METHOD FOR PREPARING AN AT LEAST PARTIALLY ACETAL-PROTECTED SUGAR

Abstract

The present invention relates to a method for preparing an at least partially acetal-protected sugar involving the step of reacting a sugar or a sugar derivative selected from the group consisting of an aldopentose, an aldohexose, an aldopentoside and an aldohexoside with an aldehyde or an aldehyde source in the presence of heterogeneous acidic catalyst to form the at least partially acetal-protected sugar selected from the group consisting of a compound of formula (I), (II), (III), (IV), (V), (VI), (VII), (VIII), (IX), (X,)(XI) and (XII) wherein R.sub.1, R.sub.1, R.sub.2, R.sub.2, R.sub.3, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, R.sub.11, R.sub.12, and R.sub.12 are Y or Z-E, and wherein R.sub.1 and R.sub.1, R.sub.2 and R.sub.2, R.sub.3 and R.sub.3, and R.sub.12 and R.sub.12 are the same or different from each other and Y is hydrogen or a linear, branched or cyclic hydrocarbon moiety having 1 to 20 carbon 69 atoms, Z is a linear, branched or cyclic hydrocarbon moiety with 0 to 12 carbon atoms, optionally substituted with 1 to 4 C1 to C4 alkyl groups, 1 to 4 halogen atoms, or benzyl groups and E is COOH, CH(COOH).sub.2, COOR.sub.19, CH(COOR.sub.20)(COOR.sub.21), CHO, CH(CHO).sub.2, C.sub.2H.sub.3, CH(C.sub.2H.sub.3).sub.2, CHCHR.sub.22, CHCR.sub.23R.sub.24, C.sub.2H, C.sub.2R.sub.25, N.sub.3, NH.sub.2, CH(NH.sub.2).sub.2, NHR.sub.26, CH(NHR.sub.27)(NHR.sub.28), NR.sub.29R.sub.30, CH(NR.sub.31R.sub.32)(NR.sub.33R.sub.34), OH, OR.sub.35, CH(R.sub.36OH)(R.sub.37OH), and R.sub.19, R.sub.20, R.sub.21, R.sub.22, R.sub.23, R.sub.24, R.sub.25, R.sub.26, R.sub.27, R.sub.28, R.sub.29, R.sub.30, R.sub.31, R.sub.32, R.sub.33, R.sub.34, and R.sub.35, are independent from each other C.sub.1 to C.sub.20 alkyl, and R.sub.20 and R.sub.21, R.sub.23 and R.sub.24, R.sub.27 and R.sub.28, R.sub.29 and R.sub.30, R.sub.31 and R.sub.32, as well as R.sub.33 and R.sub.34 are the same or different from each other, and R.sub.36 and R.sub.37 are independent from each other absent or a linear or branched C.sub.1 to C.sub.12 hydrocarbon chain and R.sub.13, R.sub.14, R.sub.15, R.sub.16, R.sub.17 and R.sub.18 are independent from each other hydrogen or a linear, branched or cyclic hydrocarbon moiety having 1 to 20 carbon atoms.

Claims

1. Method for preparing an at least partially acetal-protected sugar involving the step of reacting a sugar or a sugar derivative selected from the group consisting of an aldopentose, an aldohexose, an aldopentoside and an aldohexoside with an aldehyde or an aldehyde source in the presence of heterogeneous acidic catalyst to form the at least partially acetal-protected sugar selected from the group consisting of a compound of formula I, II, III, IV, V, VI, VII, VIII, IX, X, XI and XII ##STR00370## wherein R.sub.1, R.sub.1, R.sub.2, R.sub.2, R.sub.3, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, R.sub.11, R.sub.12, and R.sub.12 are Y or Z-E, and wherein R.sub.1 and R.sub.1, R.sub.2 and R.sub.2, R.sub.3 and R.sub.3, and R.sub.12 and R.sub.12 are the same or different from each other and 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 with 0 to 12 carbon atoms, optionally substituted with 1 to 4 C.sub.1 to C.sub.4 alkyl groups, 1 to 4 halogen atoms, or benzyl groups and E is COOH, CH(COOH).sub.2, COOR.sub.19, CH(COOR.sub.20)(COOR.sub.21), CHO, CH(CHO).sub.2, C.sub.2H.sub.3, CH(C.sub.2H.sub.3).sub.2, CHCHR.sub.22, CHCR.sub.23R.sub.24, C.sub.2H, C.sub.2R.sub.25, N.sub.3, NH.sub.2, CH(NH.sub.2).sub.2, NHR.sub.26, CH(NHR.sub.27)(NHR.sub.28), NR.sub.29R.sub.30, CH(NR.sub.31R.sub.32)(NR.sub.33R.sub.34), OH, OR.sub.35, CH(R.sub.36OH)(R.sub.37OH), and R.sub.19, R.sub.20, R.sub.21, R.sub.22, R.sub.23, R.sub.24, R.sub.25, R.sub.26, R.sub.27, R.sub.28, R.sub.29, R.sub.30, R.sub.31, R.sub.32, R.sub.33, R.sub.34, and R.sub.35, are independent from each other C.sub.1 to C.sub.20 alkyl, and R.sub.20 and R.sub.21, R.sub.23 and R.sub.24, R.sub.27 and R.sub.28, R.sub.29 and R.sub.30, R.sub.31 and R.sub.32, as well as R.sub.33 and R.sub.34 are the same or different from each other, and R.sub.36 and R.sub.37 are independent from each other absent or a linear or branched C.sub.1 to C.sub.12 hydrocarbon chain and R.sub.13, R.sub.14, R.sub.15, R.sub.16, R.sub.17 and R.sub.18 are independent from each other hydrogen or a linear, branched or cyclic hydrocarbon moiety having 1 to 20 carbon atoms.

2. Method according to claim 1, wherein the heterogeneous acidic catalyst is a Brnsted acidic catalyst, preferably selected from the group consisting of a. acidic zeolite, b. acidic doped zeolite, c. acid site-functionalized resin, d. acid site-functionalized oxide, e. acidic oxide, f. heteropolyacids and their derivates.

3. Method according to claim 2, wherein the heterogeneous Brnsted acidic catalyst is an acidic zeolite, preferably comprising at least two, preferably two or three, non-interconnected and parallel channel systems wherein, at least one of said channel systems comprises 8- or more-membered ring channels; and a framework Si/X.sub.2 ratio of at least 4 as measured by NMR; or at least two, preferably two or three, interconnected and non-parallel channel systems wherein, at least one of said channel systems comprises 10- or more-membered ring channels; and a framework Si/X.sub.2 ratio of at least 4 as measured by NMR; or three interconnected and non-parallel channel systems wherein at least two of the channel systems comprise 10- or more-membered ring channels, and a framework Si/X.sub.2 ratio of at least 4 as measured by NMR wherein each X is Al or B.

4. Method according to claim 1, wherein the aldehyde is selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, isovaleraldehyde, hexanal, heptanal, octanal, nonanal, decanal, dodecanal, tetradecanal, hexadecanal, octadecanal, crotonaldehyde, glyoxal, malonic dialdehyde, succinic dialdehyde, glutaraldehyde, adipic dialdehyde, 2-hydroxyadipic dialdehyde, pimelic dialdehyde, suberic dialdehyde, azelaic dialdehyde, sebacic dialdehyde, maleic aldehyde, fumaric aldehyde, phthalaldehyde, isophthalaldehyde, terephthalaldehyde, and 1,4-diformylcyciohexane, glyoxylic acid, glyoxylic acid monohydrate, formyl acetic acid and succinaldehydic acid, preferably formaldehyde, acetaldehyde, dodecanal, glyoxylic acid, glyoxylic acid monohydrate and glutaraldehyde.

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

6. Method according to claim 1, wherein R.sub.13, R.sub.14, R.sub.15, R.sub.16, R.sub.17 and R.sub.18 are hydrogen, methyl or ethyl, preferably hydrogen.

7. Method according to claim 1, wherein the sugar is an aldopentose.

8. Method according to claim 1, wherein the sugar is arabinose or xylose, preferably D-xylose.

9. Method according to claim 1, wherein the sugar is glucose, preferably D-glucose.

10. Method according to claim 1, wherein the catalyst has a pore structure.

11. Method according to claim 1, wherein the reaction is carried out in an organic solvent, preferably selected from the group consisting of dimethyl isosorbide, cyclic ethers, in particular 1,4-dioxane, 2-methyltetrahydrofuran, tetrahydrofuran, sulfolane, sulfolene, aliphatic acids, in particular acetic acid, alkylpyrrolidones, cyclic carbonates, cyclic esters, in particular 7-valerolactone, 7-butyrolactone, acetonitrile, dialkylethers, in particular diethylether, cyclic ethers, in particular CPME and diethylether, cyclic ethers, and glycol monoethers and glycoldiethers.

12. Method according to claim 1, wherein the reaction is carried out in an aqueous solution.

13. Method according to claim 1, wherein the reaction is carried out in a biphasic solvent system, preferably selected from the group consisting of CPME/water, anisole/water, dialkylethers/water, dialkyl ketone/water and toluene/water, preferably CPME/water and toluene/water, and most preferably CPME/water.

14. Method according to claim 1, wherein the reaction is carried out at a temperature of 50 to 160 C., preferably 80 to 140 C.

Description

EXAMPLES

[0152] The following examples 1 to 5 are based on the use of formaldehyde to produce DFX. The same principle can be applied with other aldehyde to produce different types of fully or partially protected xylose in particular for dipropyl xylose, di-n-butyl xylose, diisobutyl xylose, didodecyl xylose, etc.

Example 1

[0153] D-xylose (2 g, 13.3 mmol, 1.0 equiv.), paraformaldehyde (2 g, 66.7 mmol formaldehyde, 5.0 equiv.) and H-form Y type zeolite (SiO.sub.2:Al.sub.2O.sub.3=80:1, 2 g) were added to 2-Me-THF (32 mL) in a 50 mL round bottom flask. The mixture was then heated to 120 C. for 6 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter, and concentrated in vacuo using a rotary evaporator with a bath temperature of 45 C. HPLC measurement showed 82.3% DFX yield from D-xylose. The concentrated residue crystallized at 4-5 C.

[0154] Other catalysts can also be used using this same method. Table 1 shows the different DFX yield using different catalysts. These reactions were conducted with 0.25 g of D-xylose and all other chemicals proportionally scaled down from the above example. The reactions were conducted in 10 mL glass reactors.

TABLE-US-00006 TABLE 1 DFX yield and xylose conversion using various heterogenous catalysts and reaction time with paraformaldehyde as the source of formaldehyde DFX Xylose Temperature Reaction yield conversion Catalyst ( C.) time (h) (%) (%) H-form Zeolite Y 110 6 55 99 (SiO.sub.2:Al.sub.2O.sub.3 = 5.2:1) H-form Zeolite Y 110 6 52 98 (SiO.sub.2:Al.sub.2O.sub.3 = 12:1) H-form Zeolite Y 110 6 65 98 (SiO.sub.2:Al.sub.2O.sub.3 = 30:1) H-form Zeolite Y 110 6 77 98 (SiO.sub.2:Al.sub.2O.sub.3 = 60:1) H-form Zeolite Y 120 6 85 99 (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) H-form Zeolite 120 24 33 97 (SiO.sub.2:Al.sub.2O.sub.3 = 25:1) H-form Zeolite 120 24 50 98 (SiO.sub.2:Al.sub.2O.sub.3 = 38:1) H-form Zeolite 120 24 60 97 (SiO.sub.2:Al.sub.2O.sub.3 = 150:1) H-form Modernite 120 24 19 80 (SiO.sub.2:Al.sub.2O.sub.3 = 19:1)

Example 2

[0155] D-xylose (0.1 g, 0.67 mmol, 1.0 equiv), paraformaldehyde (0.1 g, 3.34 mmol, 5 equiv) and ZrO.sub.2/SO.sub.4.sup.2 (self-synthesized, 50 mg) were added to 2-Me-THF (2 mL) in a 10 mL glass reactor. The mixture was then heated to 110 C. for 9 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter and diluted 10 times in distilled water. HPLC measurement showed 79% DFX yield from D-xylose.

[0156] Other acidic catalyst groups (e.g. Amberlite, Sulphated ZrO.sub.2, Heteropolyacids, Niobia oxides) can also be used using this same method (Table 2).

TABLE-US-00007 TABLE 2 DFX yield and xylose conversion using various heterogenous catalysts and reaction time with paraformaldehyde as the source of formaldehyde DFX Xylose Temperature Reaction yield conversion Catalyst ( C.) time (h) (%) (%) Sulfated zirconia 110 9 79 100 Orthorhombic 110 24 6 100 niobium oxide Phosphotungstic acid 110 1.5 81 100 Amberlite IRC120 110 4 83 100

Example 3

[0157] D-xylose (0.1 g, 0.67 mmol, 1.0 equiv.), formalin 37% aq. (0.5 ml, 10.3 equiv.) and -type zeolite (SiO.sub.2:Al.sub.2O.sub.3=25:1, 0.1 g) were added to GVL (5 mL) in a 10 mL glass reactor. The mixture was then heated to 140 C. for 2 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter, and distilled at 80 C. under reduced pressure (10 mbar) to remove GVL. HPLC measurement showed 76% DFX yield from D-xylose. The concentrated residue crystallized at 4-5 C.

[0158] Other catalysts and solvents can also be used using this same method. Table 3 shows the different DFX yield using other catalysts.

TABLE-US-00008 TABLE 3 DFX yield and xylose conversion using various heterogenous catalysts and reaction time with formalin (formaldehyde aqueous solution) as the source of formaldehyde Xylose DFX con- Temperature Reaction yield version Catalyst Solvent ( C.) time (h) (%) (%) Amberlyst-15 GVL 110 24 81 100 Aluminum chloride GVL 110 24 60.4 100 H-form Modernite 1,4- 110 24 41 73 (SiO.sub.2:Al.sub.2O.sub.3 = 19:1) dioxane H-form Zeolite Aceto- 130 24 59 97 (SiO.sub.2:Al.sub.2O.sub.3 = 25:1) nitrile H-form Zeolite GVL 140 2 76 100 (SiO.sub.2:Al.sub.2O.sub.3 = 25:1) H-form Zeolite 1,4- 130 24 63 99 (SiO.sub.2:Al.sub.2O.sub.3 = 25:1) dioxane H-form Zeolite 1,4- 110 48 82 99 (SiO.sub.2:Al.sub.2O.sub.3 = 25:1) dioxane H-form Zeolite Y 1,4- 120 24 59 99 (SiO.sub.2:Al.sub.2O.sub.3 = 30:1) dioxane

Example 4

[0159] D-xylose (8 g, 53.3 mmol, 1.0 equiv.), formalin 37% aq. (40 ml, 10.3 equiv.) and Y type zeolite (SiO.sub.2:Al.sub.2O.sub.3=80:1, 1.6 g) were mixed in a 60 mL glass reactor. The mixture was then heated to 140 C. for 6 h with stirring. HPLC measurement shows 57.6% DFX yield from D-xylose. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter. The filtrate was extracted four times with 10 ml of ethyl acetate or cyclopentyl methyl ether in a separatory funnel. The resulting organic layer was concentrated at 45 C. under reduced pressure (0.02 mbar) to obtain a DFX-rich liquor. The DFX in the liquor was then crystallized at 4-5 C. or room temperature.

[0160] Other catalysts can also be used using this same method. Table 4 shows the different DFX yield using other catalysts.

TABLE-US-00009 TABLE 4 DFX yield and xylose conversion using various heterogenous catalysts and reaction time using the example 4 DFX Xylose Temperature Reaction yield conversion Catalyst ( C.) time (h) (%) (%) H-form Zeolite 110 2 43 97 (SiO.sub.2:Al.sub.2O.sub.3 = 25:1) H-form Zeolite 110 2 50 97 (SiO.sub.2:Al.sub.2O.sub.3 = 38:1) H-form Modernite 140 2 29 79 (SiO.sub.2:Al.sub.2O.sub.3 = 19:1) H-form Zeolite Y 140 2 50 90 (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) H-form Zeolite Y 120 24 59 95 (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) H-form Zeolite Y 100 24 37 76 (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) Amberlyst 36 140 2 64 96

Example 5

[0161] D-xylose (0.3 g, 2 mmol, 1.0 equiv.), formalin 37 wt % aq. (1.5 ml, 10.3 equiv.) and Y type zeolite (SiO.sub.2:Al.sub.2O.sub.3=80:1, 0.2 g) were mixed in a 10 mL glass reactor. Cyclopentyl methyl ether (4.5 ml, 3 vol. equiv.) was added to the aqueous layer. The mixture was then heated to 140 C. for 4 h with stirring. HPLC measurement shows 50.4% DFX yield in the organic cyclopentyl methyl ether layer and 18.4% DFX yield in the aqueous layer. The solution was cooled to room temperature (23-25 C.). The aqueous and organic layers were separated and filtered with nylon membrane filters. The organic layer was distilled at 45 C., under reduced pressure (0.02 mbar) to obtain a concentrated liquor. The aqueous filtrate was extracted three times with 1.5 ml of ethyl acetate or cyclopentyl methyl ether in a separatory funnel. The extractant layer was distilled at 45 C., under reduced pressure (0.02 mbar) to obtain a concentrated liquor. The two concentrated liquors were combined and then crystallized at 4-5 C. yielding DFX as white crystal.

[0162] Other extractive solvents, such as anisole, methyl isobutyl ketone, dibutyl ether, and toluene, can be used in various loadings in the same method (Table 5).

TABLE-US-00010 TABLE 5 DFX yield and xylose conversion using various heterogenous catalysts and reaction time using the example 5 DFX DFX yield in Reaction yield in extractive Xylose Temp. Extractive time water layer conversion Catalyst ( C.) solvent (h) (%) (%) (%) H-form 140 Anisole 4 2.2 3 61 Zeolite Y (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) H-form 140 MIBK 4 18 31 86 Zeolite Y (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) H-form 140 Dibutyl 4 49 7.7 89 Zeolite Y ether (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) H-form 140 Toluene 4 31 32 86 Zeolite Y (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) H-form 140 CPME 4 12 59 99 Zeolite Y (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) Amberlyst 140 CPME 2 17 45 99 36 H-form 150 CPME 2 19 47 97 Zeolite Y (SiO.sub.2:Al.sub.2O.sub.3 = 80:1) H-form 100 CPME 24 12 23 74 Zeolite Y (SiO.sub.2:Al.sub.2O.sub.3 = 80:1)

Example 6

[0163] D-xylose (0.25 g, 1.67 mmol, 1.0 equiv.),dodecanal (0.75 ml, 2 equiv.) and Y-type zeolite (SiO.sub.2:Al.sub.2O.sub.0=30:1, 0.1 g) were added to dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated to 65 C. for 5 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter, and dioxane was removed by rotary evaporator at 45 C. water bath. GC-FID measurement showed 66.2% MDX (3,5-O-dodecylidene-xylose) yield, 7.20 MDX (1,2-O-dodecylidene-xylose) yield, and 3.9% DDX (didodecylidene-xylose) from D-xylose. Similar reactions with other heterogeneous catalysts are summarized in the following table (MDX and DDX yields and xylose conversion using various heterogenous catalysts in the example 6).

TABLE-US-00011 MDX MDX (3,5-O- (1,2-O- Temper- acetal) acetal) DDX ature Reaction yield yield yield Catalyst ( C.) time (h) (%) (%) (%) H-form Zeolite 65 5 42.9 3.4 3.3 (SiO.sub.2:Al.sub.2O.sub.3 = 25:1) H-form Zeolite 65 5 45.3 2.7 10.1 (SiO.sub.2:Al.sub.2O.sub.3 = 30:1) H-form Zeolite 65 5 44.1 2.5 7.8 (SiO.sub.2:Al.sub.2O.sub.3 = 38:1) H-form Zeolite 65 5 42.5 2.3 24.9 (SiO.sub.2:Al.sub.2O.sub.3 = 150:1) H-form Zeolite Y 65 5 42.0 10.7 1.6 (SiO.sub.2:Al.sub.2O.sub.3 = 5.2:1) H-form Zeolite Y 65 5 66.2 7.2 3.9 (SiO.sub.2:Al.sub.2O.sub.3 = 30:1) H-form Zeolite Y 65 5 45.4 3.9 7.5 (SiO.sub.2:Al.sub.2O.sub.3 = 60:1) H-form Zeolite Y 65 5 50.6 3.4 9.2 (SiO.sub.2:Al.sub.2O.sub.3 = 80:1)

Example 7

[0164] Glyoxylic acid monohydrate (0.29 g, 2 equiv.) was added to 1,4-dioxane (5 mL). The mixture was pre-dried with 0.6 g 4A molecular sieve to remove water. MDX (0.5 g, 1.6 mmol, 1 equiv. separated from example 6) was added to the dried mixture with Amberlyst 15 (0.125 g) in a 10 mL glass reactor. The mixture was then heated to 80 C. for 4 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter, and dioxane was removed by rotary evaporator at 45 C. water bath. GC-FID measurement showed 59.4% GMAX (1,2-O-glyoxylic acid-3,5-O-dodecylidene-xylose) yield.

Example 8

[0165] D-xylose (5.0 g, 33 mmol, 1.0 equiv.), glyoxylic acid monohydrate (7.66 g, 2.5 equiv.) and a sulfonated resin (Dowex r 50wx8, hydrogen form, 200-400 mesh, 1.5 g) were added to Sulfolane (20 mL) in a 100 mL round bottom flask. The mixture was heated to 90 C. under reduced pressure (40 mbar) for 5 h with stirring by flask rotation. The resulted solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter to remove the Dowex catalyst. The yield of diglyoxylic acid xylose (DGAX) was 77% based on the xylose loading as measured by HPLC.

Example 9

[0166] D-xylose (0.25 g, 1.67 mmol, 1.0 equiv.), various aldehydes (2 equiv.) and Y-type zeolite (SiO.sub.2:Al.sub.2O.sub.3=80:1, 0.25 g) were added to 1,4-dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated to 65 C. for 5 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter, and dioxane was removed by rotary evaporator at 45 C. water bath.

[0167] In comparison, D-xylose (0.25 g, 1.67 mmol, 1.0 equiv.), various aldehydes (2 equiv.) and H.sub.2SO.sub.4 (5.3 L) were added to dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated to 65 C. for 5 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter, and dioxane was removed by rotary evaporator at 45 C. water bath.

[0168] The yields of various products measured by GC-FID from the heterogeneous and homogeneous reactions for each aldehyde type are compared in pairs in the following table (Yields of products IVa, Va, Xa, XIa and I and xylose conversion using various aldehydes in the example 9).

TABLE-US-00012 Yield Yield Yield Yield Yield Xylose of of of of of conversion (IVa) (Va) (Xa) (XIa) (I) Aldehyde type Catalyst [%] [%] [%] [%] [%] [%] Formaldehyde Y-type 92.5 17.7 4.1 14.7 20.8 34.4 zeolite H.sub.2SO.sub.4 94.8 7.9 2.3 55.7 25.1 2.6 Propionaldehyde Y-type 84.5 27.9 0.3 55.0 zeolite H.sub.2SO.sub.4 85.8 42.3 0.3 16.9 Valeraldehyde Y-type 87.9 12.1 1.4 57.4 zeolite H.sub.2SO.sub.4 87.3 18.3 0.4 21.4 Pivalaldehyde Y-type 82.9 18.0 18.1 45.7 zeolite H.sub.2SO.sub.4 81.1 9.9 10.6 10.5 Octanal Y-type 89.6 50.3 1.1 37.3 zeolite H.sub.2SO.sub.4 89.4 39.2 0.4 24.1 Decanal Y-type 88.4 58.8 2.0 25.8 zeolite H.sub.2SO.sub.4 91.2 24.49363 0.923798 47.8 Dodecanal Y-type 87.6 66.1 6.27 14.2 zeolite H.sub.2SO.sub.4 91.3 28.46 1.57 28.8 Octodecanal Y-type 57.4 38.29478 5.548882 2.0 zeolite H.sub.2SO.sub.4 87.0 26.30566 1.769518 18.7

Example 10

[0169] L-arabinose (0.25 g, 1.67 mmol, 1.0 equiv.), dodecanal (0.75 ml, 2 equiv.) and Y-type zeolite (SiO.sub.2:Al.sub.2O.sub.3=30:1, 0.25 g) were added to 1,4-dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated to 65 C. for 5 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter, and 1,4-dioxane was removed by rotary evaporator at 45 C. water bath. GC-FID measurement showed 77.3% partially protected arabinose and 12.7% fully protected arabinose.

Example 11

[0170] D-glucose (0.3 g, 1.67 mmol, 1.0 equiv.), dodecanal (1.85 ml, 5 equiv.) and Y-type zeolite (SiO.sub.2:Al.sub.2O.sub.3=30:1, 0.25 g) were added to 1,4-dioxane (5 mL) in a 10 mL glass reactor. The mixture was then heated to 80 C. for 5 h with stirring. The resulting solution was cooled to room temperature (23-25 C.), filtered with a nylon membrane filter, and 1,4-dioxane was removed by rotary evaporator at 45 C. water bath. GC-FID measurement showed 58.0% partially protected glucose yield and 34.3% fully protected glucose.