylose. [9] The method according to any one of the above [1] to [6], wherein the sugar is glucose, preferably D-glucose.

[10] The method according to any one of the above [1] to [9], wherein the catalyst has a pore structure.

[11] The method according to any one of [1] to

[10] above, wherein the reaction is carried out in an organic solvent, preferably an organic solvent selected from the group consisting of dimethyl isosorbide, cyclic ethers, particularly 1,4-dioxane, 2-methyltetrahydrofuran, tetrahydrofuran, sulfolane, sulfone, aliphatic acid, particularly acetic acid, alkylpyrrolidone, cyclic carbonate, cyclic ester, particularly γ-valerolactone, γ-butyrolactone, acetonitrile, dialkyl ether, particularly diethyl ether, cyclic ether, particularly CPME and diethyl ether, cyclic ether, and glycol monoether and glycol diether.

[12] The method according to any one of the above [1] to

[10] , wherein the reaction is carried out in an aqueous solution.

[13] The method according to any one of the above [1] to

[10] , wherein the reaction is carried out in a two-phase solvent system, preferably selected from the group consisting of CPME / water, anisole / water, dialkyl ether / water, dialkyl ketone / water, and toluene / water, preferably selected from the group consisting of CPME / water and toluene / water, most preferably selected from the group consisting of CPME / water.

[14] The method according to any one of the above [1] to

[13] , wherein the reaction is carried out at a temperature of 50 to 160°C, preferably 80 to 140°C.

Claims

1. A method for preparing at least partially acetal-protected sugars, comprising the step of reacting a sugar or sugar derivative selected from the group consisting of aldopentoses, aldohexoses, aldopentosides, and aldohexosides with an aldehyde or aldehyde source in the presence of a heterogeneous acidic catalyst to form at least partially acetal-protected sugars selected from the group consisting of compounds of formulas I, II, III, IV, V, VI, VII, VIII, IX, X, XI, and XII: 【Chemistry 1-1】 【Chemistry 1-2】 [Chemistry 1-3] wherein, R １ , R １ ’, R ２ , R ２ ’, R ３ , R ３ ’, R ４ , R ５ , R ６ , R ７ , R ８ , R ９ , R １０ , R １１ , R １２ and R １２ ’ are Y or Z-E, and R １ and R １ ’, R ２ and R ２ ’, R ３ and R ３ ’, and R １２ and R １２ ’ are the same as or different from each other, Y is a hydrogen atom or a linear, branched, or cyclic hydrocarbon portion having 1 to 20 carbon atoms. Z is a linear, branched, or cyclic hydrocarbon moiety having 0 to 12 carbon atoms, and 1 to 4 C １ ~C ４ It may be substituted with an alkyl group, or 1 to 4 halogen atoms, or a benzyl group, and E is -COOH, -CH(COOH) ２ , -COOR １９ , -CH (COOR ２０ ) (COOR ２１ ), -CHO, -CH(CHO) ２ , -C ２ H ３ , -CH(C ２ H ３ ) ２ _CHCHR ２２ , -CHCR ２３ R ２４ , -C ２ H, -C ２ R ２５ , -N ３ , -NH ２ , -CH(NH ２ ) ２ , - NHR ２６ ,-CH(NHR ２７ ) (NHR ２８ ), -NR ２９ R ３０ , -CH(NR ３１ R ３２ ) (NR ３３ R ３４ ), -OH, -OR ３５ , or -CH(R ３６ OH) (R ３７ OH) and, R １９ , R ２０ , R ２１ , R ２２ , R ２３ , R ２４ , R ２５ , R ２６ , R ２７ , R ２８ , R ２９ , R ３０ , R ３１ , R ３２ , R ３３ , R ３４ and R ３５ C is independent of each other. １ ~C ２０ It is alkyl, and R ２０ and R ２１ , R ２３ and R ２４ , R ２７ and R ２８ , R ２９ and R ３０ , R ３１ and R ３２ , and R ３３ and R ３４ They are either identical or different from each other, and R ３６ and R ３７ are, independently of each other, non-existent or a linear or branched C １ ~C １２ hydrocarbon chain, and R １３ 、R １４ 、R １５ 、R １６ 、R １７ and R １８ are, independently of one another, hydrogen or a linear, branched or cyclic hydrocarbon moiety having from 1 to 20 carbon atoms.

2. The method according to claim 1, wherein the heterogeneous acidic catalyst is a Brønsted acidic catalyst.

3. The method according to claim 2, wherein the Brønsted acid catalyst is selected from the group consisting of the following: a. Acidic zeolite, b. Acid-doped zeolite, c. Resins functionalized with acidic moieties, d. Oxides functionalized at the acidic site, e. Acidic oxides, f. Heteropoly acids and their derivatives.

4. The method according to claim 3, wherein the heterogeneous Brønsted acid catalyst is an acidic zeolite.

5. The method according to claim 4, wherein the acidic zeolite comprises the following: - A system comprising at least two uninterconnected parallel channel systems, where at least one of the channel systems is composed of channels with eight or more member rings; and the Si / X of the skeleton measured by NMR. ２ Zeolite having a ratio of at least 4; or - A system comprising at least two interconnected non-parallel channel systems, at least one of which consists of channels with 10 or more member rings; and wherein the Si / X of the skeleton is measured by NMR. ２ Zeolite having a ratio of at least 4; or - A system comprising three interconnected non-parallel channel systems, wherein at least two of the channel systems are composed of channels with 10 or more member rings; and the Si / X of the skeleton is measured by NMR. ２ Zeolites with a ratio of at least 4; Here, each X is either Al or B.

6. The aforementioned aldehydes include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, isovaleraldehyde, hexanal, heptanal, octanal, nonanal, decanal, dodecanal, tetradecanal, hexadecanal, octadecanal, crotonaldehyde, glyoxal, malonate dialdehyde, succinate dialdehyde, glutaraldehyde, adipic acid dialdehyde The method according to claim 1, selected from the group consisting of hydride, 2-hydroxyadipic acid dialdehyde, pimelic acid dialdehyde, suberic acid dialdehyde, azelaic acid dialdehyde, sebacate acid dialdehyde, maleic acid aldehyde, fumaric acid aldehyde, phthalaldehyde, isophthalaldehyde, terephthalaldehyde, 1,4-diformylcyclohexane, glyoxylic acid, glyoxylic acid monohydrate, formylacetic acid, and succinic acid semialdehyde.

7. The method according to claim 1, wherein the aldehyde source is selected from the group consisting of paraformaldehyde, 1,3,5-trioxane, polyoxymethylene, and metaldehyde.

8. R １３ , R １４ , R １５ , R １６ , R １７ and R １８ The method according to claim 1, wherein the element is hydrogen, methyl, or ethyl.

9. The method according to claim 1, wherein the sugar is aldopentose.

10. The method according to any one of claims 1 to 9, wherein the sugar is arabinose or xylose.

11. The method according to any one of claims 1 to 8, wherein the sugar is glucose.

12. The method according to claim 1, wherein the catalyst has a pore structure.

13. The method according to claim 1, wherein the above reaction is carried out in an organic solvent.

14. The method according to claim 1, wherein the above reaction is carried out in an aqueous solution.

15. The method according to claim 1, wherein the above reaction is carried out in a two-phase solvent system.

16. The method according to claim 1, wherein the reaction is carried out at a temperature of 50 to 160°C.

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